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skia2/docs/SkPath_Reference.bmh
Cary Clark 154beea859 Add docs for SkMatrix, SkRect, SkIRect, SkBitmap 
Also minor changes to earlier docs.

Many small changes to improve indentation in generated includes.
Added support for matrix math illustrations.

Docs-Preview: https://skia.org/?cl=58500
Bug: skia:6898
Change-Id: I7da58ad55f82d7fd41d19288beb2cd71730fb01f
Reviewed-on: https://skia-review.googlesource.com/58500
Commit-Queue: Cary Clark <caryclark@skia.org>
Reviewed-by: Cary Clark <caryclark@google.com>
Reviewed-by: Cary Clark <caryclark@skia.org>
2017-10-26 12:17:36 +00:00

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#Topic Path
#Alias Path_Reference
#Alias Paths
Path contains Lines and Curves which can be stroked or filled. Contour is
composed of a series of connected Lines and Curves. Path may contain zero,
one, or more Contours.
Each Line and Curve are described by Verb, Points, and optional Conic_Weight.
Each pair of connected Lines and Curves share common Point; for instance, Path
containing two connected Lines are described the Verb sequence:
SkPath::kMove_Verb, SkPath::kLine_Verb, SkPath::kLine_Verb; and a Point sequence
with three entries, sharing
the middle entry as the end of the first Line and the start of the second Line.
Path components Arc, Rect, Round_Rect, Circle, and Oval are composed of
Lines and Curves with as many Verbs and Points required
for an exact description. Once added to Path, these components may lose their
identity; although Path can be inspected to determine if it describes a single
Rect, Oval, Round_Rect, and so on.
#Example
#Height 192
#Description
Path contains three Contours: Line, Circle, and Quad. Line is stroked but
not filled. Circle is stroked and filled; Circle stroke forms a loop. Quad
is stroked and filled, but since it is not closed, Quad does not stroke a loop.
##
void draw(SkCanvas* canvas) {
SkPaint paint;
paint.setAntiAlias(true);
SkPath path;
path.moveTo(124, 108);
path.lineTo(172, 24);
path.addCircle(50, 50, 30);
path.moveTo(36, 148);
path.quadTo(66, 188, 120, 136);
canvas->drawPath(path, paint);
paint.setStyle(SkPaint::kStroke_Style);
paint.setColor(SK_ColorBLUE);
paint.setStrokeWidth(3);
canvas->drawPath(path, paint);
}
##
Path contains a Fill_Type which determines whether overlapping Contours
form fills or holes. Fill_Type also determines whether area inside or outside
Lines and Curves is filled.
#Example
#Height 192
#Description
Path is drawn filled, then stroked, then stroked and filled.
##
void draw(SkCanvas* canvas) {
SkPaint paint;
paint.setAntiAlias(true);
SkPath path;
path.moveTo(36, 48);
path.quadTo(66, 88, 120, 36);
canvas->drawPath(path, paint);
paint.setStyle(SkPaint::kStroke_Style);
paint.setColor(SK_ColorBLUE);
paint.setStrokeWidth(8);
canvas->translate(0, 50);
canvas->drawPath(path, paint);
paint.setStyle(SkPaint::kStrokeAndFill_Style);
paint.setColor(SK_ColorRED);
canvas->translate(0, 50);
canvas->drawPath(path, paint);
}
##
Path contents are never shared. Copying Path by value effectively creates
a new Path independent of the original. Internally, the copy does not duplicate
its contents until it is edited, to reduce memory use and improve performance.
#Subtopic Subtopics
#ToDo not all methods are in topics ##
#ToDo subtopics are not in topics ##
#Table
#Legend
# topics # description ##
#Legend ##
#Table ##
# Contour # A loop of lines and curves. ##
# Convexity # Whether Path contains simple loop. ##
# Last_Point # Final Point in Contour. ##
# Point_Array # All Points in Path. ##
# Verb # How Points and Contours are defined. ##
# Verb_Array # All Verbs in Path. ##
# Verb # How Points and Contours are defined. ##
# Conic_Weight # Strength of control Point in Conic. ##
#Subtopic ##
#Subtopic Contour
#Alias Contours
Contour contains one or more Verbs, and as many Points as
are required to satisfy Verb_Array. First Verb in Path is always
SkPath::kMove_Verb; each SkPath::kMove_Verb that follows starts a new Contour.
#Example
#Description
Each SkPath::moveTo starts a new Contour, and content after SkPath::close()
also starts a new Contour. Since SkPath::conicTo is not preceded by
SkPath::moveTo, the first Point of the third Contour starts at the last Point
of the second Contour.
##
#Height 192
SkPaint paint;
paint.setAntiAlias(true);
canvas->drawString("1st contour", 150, 100, paint);
canvas->drawString("2nd contour", 130, 160, paint);
canvas->drawString("3rd contour", 40, 30, paint);
paint.setStyle(SkPaint::kStroke_Style);
SkPath path;
path.moveTo(124, 108);
path.lineTo(172, 24);
path.moveTo(36, 148);
path.quadTo(66, 188, 120, 136);
path.close();
path.conicTo(70, 20, 110, 40, 0.6f);
canvas->drawPath(path, paint);
##
If final Verb in Contour is SkPath::kClose_Verb, Line connects Last_Point in
Contour with first Point. A closed Contour, stroked, draws
Paint_Stroke_Join at Last_Point and first Point. Without SkPath::kClose_Verb
as final Verb, Last_Point and first Point are not connected; Contour
remains open. An open Contour, stroked, draws Paint_Stroke_Cap at
Last_Point and first Point.
#Example
#Height 160
#Description
Path is drawn stroked, with an open Contour and a closed Contour.
##
void draw(SkCanvas* canvas) {
SkPaint paint;
paint.setAntiAlias(true);
paint.setStyle(SkPaint::kStroke_Style);
paint.setStrokeWidth(8);
SkPath path;
path.moveTo(36, 48);
path.quadTo(66, 88, 120, 36);
canvas->drawPath(path, paint);
path.close();
canvas->translate(0, 50);
canvas->drawPath(path, paint);
}
##
#Subtopic Zero_Length
#Alias Zero_Length_Contour
Contour length is distance traveled from first Point to Last_Point,
plus, if Contour is closed, distance from Last_Point to first Point.
Even if Contour length is zero, stroked Lines are drawn if Paint_Stroke_Cap
makes them visible.
#Example
#Height 64
SkPaint paint;
paint.setAntiAlias(true);
paint.setStyle(SkPaint::kStroke_Style);
paint.setStrokeWidth(8);
paint.setStrokeCap(SkPaint::kRound_Cap);
SkPath path;
path.moveTo(36, 48);
path.lineTo(36, 48);
canvas->drawPath(path, paint);
path.reset();
paint.setStrokeCap(SkPaint::kSquare_Cap);
path.moveTo(56, 48);
path.close();
canvas->drawPath(path, paint);
##
#Subtopic Zero_Length ##
#Subtopic Contour ##
# ------------------------------------------------------------------------------
#Class SkPath
Paths contain geometry. Paths may be empty, or contain one or more Verbs that
outline a figure. Path always starts with a move verb to a Cartesian
coordinate, and may be followed by additional verbs that add lines or curves.
Adding a close verb makes the geometry into a continuous loop, a closed contour.
Paths may contain any number of contours, each beginning with a move verb.
Path contours may contain only a move verb, or may also contain lines,
Quadratic_Beziers, Conics, and Cubic_Beziers. Path contours may be open or
closed.
When used to draw a filled area, Path describes whether the fill is inside or
outside the geometry. Path also describes the winding rule used to fill
overlapping contours.
Internally, Path lazily computes metrics likes bounds and convexity. Call
SkPath::updateBoundsCache to make Path thread safe.
#Topic Overview
#Subtopic Constants
#ToDo incomplete ##
#Table
#Legend
# constants # description ##
#Legend ##
# AddPathMode # Sets addPath options. ##
# ArcSize # Used by arcTo(SkScalar rx, SkScalar ry, SkScalar xAxisRotate, ArcSize largeArc, Direction sweep, SkScalar x, SkScalar y).##
# Convexity # Returns if Path is convex or concave. ##
# Direction # Sets Contour clockwise or counterclockwise. ##
# FillType # Sets winding rule and inverse fill. ##
# SegmentMask
# Verb # Controls how Path Points are interpreted. ##
#Table ##
#Subtopic ##
#Subtopic Classes_and_Structs
#Table
#Legend
# class or struct # description ##
#Legend ##
# Iter # Iterates through lines and curves, skipping degenerates. ##
# RawIter # Iterates through lines and curves, including degenerates. ##
#Table ##
#Subtopic ##
#Subtopic Constructors
#Table
#Legend
# # description ##
#Legend ##
# SkPath() # Constructs with default values. ##
# SkPath(const SkPath& path) # Makes a shallow copy. ##
# ~SkPath() # Decreases Reference_Count of owned objects. ##
#Table ##
#Subtopic ##
#Subtopic Operators
#Table
#Legend
# operator # description ##
#Legend ##
# operator=(const SkPath& path) # Makes a shallow copy. ##
# operator==(const SkPath& a, const SkPath& b) # Compares paths for equality. ##
# operator!=(const SkPath& a, const SkPath& b) # Compares paths for inequality. ##
#Table ##
#Subtopic ##
#Subtopic Member_Functions
#Table
#Legend
# function # description ##
#Legend ##
# ConvertConicToQuads # Approximates Conic with Quad array. ##
# ConvertToNonInverseFillType # Returns Fill_Type representing inside geometry. ##
# IsCubicDegenerate # Returns if Cubic is very small. ##
# IsInverseFillType # Returns if Fill_Type represents outside geometry. ##
# IsLineDegenerate # Returns if Line is very small. ##
# IsQuadDegenerate # Returns if Quad is very small. ##
# addArc # Adds one Contour containing Arc. ##
# addCircle # Adds one Contour containing Circle. ##
# addOval # Adds one Contour containing Oval. ##
# addPath # Adds contents of Path. ##
# addPoly # Adds one Contour containing connected lines. ##
# addRRect # Adds one Contour containing Round_Rect. ##
# addRect # Adds one Contour containing Rect. ##
# addRoundRect # Adds one Contour containing Round_Rect with common corner radii. ##
# arcTo # Appends Arc. ##
# close() # Makes last Contour a loop. ##
# computeTightBounds # Returns extent of geometry. ##
# conicTo # Appends Conic. ##
# conservativelyContainsRect # Returns true if Rect may be inside. ##
# contains() # Returns if Point is in fill area. ##
# countPoints # Returns Point_Array length. ##
# countVerbs # Returns Verb_Array length. ##
# cubicTo # Appends Cubic. ##
# dump() # Sends text representation using floats to standard output. ##
# dumpHex # Sends text representation using hexadecimal to standard output. ##
# getBounds # Returns maximum and minimum of Point_Array. ##
# getConvexity # Returns geometry convexity, computing if necessary. ##
# getConvexityOrUnknown # Returns geometry convexity if known. ##
# getFillType # Returns Fill_Type: winding, even-odd, inverse. ##
# getGenerationID # Returns unique ID. ##
# getLastPt # Returns Last_Point. ##
# getPoint # Returns entry from Point_Array. ##
# getPoints # Returns Point_Array. ##
# getSegmentMasks # Returns types in Verb_Array. ##
# getVerbs # Returns Verb_Array. ##
# incReserve # Hint to reserve space for additional data. ##
# interpolate() # Interpolates between Path pair. ##
# isConvex # Returns if geometry is convex. ##
# isEmpty # Returns if verb count is zero. ##
# isFinite # Returns if all Point values are finite. ##
# isInterpolatable # Returns if pair contains equal counts of Verb_Array and Weights. ##
# isInverseFillType # Returns if Fill_Type fills outside geometry. ##
# isLastContourClosed # Returns if final Contour forms a loop. ##
# isLine # Returns if describes Line. ##
# isNestedFillRects # Returns if describes Rect pair, one inside the other. ##
# isOval # Returns if describes Oval. ##
# isRRect # Returns if describes Round_Rect. ##
# isRect # Returns if describes Rect. ##
# isValid # Returns if data is internally consistent. ##
# isVolatile # Returns if Device should not cache. ##
# lineTo # Appends Line. ##
# moveTo # Starts Contour. ##
# offset() # Translates Point_Array. ##
# quadTo # Appends Quad. ##
# rArcTo # Appends Arc relative to Last_Point. ##
# rConicTo # Appends Conic relative to Last_Point. ##
# rCubicTo # Appends Cubic relative to Last_Point. ##
# rLineTo # Appends Line relative to Last_Point. ##
# rMoveTo # Starts Contour relative to Last_Point. ##
# rQuadTo # Appends Quad relative to Last_Point. ##
# readFromMemory # Initializes from buffer. ##
# reset() # Removes Verb_Array, Point_Array, and Weights; frees memory. ##
# reverseAddPath # Adds contents of Path back to front. ##
# rewind() # Removes Verb_Array, Point_Array, and Weights; leaves memory allocated. ##
# serialize() # Copies data to buffer. ##
# setConvexity # Sets if geometry is convex to avoid future computation. ##
# setFillType # Sets Fill_Type: winding, even-odd, inverse. ##
# setIsConvex # Deprecated. ##
# setIsVolatile # Sets if Device should not cache. ##
# setLastPt # Replaces Last_Point. ##
# swap() # Exchanges Path pair. ##
# toggleInverseFillType # Toggles Fill_Type between inside and outside geometry. ##
# transform() # Applies Matrix to Point_Array and Weights. ##
# unique() # Returns if data has single owner. ##
# updateBoundsCache # Refreshes result of getBounds. ##
# writeToMemory # Copies data to buffer. ##
#Table ##
#Subtopic Path_Member_Functions ##
#Topic Overview ##
#Subtopic Verb
#Alias Verbs
#Enum Verb
#Code
enum Verb {
kMove_Verb,
kLine_Verb,
kQuad_Verb,
kConic_Verb,
kCubic_Verb,
kClose_Verb,
kDone_Verb,
};
##
Verb instructs Path how to interpret one or more Point and optional Conic_Weight;
manage Contour, and terminate Path.
#Const kMove_Verb 0
Starts new Contour at next Point.
##
#Const kLine_Verb 1
Adds Line from Last_Point to next Point.
Line is a straight segment from Point to Point.
##
#Const kQuad_Verb 2
Adds Quad from Last_Point, using control Point, and end Point.
Quad is a parabolic section within tangents from Last_Point to control Point,
and control Point to end Point.
##
#Const kConic_Verb 3
Adds Conic from Last_Point, using control Point, end Point, and Conic_Weight.
Conic is a elliptical, parabolic, or hyperbolic section within tangents
from Last_Point to control Point, and control Point to end Point, constrained
by Conic_Weight. Conic_Weight less than one is elliptical; equal to one is
parabolic (and identical to Quad); greater than one hyperbolic.
##
#Const kCubic_Verb 4
Adds Cubic from Last_Point, using two control Points, and end Point.
Cubic is a third-order Bezier section within tangents from Last_Point to
first control Point, and from second control Point to end Point.
##
#Const kClose_Verb 5
Closes Contour, connecting Last_Point to kMove_Verb Point.
##
#Const kDone_Verb 6
Terminates Path. Not in Verb_Array, but returned by Path iterator.
##
Each Verb has zero or more Points stored in Path.
Path iterator returns complete curve descriptions, duplicating shared Points
for consecutive entries.
#Table
#Legend
# Verb # Allocated Points # Iterated Points # Weights ##
##
# kMove_Verb # 1 # 1 # 0 ##
# kLine_Verb # 1 # 2 # 0 ##
# kQuad_Verb # 2 # 3 # 0 ##
# kConic_Verb # 2 # 3 # 1 ##
# kCubic_Verb # 3 # 4 # 0 ##
# kClose_Verb # 0 # 1 # 0 ##
# kDone_Verb # -- # 0 # 0 ##
##
#Example
void draw(SkCanvas* canvas) {
SkPath path;
path.lineTo(20, 20);
path.quadTo(-10, -10, 30, 30);
path.close();
path.cubicTo(1, 2, 3, 4, 5, 6);
path.conicTo(0, 0, 0, 0, 2);
uint8_t verbs[7];
int count = path.getVerbs(verbs, (int) SK_ARRAY_COUNT(verbs));
const char* verbStr[] = { "Move", "Line", "Quad", "Conic", "Cubic", "Close" };
SkDebugf("verb count: %d\nverbs: ", count);
for (int i = 0; i < count; ++i) {
SkDebugf("k%s_Verb ", verbStr[verbs[i]]);
}
SkDebugf("\n");
}
#StdOut
verb count: 7
verbs: kMove_Verb kLine_Verb kQuad_Verb kClose_Verb kMove_Verb kCubic_Verb kConic_Verb
##
##
#Enum Verb ##
#Subtopic Verb ##
# ------------------------------------------------------------------------------
#Subtopic Direction
#Alias Directions
#Enum Direction
#Code
enum Direction {
kCW_Direction,
kCCW_Direction,
};
##
Direction describes whether Contour is clockwise or counterclockwise.
When Path contains multiple overlapping Contours, Direction together with
Fill_Type determines whether overlaps are filled or form holes.
Direction also determines how Contour is measured. For instance, dashing
measures along Path to determine where to start and stop stroke; Direction
will change dashed results as it steps clockwise or counterclockwise.
Closed Contours like Rect, Round_Rect, Circle, and Oval added with
kCW_Direction travel clockwise; the same added with kCCW_Direction
travel counterclockwise.
#Const kCW_Direction 0
Contour travels in a clockwise direction
##
#Const kCCW_Direction 1
Contour travels in a counterclockwise direction
##
#Example
#Height 100
void draw(SkCanvas* canvas) {
const SkPoint arrow[] = { {40, -5}, {45, 0}, {40, 5} };
const SkRect rect = {10, 10, 90, 90};
SkPaint rectPaint;
rectPaint.setAntiAlias(true);
SkPaint textPaint(rectPaint);
textPaint.setTextAlign(SkPaint::kCenter_Align);
rectPaint.setStyle(SkPaint::kStroke_Style);
SkPaint arrowPaint(rectPaint);
SkPath arrowPath;
arrowPath.addPoly(arrow, SK_ARRAY_COUNT(arrow), true);
arrowPaint.setPathEffect(SkPath1DPathEffect::Make(arrowPath, 320, 0,
SkPath1DPathEffect::kRotate_Style));
for (auto direction : { SkPath::kCW_Direction, SkPath::kCCW_Direction } ) {
canvas->drawRect(rect, rectPaint);
for (unsigned start : { 0, 1, 2, 3 } ) {
SkPath path;
path.addRect(rect, direction, start);
canvas->drawPath(path, arrowPaint);
}
canvas->drawString(SkPath::kCW_Direction == direction ? "CW" : "CCW", rect.centerX(),
rect.centerY(), textPaint);
canvas->translate(120, 0);
}
}
##
#SeeAlso arcTo rArcTo isRect isNestedFillRects addRect addOval
#Enum Direction ##
#Subtopic Direction ##
# ------------------------------------------------------------------------------
#Method SkPath()
By default, Path has no Verbs, no Points, and no Weights.
Fill_Type is set to kWinding_FillType.
#Return empty Path ##
#Example
SkPath path;
SkDebugf("path is " "%s" "empty", path.isEmpty() ? "" : "not ");
#StdOut
path is empty
##
##
#SeeAlso reset rewind
##
# ------------------------------------------------------------------------------
#Method SkPath(const SkPath& path)
Copy constructor makes two paths identical by value. Internally, path and
the returned result share pointer values. The underlying Verb_Array, Point_Array
and Weights are copied when modified.
Creating a Path copy is very efficient and never allocates memory.
Paths are always copied by value from the interface; the underlying shared
pointers are not exposed.
#Param path Path to copy by value ##
#Return copy of Path ##
#Example
#Description
Modifying one path does not effect another, even if they started as copies
of each other.
##
SkPath path;
path.lineTo(20, 20);
SkPath path2(path);
path2.close();
SkDebugf("path verbs: %d\n", path.countVerbs());
SkDebugf("path2 verbs: %d\n", path2.countVerbs());
path.reset();
SkDebugf("after reset\n" "path verbs: %d\n", path.countVerbs());
SkDebugf("path2 verbs: %d\n", path2.countVerbs());
#StdOut
path verbs: 2
path2 verbs: 3
after reset
path verbs: 0
path2 verbs: 3
##
##
#SeeAlso operator=(const SkPath& path)
##
# ------------------------------------------------------------------------------
#Method ~SkPath()
Releases ownership of any shared data and deletes data if Path is sole owner.
#Example
#Description
delete calls Path Destructor, but copy of original in path2 is unaffected.
##
void draw(SkCanvas* canvas) {
SkPath* path = new SkPath();
path->lineTo(20, 20);
SkPath path2(*path);
delete path;
SkDebugf("path2 is " "%s" "empty", path2.isEmpty() ? "" : "not ");
}
##
#SeeAlso SkPath() SkPath(const SkPath& path) operator=(const SkPath& path)
##
# ------------------------------------------------------------------------------
#Method SkPath& operator=(const SkPath& path)
Path assignment makes two paths identical by value. Internally, assignment
shares pointer values. The underlying Verb_Array, Point_Array and Weights
are copied when modified.
Copying Paths by assignment is very efficient and never allocates memory.
Paths are always copied by value from the interface; the underlying shared
pointers are not exposed.
#Param path Verb_Array, Point_Array, Weights, and Fill_Type to copy ##
#Return Path copied by value ##
#Example
SkPath path1;
path1.addRect({10, 20, 30, 40});
SkPath path2 = path1;
const SkRect& b1 = path1.getBounds();
SkDebugf("path1 bounds = %g, %g, %g, %g\n", b1.fLeft, b1.fTop, b1.fRight, b1.fBottom);
const SkRect& b2 = path2.getBounds();
SkDebugf("path2 bounds = %g, %g, %g, %g\n", b2.fLeft, b2.fTop, b2.fRight, b2.fBottom);
#StdOut
path1 bounds = 10, 20, 30, 40
path2 bounds = 10, 20, 30, 40
#StdOut ##
##
#SeeAlso swap() SkPath(const SkPath& path)
##
# ------------------------------------------------------------------------------
#Method bool operator==(const SkPath& a, const SkPath& b)
Compares a and b; returns true if Fill_Type, Verb_Array, Point_Array, and Weights
are equivalent.
#Param a Path to compare ##
#Param b Path to compare ##
#Return true if Path pair are equivalent ##
#Example
#Description
Rewind removes Verb_Array but leaves storage; since storage is not compared,
Path pair are equivalent.
##
void draw(SkCanvas* canvas) {
auto debugster = [](const char* prefix, const SkPath& a, const SkPath& b) -> void {
SkDebugf("%s one %c= two\n", prefix, a == b ? '=' : '!');
};
SkPath one;
SkPath two;
debugster("empty", one, two);
one.moveTo(0, 0);
debugster("moveTo", one, two);
one.rewind();
debugster("rewind", one, two);
one.moveTo(0, 0);
one.reset();
debugster("reset", one, two);
}
#StdOut
empty one == two
moveTo one != two
rewind one == two
reset one == two
##
##
##
# ------------------------------------------------------------------------------
#Method bool operator!=(const SkPath& a, const SkPath& b)
Compares a and b; returns true if Fill_Type, Verb_Array, Point_Array, and Weights
are not equivalent.
#Param a Path to compare ##
#Param b Path to compare ##
#Return true if Path pair are not equivalent ##
#Example
#Description
Path pair are equal though their convexity is not equal.
##
void draw(SkCanvas* canvas) {
auto debugster = [](const char* prefix, const SkPath& a, const SkPath& b) -> void {
SkDebugf("%s one %c= two\n", prefix, a != b ? '!' : '=');
};
SkPath one;
SkPath two;
debugster("empty", one, two);
one.addRect({10, 20, 30, 40});
two.addRect({10, 20, 30, 40});
debugster("addRect", one, two);
one.setConvexity(SkPath::kConcave_Convexity);
debugster("setConvexity", one, two);
SkDebugf("convexity %c=\n", one.getConvexity() == two.getConvexity() ? '=' : '!');
}
#StdOut
empty one == two
addRect one == two
setConvexity one == two
convexity !=
##
##
##
# ------------------------------------------------------------------------------
#Method bool isInterpolatable(const SkPath& compare) const
Return true if Paths contain equal Verbs and equal Weights.
If Paths contain one or more Conics, the Weights must match.
conicTo may add different Verbs depending on Conic_Weight, so it is not
trivial to interpolate a pair of Paths containing Conics with different
Conic_Weight values.
#Param compare Path to compare ##
#Return true if Paths Verb_Array and Weights are equivalent ##
#Example
SkPath path, path2;
path.moveTo(20, 20);
path.lineTo(40, 40);
path.lineTo(20, 20);
path.lineTo(40, 40);
path.close();
path2.addRect({20, 20, 40, 40});
SkDebugf("paths are " "%s" "interpolatable", path.isInterpolatable(path2) ? "" : "not ");
#StdOut
paths are interpolatable
##
##
#SeeAlso isInterpolatable
##
# ------------------------------------------------------------------------------
#Method bool interpolate(const SkPath& ending, SkScalar weight, SkPath* out) const
Interpolate between Paths with equal sized Point_Arrays.
Copy Verb_Array and Weights to out,
and set out Point_Array to a weighted average of this Point_Array and ending
Point_Array, using the formula:
#Formula
(this->points * weight) + ending->points * (1 - weight)
##
.
weight is most useful when between zero (ending Point_Array) and
one (this Point_Array); will work with values outside of this
range.
interpolate() returns false and leaves out unchanged if Point_Array is not
the same size as ending Point_Array. Call isInterpolatable to check Path
compatibility prior to calling interpolate().
#Param ending Point_Array averaged with this Point_Array ##
#Param weight contribution of ending Point_Array, and
one minus contribution of this Point_Array
##
#Param out Path replaced by interpolated averages ##
#Return true if Paths contain same number of Points ##
#Example
#Height 60
void draw(SkCanvas* canvas) {
SkPaint paint;
paint.setAntiAlias(true);
paint.setStyle(SkPaint::kStroke_Style);
SkPath path, path2;
path.moveTo(20, 20);
path.lineTo(40, 40);
path.lineTo(20, 40);
path.lineTo(40, 20);
path.close();
path2.addRect({20, 20, 40, 40});
for (SkScalar i = 0; i <= 1; i += 1.f / 6) {
SkPath interp;
path.interpolate(path2, i, &interp);
canvas->drawPath(interp, paint);
canvas->translate(30, 0);
}
}
##
#SeeAlso isInterpolatable
##
# ------------------------------------------------------------------------------
#Method bool unique() const
#Private
To be deprecated; only valid for Android framework.
##
#Return true if Path has one owner ##
##
# ------------------------------------------------------------------------------
#Subtopic Fill_Type
#Enum FillType
#Code
enum FillType {
kWinding_FillType,
kEvenOdd_FillType,
kInverseWinding_FillType,
kInverseEvenOdd_FillType,
};
##
Fill_Type selects the rule used to fill Path. Path set to kWinding_FillType
fills if the sum of Contour edges is not zero, where clockwise edges add one, and
counterclockwise edges subtract one. Path set to kEvenOdd_FillType fills if the
number of Contour edges is odd. Each Fill_Type has an inverse variant that
reverses the rule:
kInverseWinding_FillType fills where the sum of Contour edges is zero;
kInverseEvenOdd_FillType fills where the number of Contour edges is even.
#Example
#Height 100
#Description
The top row has two clockwise rectangles. The second row has one clockwise and
one counterclockwise rectangle. The even-odd variants draw the same. The
winding variants draw the top rectangle overlap, which has a winding of 2, the
same as the outer parts of the top rectangles, which have a winding of 1.
##
void draw(SkCanvas* canvas) {
SkPath path;
path.addRect({10, 10, 30, 30}, SkPath::kCW_Direction);
path.addRect({20, 20, 40, 40}, SkPath::kCW_Direction);
path.addRect({10, 60, 30, 80}, SkPath::kCW_Direction);
path.addRect({20, 70, 40, 90}, SkPath::kCCW_Direction);
SkPaint strokePaint;
strokePaint.setStyle(SkPaint::kStroke_Style);
SkRect clipRect = {0, 0, 51, 100};
canvas->drawPath(path, strokePaint);
SkPaint fillPaint;
for (auto fillType : { SkPath::kWinding_FillType, SkPath::kEvenOdd_FillType,
SkPath::kInverseWinding_FillType, SkPath::kInverseEvenOdd_FillType } ) {
canvas->translate(51, 0);
canvas->save();
canvas->clipRect(clipRect);
path.setFillType(fillType);
canvas->drawPath(path, fillPaint);
canvas->restore();
}
}
##
#Const kWinding_FillType 0
Specifies fill as area is enclosed by a non-zero sum of Contour Directions.
##
#Const kEvenOdd_FillType 1
Specifies fill as area enclosed by an odd number of Contours.
##
#Const kInverseWinding_FillType 2
Specifies fill as area is enclosed by a zero sum of Contour Directions.
##
#Const kInverseEvenOdd_FillType 3
Specifies fill as area enclosed by an even number of Contours.
##
#Example
#Height 230
void draw(SkCanvas* canvas) {
SkPath path;
path.addRect({20, 10, 80, 70}, SkPath::kCW_Direction);
path.addRect({40, 30, 100, 90}, SkPath::kCW_Direction);
SkPaint strokePaint;
strokePaint.setStyle(SkPaint::kStroke_Style);
SkRect clipRect = {0, 0, 128, 128};
canvas->drawPath(path, strokePaint);
canvas->drawLine({0, 50}, {120, 50}, strokePaint);
SkPaint textPaint;
textPaint.setAntiAlias(true);
textPaint.setTextAlign(SkPaint::kCenter_Align);
SkScalar textHPos[] = { 10, 30, 60, 90, 110 };
canvas->drawPosTextH("01210", 5, textHPos, 48, textPaint);
textPaint.setTextSize(18);
canvas->translate(0, 128);
canvas->scale(.5f, .5f);
canvas->drawString("inverse", 384, 150, textPaint);
SkPaint fillPaint;
for (auto fillType : { SkPath::kWinding_FillType, SkPath::kEvenOdd_FillType,
SkPath::kInverseWinding_FillType, SkPath::kInverseEvenOdd_FillType } ) {
canvas->save();
canvas->clipRect(clipRect);
path.setFillType(fillType);
canvas->drawPath(path, fillPaint);
canvas->restore();
canvas->drawString(fillType & 1 ? "even-odd" : "winding", 64, 170, textPaint);
canvas->translate(128, 0);
}
}
##
#SeeAlso SkPaint::Style Direction getFillType setFillType
##
# ------------------------------------------------------------------------------
#Method FillType getFillType() const
Returns FillType, the rule used to fill Path. FillType of a new Path is
kWinding_FillType.
#Return one of: kWinding_FillType, kEvenOdd_FillType, kInverseWinding_FillType,
kInverseEvenOdd_FillType
##
#Example
SkPath path;
SkDebugf("default path fill type is %s\n",
path.getFillType() == SkPath::kWinding_FillType ? "kWinding_FillType" :
path.getFillType() == SkPath::kEvenOdd_FillType ? "kEvenOdd_FillType" :
path.getFillType() == SkPath::kInverseWinding_FillType ? "kInverseWinding_FillType" :
"kInverseEvenOdd_FillType");
#StdOut
default path fill type is kWinding_FillType
##
##
#SeeAlso FillType setFillType isInverseFillType
##
# ------------------------------------------------------------------------------
#Method void setFillType(FillType ft)
Sets FillType, the rule used to fill Path. While there is no check
that ft is legal, values outside of FillType are not supported.
#Param ft one of: kWinding_FillType, kEvenOdd_FillType, kInverseWinding_FillType,
kInverseEvenOdd_FillType
##
#Example
#Description
If empty Path is set to inverse FillType, it fills all pixels.
##
#Height 64
SkPath path;
path.setFillType(SkPath::kInverseWinding_FillType);
SkPaint paint;
paint.setColor(SK_ColorBLUE);
canvas->drawPath(path, paint);
##
#SeeAlso FillType getFillType toggleInverseFillType
##
# ------------------------------------------------------------------------------
#Method bool isInverseFillType() const
Returns if FillType describes area outside Path geometry. The inverse fill area
extends indefinitely.
#Return true if FillType is kInverseWinding_FillType or kInverseEvenOdd_FillType ##
#Example
SkPath path;
SkDebugf("default path fill type is inverse: %s\n",
path.isInverseFillType() ? "true" : "false");
#StdOut
default path fill type is inverse: false
##
##
#SeeAlso FillType getFillType setFillType toggleInverseFillType
##
# ------------------------------------------------------------------------------
#Method void toggleInverseFillType()
Replace FillType with its inverse. The inverse of FillType describes the area
unmodified by the original FillType.
#Table
#Legend
# FillType # toggled FillType ##
##
# kWinding_FillType # kInverseWinding_FillType ##
# kEvenOdd_FillType # kInverseEvenOdd_FillType ##
# kInverseWinding_FillType # kWinding_FillType ##
# kInverseEvenOdd_FillType # kEvenOdd_FillType ##
##
#Example
#Description
Path drawn normally and through its inverse touches every pixel once.
##
#Height 100
SkPath path;
SkPaint paint;
paint.setColor(SK_ColorRED);
paint.setTextSize(80);
paint.getTextPath("ABC", 3, 20, 80, &path);
canvas->drawPath(path, paint);
path.toggleInverseFillType();
paint.setColor(SK_ColorGREEN);
canvas->drawPath(path, paint);
##
#SeeAlso FillType getFillType setFillType isInverseFillType
##
#Subtopic Fill_Type ##
# ------------------------------------------------------------------------------
#Subtopic Convexity
#Enum Convexity
#Code
enum Convexity : uint8_t {
kUnknown_Convexity,
kConvex_Convexity,
kConcave_Convexity,
};
##
Path is convex if it contains one Contour and Contour loops no more than
360 degrees, and Contour angles all have same Direction. Convex Path
may have better performance and require fewer resources on GPU_Surface.
Path is concave when either at least one Direction change is clockwise and
another is counterclockwise, or the sum of the changes in Direction is not 360
degrees.
Initially Path Convexity is kUnknown_Convexity. Path Convexity is computed
if needed by destination Surface.
#Const kUnknown_Convexity 0
Indicates Convexity has not been determined.
##
#Const kConvex_Convexity 1
Path has one Contour made of a simple geometry without indentations.
##
#Const kConcave_Convexity 2
Path has more than one Contour, or a geometry with indentations.
##
#Example
void draw(SkCanvas* canvas) {
SkPaint paint;
SkPoint quad[] = {{70, 70}, {20, 20}, {120, 20}, {120, 120}};
const char* labels[] = { "unknown", "convex", "concave" };
for (SkScalar x : { 40, 100 } ) {
SkPath path;
quad[0].fX = x;
path.addPoly(quad, SK_ARRAY_COUNT(quad), true);
canvas->drawPath(path, paint);
canvas->drawString(labels[(int) path.getConvexity()], 30, 100, paint);
canvas->translate(100, 100);
}
}
##
#SeeAlso Contour Direction getConvexity getConvexityOrUnknown setConvexity isConvex
#Enum Convexity ##
#Method Convexity getConvexity() const
Computes Convexity if required, and returns stored value.
Convexity is computed if stored value is kUnknown_Convexity,
or if Path has been altered since Convexity was computed or set.
#Return computed or stored Convexity ##
#Example
void draw(SkCanvas* canvas) {
auto debugster = [](const char* prefix, const SkPath& path) -> void {
SkDebugf("%s path convexity is %s\n", prefix,
SkPath::kUnknown_Convexity == path.getConvexity() ? "unknown" :
SkPath::kConvex_Convexity == path.getConvexity() ? "convex" : "concave"); };
SkPath path;
debugster("initial", path);
path.lineTo(50, 0);
debugster("first line", path);
path.lineTo(50, 50);
debugster("second line", path);
path.lineTo(100, 50);
debugster("third line", path);
}
##
#SeeAlso Convexity Contour Direction getConvexityOrUnknown setConvexity isConvex
##
# ------------------------------------------------------------------------------
#Method Convexity getConvexityOrUnknown() const
Returns last computed Convexity, or kUnknown_Convexity if
Path has been altered since Convexity was computed or set.
#Return stored Convexity ##
#Example
#Description
Convexity is unknown unless getConvexity is called without a subsequent call
that alters the path.
##
void draw(SkCanvas* canvas) {
auto debugster = [](const char* prefix, const SkPath& path) -> void {
SkDebugf("%s path convexity is %s\n", prefix,
SkPath::kUnknown_Convexity == path.getConvexityOrUnknown() ? "unknown" :
SkPath::kConvex_Convexity == path.getConvexityOrUnknown() ? "convex" : "concave"); };
SkPath path;
debugster("initial", path);
path.lineTo(50, 0);
debugster("first line", path);
path.getConvexity();
path.lineTo(50, 50);
debugster("second line", path);
path.lineTo(100, 50);
path.getConvexity();
debugster("third line", path);
}
##
#SeeAlso Convexity Contour Direction getConvexity setConvexity isConvex
##
# ------------------------------------------------------------------------------
#Method void setConvexity(Convexity convexity)
Stores convexity so that it is later returned by getConvexity or getConvexityOrUnknown.
convexity may differ from getConvexity, although setting an incorrect value may
cause incorrect or inefficient drawing.
If convexity is kUnknown_Convexity: getConvexity will
compute Convexity, and getConvexityOrUnknown will return kUnknown_Convexity.
If convexity is kConvex_Convexity or kConcave_Convexity, getConvexity
and getConvexityOrUnknown will return convexity until the path is
altered.
#Param convexity one of: kUnknown_Convexity, kConvex_Convexity, or kConcave_Convexity ##
#Example
void draw(SkCanvas* canvas) {
auto debugster = [](const char* prefix, const SkPath& path) -> void {
SkDebugf("%s path convexity is %s\n", prefix,
SkPath::kUnknown_Convexity == path.getConvexity() ? "unknown" :
SkPath::kConvex_Convexity == path.getConvexity() ? "convex" : "concave"); };
SkPoint quad[] = {{70, 70}, {20, 20}, {120, 20}, {120, 120}};
SkPath path;
path.addPoly(quad, SK_ARRAY_COUNT(quad), true);
debugster("initial", path);
path.setConvexity(SkPath::kConcave_Convexity);
debugster("after forcing concave", path);
path.setConvexity(SkPath::kUnknown_Convexity);
debugster("after forcing unknown", path);
}
##
#SeeAlso Convexity Contour Direction getConvexity getConvexityOrUnknown isConvex
##
# ------------------------------------------------------------------------------
#Method bool isConvex() const
Computes Convexity if required, and returns true if value is kConvex_Convexity.
If setConvexity was called with kConvex_Convexity or kConcave_Convexity, and
the path has not been altered, Convexity is not recomputed.
#Return true if Convexity stored or computed is kConvex_Convexity ##
#Example
#Description
Concave shape is erroneously considered convex after a forced call to
setConvexity.
##
void draw(SkCanvas* canvas) {
SkPaint paint;
SkPoint quad[] = {{70, 70}, {20, 20}, {120, 20}, {120, 120}};
for (SkScalar x : { 40, 100 } ) {
SkPath path;
quad[0].fX = x;
path.addPoly(quad, SK_ARRAY_COUNT(quad), true);
path.setConvexity(SkPath::kConvex_Convexity);
canvas->drawPath(path, paint);
canvas->drawString(path.isConvex() ? "convex" : "not convex", 30, 100, paint);
canvas->translate(100, 100);
}
}
##
#SeeAlso Convexity Contour Direction getConvexity getConvexityOrUnknown setConvexity
##
# ------------------------------------------------------------------------------
#Method void setIsConvex(bool isConvex)
Deprecated. Use setConvexity.
#Deprecated
##
#NoExample
##
#SeeAlso Convexity setConvexity getConvexity
##
#Subtopic Convexity ##
# ------------------------------------------------------------------------------
#Method bool isOval(SkRect* rect, Direction* dir = nullptr,
unsigned* start = nullptr) const
Returns true if constructed by addCircle, addOval; and in some cases,
addRoundRect, addRRect. Path constructed with conicTo or rConicTo will not
return true though Path draws Oval.
rect receives bounds of Oval.
dir receives Direction of Oval: kCW_Direction if clockwise, kCCW_Direction if
counterclockwise.
start receives start of Oval: 0 for top, 1 for right, 2 for bottom, 3 for left.
rect, dir, and start are unmodified if Oval is not found.
Triggers performance optimizations on some GPU_Surface implementations.
#Param rect storage for bounding Rect of Oval; may be nullptr ##
#Param dir storage for Direction; may be nullptr ##
#Param start storage for start of Oval; may be nullptr ##
#Return true if Path was constructed by method that reduces to Oval ##
#Example
void draw(SkCanvas* canvas) {
SkPaint paint;
SkPath path;
path.addOval({20, 20, 220, 220}, SkPath::kCW_Direction, 1);
SkRect bounds;
SkPath::Direction direction;
unsigned start;
path.isOval(&bounds, &direction, &start);
paint.setColor(0xFF9FBFFF);
canvas->drawRect(bounds, paint);
paint.setColor(0x3f000000);
canvas->drawPath(path, paint);
paint.setColor(SK_ColorBLACK);
canvas->rotate(start * 90, bounds.centerX(), bounds.centerY());
char startText = '0' + start;
paint.setTextSize(20);
canvas->drawText(&startText, 1, bounds.centerX(), bounds.fTop + 20, paint);
paint.setStyle(SkPaint::kStroke_Style);
paint.setStrokeWidth(4);
path.reset();
path.addArc(bounds, -90, SkPath::kCW_Direction == direction ? 90 : -90);
path.rLineTo(20, -20);
canvas->drawPath(path, paint);
}
##
#SeeAlso Oval addCircle addOval
##
# ------------------------------------------------------------------------------
#Method bool isRRect(SkRRect* rrect, Direction* dir = nullptr,
unsigned* start = nullptr) const
Returns true if constructed by addRoundRect, addRRect; and if construction
is not empty, not Rect, and not Oval. Path constructed with other calls
will not return true though Path draws Round_Rect.
rrect receives bounds of Round_Rect.
dir receives Direction of Oval: kCW_Direction if clockwise, kCCW_Direction if
counterclockwise.
start receives start of Round_Rect: 0 for top, 1 for right, 2 for bottom, 3 for left.
rrect, dir, and start are unmodified if Round_Rect is not found.
Triggers performance optimizations on some GPU_Surface implementations.
#Param rrect storage for bounding Rect of Round_Rect; may be nullptr ##
#Param dir storage for Direction; may be nullptr ##
#Param start storage for start of Round_Rect; may be nullptr ##
#Return true if Path contains only Round_Rect ##
#Example
#Description
Draw rounded rectangle and its bounds. Draw an arc indicating where the rounded
rectangle starts and its direction.
##
void draw(SkCanvas* canvas) {
SkPaint paint;
SkPath path;
path.addRRect(SkRRect::MakeRectXY({20, 20, 220, 220}, 30, 50), SkPath::kCCW_Direction, 3);
SkRRect rrect;
SkPath::Direction direction;
unsigned start;
path.isRRect(&rrect, &direction, &start);
const SkRect& bounds = rrect.rect();
paint.setColor(0xFF9FBFFF);
canvas->drawRect(bounds, paint);
paint.setColor(0x3f000000);
canvas->drawPath(path, paint);
paint.setColor(SK_ColorBLACK);
canvas->rotate(start * 90, bounds.centerX(), bounds.centerY());
char startText = '0' + start;
paint.setTextSize(20);
canvas->drawText(&startText, 1, bounds.centerX(), bounds.fTop + 20, paint);
paint.setStyle(SkPaint::kStroke_Style);
paint.setStrokeWidth(4);
path.reset();
path.addArc(bounds, -90, SkPath::kCW_Direction == direction ? 90 : -90);
path.rLineTo(20, -20);
canvas->drawPath(path, paint);
}
##
#SeeAlso Round_Rect addRoundRect addRRect
##
# ------------------------------------------------------------------------------
#Method void reset()
Sets Path to its initial state.
Removes Verb_Array, Point_Array, and Weights, and sets FillType to kWinding_FillType.
Internal storage associated with Path is released.
#Example
SkPath path1, path2;
path1.setFillType(SkPath::kInverseWinding_FillType);
path1.addRect({10, 20, 30, 40});
SkDebugf("path1 %c= path2\n", path1 == path2 ? '=' : '!');
path1.reset();
SkDebugf("path1 %c= path2\n", path1 == path2 ? '=' : '!');
##
#SeeAlso rewind()
##
# ------------------------------------------------------------------------------
#Method void rewind()
Sets Path to its initial state, preserving internal storage.
Removes Verb_Array, Point_Array, and Weights, and sets FillType to kWinding_FillType.
Internal storage associated with Path is retained.
Use rewind() instead of reset() if Path storage will be reused and performance
is critical.
#Example
#Description
Although path1 retains its internal storage, it is indistinguishable from
a newly initialized path.
##
SkPath path1, path2;
path1.setFillType(SkPath::kInverseWinding_FillType);
path1.addRect({10, 20, 30, 40});
SkDebugf("path1 %c= path2\n", path1 == path2 ? '=' : '!');
path1.rewind();
SkDebugf("path1 %c= path2\n", path1 == path2 ? '=' : '!');
##
#SeeAlso reset()
##
# ------------------------------------------------------------------------------
#Method bool isEmpty() const
Empty Path may have FillType but has no SkPoint, Verb, or Conic_Weight.
SkPath() constructs empty Path; reset() and (rewind) make Path empty.
#Return true if the path contains no Verb array ##
#Example
void draw(SkCanvas* canvas) {
auto debugster = [](const char* prefix, const SkPath& path) -> void {
SkDebugf("%s path is %s" "empty\n", prefix, path.isEmpty() ? "" : "not ");
};
SkPath path;
debugster("initial", path);
path.moveTo(0, 0);
debugster("after moveTo", path);
path.rewind();
debugster("after rewind", path);
path.lineTo(0, 0);
debugster("after lineTo", path);
path.reset();
debugster("after reset", path);
}
#StdOut
initial path is empty
after moveTo path is not empty
after rewind path is empty
after lineTo path is not empty
after reset path is empty
##
##
#SeeAlso SkPath() reset() rewind()
##
# ------------------------------------------------------------------------------
#Method bool isLastContourClosed() const
Contour is closed if Path Verb array was last modified by close(). When stroked,
closed Contour draws Paint_Stroke_Join instead of Paint_Stroke_Cap at first and last Point.
#Return true if the last Contour ends with a kClose_Verb ##
#Example
#Description
close() has no effect if Path is empty; isLastContourClosed() returns
false until Path has geometry followed by close().
##
void draw(SkCanvas* canvas) {
auto debugster = [](const char* prefix, const SkPath& path) -> void {
SkDebugf("%s last contour is %s" "closed\n", prefix,
path.isLastContourClosed() ? "" : "not ");
};
SkPath path;
debugster("initial", path);
path.close();
debugster("after close", path);
path.lineTo(0, 0);
debugster("after lineTo", path);
path.close();
debugster("after close", path);
}
#StdOut
initial last contour is not closed
after close last contour is not closed
after lineTo last contour is not closed
after close last contour is closed
##
##
#SeeAlso close()
##
# ------------------------------------------------------------------------------
#Method bool isFinite() const
Returns true for finite Point array values between negative SK_ScalarMax and
positive SK_ScalarMax. Returns false for any Point array value of
SK_ScalarInfinity, SK_ScalarNegativeInfinity, or SK_ScalarNaN.
#Return true if all Point values are finite ##
#Example
void draw(SkCanvas* canvas) {
auto debugster = [](const char* prefix, const SkPath& path) -> void {
SkDebugf("%s path is %s" "finite\n", prefix, path.isFinite() ? "" : "not ");
};
SkPath path;
debugster("initial", path);
path.lineTo(SK_ScalarMax, SK_ScalarMax);
debugster("after line", path);
SkMatrix matrix;
matrix.setScale(2, 2);
path.transform(matrix);
debugster("after scale", path);
}
#StdOut
initial path is finite
after line path is finite
after scale path is not finite
##
##
#SeeAlso SkScalar
##
# ------------------------------------------------------------------------------
#Method bool isVolatile() const
Returns true if the path is volatile; it will not be altered or discarded
by the caller after it is drawn. Paths by default have volatile set false, allowing
Surface to attach a cache of data which speeds repeated drawing. If true, Surface
may not speed repeated drawing.
#Return true if caller will alter Path after drawing ##
#Example
SkPath path;
SkDebugf("volatile by default is %s\n", path.isVolatile() ? "true" : "false");
#StdOut
volatile by default is false
##
##
#SeeAlso setIsVolatile
##
# ------------------------------------------------------------------------------
#Method void setIsVolatile(bool isVolatile)
Specify whether Path is volatile; whether it will be altered or discarded
by the caller after it is drawn. Paths by default have volatile set false, allowing
Device to attach a cache of data which speeds repeated drawing.
Mark temporary paths, discarded or modified after use, as volatile
to inform Device that the path need not be cached.
Mark animating Path volatile to improve performance.
Mark unchanging Path non-volatile to improve repeated rendering.
Raster_Surface Path draws are affected by volatile for some shadows.
GPU_Surface Path draws are affected by volatile for some shadows and concave geometries.
#Param isVolatile true if caller will alter Path after drawing ##
#Example
#Height 50
#Width 50
SkPaint paint;
paint.setStyle(SkPaint::kStroke_Style);
SkPath path;
path.setIsVolatile(true);
path.lineTo(40, 40);
canvas->drawPath(path, paint);
path.rewind();
path.moveTo(0, 40);
path.lineTo(40, 0);
canvas->drawPath(path, paint);
##
#ToDo tie example to bench to show how volatile affects speed or dm to show resource usage ##
#SeeAlso isVolatile
##
# ------------------------------------------------------------------------------
#Method static bool IsLineDegenerate(const SkPoint& p1, const SkPoint& p2, bool exact)
Test if Line between Point pair is degenerate.
Line with no length or that moves a very short distance is degenerate; it is
treated as a point.
exact changes the equality test. If true, returns true only if p1 equals p2.
If false, returns true if p1 equals or nearly equals p2.
#Param p1 line start point ##
#Param p2 line end point ##
#Param exact if false, allow nearly equals ##
#Return true if Line is degenerate; its length is effectively zero ##
#Example
#Description
As single precision floats, 100 and 100.000001 have the same bit representation,
and are exactly equal. 100 and 100.0001 have different bit representations, and
are not exactly equal, but are nearly equal.
##
void draw(SkCanvas* canvas) {
SkPoint points[] = { {100, 100}, {100.000001f, 100.000001f}, {100.0001f, 100.0001f} };
for (size_t i = 0; i < SK_ARRAY_COUNT(points) - 1; ++i) {
for (bool exact : { false, true } ) {
SkDebugf("line from (%1.8g,%1.8g) to (%1.8g,%1.8g) is %s" "degenerate, %s\n",
points[i].fX, points[i].fY, points[i + 1].fX, points[i + 1].fY,
SkPath::IsLineDegenerate(points[i], points[i + 1], exact)
? "" : "not ", exact ? "exactly" : "nearly");
}
}
}
#StdOut
line from (100,100) to (100,100) is degenerate, nearly
line from (100,100) to (100,100) is degenerate, exactly
line from (100,100) to (100.0001,100.0001) is degenerate, nearly
line from (100,100) to (100.0001,100.0001) is not degenerate, exactly
#StdOut ##
##
#SeeAlso IsQuadDegenerate IsCubicDegenerate SkPoint::equalsWithinTolerance
##
# ------------------------------------------------------------------------------
#Method static bool IsQuadDegenerate(const SkPoint& p1, const SkPoint& p2,
const SkPoint& p3, bool exact)
Test if Quad is degenerate.
Quad with no length or that moves a very short distance is degenerate; it is
treated as a point.
#Param p1 Quad start point ##
#Param p2 Quad control point ##
#Param p3 Quad end point ##
#Param exact if true, returns true only if p1, p2, and p3 are equal;
if false, returns true if p1, p2, and p3 are equal or nearly equal
##
#Return true if Quad is degenerate; its length is effectively zero ##
#Example
#Description
As single precision floats: 100, 100.00001, and 100.00002 have different bit representations
but nearly the same value. Translating all three by 1000 gives them the same bit representation;
the fractional portion of the number can not be represented by the float and is lost.
##
void draw(SkCanvas* canvas) {
auto debugster = [](const SkPath& path, bool exact) -> void {
SkDebugf("quad (%1.8g,%1.8g), (%1.8g,%1.8g), (%1.8g,%1.8g) is %s" "degenerate, %s\n",
path.getPoint(0).fX, path.getPoint(0).fY, path.getPoint(1).fX,
path.getPoint(1).fY, path.getPoint(2).fX, path.getPoint(2).fY,
SkPath::IsQuadDegenerate(path.getPoint(0), path.getPoint(1), path.getPoint(2), exact) ?
"" : "not ", exact ? "exactly" : "nearly");
};
SkPath path, offset;
path.moveTo({100, 100});
path.quadTo({100.00001f, 100.00001f}, {100.00002f, 100.00002f});
offset.addPath(path, 1000, 1000);
for (bool exact : { false, true } ) {
debugster(path, exact);
debugster(offset, exact);
}
}
#StdOut
quad (100,100), (100.00001,100.00001), (100.00002,100.00002) is degenerate, nearly
quad (1100,1100), (1100,1100), (1100,1100) is degenerate, nearly
quad (100,100), (100.00001,100.00001), (100.00002,100.00002) is not degenerate, exactly
quad (1100,1100), (1100,1100), (1100,1100) is degenerate, exactly
#StdOut ##
##
#SeeAlso IsLineDegenerate IsCubicDegenerate SkPoint::equalsWithinTolerance
##
# ------------------------------------------------------------------------------
#Method static bool IsCubicDegenerate(const SkPoint& p1, const SkPoint& p2,
const SkPoint& p3, const SkPoint& p4, bool exact)
Test if Cubic is degenerate.
Cubic with no length or that moves a very short distance is degenerate; it is
treated as a point.
#Param p1 Cubic start point ##
#Param p2 Cubic control point 1 ##
#Param p3 Cubic control point 2 ##
#Param p4 Cubic end point ##
#Param exact if true, returns true only if p1, p2, p3, and p4 are equal;
if false, returns true if p1, p2, p3, and p4 are equal or nearly equal
##
#Return true if Cubic is degenerate; its length is effectively zero ##
#Example
void draw(SkCanvas* canvas) {
SkPoint points[] = {{1, 0}, {0, 0}, {0, 0}, {0, 0}};
SkScalar step = 1;
SkScalar prior, length, degenerate;
do {
prior = points[0].fX;
step /= 2;
if (SkPath::IsCubicDegenerate(points[0], points[1], points[2], points[3], false)) {
degenerate = prior;
points[0].fX += step;
} else {
length = prior;
points[0].fX -= step;
}
} while (prior != points[0].fX);
SkDebugf("%1.8g is degenerate\n", degenerate);
SkDebugf("%1.8g is length\n", length);
}
#StdOut
0.00024414062 is degenerate
0.00024414065 is length
#StdOut ##
##
##
# ------------------------------------------------------------------------------
#Method bool isLine(SkPoint line[2]) const
Returns true if Path contains only one Line;
Path_Verb array has two entries: kMove_Verb, kLine_Verb.
If Path contains one Line and line is not nullptr, line is set to
Line start point and Line end point.
Returns false if Path is not one Line; line is unaltered.
#Param line storage for Line. May be nullptr ##
#Return true if Path contains exactly one Line ##
#Example
void draw(SkCanvas* canvas) {
auto debugster = [](const char* prefix, const SkPath& path) -> void {
SkPoint line[2];
if (path.isLine(line)) {
SkDebugf("%s is line (%1.8g,%1.8g) (%1.8g,%1.8g)\n", prefix,
line[0].fX, line[0].fY, line[1].fX, line[1].fY);
} else {
SkDebugf("%s is not line\n", prefix);
}
};
SkPath path;
debugster("empty", path);
path.lineTo(0, 0);
debugster("zero line", path);
path.rewind();
path.moveTo(10, 10);
path.lineTo(20, 20);
debugster("line", path);
path.moveTo(20, 20);
debugster("second move", path);
}
#StdOut
empty is not line
zero line is line (0,0) (0,0)
line is line (10,10) (20,20)
second move is not line
##
##
##
# ------------------------------------------------------------------------------
#Subtopic Point_Array
#Alias Point_Arrays
Point_Array contains Points satisfying the allocated Points for
each Verb in Verb_Array. For instance, Path containing one Contour with Line
and Quad is described by Verb_Array: Verb::kMoveTo, Verb::kLineTo, Verb::kQuadTo; and
one Point for move, one Point for Line, two Points for Quad; totaling four Points.
Point_Array may be read directly from Path with getPoints, or inspected with
getPoint, with Iter, or with RawIter.
#Method int getPoints(SkPoint points[], int max) const
Returns number of points in Path. Up to max points are copied.
points may be nullptr; then, max must be zero.
If max is greater than number of points, excess points storage is unaltered.
#Param points storage for Path Point array. May be nullptr ##
#Param max maximum to copy; must be greater than or equal to zero ##
#Return Path Point array length ##
#Example
void draw(SkCanvas* canvas) {
auto debugster = [](const char* prefix, const SkPath& path, SkPoint* points, int max) -> void {
int count = path.getPoints(points, max);
SkDebugf("%s point count: %d ", prefix, count);
for (int i = 0; i < SkTMin(count, max) && points; ++i) {
SkDebugf("(%1.8g,%1.8g) ", points[i].fX, points[i].fY);
}
SkDebugf("\n");
};
SkPath path;
path.lineTo(20, 20);
path.lineTo(-10, -10);
SkPoint points[3];
debugster("no points", path, nullptr, 0);
debugster("zero max", path, points, 0);
debugster("too small", path, points, 2);
debugster("just right", path, points, path.countPoints());
}
#StdOut
no points point count: 3
zero max point count: 3
too small point count: 3 (0,0) (20,20)
just right point count: 3 (0,0) (20,20) (-10,-10)
##
##
#SeeAlso countPoints getPoint
##
#Method int countPoints() const
Returns the number of points in Path.
Point count is initially zero.
#Return Path Point array length ##
#Example
void draw(SkCanvas* canvas) {
auto debugster = [](const char* prefix, const SkPath& path) -> void {
SkDebugf("%s point count: %d\n", prefix, path.countPoints());
};
SkPath path;
debugster("empty", path);
path.lineTo(0, 0);
debugster("zero line", path);
path.rewind();
path.moveTo(10, 10);
path.lineTo(20, 20);
debugster("line", path);
path.moveTo(20, 20);
debugster("second move", path);
}
#StdOut
empty point count: 0
zero line point count: 2
line point count: 2
second move point count: 3
##
##
#SeeAlso getPoints
##
#Method SkPoint getPoint(int index) const
Returns Point at index in Point_Array. Valid range for index is
0 to countPoints - 1.
Returns (0, 0) if index is out of range.
#Param index Point array element selector ##
#Return Point array value or (0, 0) ##
#Example
void draw(SkCanvas* canvas) {
auto debugster = [](const char* prefix, const SkPath& path) -> void {
SkDebugf("%s point count: %d\n", prefix, path.countPoints());
};
SkPath path;
path.lineTo(20, 20);
path.offset(-10, -10);
for (int i= 0; i < path.countPoints(); ++i) {
SkDebugf("point %d: (%1.8g,%1.8g)\n", i, path.getPoint(i).fX, path.getPoint(i).fY);
}
}
#StdOut
point 0: (-10,-10)
point 1: (10,10)
##
##
#SeeAlso countPoints getPoints
##
#Subtopic Point_Array ##
# ------------------------------------------------------------------------------
#Subtopic Verb_Array
Verb_Array always starts with kMove_Verb.
If kClose_Verb is not the last entry, it is always followed by kMove_Verb;
the quantity of kMove_Verb equals the Contour count.
Verb_Array does not include or count kDone_Verb; it is a convenience
returned when iterating through Verb_Array.
Verb_Array may be read directly from Path with getVerbs, or inspected with Iter,
or with RawIter.
#Method int countVerbs() const
Returns the number of Verbs: kMove_Verb, kLine_Verb, kQuad_Verb, kConic_Verb,
kCubic_Verb, and kClose_Verb; added to Path.
#Return length of Verb_Array ##
#Example
SkPath path;
SkDebugf("empty verb count: %d\n", path.countVerbs());
path.addRoundRect({10, 20, 30, 40}, 5, 5);
SkDebugf("round rect verb count: %d\n", path.countVerbs());
#StdOut
empty verb count: 0
round rect verb count: 10
##
##
#SeeAlso getVerbs Iter RawIter
##
#Method int getVerbs(uint8_t verbs[], int max) const
Returns the number of verbs in the path. Up to max verbs are copied. The
verbs are copied as one byte per verb.
#Param verbs storage for verbs, may be nullptr ##
#Param max maximum number to copy into verbs ##
#Return the actual number of verbs in the path ##
#Example
void draw(SkCanvas* canvas) {
auto debugster = [](const char* prefix, const SkPath& path, uint8_t* verbs, int max) -> void {
int count = path.getVerbs(verbs, max);
SkDebugf("%s verb count: %d ", prefix, count);
const char* verbStr[] = { "move", "line", "quad", "conic", "cubic", "close" };
for (int i = 0; i < SkTMin(count, max) && verbs; ++i) {
SkDebugf("%s ", verbStr[verbs[i]]);
}
SkDebugf("\n");
};
SkPath path;
path.lineTo(20, 20);
path.lineTo(-10, -10);
uint8_t verbs[3];
debugster("no verbs", path, nullptr, 0);
debugster("zero max", path, verbs, 0);
debugster("too small", path, verbs, 2);
debugster("just right", path, verbs, path.countVerbs());
}
#StdOut
no verbs verb count: 3
zero max verb count: 3
too small verb count: 3 move line
just right verb count: 3 move line line
##
##
#SeeAlso countVerbs getPoints Iter RawIter
##
#Subtopic Verb_Array ##
# ------------------------------------------------------------------------------
#Method void swap(SkPath& other)
Exchanges the Verb_Array, Point_Array, Weights, and Fill_Type with other.
Cached state is also exchanged. swap() internally exchanges pointers, so
it is lightweight and does not allocate memory.
swap() usage has largely been replaced by operator=(const SkPath& path).
Paths do not copy their content on assignment until they are written to,
making assignment as efficient as swap().
#Param other Path exchanged by value ##
#Example
SkPath path1, path2;
path1.addRect({10, 20, 30, 40});
path1.swap(path2);
const SkRect& b1 = path1.getBounds();
SkDebugf("path1 bounds = %g, %g, %g, %g\n", b1.fLeft, b1.fTop, b1.fRight, b1.fBottom);
const SkRect& b2 = path2.getBounds();
SkDebugf("path2 bounds = %g, %g, %g, %g\n", b2.fLeft, b2.fTop, b2.fRight, b2.fBottom);
#StdOut
path1 bounds = 0, 0, 0, 0
path2 bounds = 10, 20, 30, 40
#StdOut ##
##
#SeeAlso operator=(const SkPath& path)
##
# ------------------------------------------------------------------------------
#Method const SkRect& getBounds() const
Returns minimum and maximum x and y values of Point_Array.
Returns (0, 0, 0, 0) if Path contains no points. Returned bounds width and height may
be larger or smaller than area affected when Path is drawn.
Rect returned includes all Points added to Path, including Points associated with
kMove_Verb that define empty Contours.
#Return bounds of all Points in Point_Array ##
#Example
#Description
Bounds of upright Circle can be predicted from center and radius.
Bounds of rotated Circle includes control Points outside of filled area.
##
auto debugster = [](const char* prefix, const SkPath& path) -> void {
const SkRect& bounds = path.getBounds();
SkDebugf("%s bounds = %g, %g, %g, %g\n", prefix,
bounds.fLeft, bounds.fTop, bounds.fRight, bounds.fBottom);
};
SkPath path;
debugster("empty", path);
path.addCircle(50, 45, 25);
debugster("circle", path);
SkMatrix matrix;
matrix.setRotate(45, 50, 45);
path.transform(matrix);
debugster("rotated circle", path);
#StdOut
empty bounds = 0, 0, 0, 0
circle bounds = 25, 20, 75, 70
rotated circle bounds = 14.6447, 9.64466, 85.3553, 80.3553
##
##
#SeeAlso computeTightBounds updateBoundsCache
##
# ------------------------------------------------------------------------------
#Method void updateBoundsCache() const
Update internal bounds so that subsequent calls to getBounds are instantaneous.
Unaltered copies of Path may also access cached bounds through getBounds.
For now, identical to calling getBounds and ignoring the returned value.
Call to prepare Path subsequently drawn from multiple threads,
to avoid a race condition where each draw separately computes the bounds.
#Example
double times[2] = { 0, 0 };
for (int i = 0; i < 10000; ++i) {
SkPath path;
for (int j = 1; j < 100; ++ j) {
path.addCircle(50 + j, 45 + j, 25 + j);
}
if (1 & i) {
path.updateBoundsCache();
}
double start = SkTime::GetNSecs();
(void) path.getBounds();
times[1 & i] += SkTime::GetNSecs() - start;
}
SkDebugf("uncached avg: %g ms\n", times[0] * 1e-6);
SkDebugf("cached avg: %g ms\n", times[1] * 1e-6);
#StdOut
#Volatile
uncached avg: 0.18048 ms
cached avg: 0.182784 ms
##
##
#SeeAlso getBounds
#ToDo the results don't make sense, need to profile to figure this out ##
##
# ------------------------------------------------------------------------------
#Method SkRect computeTightBounds() const
Returns minimum and maximum x and y values of the lines and curves in Path.
Returns (0, 0, 0, 0) if Path contains no points.
Returned bounds width and height may be larger or smaller than area affected
when Path is drawn.
Includes Points associated with kMove_Verb that define empty
Contours.
Behaves identically to getBounds when Path contains
only lines. If Path contains curves, computed bounds includes
the maximum extent of the Quad, Conic, or Cubic; is slower than getBounds;
and unlike getBounds, does not cache the result.
#Return tight bounds of curves in Path ##
#Example
auto debugster = [](const char* prefix, const SkPath& path) -> void {
const SkRect& bounds = path.computeTightBounds();
SkDebugf("%s bounds = %g, %g, %g, %g\n", prefix,
bounds.fLeft, bounds.fTop, bounds.fRight, bounds.fBottom);
};
SkPath path;
debugster("empty", path);
path.addCircle(50, 45, 25);
debugster("circle", path);
SkMatrix matrix;
matrix.setRotate(45, 50, 45);
path.transform(matrix);
debugster("rotated circle", path);
#StdOut
empty bounds = 0, 0, 0, 0
circle bounds = 25, 20, 75, 70
rotated circle bounds = 25, 20, 75, 70
##
##
#SeeAlso getBounds
##
# ------------------------------------------------------------------------------
#Method bool conservativelyContainsRect(const SkRect& rect) const
Returns true if rect is contained by Path.
May return false when rect is contained by Path.
For now, only returns true if Path has one Contour and is convex.
rect may share points and edges with Path and be contained.
Returns true if rect is empty, that is, it has zero width or height; and
the Point or Line described by rect is contained by Path.
#Param rect Rect, Line, or Point checked for containment ##
#Return true if rect is contained ##
#Example
#Height 140
#Description
Rect is drawn in blue if it is contained by red Path.
##
void draw(SkCanvas* canvas) {
SkPath path;
path.addRoundRect({10, 20, 54, 120}, 10, 20);
SkRect tests[] = {
{ 10, 40, 54, 80 },
{ 25, 20, 39, 120 },
{ 15, 25, 49, 115 },
{ 13, 27, 51, 113 },
};
for (unsigned i = 0; i < SK_ARRAY_COUNT(tests); ++i) {
SkPaint paint;
paint.setColor(SK_ColorRED);
canvas->drawPath(path, paint);
bool rectInPath = path.conservativelyContainsRect(tests[i]);
paint.setColor(rectInPath ? SK_ColorBLUE : SK_ColorBLACK);
canvas->drawRect(tests[i], paint);
canvas->translate(64, 0);
}
}
##
#SeeAlso contains Op Rect Convexity
##
# ------------------------------------------------------------------------------
#Method void incReserve(unsigned extraPtCount)
grows Path Verb_Array and Point_Array to contain extraPtCount additional Points.
May improve performance and use less memory by
reducing the number and size of allocations when creating Path.
#Param extraPtCount number of additional Points to allocate ##
#Example
#Height 192
void draw(SkCanvas* canvas) {
auto addPoly = [](int sides, SkScalar size, SkPath* path) -> void {
path->moveTo(size, 0);
for (int i = 1; i < sides; i++) {
SkScalar c, s = SkScalarSinCos(SK_ScalarPI * 2 * i / sides, &c);
path->lineTo(c * size, s * size);
}
path->close();
};
SkPath path;
path.incReserve(3 + 4 + 5 + 6 + 7 + 8 + 9);
for (int sides = 3; sides < 10; ++sides) {
addPoly(sides, sides, &path);
}
SkMatrix matrix;
matrix.setScale(10, 10, -10, -10);
path.transform(matrix);
SkPaint paint;
paint.setStyle(SkPaint::kStroke_Style);
canvas->drawPath(path, paint);
}
##
#SeeAlso Point_Array
##
# ------------------------------------------------------------------------------
#Method void moveTo(SkScalar x, SkScalar y)
Adds beginning of Contour at Point (x, y).
#Param x x-coordinate of Contour start ##
#Param y y-coordinate of Contour start ##
#Example
#Width 140
#Height 100
void draw(SkCanvas* canvas) {
SkRect rect = { 20, 20, 120, 80 };
SkPath path;
path.addRect(rect);
path.moveTo(rect.fLeft, rect.fTop);
path.lineTo(rect.fRight, rect.fBottom);
path.moveTo(rect.fLeft, rect.fBottom);
path.lineTo(rect.fRight, rect.fTop);
SkPaint paint;
paint.setStyle(SkPaint::kStroke_Style);
canvas->drawPath(path, paint);
}
##
#SeeAlso Contour lineTo rMoveTo quadTo conicTo cubicTo close()
##
#Method void moveTo(const SkPoint& p)
Adds beginning of Contour at Point p.
#Param p contour start ##
#Example
#Width 128
#Height 128
void draw(SkCanvas* canvas) {
SkPoint data[][3] = {{{30,40},{60,60},{90,30}}, {{30,120},{60,100},{90,120}},
{{60,100},{60,40},{70,30}}, {{60,40},{50,20},{70,30}}};
SkPath path;
for (unsigned i = 0; i < SK_ARRAY_COUNT(data); ++i) {
path.moveTo(data[i][0]);
path.lineTo(data[i][1]);
path.lineTo(data[i][2]);
}
SkPaint paint;
paint.setStyle(SkPaint::kStroke_Style);
canvas->drawPath(path, paint);
}
##
#SeeAlso Contour lineTo rMoveTo quadTo conicTo cubicTo close()
##
#Method void rMoveTo(SkScalar dx, SkScalar dy)
Adds beginning of Contour relative to Last_Point.
If Path is empty, starts Contour at (dx, dy).
Otherwise, start Contour at Last_Point offset by (dx, dy).
Function name stands for "relative move to".
#Param dx offset from Last_Point x to Contour start x ##
#Param dy offset from Last_Point y to Contour start y ##
#Example
#Height 100
SkPath path;
path.addRect({20, 20, 80, 80}, SkPath::kCW_Direction, 2);
path.rMoveTo(25, 2);
SkVector arrow[] = {{0, -4}, {-20, 0}, {0, -3}, {-5, 5}, {5, 5}, {0, -3}, {20, 0}};
for (unsigned i = 0; i < SK_ARRAY_COUNT(arrow); ++i) {
path.rLineTo(arrow[i].fX, arrow[i].fY);
}
SkPaint paint;
canvas->drawPath(path, paint);
SkPoint lastPt;
path.getLastPt(&lastPt);
canvas->drawString("start", lastPt.fX, lastPt.fY, paint);
##
#SeeAlso Contour lineTo moveTo quadTo conicTo cubicTo close()
##
# ------------------------------------------------------------------------------
#Method void lineTo(SkScalar x, SkScalar y)
Adds Line from Last_Point to (x, y). If Path is empty, or last Verb is
kClose_Verb, Last_Point is set to (0, 0) before adding Line.
lineTo appends kMove_Verb to Verb_Array and (0, 0) to Point_Array, if needed.
lineTo then appends kLine_Verb to Verb_Array and (x, y) to Point_Array.
#Param x end of added Line in x ##
#Param y end of added Line in y ##
#Example
#Height 100
###$
void draw(SkCanvas* canvas) {
SkPaint paint;
paint.setAntiAlias(true);
paint.setTextSize(72);
canvas->drawString("#", 120, 80, paint);
paint.setStyle(SkPaint::kStroke_Style);
paint.setStrokeWidth(5);
SkPath path;
SkPoint hash[] = {{58, 28}, {43, 80}, {37, 45}, {85, 45}};
SkVector offsets[] = {{0, 0}, {17, 0}, {0, 0}, {-5, 17}};
unsigned o = 0;
for (unsigned i = 0; i < SK_ARRAY_COUNT(hash); i += 2) {
for (unsigned j = 0; j < 2; o++, j++) {
path.moveTo(hash[i].fX + offsets[o].fX, hash[i].fY + offsets[o].fY);
path.lineTo(hash[i + 1].fX + offsets[o].fX, hash[i + 1].fY + offsets[o].fY);
}
}
canvas->drawPath(path, paint);
}
$$$#
##
#SeeAlso Contour moveTo rLineTo addRect
##
# ------------------------------------------------------------------------------
#Method void lineTo(const SkPoint& p)
Adds Line from Last_Point to Point p. If Path is empty, or last Verb is
kClose_Verb, Last_Point is set to (0, 0) before adding Line.
lineTo first appends kMove_Verb to Verb_Array and (0, 0) to Point_Array, if needed.
lineTo then appends kLine_Verb to Verb_Array and Point p to Point_Array.
#Param p end Point of added Line ##
#Example
#Height 100
SkPath path;
SkVector oxo[] = {{25, 25}, {35, 35}, {25, 35}, {35, 25},
{40, 20}, {40, 80}, {60, 20}, {60, 80},
{20, 40}, {80, 40}, {20, 60}, {80, 60}};
for (unsigned i = 0; i < SK_ARRAY_COUNT(oxo); i += 2) {
path.moveTo(oxo[i]);
path.lineTo(oxo[i + 1]);
}
SkPaint paint;
paint.setStyle(SkPaint::kStroke_Style);
canvas->drawPath(path, paint);
##
#SeeAlso Contour moveTo rLineTo addRect
##
# ------------------------------------------------------------------------------
#Method void rLineTo(SkScalar dx, SkScalar dy)
Adds Line from Last_Point to Vector (dx, dy). If Path is empty, or last Verb is
kClose_Verb, Last_Point is set to (0, 0) before adding Line.
Appends kMove_Verb to Verb_Array and (0, 0) to Point_Array, if needed;
then appends kLine_Verb to Verb_Array and Line end to Point_Array.
Line end is Last_Point plus Vector (dx, dy).
Function name stands for "relative line to".
#Param dx offset from Last_Point x to Line end x ##
#Param dy offset from Last_Point y to Line end y ##
#Example
#Height 128
void draw(SkCanvas* canvas) {
SkPaint paint;
paint.setAntiAlias(true);
paint.setStyle(SkPaint::kStroke_Style);
SkPath path;
path.moveTo(10, 98);
SkScalar x = 0, y = 0;
for (int i = 10; i < 100; i += 5) {
x += i * ((i & 2) - 1);
y += i * (((i + 1) & 2) - 1);
path.rLineTo(x, y);
}
canvas->drawPath(path, paint);
}
##
#SeeAlso Contour moveTo lineTo addRect
##
# ------------------------------------------------------------------------------
#Topic Quad
#Alias Quad
#Alias Quads
#Alias Quadratic_Bezier
#Alias Quadratic_Beziers
Quad describes a quadratic Bezier, a second-order curve identical to a section
of a parabola. Quad begins at a start Point, curves towards a control Point,
and then curves to an end Point.
#Example
#Height 110
void draw(SkCanvas* canvas) {
SkPaint paint;
paint.setAntiAlias(true);
paint.setStyle(SkPaint::kStroke_Style);
SkPoint quadPts[] = {{20, 90}, {120, 10}, {220, 90}};
canvas->drawLine(quadPts[0], quadPts[1], paint);
canvas->drawLine(quadPts[1], quadPts[2], paint);
SkPath path;
path.moveTo(quadPts[0]);
path.quadTo(quadPts[1], quadPts[2]);
paint.setStrokeWidth(3);
canvas->drawPath(path, paint);
}
##
Quad is a special case of Conic where Conic_Weight is set to one.
Quad is always contained by the triangle connecting its three Points. Quad
begins tangent to the line between start Point and control Point, and ends
tangent to the line between control Point and end Point.
#Example
#Height 160
void draw(SkCanvas* canvas) {
SkPaint paint;
paint.setAntiAlias(true);
paint.setStyle(SkPaint::kStroke_Style);
SkPoint quadPts[] = {{20, 150}, {120, 10}, {220, 150}};
SkColor colors[] = { 0xff88ff00, 0xff0088bb, 0xff6600cc, 0xffbb3377 };
for (unsigned i = 0; i < SK_ARRAY_COUNT(colors); ++i) {
paint.setColor(0x7fffffff & colors[i]);
paint.setStrokeWidth(1);
canvas->drawLine(quadPts[0], quadPts[1], paint);
canvas->drawLine(quadPts[1], quadPts[2], paint);
SkPath path;
path.moveTo(quadPts[0]);
path.quadTo(quadPts[1], quadPts[2]);
paint.setStrokeWidth(3);
paint.setColor(colors[i]);
canvas->drawPath(path, paint);
quadPts[1].fY += 30;
}
}
##
#Method void quadTo(SkScalar x1, SkScalar y1, SkScalar x2, SkScalar y2)
Adds Quad from Last_Point towards (x1, y1), to (x2, y2).
If Path is empty, or last Verb is kClose_Verb, Last_Point is set to (0, 0)
before adding Quad.
Appends kMove_Verb to Verb_Array and (0, 0) to Point_Array, if needed;
then appends kQuad_Verb to Verb_Array; and (x1, y1), (x2, y2)
to Point_Array.
#Param x1 control Point of Quad in x ##
#Param y1 control Point of Quad in y ##
#Param x2 end Point of Quad in x ##
#Param y2 end Point of Quad in y ##
#Example
void draw(SkCanvas* canvas) {
SkPaint paint;
paint.setAntiAlias(true);
paint.setStyle(SkPaint::kStroke_Style);
SkPath path;
path.moveTo(0, -10);
for (int i = 0; i < 128; i += 16) {
path.quadTo( 10 + i, -10 - i, 10 + i, 0);
path.quadTo( 14 + i, 14 + i, 0, 14 + i);
path.quadTo(-18 - i, 18 + i, -18 - i, 0);
path.quadTo(-22 - i, -22 - i, 0, -22 - i);
}
path.offset(128, 128);
canvas->drawPath(path, paint);
}
##
#SeeAlso Contour moveTo conicTo rQuadTo
##
#Method void quadTo(const SkPoint& p1, const SkPoint& p2)
Adds Quad from Last_Point towards Point p1, to Point p2.
If Path is empty, or last Verb is kClose_Verb, Last_Point is set to (0, 0)
before adding Quad.
Appends kMove_Verb to Verb_Array and (0, 0) to Point_Array, if needed;
then appends kQuad_Verb to Verb_Array; and Points p1, p2
to Point_Array.
#Param p1 control Point of added Quad ##
#Param p2 end Point of added Quad ##
#Example
void draw(SkCanvas* canvas) {
SkPaint paint;
paint.setStyle(SkPaint::kStroke_Style);
paint.setAntiAlias(true);
SkPath path;
SkPoint pts[] = {{128, 10}, {10, 214}, {236, 214}};
path.moveTo(pts[1]);
for (int i = 0; i < 3; ++i) {
path.quadTo(pts[i % 3], pts[(i + 2) % 3]);
}
canvas->drawPath(path, paint);
}
##
#SeeAlso Contour moveTo conicTo rQuadTo
##
#Method void rQuadTo(SkScalar dx1, SkScalar dy1, SkScalar dx2, SkScalar dy2)
Adds Quad from Last_Point towards Vector (dx1, dy1), to Vector (dx2, dy2).
If Path is empty, or last Verb
is kClose_Verb, Last_Point is set to (0, 0) before adding Quad.
Appends kMove_Verb to Verb_Array and (0, 0) to Point_Array,
if needed; then appends kQuad_Verb to Verb_Array; and appends Quad
control and Quad end to Point_Array.
Quad control is Last_Point plus Vector (dx1, dy1).
Quad end is Last_Point plus Vector (dx2, dy2).
Function name stands for "relative quad to".
#Param dx1 offset from Last_Point x to Quad control x ##
#Param dy1 offset from Last_Point x to Quad control y ##
#Param dx2 offset from Last_Point x to Quad end x ##
#Param dy2 offset from Last_Point x to Quad end y ##
#Example
void draw(SkCanvas* canvas) {
SkPaint paint;
paint.setAntiAlias(true);
SkPath path;
path.moveTo(128, 20);
path.rQuadTo(-6, 10, -7, 10);
for (int i = 1; i < 32; i += 4) {
path.rQuadTo(10 + i, 10 + i, 10 + i * 4, 10);
path.rQuadTo(-10 - i, 10 + i, -10 - (i + 2) * 4, 10);
}
path.quadTo(92, 220, 128, 215);
canvas->drawPath(path, paint);
}
##
#SeeAlso Contour moveTo conicTo quadTo
##
#Topic Quad ##
# ------------------------------------------------------------------------------
#Topic Conic
#Alias Conics
Conic describes a conical section: a piece of an ellipse, or a piece of a
parabola, or a piece of a hyperbola. Conic begins at a start Point,
curves towards a control Point, and then curves to an end Point. The influence
of the control Point is determined by Conic_Weight.
Each Conic in Path adds two Points and one Conic_Weight. Conic_Weights in Path
may be inspected with Iter, or with RawIter.
#Subtopic Weight
#Alias Conic_Weights
#Alias Weights
Weight determines both the strength of the control Point and the type of Conic.
If Weight is exactly one, then Conic is identical to Quad; it is always a
parabolic segment.
#Example
#Description
When Conic_Weight is one, Quad is added to path; the two are identical.
##
void draw(SkCanvas* canvas) {
const char* verbNames[] = { "move", "line", "quad", "conic", "cubic", "close", "done" };
const int pointCount[] = { 1 , 2 , 3 , 3 , 4 , 1 , 0 };
SkPath path;
path.conicTo(20, 30, 50, 60, 1);
SkPath::Iter iter(path, false);
SkPath::Verb verb;
do {
SkPoint points[4];
verb = iter.next(points);
SkDebugf("%s ", verbNames[(int) verb]);
for (int i = 0; i < pointCount[(int) verb]; ++i) {
SkDebugf("{%g, %g}, ", points[i].fX, points[i].fY);
}
if (SkPath::kConic_Verb == verb) {
SkDebugf("weight = %g", iter.conicWeight());
}
SkDebugf("\n");
} while (SkPath::kDone_Verb != verb);
}
#StdOut
move {0, 0},
quad {0, 0}, {20, 30}, {50, 60},
done
##
##
If weight is less than one, Conic is an elliptical segment.
#Example
#Description
A 90 degree circular arc has the weight
#Formula
1 / sqrt(2)
##
.
##
void draw(SkCanvas* canvas) {
const char* verbNames[] = { "move", "line", "quad", "conic", "cubic", "close", "done" };
const int pointCount[] = { 1 , 2 , 3 , 3 , 4 , 1 , 0 };
SkPath path;
path.arcTo(20, 0, 20, 20, 20);
SkPath::Iter iter(path, false);
SkPath::Verb verb;
do {
SkPoint points[4];
verb = iter.next(points);
SkDebugf("%s ", verbNames[(int) verb]);
for (int i = 0; i < pointCount[(int) verb]; ++i) {
SkDebugf("{%g, %g}, ", points[i].fX, points[i].fY);
}
if (SkPath::kConic_Verb == verb) {
SkDebugf("weight = %g", iter.conicWeight());
}
SkDebugf("\n");
} while (SkPath::kDone_Verb != verb);
}
#StdOut
move {0, 0},
conic {0, 0}, {20, 0}, {20, 20}, weight = 0.707107
done
##
##
If weight is greater than one, Conic is a hyperbolic segment. As weight gets large,
a hyperbolic segment can be approximated by straight lines connecting the
control Point with the end Points.
#Example
void draw(SkCanvas* canvas) {
const char* verbNames[] = { "move", "line", "quad", "conic", "cubic", "close", "done" };
const int pointCount[] = { 1 , 2 , 3 , 3 , 4 , 1 , 0 };
SkPath path;
path.conicTo(20, 0, 20, 20, SK_ScalarInfinity);
SkPath::Iter iter(path, false);
SkPath::Verb verb;
do {
SkPoint points[4];
verb = iter.next(points);
SkDebugf("%s ", verbNames[(int) verb]);
for (int i = 0; i < pointCount[(int) verb]; ++i) {
SkDebugf("{%g, %g}, ", points[i].fX, points[i].fY);
}
if (SkPath::kConic_Verb == verb) {
SkDebugf("weight = %g", iter.conicWeight());
}
SkDebugf("\n");
} while (SkPath::kDone_Verb != verb);
}
#StdOut
move {0, 0},
line {0, 0}, {20, 0},
line {20, 0}, {20, 20},
done
##
##
#Subtopic Weight ##
#Method void conicTo(SkScalar x1, SkScalar y1, SkScalar x2, SkScalar y2,
SkScalar w)
Adds Conic from Last_Point towards (x1, y1), to (x2, y2), weighted by w.
If Path is empty, or last Verb is kClose_Verb, Last_Point is set to (0, 0)
before adding Conic.
Appends kMove_Verb to Verb_Array and (0, 0) to Point_Array, if needed.
If w is finite and not one, appends kConic_Verb to Verb_Array;
and (x1, y1), (x2, y2) to Point_Array; and w to Conic_Weights.
If w is one, appends kQuad_Verb to Verb_Array, and
(x1, y1), (x2, y2) to Point_Array.
If w is not finite, appends kLine_Verb twice to Verb_Array, and
(x1, y1), (x2, y2) to Point_Array.
#Param x1 control Point of Conic in x ##
#Param y1 control Point of Conic in y ##
#Param x2 end Point of Conic in x ##
#Param y2 end Point of Conic in y ##
#Param w weight of added Conic ##
#Example
#Height 160
#Description
As weight increases, curve is pulled towards control point.
The bottom two curves are elliptical; the next is parabolic; the
top curve is hyperbolic.
##
void draw(SkCanvas* canvas) {
SkPaint paint;
paint.setAntiAlias(true);
paint.setStyle(SkPaint::kStroke_Style);
SkPoint conicPts[] = {{20, 150}, {120, 10}, {220, 150}};
canvas->drawLine(conicPts[0], conicPts[1], paint);
canvas->drawLine(conicPts[1], conicPts[2], paint);
SkColor colors[] = { 0xff88ff00, 0xff0088bb, 0xff6600cc, 0xffbb3377 };
paint.setStrokeWidth(3);
SkScalar weight = 0.5f;
for (unsigned i = 0; i < SK_ARRAY_COUNT(colors); ++i) {
SkPath path;
path.moveTo(conicPts[0]);
path.conicTo(conicPts[1], conicPts[2], weight);
paint.setColor(colors[i]);
canvas->drawPath(path, paint);
weight += 0.25f;
}
}
##
#SeeAlso rConicTo arcTo addArc quadTo
##
#Method void conicTo(const SkPoint& p1, const SkPoint& p2, SkScalar w)
Adds Conic from Last_Point towards Point p1, to Point p2, weighted by w.
If Path is empty, or last Verb is kClose_Verb, Last_Point is set to (0, 0)
before adding Conic.
Appends kMove_Verb to Verb_Array and (0, 0) to Point_Array, if needed.
If w is finite and not one, appends kConic_Verb to Verb_Array;
and Points p1, p2 to Point_Array; and w to Conic_Weights.
If w is one, appends kQuad_Verb to Verb_Array, and Points p1, p2
to Point_Array.
If w is not finite, appends kLine_Verb twice to Verb_Array, and
Points p1, p2 to Point_Array.
#Param p1 control Point of added Conic ##
#Param p2 end Point of added Conic ##
#Param w weight of added Conic ##
#Example
#Height 128
#Description
Conics and arcs use identical representations. As the arc sweep increases
the Conic_Weight also increases, but remains smaller than one.
##
void draw(SkCanvas* canvas) {
SkPaint paint;
paint.setAntiAlias(true);
paint.setStyle(SkPaint::kStroke_Style);
SkRect oval = {0, 20, 120, 140};
SkPath path;
for (int i = 0; i < 4; ++i) {
path.moveTo(oval.centerX(), oval.fTop);
path.arcTo(oval, -90, 90 - 20 * i, false);
oval.inset(15, 15);
}
path.offset(100, 0);
SkScalar conicWeights[] = { 0.707107f, 0.819152f, 0.906308f, 0.965926f };
SkPoint conicPts[][3] = { { {40, 20}, {100, 20}, {100, 80} },
{ {40, 35}, {71.509f, 35}, {82.286f, 64.6091f} },
{ {40, 50}, {53.9892f, 50}, {62.981f, 60.7164f} },
{ {40, 65}, {44.0192f, 65}, {47.5f, 67.0096f} } };
for (int i = 0; i < 4; ++i) {
path.moveTo(conicPts[i][0]);
path.conicTo(conicPts[i][1], conicPts[i][2], conicWeights[i]);
}
canvas->drawPath(path, paint);
}
##
#SeeAlso rConicTo arcTo addArc quadTo
##
#Method void rConicTo(SkScalar dx1, SkScalar dy1, SkScalar dx2, SkScalar dy2,
SkScalar w)
Adds Conic from Last_Point towards Vector (dx1, dy1), to Vector (dx2, dy2),
weighted by w. If Path is empty, or last Verb
is kClose_Verb, Last_Point is set to (0, 0) before adding Conic.
Appends kMove_Verb to Verb_Array and (0, 0) to Point_Array,
if needed.
If w is finite and not one, next appends kConic_Verb to Verb_Array,
and w is recorded as Conic_Weight; otherwise, if w is one, appends
kQuad_Verb to Verb_Array; or if w is not finite, appends kLine_Verb
twice to Verb_Array.
In all cases appends Points control and end to Point_Array.
control is Last_Point plus Vector (dx1, dy1).
end is Last_Point plus Vector (dx2, dy2).
Function name stands for "relative conic to".
#Param dx1 offset from Last_Point x to Conic control x ##
#Param dy1 offset from Last_Point x to Conic control y ##
#Param dx2 offset from Last_Point x to Conic end x ##
#Param dy2 offset from Last_Point x to Conic end y ##
#Param w weight of added Conic ##
#Example
#Height 140
void draw(SkCanvas* canvas) {
SkPaint paint;
paint.setAntiAlias(true);
paint.setStyle(SkPaint::kStroke_Style);
SkPath path;
path.moveTo(20, 80);
path.rConicTo( 60, 0, 60, 60, 0.707107f);
path.rConicTo( 0, -60, 60, -60, 0.707107f);
path.rConicTo(-60, 0, -60, -60, 0.707107f);
path.rConicTo( 0, 60, -60, 60, 0.707107f);
canvas->drawPath(path, paint);
}
##
#SeeAlso conicTo arcTo addArc quadTo
##
#Topic Conic ##
# ------------------------------------------------------------------------------
#Topic Cubic
#Alias Cubic
#Alias Cubics
#Alias Cubic_Bezier
#Alias Cubic_Beziers
Cubic describes a Bezier curve segment described by a third-order polynomial.
Cubic begins at a start Point, curving towards the first control Point;
and curves from the end Point towards the second control Point.
#Example
#Height 160
void draw(SkCanvas* canvas) {
SkPaint paint;
paint.setAntiAlias(true);
paint.setStyle(SkPaint::kStroke_Style);
SkPoint cubicPts[] = {{20, 150}, {90, 10}, {160, 150}, {230, 10}};
SkColor colors[] = { 0xff88ff00, 0xff0088bb, 0xff6600cc, 0xffbb3377 };
for (unsigned i = 0; i < SK_ARRAY_COUNT(colors); ++i) {
paint.setColor(0x7fffffff & colors[i]);
paint.setStrokeWidth(1);
for (unsigned j = 0; j < 3; ++j) {
canvas->drawLine(cubicPts[j], cubicPts[j + 1], paint);
}
SkPath path;
path.moveTo(cubicPts[0]);
path.cubicTo(cubicPts[1], cubicPts[2], cubicPts[3]);
paint.setStrokeWidth(3);
paint.setColor(colors[i]);
canvas->drawPath(path, paint);
cubicPts[1].fY += 30;
cubicPts[2].fX += 30;
}
}
##
#Method void cubicTo(SkScalar x1, SkScalar y1, SkScalar x2, SkScalar y2,
SkScalar x3, SkScalar y3)
Adds Cubic from Last_Point towards (x1, y1), then towards (x2, y2), ending at
(x3, y3). If Path is empty, or last Verb is kClose_Verb, Last_Point is set to
(0, 0) before adding Cubic.
Appends kMove_Verb to Verb_Array and (0, 0) to Point_Array, if needed;
then appends kCubic_Verb to Verb_Array; and (x1, y1), (x2, y2), (x3, y3)
to Point_Array.
#Param x1 first control Point of Cubic in x ##
#Param y1 first control Point of Cubic in y ##
#Param x2 second control Point of Cubic in x ##
#Param y2 second control Point of Cubic in y ##
#Param x3 end Point of Cubic in x ##
#Param y3 end Point of Cubic in y ##
#Example
void draw(SkCanvas* canvas) {
SkPaint paint;
paint.setAntiAlias(true);
paint.setStyle(SkPaint::kStroke_Style);
SkPath path;
path.moveTo(0, -10);
for (int i = 0; i < 128; i += 16) {
SkScalar c = i * 0.5f;
path.cubicTo( 10 + c, -10 - i, 10 + i, -10 - c, 10 + i, 0);
path.cubicTo( 14 + i, 14 + c, 14 + c, 14 + i, 0, 14 + i);
path.cubicTo(-18 - c, 18 + i, -18 - i, 18 + c, -18 - i, 0);
path.cubicTo(-22 - i, -22 - c, -22 - c, -22 - i, 0, -22 - i);
}
path.offset(128, 128);
canvas->drawPath(path, paint);
}
##
#SeeAlso Contour moveTo rCubicTo quadTo
##
# ------------------------------------------------------------------------------
#Method void cubicTo(const SkPoint& p1, const SkPoint& p2, const SkPoint& p3)
Adds Cubic from Last_Point towards Point p1, then towards Point p2, ending at
Point p3. If Path is empty, or last Verb is kClose_Verb, Last_Point is set to
(0, 0) before adding Cubic.
Appends kMove_Verb to Verb_Array and (0, 0) to Point_Array, if needed;
then appends kCubic_Verb to Verb_Array; and Points p1, p2, p3
to Point_Array.
#Param p1 first control Point of Cubic ##
#Param p2 second control Point of Cubic ##
#Param p3 end Point of Cubic ##
#Example
#Height 84
SkPaint paint;
paint.setAntiAlias(true);
paint.setStyle(SkPaint::kStroke_Style);
SkPoint pts[] = { {20, 20}, {300, 80}, {-140, 90}, {220, 10} };
SkPath path;
path.moveTo(pts[0]);
path.cubicTo(pts[1], pts[2], pts[3]);
canvas->drawPath(path, paint);
##
#SeeAlso Contour moveTo rCubicTo quadTo
##
# ------------------------------------------------------------------------------
#Method void rCubicTo(SkScalar x1, SkScalar y1, SkScalar x2, SkScalar y2,
SkScalar x3, SkScalar y3)
Adds Cubic from Last_Point towards Vector (dx1, dy1), then towards
Vector (dx2, dy2), to Vector (dx3, dy3).
If Path is empty, or last Verb
is kClose_Verb, Last_Point is set to (0, 0) before adding Cubic.
Appends kMove_Verb to Verb_Array and (0, 0) to Point_Array,
if needed; then appends kCubic_Verb to Verb_Array; and appends Cubic
control and Cubic end to Point_Array.
Cubic control is Last_Point plus Vector (dx1, dy1).
Cubic end is Last_Point plus Vector (dx2, dy2).
Function name stands for "relative cubic to".
#Param x1 offset from Last_Point x to first Cubic control x ##
#Param y1 offset from Last_Point x to first Cubic control y ##
#Param x2 offset from Last_Point x to second Cubic control x ##
#Param y2 offset from Last_Point x to second Cubic control y ##
#Param x3 offset from Last_Point x to Cubic end x ##
#Param y3 offset from Last_Point x to Cubic end y ##
#Example
void draw(SkCanvas* canvas) {
SkPaint paint;
paint.setAntiAlias(true);
paint.setStyle(SkPaint::kStroke_Style);
SkPath path;
path.moveTo(24, 108);
for (int i = 0; i < 16; i++) {
SkScalar sx, sy;
sx = SkScalarSinCos(i * SK_ScalarPI / 8, &sy);
path.rCubicTo(40 * sx, 4 * sy, 4 * sx, 40 * sy, 40 * sx, 40 * sy);
}
canvas->drawPath(path, paint);
}
##
#SeeAlso Contour moveTo cubicTo quadTo
##
#Topic Cubic ##
# ------------------------------------------------------------------------------
#Topic Arc
Arc can be constructed in a number of ways. Arc may be described by part of Oval and angles,
by start point and end point, and by radius and tangent lines. Each construction has advantages,
and some constructions correspond to Arc drawing in graphics standards.
All Arc draws are implemented by one or more Conic draws. When Conic_Weight is less than one,
Conic describes an Arc of some Oval or Circle.
arcTo(const SkRect& oval, SkScalar startAngle, SkScalar sweepAngle, bool forceMoveTo)
describes Arc as a piece of Oval, beginning at start angle, sweeping clockwise or counterclockwise,
which may continue Contour or start a new one. This construction is similar to PostScript and
HTML_Canvas arcs. Variation addArc always starts new Contour. Canvas::drawArc draws without
requiring Path.
arcTo(SkScalar x1, SkScalar y1, SkScalar x2, SkScalar y2, SkScalar radius)
describes Arc as tangent to the line (x0, y0), (x1, y1) and tangent to the line (x1, y1), (x2, y2)
where (x0, y0) is the last Point added to Path. This construction is similar to PostScript and
HTML_Canvas arcs.
arcTo(SkScalar rx, SkScalar ry, SkScalar xAxisRotate, ArcSize largeArc, Direction sweep,
SkScalar x, SkScalar y)
describes Arc as part of Oval with radii (rx, ry), beginning at
last Point added to Path and ending at (x, y). More than one Arc satisfies this criteria,
so additional values choose a single solution. This construction is similar to SVG arcs.
conicTo describes Arc of less than 180 degrees as a pair of tangent lines and Conic_Weight.
conicTo can represent any Arc with a sweep less than 180 degrees at any rotation. All arcTo
constructions are converted to Conic data when added to Path.
#ToDo allow example to hide source and not be exposed as fiddle since markdown / html can't
do the kind of table shown in the illustration.
example is spaced correctly on fiddle but spacing is too wide on pc
##
#Example
#Height 300
#Width 600
#Description
#List
# <sup>1</sup> arcTo(const SkRect& oval, SkScalar startAngle, SkScalar sweepAngle, bool forceMoveTo) ##
# <sup>2</sup> parameter sets force MoveTo ##
# <sup>3</sup> start angle must be multiple of 90 degrees. ##
# <sup>4</sup> arcTo(SkScalar x1, SkScalar y1, SkScalar x2, SkScalar y2, SkScalar radius) ##
# <sup>5</sup> arcTo(SkScalar rx, SkScalar ry, SkScalar xAxisRotate, ArcSize largeArc,
Direction sweep, SkScalar x, SkScalar y) ##
#List ##
#Description ##
#Function
struct data {
const char* name;
char super;
int yn[10];
};
const data dataSet[] = {
{ "arcTo sweep", '1', {1, 3, 1, 0, 0, 0, 0, 1, 0, 0 }},
{ "drawArc", 0, {1, -1, 1, 1, 1, 1, 1, 0, 0, 0 }},
{ "addArc", 0, {1, 1, 1, 4, 0, 1, 1, 1, 0, 0 }},
{ "arcTo tangents", '4', {0, 0, 0, 0, 0, 0, 0, 1, 1, 0 }},
{ "arcTo radii", '5', {1, 0, 1, 0, 0, 0, 0, 1, 1, 0 }},
{ "conicTo", 0, {1, 1, 0, 0, 0, 0, 0, 1, 1, 1 }}
};
#define __degree_symbol__ "\xC2" "\xB0"
const char* headers[] = {
"Oval part",
"force moveTo",
"can draw 180" __degree_symbol__,
"can draw 360" __degree_symbol__,
"can draw greater than 360" __degree_symbol__,
"ignored if radius is zero",
"ignored if sweep is zero",
"requires Path",
"describes rotation",
"describes perspective",
};
const char* yna[] = {
"n/a",
"no",
"yes"
};
##
void draw(SkCanvas* canvas) {
SkPaint lp;
lp.setAntiAlias(true);
SkPaint tp(lp);
SkPaint sp(tp);
SkPaint bp(tp);
bp.setFakeBoldText(true);
sp.setTextSize(10);
lp.setColor(SK_ColorGRAY);
canvas->translate(0, 32);
const int tl = 115;
for (unsigned col = 0; col <= SK_ARRAY_COUNT(headers); ++col) {
canvas->drawLine(tl + col * 35, 100, tl + col * 35, 250, lp);
if (0 == col) {
continue;
}
canvas->drawLine(tl + col * 35, 100, tl + 100 + col * 35, 0, lp);
SkPath path;
path.moveTo(tl - 3 + col * 35, 103);
path.lineTo(tl + 124 + col * 35, -24);
canvas->drawTextOnPathHV(headers[col -1], strlen(headers[col -1]), path, 0, -9, bp);
}
for (unsigned row = 0; row <= SK_ARRAY_COUNT(dataSet); ++row) {
if (0 == row) {
canvas->drawLine(tl, 100, tl + 350, 100, lp);
} else {
canvas->drawLine(5, 100 + row * 25, tl + 350, 100 + row * 25, lp);
}
if (row == SK_ARRAY_COUNT(dataSet)) {
break;
}
canvas->drawString(dataSet[row].name, 5, 117 + row * 25, bp);
if (dataSet[row].super) {
SkScalar width = bp.measureText(dataSet[row].name, strlen(dataSet[row].name));
canvas->drawText(&dataSet[row].super, 1, 8 + width, 112 + row * 25, sp);
}
for (unsigned col = 0; col < SK_ARRAY_COUNT(headers); ++col) {
int val = dataSet[row].yn[col];
canvas->drawString(yna[SkTMin(2, val + 1)], tl + 5 + col * 35, 117 + row * 25, tp);
if (val > 1) {
char supe = '0' + val - 1;
canvas->drawText(&supe, 1, tl + 25 + col * 35, 112 + row * 25, sp);
}
}
}
}
#Example ##
#Example
#Height 128
#Description
#ToDo make this a list or table ##
1 describes an arc from an oval, a starting angle, and a sweep angle.
2 is similar to 1, but does not require building a path to draw.
3 is similar to 1, but always begins new Contour.
4 describes an arc from a pair of tangent lines and a radius.
5 describes an arc from Oval center, arc start Point and arc end Point.
6 describes an arc from a pair of tangent lines and a Conic_Weight.
##
void draw(SkCanvas* canvas) {
SkRect oval = {8, 8, 56, 56};
SkPaint ovalPaint;
ovalPaint.setAntiAlias(true);
SkPaint textPaint(ovalPaint);
ovalPaint.setStyle(SkPaint::kStroke_Style);
SkPaint arcPaint(ovalPaint);
arcPaint.setStrokeWidth(5);
arcPaint.setColor(SK_ColorBLUE);
canvas->translate(-64, 0);
for (char arcStyle = '1'; arcStyle <= '6'; ++arcStyle) {
'4' == arcStyle ? canvas->translate(-96, 55) : canvas->translate(64, 0);
canvas->drawText(&arcStyle, 1, 30, 36, textPaint);
canvas->drawOval(oval, ovalPaint);
SkPath path;
path.moveTo({56, 32});
switch (arcStyle) {
case '1':
path.arcTo(oval, 0, 90, false);
break;
case '2':
canvas->drawArc(oval, 0, 90, false, arcPaint);
continue;
case '3':
path.addArc(oval, 0, 90);
break;
case '4':
path.arcTo({56, 56}, {32, 56}, 24);
break;
case '5':
path.arcTo({24, 24}, 0, SkPath::kSmall_ArcSize, SkPath::kCW_Direction, {32, 56});
break;
case '6':
path.conicTo({56, 56}, {32, 56}, SK_ScalarRoot2Over2);
break;
}
canvas->drawPath(path, arcPaint);
}
}
#Example ##
#Method void arcTo(const SkRect& oval, SkScalar startAngle, SkScalar sweepAngle, bool forceMoveTo)
Append Arc to Path. Arc added is part of ellipse
bounded by oval, from startAngle through sweepAngle. Both startAngle and
sweepAngle are measured in degrees, where zero degrees is aligned with the
positive x-axis, and positive sweeps extends Arc clockwise.
arcTo adds Line connecting Path last Point to initial Arc Point if forceMoveTo
is false and Path is not empty. Otherwise, added Contour begins with first point
of Arc. Angles greater than -360 and less than 360 are treated modulo 360.
#Param oval bounds of ellipse containing Arc ##
#Param startAngle starting angle of Arc in degrees ##
#Param sweepAngle sweep, in degrees. Positive is clockwise; treated modulo 360 ##
#Param forceMoveTo true to start a new contour with Arc ##
#Example
#Height 200
#Description
arcTo continues a previous contour when forceMoveTo is false and when Path
is not empty.
##
void draw(SkCanvas* canvas) {
SkPaint paint;
SkPath path;
paint.setStyle(SkPaint::kStroke_Style);
paint.setStrokeWidth(4);
path.moveTo(0, 0);
path.arcTo({20, 20, 120, 120}, -90, 90, false);
canvas->drawPath(path, paint);
path.rewind();
path.arcTo({120, 20, 220, 120}, -90, 90, false);
canvas->drawPath(path, paint);
path.rewind();
path.moveTo(0, 0);
path.arcTo({20, 120, 120, 220}, -90, 90, true);
canvas->drawPath(path, paint);
}
##
#SeeAlso addArc SkCanvas::drawArc conicTo
##
# ------------------------------------------------------------------------------
#Method void arcTo(SkScalar x1, SkScalar y1, SkScalar x2, SkScalar y2, SkScalar radius)
Append Arc to Path, after appending Line if needed. Arc is implemented by Conic
weighted to describe part of Circle. Arc is contained by tangent from
last Path point (x0, y0) to (x1, y1), and tangent from (x1, y1) to (x2, y2). Arc
is part of Circle sized to radius, positioned so it touches both tangent lines.
#ToDo allow example to hide source and not be exposed as fiddle ##
#Example
#Height 226
void draw(SkCanvas* canvas) {
SkPaint tangentPaint;
tangentPaint.setAntiAlias(true);
SkPaint textPaint(tangentPaint);
tangentPaint.setStyle(SkPaint::kStroke_Style);
tangentPaint.setColor(SK_ColorGRAY);
SkPaint arcPaint(tangentPaint);
arcPaint.setStrokeWidth(5);
arcPaint.setColor(SK_ColorBLUE);
SkPath path;
SkPoint pts[] = { {56, 20}, {200, 20}, {90, 190} };
SkScalar radius = 50;
path.moveTo(pts[0]);
path.arcTo(pts[1], pts[2], radius);
canvas->drawLine(pts[0], pts[1], tangentPaint);
canvas->drawLine(pts[1], pts[2], tangentPaint);
SkPoint lastPt;
(void) path.getLastPt(&lastPt);
SkVector radial = pts[2] - pts[1];
radial.setLength(radius);
SkPoint center = { lastPt.fX - radial.fY, lastPt.fY + radial.fX };
canvas->drawCircle(center, radius, tangentPaint);
canvas->drawLine(lastPt, center, tangentPaint);
radial = pts[1] - pts[0];
radial.setLength(radius);
SkPoint arcStart = { center.fX + radial.fY, center.fY - radial.fX };
canvas->drawLine(center, arcStart, tangentPaint);
canvas->drawPath(path, arcPaint);
textPaint.setTextAlign(SkPaint::kRight_Align);
canvas->drawString("(x0, y0)", pts[0].fX - 5, pts[0].fY, textPaint);
textPaint.setTextAlign(SkPaint::kLeft_Align);
canvas->drawString("(x1, y1)", pts[1].fX + 5, pts[1].fY, textPaint);
textPaint.setTextAlign(SkPaint::kCenter_Align);
canvas->drawString("(x2, y2)", pts[2].fX, pts[2].fY + 15, textPaint);
textPaint.setTextAlign(SkPaint::kRight_Align);
canvas->drawString("radius", center.fX + 15, center.fY + 25, textPaint);
canvas->drawString("radius", center.fX - 3, center.fY - 16, textPaint);
}
##
If last Path Point does not start Arc, arcTo appends connecting Line to Path.
The length of Vector from (x1, y1) to (x2, y2) does not affect Arc.
#Example
#Height 128
void draw(SkCanvas* canvas) {
SkPaint tangentPaint;
tangentPaint.setAntiAlias(true);
SkPaint textPaint(tangentPaint);
tangentPaint.setStyle(SkPaint::kStroke_Style);
tangentPaint.setColor(SK_ColorGRAY);
SkPaint arcPaint(tangentPaint);
arcPaint.setStrokeWidth(5);
arcPaint.setColor(SK_ColorBLUE);
SkPath path;
SkPoint pts[] = { {156, 20}, {200, 20}, {170, 50} };
SkScalar radius = 50;
path.moveTo(pts[0]);
path.arcTo(pts[1], pts[2], radius);
canvas->drawLine(pts[0], pts[1], tangentPaint);
canvas->drawLine(pts[1], pts[2], tangentPaint);
SkPoint lastPt;
(void) path.getLastPt(&lastPt);
SkVector radial = pts[2] - pts[1];
radial.setLength(radius);
SkPoint center = { lastPt.fX - radial.fY, lastPt.fY + radial.fX };
canvas->drawLine(lastPt, center, tangentPaint);
radial = pts[1] - pts[0];
radial.setLength(radius);
SkPoint arcStart = { center.fX + radial.fY, center.fY - radial.fX };
canvas->drawLine(center, arcStart, tangentPaint);
canvas->drawPath(path, arcPaint);
textPaint.setTextAlign(SkPaint::kCenter_Align);
canvas->drawString("(x0, y0)", pts[0].fX, pts[0].fY - 7, textPaint);
textPaint.setTextAlign(SkPaint::kLeft_Align);
canvas->drawString("(x1, y1)", pts[1].fX + 5, pts[1].fY, textPaint);
textPaint.setTextAlign(SkPaint::kCenter_Align);
canvas->drawString("(x2, y2)", pts[2].fX, pts[2].fY + 15, textPaint);
textPaint.setTextAlign(SkPaint::kRight_Align);
canvas->drawString("radius", center.fX + 15, center.fY + 25, textPaint);
canvas->drawString("radius", center.fX - 5, center.fY - 20, textPaint);
}
##
Arc sweep is always less than 180 degrees. If radius is zero, or if
tangents are nearly parallel, arcTo appends Line from last Path Point to (x1, y1).
arcTo appends at most one Line and one Conic.
arcTo implements the functionality of PostScript_Arct and HTML_Canvas_ArcTo.
#Param x1 x common to pair of tangents ##
#Param y1 y common to pair of tangents ##
#Param x2 x end of second tangent ##
#Param y2 y end of second tangent ##
#Param radius distance from Arc to Circle center ##
#Example
#Description
arcTo is represented by Line and circular Conic in Path.
##
void draw(SkCanvas* canvas) {
SkPath path;
path.moveTo({156, 20});
path.arcTo(200, 20, 170, 50, 50);
SkPath::Iter iter(path, false);
SkPoint p[4];
SkPath::Verb verb;
while (SkPath::kDone_Verb != (verb = iter.next(p))) {
switch (verb) {
case SkPath::kMove_Verb:
SkDebugf("move to (%g,%g)\n", p[0].fX, p[0].fY);
break;
case SkPath::kLine_Verb:
SkDebugf("line (%g,%g),(%g,%g)\n", p[0].fX, p[0].fY, p[1].fX, p[1].fY);
break;
case SkPath::kConic_Verb:
SkDebugf("conic (%g,%g),(%g,%g),(%g,%g) weight %g\n",
p[0].fX, p[0].fY, p[1].fX, p[1].fY, p[2].fX, p[2].fY, iter.conicWeight());
break;
default:
SkDebugf("unexpected verb\n");
}
}
}
#StdOut
move to (156,20)
line (156,20),(79.2893,20)
conic (79.2893,20),(200,20),(114.645,105.355) weight 0.382683
##
##
#SeeAlso conicTo
##
# ------------------------------------------------------------------------------
#Method void arcTo(const SkPoint p1, const SkPoint p2, SkScalar radius)
Append Arc to Path, after appending Line if needed. Arc is implemented by Conic
weighted to describe part of Circle. Arc is contained by tangent from
last Path point to p1, and tangent from p1 to p2. Arc
is part of Circle sized to radius, positioned so it touches both tangent lines.
If last Path Point does not start Arc, arcTo appends connecting Line to Path.
The length of Vector from p1 to p2 does not affect Arc.
Arc sweep is always less than 180 degrees. If radius is zero, or if
tangents are nearly parallel, arcTo appends Line from last Path Point to p1.
arcTo appends at most one Line and one Conic.
arcTo implements the functionality of PostScript_Arct and HTML_Canvas_ArcTo.
#Param p1 Point common to pair of tangents ##
#Param p2 end of second tangent ##
#Param radius distance from Arc to Circle center ##
#Example
#Description
Because tangent lines are parallel, arcTo appends line from last Path Point to
p1, but does not append a circular Conic.
##
void draw(SkCanvas* canvas) {
SkPath path;
path.moveTo({156, 20});
path.arcTo({200, 20}, {170, 20}, 50);
SkPath::Iter iter(path, false);
SkPoint p[4];
SkPath::Verb verb;
while (SkPath::kDone_Verb != (verb = iter.next(p))) {
switch (verb) {
case SkPath::kMove_Verb:
SkDebugf("move to (%g,%g)\n", p[0].fX, p[0].fY);
break;
case SkPath::kLine_Verb:
SkDebugf("line (%g,%g),(%g,%g)\n", p[0].fX, p[0].fY, p[1].fX, p[1].fY);
break;
case SkPath::kConic_Verb:
SkDebugf("conic (%g,%g),(%g,%g),(%g,%g) weight %g\n",
p[0].fX, p[0].fY, p[1].fX, p[1].fY, p[2].fX, p[2].fY, iter.conicWeight());
break;
default:
SkDebugf("unexpected verb\n");
}
}
}
#StdOut
move to (156,20)
line (156,20),(200,20)
##
##
#SeeAlso conicTo
##
# ------------------------------------------------------------------------------
#Enum ArcSize
#Code
enum ArcSize {
kSmall_ArcSize,
kLarge_ArcSize,
};
##
Four Oval parts with radii (rx, ry) start at last Path Point and ends at (x, y).
ArcSize and Direction select one of the four Oval parts.
#Const kSmall_ArcSize 0
smaller of Arc pair
##
#Const kLarge_ArcSize 1
larger of Arc pair
##
#Example
#Height 160
#Description
Arc begins at top of Oval pair and ends at bottom. Arc can take four routes to get there.
Two routes are large, and two routes are counterclockwise. The one route both large
and counterclockwise is blue.
##
void draw(SkCanvas* canvas) {
SkPaint paint;
paint.setAntiAlias(true);
paint.setStyle(SkPaint::kStroke_Style);
for (auto sweep: { SkPath::kCW_Direction, SkPath::kCCW_Direction } ) {
for (auto arcSize : { SkPath::kSmall_ArcSize, SkPath::kLarge_ArcSize } ) {
SkPath path;
path.moveTo({120, 50});
path.arcTo(70, 40, 30, arcSize, sweep, 156, 100);
if (SkPath::kCCW_Direction == sweep && SkPath::kLarge_ArcSize == arcSize) {
paint.setColor(SK_ColorBLUE);
paint.setStrokeWidth(3);
}
canvas->drawPath(path, paint);
}
}
}
##
#SeeAlso arcTo Direction
##
# ------------------------------------------------------------------------------
#Method void arcTo(SkScalar rx, SkScalar ry, SkScalar xAxisRotate, ArcSize largeArc,
Direction sweep, SkScalar x, SkScalar y)
Append Arc to Path. Arc is implemented by one or more Conics weighted to
describe part of Oval with radii (rx, ry) rotated by xAxisRotate degrees. Arc
curves from last Path Point to (x, y), choosing one of four possible routes:
clockwise or counterclockwise, and smaller or larger.
Arc sweep is always less than 360 degrees. arcTo appends Line to (x, y) if
either radii are zero, or if last Path Point equals (x, y). arcTo scales radii
(rx, ry) to fit last Path Point and (x, y) if both are greater than zero but
too small.
arcTo appends up to four Conic curves.
arcTo implements the functionality of SVG_Arc, although SVG "sweep-flag" value
is opposite the integer value of sweep; SVG "sweep-flag" uses 1 for clockwise,
while kCW_Direction cast to int is zero.
#Param rx radius in x before x-axis rotation ##
#Param ry radius in y before x-axis rotation ##
#Param xAxisRotate x-axis rotation in degrees; positive values are clockwise ##
#Param largeArc chooses smaller or larger Arc ##
#Param sweep chooses clockwise or counterclockwise Arc ##
#Param x end of Arc ##
#Param y end of Arc ##
#Example
#Height 160
void draw(SkCanvas* canvas) {
SkPaint paint;
paint.setAntiAlias(true);
paint.setStyle(SkPaint::kStroke_Style);
for (auto sweep: { SkPath::kCW_Direction, SkPath::kCCW_Direction } ) {
for (auto arcSize : { SkPath::kSmall_ArcSize, SkPath::kLarge_ArcSize } ) {
SkPath path;
path.moveTo({120, 50});
path.arcTo(70, 40, 30, arcSize, sweep, 120.1, 50);
if (SkPath::kCCW_Direction == sweep && SkPath::kLarge_ArcSize == arcSize) {
paint.setColor(SK_ColorBLUE);
paint.setStrokeWidth(3);
}
canvas->drawPath(path, paint);
}
}
}
##
#SeeAlso rArcTo ArcSize Direction
##
# ------------------------------------------------------------------------------
#Method void arcTo(const SkPoint r, SkScalar xAxisRotate, ArcSize largeArc, Direction sweep,
const SkPoint xy)
Append Arc to Path. Arc is implemented by one or more Conic weighted to describe part of Oval
with radii (r.fX, r.fY) rotated by xAxisRotate degrees. Arc curves from last Path Point to
(xy.fX, xy.fY), choosing one of four possible routes: clockwise or counterclockwise,
and smaller or larger.
Arc sweep is always less than 360 degrees. arcTo appends Line to xy if either radii are zero,
or if last Path Point equals (x, y). arcTo scales radii r to fit last Path Point and
xy if both are greater than zero but too small to describe an arc.
arcTo appends up to four Conic curves.
arcTo implements the functionality of SVG_Arc, although SVG "sweep-flag" value is
opposite the integer value of sweep; SVG "sweep-flag" uses 1 for clockwise, while
kCW_Direction cast to int is zero.
#Param r radii in x and y before x-axis rotation ##
#Param xAxisRotate x-axis rotation in degrees; positive values are clockwise ##
#Param largeArc chooses smaller or larger Arc ##
#Param sweep chooses clockwise or counterclockwise Arc ##
#Param xy end of Arc ##
#Example
#Height 108
void draw(SkCanvas* canvas) {
SkPaint paint;
SkPath path;
const SkPoint starts[] = {{20, 20}, {120, 20}, {70, 60}};
for (auto start : starts) {
path.moveTo(start.fX, start.fY);
path.rArcTo(20, 20, 0, SkPath::kSmall_ArcSize, SkPath::kCCW_Direction, 60, 0);
}
canvas->drawPath(path, paint);
}
##
#SeeAlso rArcTo ArcSize Direction
##
# ------------------------------------------------------------------------------
#Method void rArcTo(SkScalar rx, SkScalar ry, SkScalar xAxisRotate, ArcSize largeArc,
Direction sweep, SkScalar dx, SkScalar dy)
Append Arc to Path, relative to last Path Point. Arc is implemented by one or
more Conic, weighted to describe part of Oval with radii (rx, ry) rotated by
xAxisRotate degrees. Arc curves from last Path Point (x0, y0) to end Point:
#Formula
(x0 + dx, y0 + dy)
##
, choosing one of four possible routes: clockwise or
counterclockwise, and smaller or larger. If Path is empty, the start Arc Point
is (0, 0).
Arc sweep is always less than 360 degrees. arcTo appends Line to end Point
if either radii are zero, or if last Path Point equals end Point.
arcTo scales radii (rx, ry) to fit last Path Point and end Point if both are
greater than zero but too small to describe an arc.
arcTo appends up to four Conic curves.
arcTo implements the functionality of SVG_Arc, although SVG "sweep-flag" value is
opposite the integer value of sweep; SVG "sweep-flag" uses 1 for clockwise, while
kCW_Direction cast to int is zero.
#Param rx radius in x before x-axis rotation ##
#Param ry radius in y before x-axis rotation ##
#Param xAxisRotate x-axis rotation in degrees; positive values are clockwise ##
#Param largeArc chooses smaller or larger Arc ##
#Param sweep chooses clockwise or counterclockwise Arc ##
#Param dx x offset end of Arc from last Path Point ##
#Param dy y offset end of Arc from last Path Point ##
#Example
#Height 108
void draw(SkCanvas* canvas) {
SkPaint paint;
SkPath path;
const SkPoint starts[] = {{20, 20}, {120, 20}, {70, 60}};
for (auto start : starts) {
path.moveTo(start.fX, start.fY);
path.rArcTo(20, 20, 0, SkPath::kSmall_ArcSize, SkPath::kCCW_Direction, 60, 0);
}
canvas->drawPath(path, paint);
}
##
#SeeAlso arcTo ArcSize Direction
##
#Topic Arc ##
# ------------------------------------------------------------------------------
#Method void close()
Append kClose_Verb to Path. A closed Contour connects the first and last Point
with Line, forming a continuous loop. Open and closed Contour draw the same
with SkPaint::kFill_Style. With SkPaint::kStroke_Style, open Contour draws
Paint_Stroke_Cap at Contour start and end; closed Contour draws
Paint_Stroke_Join at Contour start and end.
close() has no effect if Path is empty or last Path Verb is kClose_Verb.
#Example
void draw(SkCanvas* canvas) {
SkPaint paint;
paint.setStrokeWidth(15);
paint.setStrokeCap(SkPaint::kRound_Cap);
SkPath path;
const SkPoint points[] = {{20, 20}, {70, 20}, {40, 90}};
path.addPoly(points, SK_ARRAY_COUNT(points), false);
for (int loop = 0; loop < 2; ++loop) {
for (auto style : {SkPaint::kStroke_Style, SkPaint::kFill_Style,
SkPaint::kStrokeAndFill_Style} ) {
paint.setStyle(style);
canvas->drawPath(path, paint);
canvas->translate(85, 0);
}
path.close();
canvas->translate(-255, 128);
}
}
##
#SeeAlso
##
# ------------------------------------------------------------------------------
#Method static bool IsInverseFillType(FillType fill)
Returns true if fill is inverted and Path with fill represents area outside
of its geometric bounds.
#Table
#Legend
# FillType # is inverse ##
##
# kWinding_FillType # false ##
# kEvenOdd_FillType # false ##
# kInverseWinding_FillType # true ##
# kInverseEvenOdd_FillType # true ##
##
#Param fill one of: kWinding_FillType, kEvenOdd_FillType,
kInverseWinding_FillType, kInverseEvenOdd_FillType
##
#Return true if Path fills outside its bounds ##
#Example
#Function
#define nameValue(fill) { SkPath::fill, #fill }
##
void draw(SkCanvas* canvas) {
struct {
SkPath::FillType fill;
const char* name;
} fills[] = {
nameValue(kWinding_FillType),
nameValue(kEvenOdd_FillType),
nameValue(kInverseWinding_FillType),
nameValue(kInverseEvenOdd_FillType),
};
for (auto fill: fills ) {
SkDebugf("IsInverseFillType(%s) == %s\n", fill.name, SkPath::IsInverseFillType(fill.fill) ?
"true" : "false");
}
}
#StdOut
IsInverseFillType(kWinding_FillType) == false
IsInverseFillType(kEvenOdd_FillType) == false
IsInverseFillType(kInverseWinding_FillType) == true
IsInverseFillType(kInverseEvenOdd_FillType) == true
##
##
#SeeAlso FillType getFillType setFillType ConvertToNonInverseFillType
##
# ------------------------------------------------------------------------------
#Method static FillType ConvertToNonInverseFillType(FillType fill)
Returns equivalent Fill_Type representing Path fill inside its bounds.
.
#Table
#Legend
# FillType # inside FillType ##
##
# kWinding_FillType # kWinding_FillType ##
# kEvenOdd_FillType # kEvenOdd_FillType ##
# kInverseWinding_FillType # kWinding_FillType ##
# kInverseEvenOdd_FillType # kEvenOdd_FillType ##
##
#Param fill one of: kWinding_FillType, kEvenOdd_FillType,
kInverseWinding_FillType, kInverseEvenOdd_FillType
##
#Return fill, or kWinding_FillType or kEvenOdd_FillType if fill is inverted ##
#Example
#Function
#define nameValue(fill) { SkPath::fill, #fill }
##
void draw(SkCanvas* canvas) {
struct {
SkPath::FillType fill;
const char* name;
} fills[] = {
nameValue(kWinding_FillType),
nameValue(kEvenOdd_FillType),
nameValue(kInverseWinding_FillType),
nameValue(kInverseEvenOdd_FillType),
};
for (unsigned i = 0; i < SK_ARRAY_COUNT(fills); ++i) {
if (fills[i].fill != (SkPath::FillType) i) {
SkDebugf("fills array order does not match FillType enum order");
break;
}
SkDebugf("ConvertToNonInverseFillType(%s) == %s\n", fills[i].name,
fills[(int) SkPath::ConvertToNonInverseFillType(fills[i].fill)].name);
}
}
#StdOut
ConvertToNonInverseFillType(kWinding_FillType) == kWinding_FillType
ConvertToNonInverseFillType(kEvenOdd_FillType) == kEvenOdd_FillType
ConvertToNonInverseFillType(kInverseWinding_FillType) == kWinding_FillType
ConvertToNonInverseFillType(kInverseEvenOdd_FillType) == kEvenOdd_FillType
##
##
#SeeAlso FillType getFillType setFillType IsInverseFillType
##
# ------------------------------------------------------------------------------
#Method static int ConvertConicToQuads(const SkPoint& p0, const SkPoint& p1, const SkPoint& p2,
SkScalar w, SkPoint pts[], int pow2)
Approximates Conic with Quad array. Conic is constructed from start Point p0,
control Point p1, end Point p2, and weight w.
Quad array is stored in pts; this storage is supplied by caller.
Maximum Quad count is 2 to the pow2.
Every third point in array shares last Point of previous Quad and first Point of
next Quad. Maximum pts storage size is given by:
#Formula
(1 + 2 * (1 << pow2)) * sizeof(SkPoint)
##
.
Returns Quad count used the approximation, which may be smaller
than the number requested.
Conic_Weight determines the amount of influence Conic control point has on the curve.
w less than one represents an elliptical section. w greater than one represents
a hyperbolic section. w equal to one represents a parabolic section.
Two Quad curves are sufficient to approximate an elliptical Conic with a sweep
of up to 90 degrees; in this case, set pow2 to one.
#Param p0 Conic start Point ##
#Param p1 Conic control Point ##
#Param p2 Conic end Point ##
#Param w Conic weight ##
#Param pts storage for Quad array ##
#Param pow2 Quad count, as power of two, normally 0 to 5 (1 to 32 Quad curves) ##
#Return number of Quad curves written to pts ##
#Example
#Description
A pair of Quad curves are drawn in red on top of the elliptical Conic curve in black.
The middle curve is nearly circular. The top-right curve is parabolic, which can
be drawn exactly with a single Quad.
##
void draw(SkCanvas* canvas) {
SkPaint conicPaint;
conicPaint.setAntiAlias(true);
conicPaint.setStyle(SkPaint::kStroke_Style);
SkPaint quadPaint(conicPaint);
quadPaint.setColor(SK_ColorRED);
SkPoint conic[] = { {20, 170}, {80, 170}, {80, 230} };
for (auto weight : { .25f, .5f, .707f, .85f, 1.f } ) {
SkPoint quads[5];
SkPath::ConvertConicToQuads(conic[0], conic[1], conic[2], weight, quads, 1);
SkPath path;
path.moveTo(conic[0]);
path.conicTo(conic[1], conic[2], weight);
canvas->drawPath(path, conicPaint);
path.rewind();
path.moveTo(quads[0]);
path.quadTo(quads[1], quads[2]);
path.quadTo(quads[3], quads[4]);
canvas->drawPath(path, quadPaint);
canvas->translate(50, -50);
}
}
##
#SeeAlso Conic Quad
##
# ------------------------------------------------------------------------------
#Method bool isRect(SkRect* rect, bool* isClosed = nullptr, Direction* direction = nullptr) const
Returns true if Path is equivalent to Rect when filled.
If false: rect, isClosed, and direction are unchanged.
If true: rect, isClosed, and direction are written to if not nullptr.
rect may be smaller than the Path bounds. Path bounds may include kMove_Verb points
that do not alter the area drawn by the returned rect.
#Param rect storage for bounds of Rect; may be nullptr ##
#Param isClosed storage set to true if Path is closed; may be nullptr ##
#Param direction storage set to Rect direction; may be nullptr ##
#Return true if Path contains Rect ##
#Example
#Description
After addRect, isRect returns true. Following moveTo permits isRect to return true, but
following lineTo does not. addPoly returns true even though rect is not closed, and one
side of rect is made up of consecutive line segments.
##
void draw(SkCanvas* canvas) {
auto debugster = [](const char* prefix, const SkPath& path) -> void {
SkRect rect;
SkPath::Direction direction;
bool isClosed;
path.isRect(&rect, &isClosed, &direction) ?
SkDebugf("%s is rect (%g, %g, %g, %g); is %s" "closed; direction %s\n", prefix,
rect.fLeft, rect.fTop, rect.fRight, rect.fBottom, isClosed ? "" : "not ",
SkPath::kCW_Direction == direction ? "CW" : "CCW") :
SkDebugf("%s is not rect\n", prefix);
};
SkPath path;
debugster("empty", path);
path.addRect({10, 20, 30, 40});
debugster("addRect", path);
path.moveTo(60, 70);
debugster("moveTo", path);
path.lineTo(60, 70);
debugster("lineTo", path);
path.reset();
const SkPoint pts[] = { {0, 0}, {0, 80}, {80, 80}, {80, 0}, {40, 0}, {20, 0} };
path.addPoly(pts, SK_ARRAY_COUNT(pts), false);
debugster("addPoly", path);
}
#StdOut
empty is not rect
addRect is rect (10, 20, 30, 40); is closed; direction CW
moveTo is rect (10, 20, 30, 40); is closed; direction CW
lineTo is not rect
addPoly is rect (0, 0, 80, 80); is not closed; direction CCW
##
##
#SeeAlso computeTightBounds conservativelyContainsRect getBounds isConvex isLastContourClosed isNestedFillRects
##
# ------------------------------------------------------------------------------
#Method bool isNestedFillRects(SkRect rect[2], Direction dirs[2] = nullptr) const
Returns true if Path is equivalent to nested Rect pair when filled.
If false, rect and dirs are unchanged.
If true, rect and dirs are written to if not nullptr:
setting rect[0] to outer Rect, and rect[1] to inner Rect;
setting dirs[0] to Direction of outer Rect, and dirs[1] to Direction of inner
Rect.
#Param rect storage for Rect pair; may be nullptr ##
#Param dirs storage for Direction pair; may be nullptr ##
#Return true if Path contains nested Rect pair ##
#Example
void draw(SkCanvas* canvas) {
SkPaint paint;
paint.setStyle(SkPaint::kStroke_Style);
paint.setStrokeWidth(5);
SkPath path;
path.addRect({10, 20, 30, 40});
paint.getFillPath(path, &path);
SkRect rects[2];
SkPath::Direction directions[2];
if (path.isNestedFillRects(rects, directions)) {
for (int i = 0; i < 2; ++i) {
SkDebugf("%s (%g, %g, %g, %g); direction %s\n", i ? "inner" : "outer",
rects[i].fLeft, rects[i].fTop, rects[i].fRight, rects[i].fBottom,
SkPath::kCW_Direction == directions[i] ? "CW" : "CCW");
}
} else {
SkDebugf("is not nested rectangles\n");
}
}
#StdOut
outer (7.5, 17.5, 32.5, 42.5); direction CW
inner (12.5, 22.5, 27.5, 37.5); direction CCW
##
##
#SeeAlso computeTightBounds conservativelyContainsRect getBounds isConvex isLastContourClosed isRect
##
# ------------------------------------------------------------------------------
#Method void addRect(const SkRect& rect, Direction dir = kCW_Direction)
Add Rect to Path, appending kMove_Verb, three kLine_Verb, and kClose_Verb,
starting with top-left corner of Rect; followed by top-right, bottom-right,
and bottom-left if dir is kCW_Direction; or followed by bottom-left,
bottom-right, and top-right if dir is kCCW_Direction.
#Param rect Rect to add as a closed contour ##
#Param dir Direction to wind added contour ##
#Example
#Description
The left Rect dashes starting at the top-left corner, to the right.
The right Rect dashes starting at the top-left corner, towards the bottom.
##
#Height 128
void draw(SkCanvas* canvas) {
SkPaint paint;
paint.setStrokeWidth(15);
paint.setStrokeCap(SkPaint::kSquare_Cap);
float intervals[] = { 5, 21.75f };
paint.setStyle(SkPaint::kStroke_Style);
paint.setPathEffect(SkDashPathEffect::Make(intervals, SK_ARRAY_COUNT(intervals), 0));
SkPath path;
path.addRect({20, 20, 100, 100}, SkPath::kCW_Direction);
canvas->drawPath(path, paint);
path.rewind();
path.addRect({140, 20, 220, 100}, SkPath::kCCW_Direction);
canvas->drawPath(path, paint);
}
##
#SeeAlso SkCanvas::drawRect Direction
##
# ------------------------------------------------------------------------------
#Method void addRect(const SkRect& rect, Direction dir, unsigned start)
Add Rect to Path, appending kMove_Verb, three kLine_Verb, and kClose_Verb.
If dir is kCW_Direction, Rect corners are added clockwise; if dir is
kCCW_Direction, Rect corners are added counterclockwise.
start determines the first corner added.
#Table
#Legend
# start # first corner ##
#Legend ##
# 0 # top-left ##
# 1 # top-right ##
# 2 # bottom-right ##
# 3 # bottom-left ##
#Table ##
#Param rect Rect to add as a closed contour ##
#Param dir Direction to wind added contour ##
#Param start initial corner of Rect to add ##
#Example
#Height 128
#Description
The arrow is just after the initial corner and points towards the next
corner appended to Path.
##
void draw(SkCanvas* canvas) {
const SkPoint arrow[] = { {5, -5}, {15, -5}, {20, 0}, {15, 5}, {5, 5}, {10, 0} };
const SkRect rect = {10, 10, 54, 54};
SkPaint rectPaint;
rectPaint.setAntiAlias(true);
rectPaint.setStyle(SkPaint::kStroke_Style);
SkPaint arrowPaint(rectPaint);
SkPath arrowPath;
arrowPath.addPoly(arrow, SK_ARRAY_COUNT(arrow), true);
arrowPaint.setPathEffect(SkPath1DPathEffect::Make(arrowPath, 176, 0,
SkPath1DPathEffect::kRotate_Style));
for (auto direction : { SkPath::kCW_Direction, SkPath::kCCW_Direction } ) {
for (unsigned start : { 0, 1, 2, 3 } ) {
SkPath path;
path.addRect(rect, direction, start);
canvas->drawPath(path, rectPaint);
canvas->drawPath(path, arrowPaint);
canvas->translate(64, 0);
}
canvas->translate(-256, 64);
}
}
##
#SeeAlso SkCanvas::drawRect Direction
##
# ------------------------------------------------------------------------------
#Method void addRect(SkScalar left, SkScalar top, SkScalar right, SkScalar bottom,
Direction dir = kCW_Direction)
Add Rect (left, top, right, bottom) to Path,
appending kMove_Verb, three kLine_Verb, and kClose_Verb,
starting with top-left corner of Rect; followed by top-right, bottom-right,
and bottom-left if dir is kCW_Direction; or followed by bottom-left,
bottom-right, and top-right if dir is kCCW_Direction.
#Param left smaller x of Rect ##
#Param top smaller y of Rect ##
#Param right larger x of Rect ##
#Param bottom larger y of Rect ##
#Param dir Direction to wind added contour ##
#Example
#Description
The left Rect dashes start at the top-left corner, and continue to the right.
The right Rect dashes start at the top-left corner, and continue down.
##
#Height 128
void draw(SkCanvas* canvas) {
SkPaint paint;
paint.setStrokeWidth(15);
paint.setStrokeCap(SkPaint::kSquare_Cap);
float intervals[] = { 5, 21.75f };
paint.setStyle(SkPaint::kStroke_Style);
paint.setPathEffect(SkDashPathEffect::Make(intervals, SK_ARRAY_COUNT(intervals), 0));
for (auto direction : { SkPath::kCW_Direction, SkPath::kCCW_Direction } ) {
SkPath path;
path.addRect(20, 20, 100, 100, direction);
canvas->drawPath(path, paint);
canvas->translate(128, 0);
}
}
##
#SeeAlso SkCanvas::drawRect Direction
##
# ------------------------------------------------------------------------------
#Method void addOval(const SkRect& oval, Direction dir = kCW_Direction)
Add Oval to path, appending kMove_Verb, four kConic_Verb, and kClose_Verb.
Oval is upright ellipse bounded by Rect oval with radii equal to half oval width
and half oval height. Oval begins at (oval.fRight, oval.centerY()) and continues
clockwise if dir is kCW_Direction, counterclockwise if dir is kCCW_Direction.
This form is identical to addOval(oval, dir, 1).
#Param oval bounds of ellipse added ##
#Param dir Direction to wind ellipse ##
#Example
#Height 120
SkPaint paint;
SkPath oval;
oval.addOval({20, 20, 160, 80});
canvas->drawPath(oval, paint);
##
#SeeAlso SkCanvas::drawOval Direction Oval
##
# ------------------------------------------------------------------------------
#Method void addOval(const SkRect& oval, Direction dir, unsigned start)
Add Oval to Path, appending kMove_Verb, four kConic_Verb, and kClose_Verb.
Oval is upright ellipse bounded by Rect oval with radii equal to half oval width
and half oval height. Oval begins at start and continues
clockwise if dir is kCW_Direction, counterclockwise if dir is kCCW_Direction.
#Table
#Legend
# start # Point ##
#Legend ##
# 0 # oval.centerX(), oval.fTop ##
# 1 # oval.fRight, oval.centerY() ##
# 2 # oval.centerX(), oval.fBottom ##
# 3 # oval.fLeft, oval.centerY() ##
#Table ##
#Param oval bounds of ellipse added ##
#Param dir Direction to wind ellipse ##
#Param start index of initial point of ellipse ##
#Example
#Height 160
void draw(SkCanvas* canvas) {
const SkPoint arrow[] = { {0, -5}, {10, 0}, {0, 5} };
const SkRect rect = {10, 10, 54, 54};
SkPaint ovalPaint;
ovalPaint.setAntiAlias(true);
SkPaint textPaint(ovalPaint);
textPaint.setTextAlign(SkPaint::kCenter_Align);
ovalPaint.setStyle(SkPaint::kStroke_Style);
SkPaint arrowPaint(ovalPaint);
SkPath arrowPath;
arrowPath.addPoly(arrow, SK_ARRAY_COUNT(arrow), true);
arrowPaint.setPathEffect(SkPath1DPathEffect::Make(arrowPath, 176, 0,
SkPath1DPathEffect::kRotate_Style));
for (auto direction : { SkPath::kCW_Direction, SkPath::kCCW_Direction } ) {
for (unsigned start : { 0, 1, 2, 3 } ) {
SkPath path;
path.addOval(rect, direction, start);
canvas->drawPath(path, ovalPaint);
canvas->drawPath(path, arrowPaint);
canvas->drawText(&"0123"[start], 1, rect.centerX(), rect.centerY() + 5, textPaint);
canvas->translate(64, 0);
}
canvas->translate(-256, 72);
canvas->drawString(SkPath::kCW_Direction == direction ? "clockwise" : "counterclockwise",
128, 0, textPaint);
}
}
##
#SeeAlso SkCanvas::drawOval Direction Oval
##
# ------------------------------------------------------------------------------
#Method void addCircle(SkScalar x, SkScalar y, SkScalar radius,
Direction dir = kCW_Direction)
Add Circle centered at (x, y) of size radius to Path, appending kMove_Verb,
four kConic_Verb, and kClose_Verb. Circle begins at:
#Formula
(x + radius, y)
##
, continuing
clockwise if dir is kCW_Direction, and counterclockwise if dir is kCCW_Direction.
Has no effect if radius is zero or negative.
#Param x center of Circle ##
#Param y center of Circle ##
#Param radius distance from center to edge ##
#Param dir Direction to wind Circle ##
#Example
void draw(SkCanvas* canvas) {
SkPaint paint;
paint.setAntiAlias(true);
paint.setStyle(SkPaint::kStroke_Style);
paint.setStrokeWidth(10);
for (int size = 10; size < 300; size += 20) {
SkPath path;
path.addCircle(128, 128, size, SkPath::kCW_Direction);
canvas->drawPath(path, paint);
}
}
##
#SeeAlso SkCanvas::drawCircle Direction Circle
##
# ------------------------------------------------------------------------------
#Method void addArc(const SkRect& oval, SkScalar startAngle, SkScalar sweepAngle)
Append Arc to Path, as the start of new Contour. Arc added is part of ellipse
bounded by oval, from startAngle through sweepAngle. Both startAngle and
sweepAngle are measured in degrees, where zero degrees is aligned with the
positive x-axis, and positive sweeps extends Arc clockwise.
If sweepAngle <= -360, or sweepAngle >= 360; and startAngle modulo 90 is nearly
zero, append Oval instead of Arc. Otherwise, sweepAngle values are treated
modulo 360, and Arc may or may not draw depending on numeric rounding.
#Param oval bounds of ellipse containing Arc ##
#Param startAngle starting angle of Arc in degrees ##
#Param sweepAngle sweep, in degrees. Positive is clockwise; treated modulo 360 ##
#Example
#Description
The middle row of the left and right columns draw differently from the entries
above and below because sweepAngle is outside of the range of +/-360,
and startAngle modulo 90 is not zero.
##
void draw(SkCanvas* canvas) {
SkPaint paint;
for (auto start : { 0, 90, 135, 180, 270 } ) {
for (auto sweep : { -450.f, -180.f, -90.f, 90.f, 180.f, 360.1f } ) {
SkPath path;
path.addArc({10, 10, 35, 45}, start, sweep);
canvas->drawPath(path, paint);
canvas->translate(252 / 6, 0);
}
canvas->translate(-252, 255 / 5);
}
}
##
#SeeAlso Arc arcTo SkCanvas::drawArc
##
# ------------------------------------------------------------------------------
#Method void addRoundRect(const SkRect& rect, SkScalar rx, SkScalar ry,
Direction dir = kCW_Direction)
Append Round_Rect to Path, creating a new closed Contour. Round_Rect has bounds
equal to rect; each corner is 90 degrees of an ellipse with radii (rx, ry). If
dir is kCW_Direction, Round_Rect starts at top-left of the lower-left corner and
winds clockwise. If dir is kCCW_Direction, Round_Rect starts at the bottom-left
of the upper-left corner and winds counterclockwise.
If either rx or ry is too large, rx and ry are scaled uniformly until the
corners fit. If rx or ry is less than or equal to zero, addRoundRect appends
Rect rect to Path.
After appending, Path may be empty, or may contain: Rect, Oval, or RoundRect.
#Param rect bounds of Round_Rect ##
#Param rx x-radius of rounded corners on the Round_Rect ##
#Param ry y-radius of rounded corners on the Round_Rect ##
#Param dir Direction to wind Round_Rect ##
#Example
#Description
If either radius is zero, path contains Rect and is drawn red.
If sides are only radii, path contains Oval and is drawn blue.
All remaining path draws are convex, and are drawn in gray; no
paths constructed from addRoundRect are concave, so none are
drawn in green.
##
void draw(SkCanvas* canvas) {
SkPaint paint;
paint.setAntiAlias(true);
for (auto xradius : { 0, 7, 13, 20 } ) {
for (auto yradius : { 0, 9, 18, 40 } ) {
SkPath path;
path.addRoundRect({10, 10, 36, 46}, xradius, yradius);
paint.setColor(path.isRect(nullptr) ? SK_ColorRED : path.isOval(nullptr) ?
SK_ColorBLUE : path.isConvex() ? SK_ColorGRAY : SK_ColorGREEN);
canvas->drawPath(path, paint);
canvas->translate(64, 0);
}
canvas->translate(-256, 64);
}
}
##
#SeeAlso addRRect SkCanvas::drawRoundRect
##
# ------------------------------------------------------------------------------
#Method void addRoundRect(const SkRect& rect, const SkScalar radii[],
Direction dir = kCW_Direction)
Append Round_Rect to Path, creating a new closed Contour. Round_Rect has bounds
equal to rect; each corner is 90 degrees of an ellipse with radii from the
array.
#Table
#Legend
# radii index # location ##
#Legend ##
# 0 # x-radius of top-left corner ##
# 1 # y-radius of top-left corner ##
# 2 # x-radius of top-right corner ##
# 3 # y-radius of top-right corner ##
# 4 # x-radius of bottom-right corner ##
# 5 # y-radius of bottom-right corner ##
# 6 # x-radius of bottom-left corner ##
# 7 # y-radius of bottom-left corner ##
#Table ##
If dir is kCW_Direction, Round_Rect starts at top-left of the lower-left corner
and winds clockwise. If dir is kCCW_Direction, Round_Rect starts at the
bottom-left of the upper-left corner and winds counterclockwise.
If both radii on any side of rect exceed its length, all radii are scaled
uniformly until the corners fit. If either radius of a corner is less than or
equal to zero, both are treated as zero.
After appending, Path may be empty, or may contain: Rect, Oval, or RoundRect.
#Param rect bounds of Round_Rect ##
#Param radii array of 8 SkScalar values, a radius pair for each corner ##
#Param dir Direction to wind Round_Rect ##
#Example
void draw(SkCanvas* canvas) {
SkPaint paint;
paint.setAntiAlias(true);
SkScalar radii[] = { 80, 100, 0, 0, 40, 60, 0, 0 };
SkPath path;
SkMatrix rotate90;
rotate90.setRotate(90, 128, 128);
for (int i = 0; i < 4; ++i) {
path.addRoundRect({10, 10, 110, 110}, radii);
path.transform(rotate90);
}
canvas->drawPath(path, paint);
}
##
#SeeAlso addRRect SkCanvas::drawRoundRect
##
# ------------------------------------------------------------------------------
#Method void addRRect(const SkRRect& rrect, Direction dir = kCW_Direction)
Add rrect to Path, creating a new closed Contour. If
dir is kCW_Direction, rrect starts at top-left of the lower-left corner and
winds clockwise. If dir is kCCW_Direction, rrect starts at the bottom-left
of the upper-left corner and winds counterclockwise.
After appending, Path may be empty, or may contain: Rect, Oval, or Round_Rect.
#Param rrect bounds and radii of rounded rectangle ##
#Param dir Direction to wind Round_Rect ##
#Example
void draw(SkCanvas* canvas) {
SkPaint paint;
paint.setAntiAlias(true);
SkRRect rrect;
SkVector radii[] = {{50, 50}, {0, 0}, {0, 0}, {50, 50}};
rrect.setRectRadii({10, 10, 110, 110}, radii);
SkPath path;
SkMatrix rotate90;
rotate90.setRotate(90, 128, 128);
for (int i = 0; i < 4; ++i) {
path.addRRect(rrect);
path.transform(rotate90);
}
canvas->drawPath(path, paint);
}
##
#SeeAlso addRoundRect SkCanvas::drawRRect
##
# ------------------------------------------------------------------------------
#Method void addRRect(const SkRRect& rrect, Direction dir, unsigned start)
Add rrect to Path, creating a new closed Contour. If dir is kCW_Direction, rrect
winds clockwise; if dir is kCCW_Direction, rrect winds counterclockwise.
start determines the first point of rrect to add.
#Table
#Legend
# start # location ##
#Legend ##
# 0 # right of top-left corner ##
# 1 # left of top-right corner ##
# 2 # bottom of top-right corner ##
# 3 # top of bottom-right corner ##
# 4 # left of bottom-right corner ##
# 5 # right of bottom-left corner ##
# 6 # top of bottom-left corner ##
# 7 # bottom of top-left corner ##
#Table ##
After appending, Path may be empty, or may contain: Rect, Oval, or Round_Rect.
#Param rrect bounds and radii of rounded rectangle ##
#Param dir Direction to wind Round_Rect ##
#Param start index of initial point of Round_Rect ##
#Example
void draw(SkCanvas* canvas) {
SkPaint paint;
paint.setAntiAlias(true);
SkRRect rrect;
rrect.setRectXY({40, 40, 215, 215}, 50, 50);
SkPath path;
path.addRRect(rrect);
canvas->drawPath(path, paint);
for (int start = 0; start < 8; ++start) {
SkPath textPath;
textPath.addRRect(rrect, SkPath::kCW_Direction, start);
canvas->drawTextOnPathHV(&"01234567"[start], 1, textPath, 0, -5, paint);
}
}
##
#SeeAlso addRoundRect SkCanvas::drawRRect
##
# ------------------------------------------------------------------------------
#Method void addPoly(const SkPoint pts[], int count, bool close)
Add Contour created from Line array, adding (count - 1) Line segments.
Contour added starts at pts[0], then adds a line for every additional Point
in pts array. If close is true,appends kClose_Verb to Path, connecting
pts[count - 1] and pts[0].
If count is zero, append kMove_Verb to path.
Has no effect if count is less than one.
#Param pts array of Line sharing end and start Point ##
#Param count length of Point array ##
#Param close true to add Line connecting Contour end and start ##
#Example
void draw(SkCanvas* canvas) {
SkPaint paint;
paint.setStrokeWidth(15);
paint.setStrokeCap(SkPaint::kRound_Cap);
const SkPoint points[] = {{20, 20}, {70, 20}, {40, 90}};
for (bool close : { false, true } ) {
SkPath path;
path.addPoly(points, SK_ARRAY_COUNT(points), close);
for (auto style : {SkPaint::kStroke_Style, SkPaint::kFill_Style,
SkPaint::kStrokeAndFill_Style} ) {
paint.setStyle(style);
canvas->drawPath(path, paint);
canvas->translate(85, 0);
}
canvas->translate(-255, 128);
}
}
##
#SeeAlso SkCanvas::drawPoints
##
# ------------------------------------------------------------------------------
#Enum AddPathMode
#Code
enum AddPathMode {
kAppend_AddPathMode,
kExtend_AddPathMode,
};
##
AddPathMode chooses how addPath appends. Adding one Path to another can extend
the last Contour or start a new Contour.
#Const kAppend_AddPathMode
Path Verbs, Points, and Conic_Weights are appended to destination unaltered.
Since Path Verb_Array begins with kMove_Verb if src is not empty, this
starts a new Contour.
##
#Const kExtend_AddPathMode
If destination is closed or empty, start a new Contour. If destination
is not empty, add Line from Last_Point to added Path first Point. Skip added
Path initial kMove_Verb, then append remining Verbs, Points, and Conic_Weights.
##
#Example
#Description
test is built from path, open on the top row, and closed on the bottom row.
The left column uses kAppend_AddPathMode; the right uses kExtend_AddPathMode.
The top right composition is made up of one contour; the other three have two.
##
#Height 180
SkPath path, path2;
path.moveTo(20, 20);
path.lineTo(20, 40);
path.lineTo(40, 20);
path2.moveTo(60, 60);
path2.lineTo(80, 60);
path2.lineTo(80, 40);
SkPaint paint;
paint.setStyle(SkPaint::kStroke_Style);
for (int i = 0; i < 2; i++) {
for (auto addPathMode : { SkPath::kAppend_AddPathMode, SkPath::kExtend_AddPathMode } ) {
SkPath test(path);
test.addPath(path2, addPathMode);
canvas->drawPath(test, paint);
canvas->translate(100, 0);
}
canvas->translate(-200, 100);
path.close();
}
##
#SeeAlso addPath reverseAddPath
##
# ------------------------------------------------------------------------------
#Method void addPath(const SkPath& src, SkScalar dx, SkScalar dy,
AddPathMode mode = kAppend_AddPathMode)
Append src to Path, offset by (dx, dy).
If mode is kAppend_AddPathMode, src Verb_Array, Point_Array, and Conic_Weights are
added unaltered. If mode is kExtend_AddPathMode, add Line before appending
Verbs, Points, and Conic_Weights.
#Param src Path Verbs, Points, and Conic_Weights to add ##
#Param dx offset added to src Point_Array x coordinates ##
#Param dy offset added to src Point_Array y coordinates ##
#Param mode kAppend_AddPathMode or kExtend_AddPathMode ##
#Example
#Height 180
SkPaint paint;
paint.setTextSize(128);
paint.setFakeBoldText(true);
SkPath dest, text;
paint.getTextPath("O", 1, 50, 120, &text);
for (int i = 0; i < 3; i++) {
dest.addPath(text, i * 20, i * 20);
}
Simplify(dest, &dest);
paint.setStyle(SkPaint::kStroke_Style);
paint.setStrokeWidth(3);
canvas->drawPath(dest, paint);
##
#SeeAlso AddPathMode offset() reverseAddPath
##
# ------------------------------------------------------------------------------
#Method void addPath(const SkPath& src, AddPathMode mode = kAppend_AddPathMode)
Append src to Path.
If mode is kAppend_AddPathMode, src Verb_Array, Point_Array, and Conic_Weights are
added unaltered. If mode is kExtend_AddPathMode, add Line before appending
Verbs, Points, and Conic_Weights.
#Param src Path Verbs, Points, and Conic_Weights to add ##
#Param mode kAppend_AddPathMode or kExtend_AddPathMode ##
#Example
#Height 80
SkPaint paint;
paint.setStyle(SkPaint::kStroke_Style);
SkPath dest, path;
path.addOval({-80, 20, 0, 60}, SkPath::kCW_Direction, 1);
for (int i = 0; i < 2; i++) {
dest.addPath(path, SkPath::kExtend_AddPathMode);
dest.offset(100, 0);
}
canvas->drawPath(dest, paint);
##
#SeeAlso AddPathMode reverseAddPath
##
# ------------------------------------------------------------------------------
#Method void addPath(const SkPath& src, const SkMatrix& matrix, AddPathMode mode = kAppend_AddPathMode)
Append src to Path, transformed by matrix. Transformed curves may have different
Verbs, Points, and Conic_Weights.
If mode is kAppend_AddPathMode, src Verb_Array, Point_Array, and Conic_Weights are
added unaltered. If mode is kExtend_AddPathMode, add Line before appending
Verbs, Points, and Conic_Weights.
#Param src Path Verbs, Points, and Conic_Weights to add ##
#Param matrix transform applied to src ##
#Param mode kAppend_AddPathMode or kExtend_AddPathMode ##
#Example
#Height 160
SkPaint paint;
paint.setStyle(SkPaint::kStroke_Style);
SkPath dest, path;
path.addOval({20, 20, 200, 120}, SkPath::kCW_Direction, 1);
for (int i = 0; i < 6; i++) {
SkMatrix matrix;
matrix.reset();
matrix.setPerspX(i / 400.f);
dest.addPath(path, matrix);
}
canvas->drawPath(dest, paint);
##
#SeeAlso AddPathMode transform() offset() reverseAddPath
##
# ------------------------------------------------------------------------------
#Method void reverseAddPath(const SkPath& src)
Append src to Path, from back to front.
Reversed src always appends a new Contour to Path.
#Param src Path Verbs, Points, and Conic_Weights to add ##
#Example
#Height 200
SkPath path;
path.moveTo(20, 20);
path.lineTo(20, 40);
path.lineTo(40, 20);
SkPaint paint;
paint.setStyle(SkPaint::kStroke_Style);
for (int i = 0; i < 2; i++) {
SkPath path2;
path2.moveTo(60, 60);
path2.lineTo(80, 60);
path2.lineTo(80, 40);
for (int j = 0; j < 2; j++) {
SkPath test(path);
test.reverseAddPath(path2);
canvas->drawPath(test, paint);
canvas->translate(100, 0);
path2.close();
}
canvas->translate(-200, 100);
path.close();
}
##
#SeeAlso AddPathMode transform() offset() addPath
##
# ------------------------------------------------------------------------------
#Method void offset(SkScalar dx, SkScalar dy, SkPath* dst) const
Offset Point_Array by (dx, dy). Offset Path replaces dst.
If dst is nullptr, Path is replaced by offset data.
#Param dx offset added to Point_Array x coordinates ##
#Param dy offset added to Point_Array y coordinates ##
#Param dst overwritten, translated copy of Path; may be nullptr ##
#Example
#Height 60
SkPath pattern;
pattern.moveTo(20, 20);
pattern.lineTo(20, 40);
pattern.lineTo(40, 20);
SkPaint paint;
paint.setStyle(SkPaint::kStroke_Style);
for (int i = 0; i < 10; i++) {
SkPath path;
pattern.offset(20 * i, 0, &path);
canvas->drawPath(path, paint);
}
##
#SeeAlso addPath transform
##
# ------------------------------------------------------------------------------
#Method void offset(SkScalar dx, SkScalar dy)
Offset Point_Array by (dx, dy). Path is replaced by offset data.
#Param dx offset added to Point_Array x coordinates ##
#Param dy offset added to Point_Array y coordinates ##
#Example
#Height 60
SkPath path;
path.moveTo(20, 20);
path.lineTo(20, 40);
path.lineTo(40, 20);
SkPaint paint;
paint.setStyle(SkPaint::kStroke_Style);
for (int i = 0; i < 10; i++) {
canvas->drawPath(path, paint);
path.offset(20, 0);
}
##
#SeeAlso addPath transform SkCanvas::translate()
##
# ------------------------------------------------------------------------------
#Method void transform(const SkMatrix& matrix, SkPath* dst) const
Transform Verb_Array, Point_Array, and weight by matrix.
transform may change Verbs and increase their number.
Transformed Path replaces dst; if dst is nullptr, original data
is replaced.
#Param matrix Matrix to apply to Path ##
#Param dst overwritten, transformed copy of Path; may be nullptr ##
#Example
#Height 200
SkPath pattern;
pattern.moveTo(100, 100);
pattern.lineTo(100, 20);
pattern.lineTo(20, 100);
SkPaint paint;
paint.setStyle(SkPaint::kStroke_Style);
for (int i = 0; i < 10; i++) {
SkPath path;
SkMatrix matrix;
matrix.setRotate(36 * i, 100, 100);
pattern.transform(matrix, &path);
canvas->drawPath(path, paint);
}
##
#SeeAlso addPath offset SkCanvas::concat() SkMatrix
##
# ------------------------------------------------------------------------------
#Method void transform(const SkMatrix& matrix)
Transform Verb_Array, Point_Array, and weight by matrix.
transform may change Verbs and increase their number.
Path is replaced by transformed data.
#Param matrix Matrix to apply to Path ##
#Example
#Height 200
SkPath path;
path.moveTo(100, 100);
path.quadTo(100, 20, 20, 100);
SkPaint paint;
paint.setStyle(SkPaint::kStroke_Style);
for (int i = 0; i < 10; i++) {
SkMatrix matrix;
matrix.setRotate(36, 100, 100);
path.transform(matrix);
canvas->drawPath(path, paint);
}
##
#SeeAlso addPath offset SkCanvas::concat() SkMatrix
##
# ------------------------------------------------------------------------------
#Subtopic Last_Point
Path is defined cumulatively, often by adding a segment to the end of last
Contour. Last_Point of Contour is shared as first Point of added Line or Curve.
Last_Point can be read and written directly with getLastPt and setLastPt.
#Method bool getLastPt(SkPoint* lastPt) const
Returns Last_Point on Path in lastPt. Returns false if Point_Array is empty,
storing (0, 0) if lastPt is not nullptr.
#Param lastPt storage for final Point in Point_Array; may be nullptr ##
#Return true if Point_Array contains one or more Points ##
#Example
SkPath path;
path.moveTo(100, 100);
path.quadTo(100, 20, 20, 100);
SkMatrix matrix;
matrix.setRotate(36, 100, 100);
path.transform(matrix);
SkPoint last;
path.getLastPt(&last);
SkDebugf("last point: %g, %g\n", last.fX, last.fY);
#StdOut
last point: 35.2786, 52.9772
##
##
#SeeAlso setLastPt
##
#Method void setLastPt(SkScalar x, SkScalar y)
Set Last_Point to (x, y). If Point_Array is empty, append kMove_Verb to
Verb_Array and (x, y) to Point_Array.
#Param x set x-coordinate of Last_Point ##
#Param y set y-coordinate of Last_Point ##
#Example
#Height 128
SkPaint paint;
paint.setTextSize(128);
SkPath path;
paint.getTextPath("@", 1, 60, 100, &path);
path.setLastPt(20, 120);
canvas->drawPath(path, paint);
##
#SeeAlso getLastPt
##
#Method void setLastPt(const SkPoint& p)
Set the last point on the path. If no points have been added, moveTo(p)
is automatically called.
#Param p set value of Last_Point ##
#Example
#Height 128
SkPaint paint;
paint.setTextSize(128);
SkPath path, path2;
paint.getTextPath("A", 1, 60, 100, &path);
paint.getTextPath("Z", 1, 60, 100, &path2);
SkPoint pt, pt2;
path.getLastPt(&pt);
path2.getLastPt(&pt2);
path.setLastPt(pt2);
path2.setLastPt(pt);
canvas->drawPath(path, paint);
canvas->drawPath(path2, paint);
##
#SeeAlso getLastPt
##
#Subtopic Last_Point ##
# ------------------------------------------------------------------------------
#Enum SegmentMask
#Code
enum SegmentMask {
kLine_SegmentMask = 1 << 0,
kQuad_SegmentMask = 1 << 1,
kConic_SegmentMask = 1 << 2,
kCubic_SegmentMask = 1 << 3,
};
##
SegmentMask constants correspond to each drawing Verb type in Path; for
instance, if Path only contains Lines, only the kLine_SegmentMask bit is set.
#Bug 6785 ##
#Const kLine_SegmentMask 1
Set if Verb_Array contains kLine_Verb.
##
#Const kQuad_SegmentMask 2
Set if Verb_Array contains kQuad_Verb. Note that conicTo may add a Quad.
##
#Const kConic_SegmentMask 4
Set if Verb_Array contains kConic_Verb.
##
#Const kCubic_SegmentMask 8
Set if Verb_Array contains kCubic_Verb.
##
#Example
#Description
When conicTo has a weight of one, Quad is added to Path.
##
SkPath path;
path.conicTo(10, 10, 20, 30, 1);
SkDebugf("Path kConic_SegmentMask is %s\n", path.getSegmentMasks() &
SkPath::kConic_SegmentMask ? "set" : "clear");
SkDebugf("Path kQuad_SegmentMask is %s\n", path.getSegmentMasks() &
SkPath::kQuad_SegmentMask ? "set" : "clear");
#StdOut
Path kConic_SegmentMask is clear
Path kQuad_SegmentMask is set
##
##
#SeeAlso getSegmentMasks Verb
##
# ------------------------------------------------------------------------------
#Method uint32_t getSegmentMasks() const
Returns a mask, where each set bit corresponds to a SegmentMask constant
if Path contains one or more Verbs of that type.
Returns zero if Path contains no Lines, or Curves: Quads, Conics, or Cubics.
getSegmentMasks() returns a cached result; it is very fast.
#Return SegmentMask bits or zero ##
#Example
SkPath path;
path.quadTo(20, 30, 40, 50);
path.close();
const char* masks[] = { "line", "quad", "conic", "cubic" };
int index = 0;
for (auto mask : { SkPath::kLine_SegmentMask, SkPath::kQuad_SegmentMask,
SkPath::kConic_SegmentMask, SkPath::kCubic_SegmentMask } ) {
if (mask & path.getSegmentMasks()) {
SkDebugf("mask %s set\n", masks[index]);
}
++index;
}
#StdOut
mask quad set
##
##
#SeeAlso getSegmentMasks Verb
##
# ------------------------------------------------------------------------------
#Method bool contains(SkScalar x, SkScalar y) const
Returns true if the point (x, y) is contained by Path, taking into
account FillType.
#Table
#Legend
# FillType # contains() returns true if Point is enclosed by ##
##
# kWinding_FillType # a non-zero sum of Contour Directions. ##
# kEvenOdd_FillType # an odd number of Contours. ##
# kInverseWinding_FillType # a zero sum of Contour Directions. ##
# kInverseEvenOdd_FillType # and even number of Contours. ##
##
#Param x x-coordinate of containment test ##
#Param y y-coordinate of containment test ##
#Return true if Point is in Path ##
#Example
SkPath path;
SkPaint paint;
paint.setTextSize(256);
paint.getTextPath("&", 1, 30, 220, &path);
for (int y = 2; y < 256; y += 9) {
for (int x = 2; x < 256; x += 9) {
int coverage = 0;
for (int iy = -4; iy <= 4; iy += 2) {
for (int ix = -4; ix <= 4; ix += 2) {
coverage += path.contains(x + ix, y + iy);
}
}
paint.setColor(SkColorSetARGB(0x5f, 0xff * coverage / 25, 0, 0xff * (25 - coverage) / 25));
canvas->drawCircle(x, y, 8, paint);
}
}
##
#SeeAlso conservativelyContainsRect Fill_Type Op
##
# ------------------------------------------------------------------------------
#Method void dump(SkWStream* stream, bool forceClose, bool dumpAsHex) const
Writes text representation of Path to stream. If stream is nullptr, writes to
standard output. Set forceClose to true to get edges used to fill Path.
Set dumpAsHex true to generate exact binary representations
of floating point numbers used in Point_Array and Conic_Weights.
#Param stream writable Stream receiving Path text representation; may be nullptr ##
#Param forceClose true if missing kClose_Verb is output ##
#Param dumpAsHex true if SkScalar values are written as hexadecimal ##
#Example
SkPath path;
path.quadTo(20, 30, 40, 50);
for (bool forceClose : { false, true } ) {
for (bool dumpAsHex : { false, true } ) {
path.dump(nullptr, forceClose, dumpAsHex);
SkDebugf("\n");
}
}
#StdOut
path.setFillType(SkPath::kWinding_FillType);
path.moveTo(0, 0);
path.quadTo(20, 30, 40, 50);
path.setFillType(SkPath::kWinding_FillType);
path.moveTo(SkBits2Float(0x00000000), SkBits2Float(0x00000000)); // 0, 0
path.quadTo(SkBits2Float(0x41a00000), SkBits2Float(0x41f00000), SkBits2Float(0x42200000), SkBits2Float(0x42480000)); // 20, 30, 40, 50
path.setFillType(SkPath::kWinding_FillType);
path.moveTo(0, 0);
path.quadTo(20, 30, 40, 50);
path.lineTo(0, 0);
path.close();
path.setFillType(SkPath::kWinding_FillType);
path.moveTo(SkBits2Float(0x00000000), SkBits2Float(0x00000000)); // 0, 0
path.quadTo(SkBits2Float(0x41a00000), SkBits2Float(0x41f00000), SkBits2Float(0x42200000), SkBits2Float(0x42480000)); // 20, 30, 40, 50
path.lineTo(SkBits2Float(0x00000000), SkBits2Float(0x00000000)); // 0, 0
path.close();
##
##
#SeeAlso SkRect::dump() SkRRect::dump() SkPathMeasure::dump()
##
# ------------------------------------------------------------------------------
#Method void dump() const
Writes text representation of Path to standard output. The representation may be
directly compiled as C++ code. Floating point values are written
with limited precision; it may not be possible to reconstruct original Path
from output.
#Example
SkPath path, copy;
path.lineTo(6.f / 7, 2.f / 3);
path.dump();
copy.setFillType(SkPath::kWinding_FillType);
copy.moveTo(0, 0);
copy.lineTo(0.857143f, 0.666667f);
SkDebugf("path is " "%s" "equal to copy\n", path == copy ? "" : "not ");
#StdOut
path.setFillType(SkPath::kWinding_FillType);
path.moveTo(0, 0);
path.lineTo(0.857143f, 0.666667f);
path is not equal to copy
##
##
#SeeAlso dumpHex SkRect::dump() SkRRect::dump() SkPathMeasure::dump() writeToMemory
##
# ------------------------------------------------------------------------------
#Method void dumpHex() const
Writes text representation of Path to standard output. The representation may be
directly compiled as C++ code. Floating point values are written
in hexadecimal to preserve their exact bit pattern. The output reconstructs the
original Path.
Use instead of dump() when submitting
#A bug reports against Skia # http://bug.skia.org ##
.
#Example
SkPath path, copy;
path.lineTo(6.f / 7, 2.f / 3);
path.dumpHex();
copy.setFillType(SkPath::kWinding_FillType);
copy.moveTo(SkBits2Float(0x00000000), SkBits2Float(0x00000000)); // 0, 0
copy.lineTo(SkBits2Float(0x3f5b6db7), SkBits2Float(0x3f2aaaab)); // 0.857143f, 0.666667f
SkDebugf("path is " "%s" "equal to copy\n", path == copy ? "" : "not ");
#StdOut
path.setFillType(SkPath::kWinding_FillType);
path.moveTo(SkBits2Float(0x00000000), SkBits2Float(0x00000000)); // 0, 0
path.lineTo(SkBits2Float(0x3f5b6db7), SkBits2Float(0x3f2aaaab)); // 0.857143f, 0.666667f
path is equal to copy
##
##
#SeeAlso dump SkRect::dumpHex() SkRRect::dumpHex() writeToMemory
##
# ------------------------------------------------------------------------------
#Method size_t writeToMemory(void* buffer) const
Writes Path to buffer, returning the number of bytes written.
Pass nullptr to obtain the storage size.
Writes Fill_Type, Verb_Array, Point_Array, Conic_Weight, and
additionally writes computed information like Convexity and bounds.
Use only be used in concert with readFromMemory;
the format used for Path in memory is not guaranteed.
#Param buffer storage for Path; may be nullptr ##
#Return size of storage required for Path; always a multiple of 4 ##
#Example
void draw(SkCanvas* canvas) {
SkPath path, copy;
path.lineTo(6.f / 7, 2.f / 3);
size_t size = path.writeToMemory(nullptr);
SkTDArray<char> storage;
storage.setCount(size);
path.writeToMemory(storage.begin());
copy.readFromMemory(storage.begin(), size);
SkDebugf("path is " "%s" "equal to copy\n", path == copy ? "" : "not ");
}
#StdOut
path is equal to copy
##
##
#SeeAlso serialize readFromMemory dump dumpHex
##
#Method sk_sp<SkData> serialize() const
Write Path to buffer, returning the buffer written to, wrapped in Data.
serialize() writes Fill_Type, Verb_Array, Point_Array, Conic_Weight, and
additionally writes computed information like Convexity and bounds.
serialize() should only be used in concert with readFromMemory.
The format used for Path in memory is not guaranteed.
#Return Path data wrapped in Data buffer ##
#Example
void draw(SkCanvas* canvas) {
SkPath path, copy;
path.lineTo(6.f / 7, 2.f / 3);
sk_sp<SkData> data = path.serialize();
copy.readFromMemory(data->data(), data->size());
SkDebugf("path is " "%s" "equal to copy\n", path == copy ? "" : "not ");
}
#StdOut
path is equal to copy
##
##
#SeeAlso writeToMemory readFromMemory dump dumpHex
##
# ------------------------------------------------------------------------------
#Method size_t readFromMemory(const void* buffer, size_t length)
Initializes Path from buffer of size length. Returns zero if the buffer is
data is inconsistent, or the length is too small.
Reads Fill_Type, Verb_Array, Point_Array, Conic_Weight, and
additionally reads computed information like Convexity and bounds.
Used only in concert with writeToMemory;
the format used for Path in memory is not guaranteed.
#Param buffer storage for Path ##
#Param length buffer size in bytes; must be multiple of 4 ##
#Return number of bytes read, or zero on failure ##
#Example
void draw(SkCanvas* canvas) {
SkPath path, copy;
path.lineTo(6.f / 7, 2.f / 3);
size_t size = path.writeToMemory(nullptr);
SkTDArray<char> storage;
storage.setCount(size);
path.writeToMemory(storage.begin());
size_t wrongSize = size - 4;
size_t bytesRead = copy.readFromMemory(storage.begin(), wrongSize);
SkDebugf("length = %u; returned by readFromMemory = %u\n", wrongSize, bytesRead);
size_t largerSize = size + 4;
bytesRead = copy.readFromMemory(storage.begin(), largerSize);
SkDebugf("length = %u; returned by readFromMemory = %u\n", largerSize, bytesRead);
}
#StdOut
length = 60; returned by readFromMemory = 0
length = 68; returned by readFromMemory = 64
##
##
#SeeAlso writeToMemory
##
# ------------------------------------------------------------------------------
#Topic Generation_ID
#Alias Generation_IDs
Generation_ID provides a quick way to check if Verb_Array, Point_Array, or
Conic_Weight has changed. Generation_ID is not a hash; identical Paths will
not necessarily have matching Generation_IDs.
Empty Paths have a Generation_ID of one.
#Method uint32_t getGenerationID() const
Returns a non-zero, globally unique value. A different value is returned
if Verb_Array, Point_Array, or Conic_Weight changes.
Setting Fill_Type does not change Generation_ID.
Each time the path is modified, a different Generation_ID will be returned.
#Bug 1762
Fill_Type does affect Generation_ID on Android framework.
##
#Return non-zero, globally unique value ##
#Example
SkPath path;
SkDebugf("empty genID = %u\n", path.getGenerationID());
path.lineTo(1, 2);
SkDebugf("1st lineTo genID = %u\n", path.getGenerationID());
path.rewind();
SkDebugf("empty genID = %u\n", path.getGenerationID());
path.lineTo(1, 2);
SkDebugf("2nd lineTo genID = %u\n", path.getGenerationID());
#StdOut
empty genID = 1
1st lineTo genID = 2
empty genID = 1
2nd lineTo genID = 3
##
##
#SeeAlso operator==(const SkPath& a, const SkPath& b)
##
#Topic ##
# ------------------------------------------------------------------------------
#Method bool isValid() const
Returns if Path data is consistent. Corrupt Path data is detected if
internal values are out of range or internal storage does not match
array dimensions.
#Return true if Path data is consistent ##
#NoExample
##
##
#Method bool pathRefIsValid() const
Returns if Path data is consistent.
#Deprecated
To be deprecated soon.
##
#Return true if Path data is consistent ##
#NoExample
##
##
# ------------------------------------------------------------------------------
#Class Iter
Iterates through Verb_Array, and associated Point_Array and Conic_Weight.
Provides options to treat open Contours as closed, and to ignore
degenerate data.
#Code
class Iter {
public:
Iter();
Iter(const SkPath& path, bool forceClose);
void setPath(const SkPath& path, bool forceClose);
Verb next(SkPoint pts[4], bool doConsumeDegenerates = true, bool exact = false);
SkScalar conicWeight() const;
bool isCloseLine() const;
bool isClosedContour() const;
};
##
#Example
#Height 128
#Description
Ignoring the actual Verbs and replacing them with Quads rounds the
path of the glyph.
##
void draw(SkCanvas* canvas) {
SkPaint paint;
paint.setAntiAlias(true);
paint.setTextSize(256);
SkPath asterisk, path;
paint.getTextPath("*", 1, 50, 192, &asterisk);
SkPath::Iter iter(asterisk, true);
SkPoint start[4], pts[4];
iter.next(start); // skip moveTo
iter.next(start); // first quadTo
path.moveTo((start[0] + start[1]) * 0.5f);
while (SkPath::kClose_Verb != iter.next(pts)) {
path.quadTo(pts[0], (pts[0] + pts[1]) * 0.5f);
}
path.quadTo(start[0], (start[0] + start[1]) * 0.5f);
canvas->drawPath(path, paint);
}
##
#SeeAlso RawIter
#Method Iter()
Initializes Iter with an empty Path. next() on Iter returns kDone_Verb.
Call setPath to initialize Iter at a later time.
#Return Iter of empty Path ##
#Example
void draw(SkCanvas* canvas) {
SkPath::Iter iter;
SkPoint points[4];
SkDebugf("iter is " "%s" "done\n", SkPath::kDone_Verb == iter.next(points) ? "" : "not ");
SkPath path;
iter.setPath(path, false);
SkDebugf("iter is " "%s" "done\n", SkPath::kDone_Verb == iter.next(points) ? "" : "not ");
}
#StdOut
iter is done
iter is done
##
##
#SeeAlso setPath
##
#Method Iter(const SkPath& path, bool forceClose)
Sets Iter to return elements of Verb_Array, Point_Array, and Conic_Weight in path.
If forceClose is true, Iter will add kLine_Verb and kClose_Verb after each
open Contour. path is not altered.
#Param path Path to iterate ##
#Param forceClose true if open Contours generate kClose_Verb ##
#Return Iter of path ##
#Example
void draw(SkCanvas* canvas) {
auto debugster = [](const char* prefix, SkPath::Iter& iter) -> void {
SkDebugf("%s:\n", prefix);
const char* verbStr[] = { "Move", "Line", "Quad", "Conic", "Cubic", "Close", "Done" };
const int pointCount[] = { 1 , 2 , 3 , 3 , 4 , 1 , 0 };
SkPath::Verb verb;
do {
SkPoint points[4];
verb = iter.next(points);
SkDebugf("k%s_Verb ", verbStr[(int) verb]);
for (int i = 0; i < pointCount[(int) verb]; ++i) {
SkDebugf("{%g, %g}, ", points[i].fX, points[i].fY);
}
if (SkPath::kConic_Verb == verb) {
SkDebugf("weight = %g", iter.conicWeight());
}
SkDebugf("\n");
} while (SkPath::kDone_Verb != verb);
SkDebugf("\n");
};
SkPath path;
path.quadTo(10, 20, 30, 40);
SkPath::Iter openIter(path, false);
debugster("open", openIter);
SkPath::Iter closedIter(path, true);
debugster("closed", closedIter);
}
#StdOut
open:
kMove_Verb {0, 0},
kQuad_Verb {0, 0}, {10, 20}, {30, 40},
kDone_Verb
closed:
kMove_Verb {0, 0},
kQuad_Verb {0, 0}, {10, 20}, {30, 40},
kLine_Verb {30, 40}, {0, 0},
kClose_Verb {0, 0},
kDone_Verb
##
##
#SeeAlso setPath
##
#Method void setPath(const SkPath& path, bool forceClose)
Sets Iter to return elements of Verb_Array, Point_Array, and Conic_Weight in path.
If forceClose is true, Iter will add kLine_Verb and kClose_Verb after each
open Contour. path is not altered.
#Param path Path to iterate ##
#Param forceClose true if open Contours generate kClose_Verb ##
#Example
void draw(SkCanvas* canvas) {
auto debugster = [](const char* prefix, SkPath::Iter& iter) -> void {
SkDebugf("%s:\n", prefix);
const char* verbStr[] = { "Move", "Line", "Quad", "Conic", "Cubic", "Close", "Done" };
const int pointCount[] = { 1 , 2 , 3 , 3 , 4 , 1 , 0 };
SkPath::Verb verb;
do {
SkPoint points[4];
verb = iter.next(points);
SkDebugf("k%s_Verb ", verbStr[(int) verb]);
for (int i = 0; i < pointCount[(int) verb]; ++i) {
SkDebugf("{%g, %g}, ", points[i].fX, points[i].fY);
}
if (SkPath::kConic_Verb == verb) {
SkDebugf("weight = %g", iter.conicWeight());
}
SkDebugf("\n");
} while (SkPath::kDone_Verb != verb);
SkDebugf("\n");
};
SkPath path;
path.quadTo(10, 20, 30, 40);
SkPath::Iter iter(path, false);
debugster("quad open", iter);
SkPath path2;
path2.conicTo(1, 2, 3, 4, .5f);
iter.setPath(path2, true);
debugster("conic closed", iter);
}
#StdOut
quad open:
kMove_Verb {0, 0},
kQuad_Verb {0, 0}, {10, 20}, {30, 40},
kDone_Verb
conic closed:
kMove_Verb {0, 0},
kConic_Verb {0, 0}, {1, 2}, {3, 4}, weight = 0.5
kLine_Verb {3, 4}, {0, 0},
kClose_Verb {0, 0},
kDone_Verb
##
##
#SeeAlso Iter(const SkPath& path, bool forceClose)
##
#Method Verb next(SkPoint pts[4], bool doConsumeDegenerates = true, bool exact = false)
Returns next Verb in Verb_Array, and advances Iter.
When Verb_Array is exhausted, returns kDone_Verb.
Zero to four Points are stored in pts, depending on the returned Verb.
If doConsumeDegenerates is true, skip consecutive kMove_Verb entries, returning
only the last in the series; and skip very small Lines, Quads, and Conics; and
skip kClose_Verb following kMove_Verb.
if doConsumeDegenerates is true and exact is true, only skip Lines, Quads, and
Conics with zero lengths.
#Param pts storage for Point data describing returned Verb ##
#Param doConsumeDegenerates if true, skip degenerate Verbs ##
#Param exact skip zero length curves ##
#Return next Verb from Verb_Array ##
#Example
#Description
skip degenerate skips the first in a kMove_Verb pair, the kMove_Verb
followed by the kClose_Verb, the zero length Line and the very small Line.
skip degenerate if exact skips the same as skip degenerate, but shows
the very small Line.
skip none shows all of the Verbs and Points in Path.
##
void draw(SkCanvas* canvas) {
auto debugster = [](const char* prefix, const SkPath& path, bool degen, bool exact) -> void {
SkPath::Iter iter(path, false);
SkDebugf("%s:\n", prefix);
const char* verbStr[] = { "Move", "Line", "Quad", "Conic", "Cubic", "Close", "Done" };
const int pointCount[] = { 1 , 2 , 3 , 3 , 4 , 1 , 0 };
SkPath::Verb verb;
do {
SkPoint points[4];
verb = iter.next(points, degen, exact);
SkDebugf("k%s_Verb ", verbStr[(int) verb]);
for (int i = 0; i < pointCount[(int) verb]; ++i) {
SkDebugf("{%1.8g, %1.8g}, ", points[i].fX, points[i].fY);
}
SkDebugf("\n");
} while (SkPath::kDone_Verb != verb);
SkDebugf("\n");
};
SkPath path;
path.moveTo(10, 10);
path.moveTo(20, 20);
path.quadTo(10, 20, 30, 40);
path.moveTo(1, 1);
path.close();
path.moveTo(30, 30);
path.lineTo(30, 30);
path.moveTo(30, 30);
path.lineTo(30.00001f, 30);
debugster("skip degenerate", path, true, false);
debugster("skip degenerate if exact", path, true, true);
debugster("skip none", path, false, false);
}
#StdOut
skip degenerate:
kMove_Verb {20, 20},
kQuad_Verb {20, 20}, {10, 20}, {30, 40},
kDone_Verb
skip degenerate if exact:
kMove_Verb {20, 20},
kQuad_Verb {20, 20}, {10, 20}, {30, 40},
kMove_Verb {30, 30},
kLine_Verb {30, 30}, {30.00001, 30},
kDone_Verb
skip none:
kMove_Verb {10, 10},
kMove_Verb {20, 20},
kQuad_Verb {20, 20}, {10, 20}, {30, 40},
kMove_Verb {1, 1},
kClose_Verb {1, 1},
kMove_Verb {30, 30},
kLine_Verb {30, 30}, {30, 30},
kMove_Verb {30, 30},
kLine_Verb {30, 30}, {30.00001, 30},
kDone_Verb
##
##
#SeeAlso Verb IsLineDegenerate IsCubicDegenerate IsQuadDegenerate
##
#Method SkScalar conicWeight() const
Returns Conic_Weight if next() returned kConic_Verb.
If next() has not been called, or next() did not return kConic_Verb,
result is undefined.
#Return Conic_Weight for Conic Points returned by next() ##
#Example
void draw(SkCanvas* canvas) {
SkPath path;
path.conicTo(1, 2, 3, 4, .5f);
SkPath::Iter iter(path, false);
SkPoint p[4];
SkDebugf("first verb is " "%s" "move\n", SkPath::kMove_Verb == iter.next(p) ? "" : "not ");
SkDebugf("next verb is " "%s" "conic\n", SkPath::kConic_Verb == iter.next(p) ? "" : "not ");
SkDebugf("conic points: {%g,%g}, {%g,%g}, {%g,%g}\n", p[0].fX, p[0].fY, p[1].fX, p[1].fY,
p[2].fX, p[2].fY);
SkDebugf("conic weight: %g\n", iter.conicWeight());
}
#StdOut
first verb is move
next verb is conic
conic points: {0,0}, {1,2}, {3,4}
conic weight: 0.5
##
##
#SeeAlso Conic_Weight
##
#Method bool isCloseLine() const
Returns true if last kLine_Verb returned by next() was generated
by kClose_Verb. When true, the end point returned by next() is
also the start point of Contour.
If next() has not been called, or next() did not return kLine_Verb,
result is undefined.
#Return true if last kLine_Verb was generated by kClose_Verb ##
#Example
void draw(SkCanvas* canvas) {
SkPath path;
path.moveTo(6, 7);
path.conicTo(1, 2, 3, 4, .5f);
path.close();
SkPath::Iter iter(path, false);
SkPoint p[4];
SkDebugf("1st verb is " "%s" "move\n", SkPath::kMove_Verb == iter.next(p) ? "" : "not ");
SkDebugf("moveTo point: {%g,%g}\n", p[0].fX, p[0].fY);
SkDebugf("2nd verb is " "%s" "conic\n", SkPath::kConic_Verb == iter.next(p) ? "" : "not ");
SkDebugf("3rd verb is " "%s" "line\n", SkPath::kLine_Verb == iter.next(p) ? "" : "not ");
SkDebugf("line points: {%g,%g}, {%g,%g}\n", p[0].fX, p[0].fY, p[1].fX, p[1].fY);
SkDebugf("line " "%s" "generated by close\n", iter.isCloseLine() ? "" : "not ");
SkDebugf("4th verb is " "%s" "close\n", SkPath::kClose_Verb == iter.next(p) ? "" : "not ");
}
#StdOut
1st verb is move
moveTo point: {6,7}
2nd verb is conic
3rd verb is line
line points: {3,4}, {6,7}
line generated by close
4th verb is close
##
##
#SeeAlso close()
##
#Method bool isClosedContour() const
Returns true if subsequent calls to next() return kClose_Verb before returning
kMove_Verb. if true, Contour Iter is processing may end with kClose_Verb, or
Iter may have been initialized with force close set to true.
#Return true if Contour is closed ##
#Example
void draw(SkCanvas* canvas) {
for (bool forceClose : { false, true } ) {
SkPath path;
path.conicTo(1, 2, 3, 4, .5f);
SkPath::Iter iter(path, forceClose);
SkDebugf("without close(), forceClose is %s: isClosedContour returns %s\n",
forceClose ? "true " : "false", iter.isClosedContour() ? "true" : "false");
path.close();
iter.setPath(path, forceClose);
SkDebugf("with close(), forceClose is %s: isClosedContour returns %s\n",
forceClose ? "true " : "false", iter.isClosedContour() ? "true" : "false");
}
}
#StdOut
without close(), forceClose is false: isClosedContour returns false
with close(), forceClose is false: isClosedContour returns true
without close(), forceClose is true : isClosedContour returns true
with close(), forceClose is true : isClosedContour returns true
##
##
#SeeAlso Iter(const SkPath& path, bool forceClose)
##
#Class Iter ##
#Class RawIter
Iterates through Verb_Array, and associated Point_Array and Conic_Weight.
Verb_Array, Point_Array, and Conic_Weight are returned unaltered.
#Code
class RawIter {
public:
RawIter();
RawIter(const SkPath& path);
void setPath(const SkPath& path);
Verb next(SkPoint pts[4]);
Verb peek() const;
SkScalar conicWeight() const;
}
##
#Method RawIter()
Initializes RawIter with an empty Path. next() on RawIter returns kDone_Verb.
Call setPath to initialize Iter at a later time.
#Return RawIter of empty Path ##
#NoExample
##
##
#Method RawIter(const SkPath& path)
Sets RawIter to return elements of Verb_Array, Point_Array, and Conic_Weight in path.
#Param path Path to iterate ##
#Return RawIter of path ##
#NoExample
##
##
#Method void setPath(const SkPath& path)
Sets Iter to return elements of Verb_Array, Point_Array, and Conic_Weight in path.
#Param path Path to iterate ##
#NoExample
##
##
#Method Verb next(SkPoint pts[4])
Returns next Verb in Verb_Array, and advances RawIter.
When Verb_Array is exhausted, returns kDone_Verb.
Zero to four Points are stored in pts, depending on the returned Verb.
#Param pts storage for Point data describing returned Verb ##
#Return next Verb from Verb_Array ##
#Example
void draw(SkCanvas* canvas) {
SkPath path;
path.moveTo(50, 60);
path.quadTo(10, 20, 30, 40);
path.close();
path.lineTo(30, 30);
path.conicTo(1, 2, 3, 4, .5f);
path.cubicTo(-1, -2, -3, -4, -5, -6);
SkPath::RawIter iter(path);
const char* verbStr[] = { "Move", "Line", "Quad", "Conic", "Cubic", "Close", "Done" };
const int pointCount[] = { 1 , 2 , 3 , 3 , 4 , 1 , 0 };
SkPath::Verb verb;
do {
SkPoint points[4];
verb = iter.next(points);
SkDebugf("k%s_Verb ", verbStr[(int) verb]);
for (int i = 0; i < pointCount[(int) verb]; ++i) {
SkDebugf("{%1.8g, %1.8g}, ", points[i].fX, points[i].fY);
}
if (SkPath::kConic_Verb == verb) {
SkDebugf("weight = %g", iter.conicWeight());
}
SkDebugf("\n");
} while (SkPath::kDone_Verb != verb);
}
#StdOut
kMove_Verb {50, 60},
kQuad_Verb {50, 60}, {10, 20}, {30, 40},
kClose_Verb {50, 60},
kMove_Verb {50, 60},
kLine_Verb {50, 60}, {30, 30},
kConic_Verb {30, 30}, {1, 2}, {3, 4}, weight = 0.5
kCubic_Verb {3, 4}, {-1, -2}, {-3, -4}, {-5, -6},
kDone_Verb
##
##
#SeeAlso peek()
##
#Method Verb peek() const
Returns next Verb, but does not advance RawIter.
#Return next Verb from Verb_Array ##
#Example
SkPath path;
path.quadTo(10, 20, 30, 40);
path.conicTo(1, 2, 3, 4, .5f);
path.cubicTo(1, 2, 3, 4, .5, 6);
SkPath::RawIter iter(path);
SkPath::Verb verb, peek = iter.peek();
const char* verbStr[] = { "Move", "Line", "Quad", "Conic", "Cubic", "Close", "Done" };
do {
SkPoint points[4];
verb = iter.next(points);
SkDebugf("peek %s %c= verb %s\n", verbStr[peek], peek == verb ? '=' : '!', verbStr[verb]);
peek = iter.peek();
} while (SkPath::kDone_Verb != verb);
SkDebugf("peek %s %c= verb %s\n", verbStr[peek], peek == verb ? '=' : '!', verbStr[verb]);
#StdOut
#Volatile
peek Move == verb Move
peek Quad == verb Quad
peek Conic == verb Conic
peek Cubic == verb Cubic
peek Done == verb Done
peek Done == verb Done
##
##
#Bug 6832
StdOut isn't really volatile, it just produces the wrong result.
A simple fix changes the output of hairlines and needs to be
investigated to see if the change is correct or not.
https://skia-review.googlesource.com/c/21340/
##
#SeeAlso next()
##
#Method SkScalar conicWeight() const
Returns Conic_Weight if next() returned kConic_Verb.
If next() has not been called, or next() did not return kConic_Verb,
result is undefined.
#Return Conic_Weight for Conic Points returned by next() ##
#Example
void draw(SkCanvas* canvas) {
SkPath path;
path.conicTo(1, 2, 3, 4, .5f);
SkPath::RawIter iter(path);
SkPoint p[4];
SkDebugf("first verb is " "%s" "move\n", SkPath::kMove_Verb == iter.next(p) ? "" : "not ");
SkDebugf("next verb is " "%s" "conic\n", SkPath::kConic_Verb == iter.next(p) ? "" : "not ");
SkDebugf("conic points: {%g,%g}, {%g,%g}, {%g,%g}\n", p[0].fX, p[0].fY, p[1].fX, p[1].fY,
p[2].fX, p[2].fY);
SkDebugf("conic weight: %g\n", iter.conicWeight());
}
#StdOut
first verb is move
next verb is conic
conic points: {0,0}, {1,2}, {3,4}
conic weight: 0.5
##
##
#SeeAlso Conic_Weight
##
#Class RawIter ##
#Class SkPath ##
#Topic Path ##
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