Cary Clark f960398f33 polish picture and rrect docs

TBR=caryclark@google.com

Docs-Preview: https://skia.org/?cl=141263
Bug: skia:6818
Change-Id: I33a197892b3dd5788499dda9dd9e95ddab861388
Reviewed-on: https://skia-review.googlesource.com/141263
Commit-Queue: Cary Clark <caryclark@skia.org>
Auto-Submit: Cary Clark <caryclark@skia.org>
Reviewed-by: Cary Clark <caryclark@skia.org>

2018-07-17 12:47:40 +00:00

320 KiB

Raw Blame History

SkPath Reference

Path

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

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.

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

Path is drawn filled, then stroked, then stroked and filled.

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.

Contour

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

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.

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

Path is drawn stroked, with an open Contour and a closed Contour.

Contour Zero Length

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

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.

Overview

Topic	Description
Class Declarations	embedded class members
Constants	enum and enum class, and their const values
Constructors	functions that construct SkPath
Functions	global and class member functions
Operators	operator overloading methods
Related Functions	similar member functions grouped together

Related Function

SkPath global, struct, and class related member functions share a topic.

Topic	Description
Arc	part of Oval or Circle
Build	adds points and verbs to path
Conic	conic section defined by three points and a weight
Conic Weight	strength of Conic control Point
Contour	loop of lines and curves
Contour Zero Length	consideration when contour has no length
Convexity	if Path is concave or convex
Cubic	curve described by third-order polynomial
Direction	contour orientation, clockwise or counterclockwise
Fill Type	fill rule, normal and inverted
Generation ID	value reflecting contents change
Interpolate	weighted average of Path pair
Last Point	final Point in Contour
Point Array	end points and control points for lines and curves
Property	metrics and attributes
Quad	curve described by second-order polynomial
Transform	modify all points
Utility	rarely called management functions
Verb	line and curve type
Verb Array	line and curve type for points
Volatile	caching attribute

Constant

SkPath related constants are defined by enum, enum class, #define, const, and constexpr.

Topic	Description
AddPathMode	sets addPath options
ArcSize	used by arcTo variation
Convexity	returns if Path is convex or concave
Direction	sets Contour clockwise or counterclockwise
FillType	sets winding rule and inverse fill
SegmentMask	returns Verb types in Path
Verb	controls how Path Points are interpreted
kAppend AddPathMode	appended to destination unaltered
kCCW Direction	contour travels counterclockwise
kCW Direction	contour travels clockwise
kClose Verb	closes Contour
kConcave Convexity	more than one Contour, or a geometry with indentations
kConic SegmentMask	contains one or more Conics
kConic Verb	adds Conic from Last Point
kConvex Convexity	one Contour made of a simple geometry without indentations
kCubic SegmentMask	contains one or more Cubics
kCubic Verb	adds Cubic from Last Point
kDone Verb	terminates Path
kEvenOdd FillType	is enclosed by an odd number of Contours
kExtend AddPathMode	add line if prior Contour is not closed
kInverseEvenOdd FillType	is enclosed by an even number of Contours
kInverseWinding FillType	is enclosed by a zero sum of Contour Directions
kLarge ArcSize	larger of Arc pair
kLine SegmentMask	contains one or more Lines
kLine Verb	adds Line from Last Point to next Point
kMove Verb	starts new Contour at next Point
kQuad SegmentMask	contains one or more Quads
kQuad Verb	adds Quad from Last Point
kSmall ArcSize	smaller of Arc pair
kUnknown Convexity	indicates Convexity has not been determined
kWinding FillType	is enclosed by a non-zero sum of Contour Directions

Class

SkPath uses C++ classes to declare the public data structures and interfaces.

Topic	Description
Iter	data iterator
RawIter	raw data iterator

Constructor

SkPath can be constructed or initialized by these functions, including C++ class constructors.

Topic	Description
SkPath()	constructs with default values
SkPath(const SkPath& path)	makes a shallow copy
reset	removes Verb Array, Point Array, and Weights; frees memory
rewind	removes Verb Array, Point Array, and Weights, keeping memory
~SkPath()	decreases Reference Count of owned objects

Operator

SkPath operators inline class member functions with arithmetic equivalents.

Topic	Description
operator!=(const SkPath& a, const SkPath& b)	compares paths for inequality
operator=(const SkPath& path)	makes a shallow copy
operator==(const SkPath& a, const SkPath& b)	compares paths for equality
swap	exchanges Path pair

Member Function

SkPath member functions read and modify the structure properties.

Topic	Description
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 to stream
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	reserves 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, keeping memory
serialize	copies data to buffer
setConvexity	sets if geometry is convex to avoid future computation
setFillType	sets Fill Type: winding, even-odd, inverse
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
updateBoundsCache	refreshes result of getBounds
writeToMemory	copies data to buffer

Verb

Enum SkPath::Verb

    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.

Constants

Each Verb has zero or more Points stored in Path. Path iterator returns complete curve descriptions, duplicating shared Points for consecutive entries.

Const	Value	Description
`SkPath::kMove_Verb`	0	Consecutive kMove Verb are preserved but all but the last kMove Verb is ignored. kMove Verb after other Verbs implicitly closes the previous Contour if SkPaint::kFill Style is set when drawn; otherwise, stroke is drawn open. kMove Verb as the last Verb is preserved but ignored.
`SkPath::kLine_Verb`	1	Line is a straight segment from Point to Point. Consecutive kLine Verb extend Contour. kLine Verb at same position as prior kMove Verb is preserved, and draws Point if SkPaint::kStroke Style is set, and SkPaint::Cap is SkPaint::kSquare Cap or SkPaint::kRound Cap. kLine Verb at same position as prior line or curve Verb is preserved but is ignored.
`SkPath::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.
`SkPath::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.
`SkPath::kCubic_Verb`	4	Adds Cubic from Last Point, using two control Points, and end Point. Cubic is a third-order Bezier Curve section within tangents from Last Point to first control Point, and from second control Point to end Point.
`SkPath::kClose_Verb`	5	Closes Contour, connecting Last Point to kMove Verb Point. Consecutive kClose Verb are preserved but only first has an effect. kClose Verb after kMove Verb has no effect.
`SkPath::kDone_Verb`	6	Not in Verb Array, but returned by Path iterator.

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

Example Output

verb count: 7
verbs: kMove_Verb kLine_Verb kQuad_Verb kClose_Verb kMove_Verb kCubic_Verb kConic_Verb

Direction

Enum SkPath::Direction

    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.

Constants

Const	Value	Description
`SkPath::kCW_Direction`	0	contour travels clockwise
`SkPath::kCCW_Direction`	1	contour travels counterclockwise

Example

SkPath

SkPath()

Constucts an empty path. By default, Path has no Verbs, no Points, and no Weights. Fill Type is set to kWinding FillType.

Return Value

empty Path

Example

Example Output

path is empty

SkPath

SkPath(const SkPath& path)

Constructs a copy of an existing 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.

Parameters

path Path to copy by value

Return Value

copy of Path

Example

Modifying one path does not effect another, even if they started as copies of each other.

Example Output

path verbs: 2
path2 verbs: 3
after reset
path verbs: 0
path2 verbs: 3

~SkPath

~SkPath()

Releases ownership of any shared data and deletes data if Path is sole owner.

Example

delete calls Path Destructor, but copy of original in path2 is unaffected.

operator=

SkPath& operator=(const SkPath& path)

Constructs a copy of an existing 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.

Parameters

path Verb Array, Point Array, Weights, and Fill Type to copy

Return Value

Path copied by value

Example

Example Output

path1 bounds = 10, 20, 30, 40
path2 bounds = 10, 20, 30, 40

operator==

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.

Parameters

`a`	Path to compare
`b`	Path to compare

Return Value

true if Path pair are equivalent

Example

Rewind removes Verb Array but leaves storage; since storage is not compared, Path pair are equivalent.

Example Output

empty one == two
moveTo one != two
rewind one == two
reset one == two

operator!=

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.

Parameters

`a`	Path to compare
`b`	Path to compare

Return Value

true if Path pair are not equivalent

Example

Path pair are equal though their convexity is not equal.

Example Output

empty one == two
addRect one == two
setConvexity one == two
convexity !=

Property

Topic	Description
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
computeTightBounds	returns extent of geometry
conservativelyContainsRect	returns true if Rect may be inside
contains	returns if Point is in fill area
getBounds	returns maximum and minimum of Point Array
getLastPt	returns Last Point
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
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

isInterpolatable

bool isInterpolatable(const SkPath& compare) const

Returns 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.

Parameters

compare Path to compare

Return Value

true if Paths Verb Array and Weights are equivalent

Example

Example Output

paths are interpolatable

Interpolate

Topic	Description
interpolate	interpolates between Path pair

interpolate

bool interpolate(const SkPath& ending, SkScalar weight, SkPath* out) const

Interpolates between Paths with Point Array of equal size. 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: (Path Point * weight) + ending Point * (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.

Parameters

`ending`	Point Array averaged with this Point Array
`weight`	contribution of this Point Array, and one minus contribution of ending Point Array
`out`	Path replaced by interpolated averages

Return Value

true if Paths contain same number of Points

Example

unique

bool unique() const

Deprecated.

soonOnly valid for Android framework.

Fill Type

Enum SkPath::FillType

    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

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.

Constants

Const	Value	Description
`SkPath::kWinding_FillType`	0	is enclosed by a non-zero sum of Contour Directions
`SkPath::kEvenOdd_FillType`	1	is enclosed by an odd number of Contours
`SkPath::kInverseWinding_FillType`	2	is enclosed by a zero sum of Contour Directions
`SkPath::kInverseEvenOdd_FillType`	3	is enclosed by an even number of Contours

Example

getFillType

FillType getFillType() const

Returns FillType, the rule used to fill Path. FillType of a new Path is kWinding FillType.

Return Value

one of: kWinding FillType, kEvenOdd FillType, kInverseWinding FillType, kInverseEvenOdd FillType

Example

Example Output

default path fill type is kWinding_FillType

setFillType

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.

Parameters

`ft`	one of: kWinding FillType, kEvenOdd FillType, kInverseWinding FillType, kInverseEvenOdd FillType

Example

If empty Path is set to inverse FillType, it fills all pixels.

isInverseFillType

bool isInverseFillType() const

Returns if FillType describes area outside Path geometry. The inverse fill area extends indefinitely.

Return Value

true if FillType is kInverseWinding FillType or kInverseEvenOdd FillType

Example

Example Output

default path fill type is inverse: false

toggleInverseFillType

void toggleInverseFillType()

Replaces FillType with its inverse. The inverse of FillType describes the area unmodified by the original FillType.

FillType	toggled FillType
kWinding FillType	kInverseWinding FillType
kEvenOdd FillType	kInverseEvenOdd FillType
kInverseWinding FillType	kWinding FillType
kInverseEvenOdd FillType	kEvenOdd FillType

Example

Path drawn normally and through its inverse touches every pixel once.

Convexity

Enum SkPath::Convexity

    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.

Constants

Const	Value	Description
`SkPath::kUnknown_Convexity`	0	indicates Convexity has not been determined
`SkPath::kConvex_Convexity`	1	one Contour made of a simple geometry without indentations
`SkPath::kConcave_Convexity`	2	more than one Contour, or a geometry with indentations

Example

getConvexity

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 Value

computed or stored Convexity

Example

getConvexityOrUnknown

Convexity getConvexityOrUnknown() const

Returns last computed Convexity, or kUnknown Convexity if Path has been altered since Convexity was computed or set.

Return Value

stored Convexity

Example

Convexity is unknown unless getConvexity is called without a subsequent call that alters the path.

setConvexity

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.

Parameters

convexity one of: kUnknown Convexity, kConvex Convexity, or kConcave Convexity

Example

isConvex

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 Value

true if Convexity stored or computed is kConvex Convexity

Example

Concave shape is erroneously considered convex after a forced call to setConvexity.

isOval

bool isOval(SkRect* bounds) const

Returns true if this path is recognized as an oval or circle.

bounds receives bounds of Oval.

bounds is unmodified if Oval is not found.

Parameters

bounds storage for bounding Rect of Oval; may be nullptr

Return Value

true if Path is recognized as an oval or circle

Example

isRRect

bool isRRect(SkRRect* rrect) const

Returns true if this path is recognized as a SkRRect (but not an oval/circle or rect).

rrect receives bounds of Round Rect.

rrect is unmodified if Round Rect is not found.

Parameters

rrect storage for bounding Rect of Round Rect; may be nullptr

Return Value

true if Path contains only Round Rect

Example

Draw rounded rectangle and its bounds.

reset

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

Although path1 retains its internal storage, it is indistinguishable from a newly initialized path.

isEmpty

bool isEmpty() const

Returns if Path is empty. Empty Path may have FillType but has no SkPoint, Verb, or Conic Weight. SkPath() constructs empty Path; reset and (rewind) make Path empty.

Return Value

true if the path contains no Verb array

Example

Example Output

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

isLastContourClosed

bool isLastContourClosed() const

Returns if Contour is closed. 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 Value

true if the last Contour ends with a kClose Verb

Example

close has no effect if Path is empty; isLastContourClosed returns false until Path has geometry followed by close.

Example Output

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

isFinite

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 Value

true if all Point values are finite

Example

Example Output

initial path is finite
after line path is finite
after scale path is not finite

isVolatile

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 Value

true if caller will alter Path after drawing

Example

Example Output

volatile by default is false

Volatile

Topic	Description
setIsVolatile	sets if Device should not cache

setIsVolatile

void setIsVolatile(bool isVolatile)

Specifies 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.

Parameters

isVolatile true if caller will alter Path after drawing

Example

IsLineDegenerate

static bool IsLineDegenerate(const SkPoint& p1, const SkPoint& p2, bool exact)

Tests 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.

Parameters

`p1`	line start point
`p2`	line end point
`exact`	if false, allow nearly equals

Return Value

true if Line is degenerate; its length is effectively zero

Example

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.

Example Output

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

IsQuadDegenerate

static bool IsQuadDegenerate(const SkPoint& p1, const SkPoint& p2, const SkPoint& p3, bool exact)

Tests if Quad is degenerate. Quad with no length or that moves a very short distance is degenerate; it is treated as a point.

Parameters

`p1`	Quad start point
`p2`	Quad control point
`p3`	Quad end point
`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 Value

true if Quad is degenerate; its length is effectively zero

Example

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.

Example Output

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

IsCubicDegenerate

static bool IsCubicDegenerate(const SkPoint& p1, const SkPoint& p2, const SkPoint& p3,
                              const SkPoint& p4, bool exact)

Tests if Cubic is degenerate. Cubic with no length or that moves a very short distance is degenerate; it is treated as a point.

Parameters

`p1`	Cubic start point
`p2`	Cubic control point 1
`p3`	Cubic control point 2
`p4`	Cubic end point
`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 Value

true if Cubic is degenerate; its length is effectively zero

Example

Example Output

0.00024414062 is degenerate
0.00024414065 is length

isLine

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.

Parameters

line storage for Line. May be nullptr

Return Value

true if Path contains exactly one Line

Example

Example Output

empty is not line
zero line is line (0,0) (0,0)
line is line (10,10) (20,20)
second move is not line

Point Array

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.

getPoints

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.

Parameters

`points`	storage for Path Point array. May be nullptr
`max`	maximum to copy; must be greater than or equal to zero

Return Value

Path Point array length

Example

Example Output

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)

countPoints

int countPoints() const

Returns the number of points in Path. Point count is initially zero.

Return Value

Path Point array length

Example

Example Output

empty point count: 0
zero line point count: 2
line point count: 2
second move point count: 3

getPoint

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.

Parameters

index Point array element selector

Return Value

Point array value or (0, 0)

Example

Example Output

point 0: (-10,-10)
point 1: (10,10)

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.

countVerbs

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 Value

length of Verb Array

Example

Example Output

empty verb count: 0
round rect verb count: 10

getVerbs

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.

Parameters

`verbs`	storage for verbs, may be nullptr
`max`	maximum number to copy into verbs

Return Value

the actual number of verbs in the path

Example

Example Output

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

swap

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.

Parameters

other Path exchanged by value

Example

Example Output

path1 bounds = 0, 0, 0, 0
path2 bounds = 10, 20, 30, 40

getBounds

const SkRect& getBounds() const

Returns minimum and maximum axes 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 Value

bounds of all Points in Point Array

Example

Bounds of upright Circle can be predicted from center and radius. Bounds of rotated Circle includes control Points outside of filled area.

Example Output

empty bounds = 0, 0, 0, 0
circle bounds = 25, 20, 75, 70
rotated circle bounds = 14.6447, 9.64466, 85.3553, 80.3553

Utility

Topic	Description
ConvertConicToQuads	approximates Conic with Quad array
ConvertToNonInverseFillType	returns Fill Type representing inside geometry
dump	sends text representation to stream
	dump(SkWStream* stream, bool forceClose, bool dumpAsHex) const
	dump const
dumpHex	sends text representation using hexadecimal to standard output
getSegmentMasks	returns types in Verb Array
incReserve	reserves space for additional data
readFromMemory	initializes from buffer
serialize	copies data to buffer
setLastPt	replaces Last Point
	setLastPt(SkScalar x, SkScalar y)
updateBoundsCache	refreshes result of getBounds
writeToMemory	copies data to buffer

updateBoundsCache

void updateBoundsCache() const

Updates 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

Example Output

#Volatile
uncached avg: 0.18048 ms
cached avg: 0.182784 ms

computeTightBounds

SkRect computeTightBounds() const

Returns minimum and maximum axes 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 Value

tight bounds of curves in Path

Example

Example Output

empty bounds = 0, 0, 0, 0
circle bounds = 25, 20, 75, 70
rotated circle bounds = 25, 20, 75, 70

conservativelyContainsRect

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.

Parameters

rect Rect, Line, or Point checked for containment

Return Value

true if rect is contained

Example

Rect is drawn in blue if it is contained by red Path.

incReserve

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.

Parameters

extraPtCount number of additional Points to allocate

Example

Build

Topic	Description
addArc	adds one Contour containing Arc
addCircle	adds one Contour containing Circle
addOval	adds one Contour containing Oval
	addOval(const SkRect& oval, Direction dir = kCW Direction)
	addOval(const SkRect& oval, Direction dir, unsigned start)
addPath	adds contents of Path
	addPath(const SkPath& src, SkScalar dx, SkScalar dy, AddPathMode mode = kAppend AddPathMode)
	addPath(const SkPath& src, AddPathMode mode = kAppend AddPathMode)
	addPath(const SkPath& src, const SkMatrix& matrix, AddPathMode mode = kAppend AddPathMode)
addPoly	adds one Contour containing connected lines
addRRect	adds one Contour containing Round Rect
	addRRect(const SkRRect& rrect, Direction dir = kCW Direction)
	addRRect(const SkRRect& rrect, Direction dir, unsigned start)
addRect	adds one Contour containing Rect
	addRect(const SkRect& rect, Direction dir = kCW Direction)
	addRect(const SkRect& rect, Direction dir, unsigned start)
	addRect(SkScalar left, SkScalar top, SkScalar right, SkScalar bottom, Direction dir = kCW Direction)
addRoundRect	adds one Contour containing Round Rect with common corner radii
	addRoundRect(const SkRect& rect, SkScalar rx, SkScalar ry, Direction dir = kCW Direction)
	addRoundRect(const SkRect& rect, const SkScalar radii[], Direction dir = kCW Direction)
arcTo	appends Arc
	arcTo(const SkRect& oval, SkScalar startAngle, SkScalar sweepAngle, bool forceMoveTo)
close	makes last Contour a loop
cubicTo	appends Cubic
	cubicTo(SkScalar x1, SkScalar y1, SkScalar x2, SkScalar y2, SkScalar x3, SkScalar y3)
lineTo	appends Line
	lineTo(SkScalar x, SkScalar y)
	lineTo(const SkPoint& p)
moveTo	starts Contour
	moveTo(SkScalar x, SkScalar y)
	moveTo(const SkPoint& p)
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
reverseAddPath	adds contents of Path back to front

moveTo

void moveTo(SkScalar x, SkScalar y)

Adds beginning of Contour at Point (x, y).

Parameters

`x`	x-axis value of Contour start
`y`	y-axis value of Contour start

Example

Parameters

`p`	contour start

Example

rMoveTo

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".

Parameters

`dx`	offset from Last Point to Contour start on x-axis
`dy`	offset from Last Point to Contour start on y-axis

Example

lineTo

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.

Parameters

`x`	end of added Line in x
`y`	end of added Line in y

Example

Parameters

`p`	end Point of added Line

Example

rLineTo

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".

Parameters

`dx`	offset from Last Point to Line end on x-axis
`dy`	offset from Last Point to Line end on y-axis

Example

Quad

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

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

quadTo

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.

Parameters

`x1`	control Point of Quad in x
`y1`	control Point of Quad in y
`x2`	end Point of Quad in x
`y2`	end Point of Quad in y

Example

Parameters

`p1`	control Point of added Quad
`p2`	end Point of added Quad

Example

rQuadTo

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".

Parameters

`dx1`	offset from Last Point to Quad control on x-axis
`dy1`	offset from Last Point to Quad control on y-axis
`dx2`	offset from Last Point to Quad end on x-axis
`dy2`	offset from Last Point to Quad end on y-axis

Example

Conic

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.

Conic Weight

Weight determines both the strength of the control Point and the type of Conic. Weight varies from zero to infinity. At zero, Weight causes the control Point to have no effect; Conic is identical to a line segment from start Point to end point. If Weight is less than one, Conic follows an elliptical arc. If Weight is exactly one, then Conic is identical to Quad; Conic follows a parabolic arc. If Weight is greater than one, Conic follows a hyperbolic arc. If Weight is infinity, Conic is identical to two line segments, connecting start Point to control Point, and control Point to end Point.

Example

When Conic Weight is one, Quad is added to path; the two are identical.

Example Output

move {0, 0},
quad {0, 0}, {20, 30}, {50, 60},
done

If weight is less than one, Conic is an elliptical segment.

Example

A 90 degree circular arc has the weight1 / sqrt(2).

Example Output

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

Example Output

move {0, 0},
line {0, 0}, {20, 0},
line {20, 0}, {20, 20},
done

conicTo

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.

Parameters

`x1`	control Point of Conic in x
`y1`	control Point of Conic in y
`x2`	end Point of Conic in x
`y2`	end Point of Conic in y
`w`	weight of added Conic

Example

As weight increases, curve is pulled towards control point. The bottom two curves are elliptical; the next is parabolic; the top curve is hyperbolic.

Parameters

`p1`	control Point of added Conic
`p2`	end Point of added Conic
`w`	weight of added Conic

Example

Conics and arcs use identical representations. As the arc sweep increases the Conic Weight also increases, but remains smaller than one.

rConicTo

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".

Parameters

`dx1`	offset from Last Point to Conic control on x-axis
`dy1`	offset from Last Point to Conic control on y-axis
`dx2`	offset from Last Point to Conic end on x-axis
`dy2`	offset from Last Point to Conic end on y-axis
`w`	weight of added Conic

Example

Cubic

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

cubicTo

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.

Parameters

`x1`	first control Point of Cubic in x
`y1`	first control Point of Cubic in y
`x2`	second control Point of Cubic in x
`y2`	second control Point of Cubic in y
`x3`	end Point of Cubic in x
`y3`	end Point of Cubic in y

Example

Parameters

`p1`	first control Point of Cubic
`p2`	second control Point of Cubic
`p3`	end Point of Cubic

Example

rCubicTo

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".

Parameters

`x1`	offset from Last Point to first Cubic control on x-axis
`y1`	offset from Last Point to first Cubic control on y-axis
`x2`	offset from Last Point to second Cubic control on x-axis
`y2`	offset from Last Point to second Cubic control on y-axis
`x3`	offset from Last Point to Cubic end on x-axis
`y3`	offset from Last Point to Cubic end on y-axis

Example

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.

Example

¹ arcTo(const SkRect& oval, SkScalar startAngle, SkScalar sweepAngle, bool forceMoveTo)

² parameter sets force MoveTo

³ start angle must be multiple of 90 degrees

⁴ arcTo(SkScalar x1, SkScalar y1, SkScalar x2, SkScalar y2, SkScalar radius)

⁵ arcTo(SkScalar rx, SkScalar ry, SkScalar xAxisRotate, ArcSize largeArc, Direction sweep, SkScalar x, SkScalar y)

Example

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.

arcTo

void arcTo(const SkRect& oval, SkScalar startAngle, SkScalar sweepAngle, bool forceMoveTo)

Appends 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.

Parameters

`oval`	bounds of ellipse containing Arc
`startAngle`	starting angle of Arc in degrees
`sweepAngle`	sweep, in degrees. Positive is clockwise; treated modulo 360
`forceMoveTo`	true to start a new contour with Arc

Example

arcTo continues a previous contour when forceMoveTo is false and when Path is not empty.

Example

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

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.

Parameters

`x1`	x-axis value common to pair of tangents
`y1`	y-axis value common to pair of tangents
`x2`	x-axis value end of second tangent
`y2`	y-axis value end of second tangent
`radius`	distance from Arc to Circle center

Example

arcTo is represented by Line and circular Conic in Path.

Example Output

move to (156,20)
line (156,20),(79.2893,20)
conic (79.2893,20),(200,20),(114.645,105.355) weight 0.382683

Parameters

`p1`	Point common to pair of tangents
`p2`	end of second tangent
`radius`	distance from Arc to Circle center

Example

Because tangent lines are parallel, arcTo appends line from last Path Point to p1, but does not append a circular Conic.

Example Output

move to (156,20)
line (156,20),(200,20)

Enum SkPath::ArcSize

    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.

Constants

Const	Value	Description
`SkPath::kSmall_ArcSize`	0	smaller of Arc pair
`SkPath::kLarge_ArcSize`	1	larger of Arc pair

Example

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.

Parameters

`rx`	radius in x before x-axis rotation
`ry`	radius in y before x-axis rotation
`xAxisRotate`	x-axis rotation in degrees; positive values are clockwise
`largeArc`	chooses smaller or larger Arc
`sweep`	chooses clockwise or counterclockwise Arc
`x`	end of Arc
`y`	end of Arc

Example

Parameters

`r`	radii on axes before x-axis rotation
`xAxisRotate`	x-axis rotation in degrees; positive values are clockwise
`largeArc`	chooses smaller or larger Arc
`sweep`	chooses clockwise or counterclockwise Arc
`xy`	end of Arc

Example

rArcTo

void rArcTo(SkScalar rx, SkScalar ry, SkScalar xAxisRotate, ArcSize largeArc, Direction sweep,
            SkScalar dx, SkScalar dy)

Appends 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:

(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.

Parameters

`rx`	radius before x-axis rotation
`ry`	radius before x-axis rotation
`xAxisRotate`	x-axis rotation in degrees; positive values are clockwise
`largeArc`	chooses smaller or larger Arc
`sweep`	chooses clockwise or counterclockwise Arc
`dx`	x-axis offset end of Arc from last Path Point
`dy`	y-axis offset end of Arc from last Path Point

Example

close

void close()

Appends 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

IsInverseFillType

static bool IsInverseFillType(FillType fill)

Returns true if fill is inverted and Path with fill represents area outside of its geometric bounds.

FillType	is inverse
kWinding FillType	false
kEvenOdd FillType	false
kInverseWinding FillType	true
kInverseEvenOdd FillType	true

Parameters

fill one of: kWinding FillType, kEvenOdd FillType, kInverseWinding FillType, kInverseEvenOdd FillType

Return Value

true if Path fills outside its bounds

Example

Example Output

IsInverseFillType(kWinding_FillType) == false
IsInverseFillType(kEvenOdd_FillType) == false
IsInverseFillType(kInverseWinding_FillType) == true
IsInverseFillType(kInverseEvenOdd_FillType) == true

ConvertToNonInverseFillType

static FillType ConvertToNonInverseFillType(FillType fill)

Returns equivalent Fill Type representing Path fill inside its bounds. .

FillType	inside FillType
kWinding FillType	kWinding FillType
kEvenOdd FillType	kEvenOdd FillType
kInverseWinding FillType	kWinding FillType
kInverseEvenOdd FillType	kEvenOdd FillType

Parameters

fill one of: kWinding FillType, kEvenOdd FillType, kInverseWinding FillType, kInverseEvenOdd FillType

Return Value

fill, or kWinding FillType or kEvenOdd FillType if fill is inverted

Example

Example Output

ConvertToNonInverseFillType(kWinding_FillType) == kWinding_FillType
ConvertToNonInverseFillType(kEvenOdd_FillType) == kEvenOdd_FillType
ConvertToNonInverseFillType(kInverseWinding_FillType) == kWinding_FillType
ConvertToNonInverseFillType(kInverseEvenOdd_FillType) == kEvenOdd_FillType

ConvertConicToQuads

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: (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.

Parameters

`p0`	Conic start Point
`p1`	Conic control Point
`p2`	Conic end Point
`w`	Conic weight
`pts`	storage for Quad array
`pow2`	Quad count, as power of two, normally 0 to 5 (1 to 32 Quad curves)

Return Value

number of Quad curves written to pts

Example

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.

isRect

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.

Parameters

`rect`	storage for bounds of Rect; may be nullptr
`isClosed`	storage set to true if Path is closed; may be nullptr
`direction`	storage set to Rect direction; may be nullptr

Return Value

true if Path contains Rect

Example

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.

Example Output

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

isNestedFillRects

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.

Parameters

`rect`	storage for Rect pair; may be nullptr
`dirs`	storage for Direction pair; may be nullptr

Return Value

true if Path contains nested Rect pair

Example

Example Output

outer (7.5, 17.5, 32.5, 42.5); direction CW
inner (12.5, 22.5, 27.5, 37.5); direction CCW

addRect

void addRect(const SkRect& rect, Direction dir = kCW Direction)

Adds 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.

Parameters

`rect`	Rect to add as a closed contour
`dir`	Direction to wind added contour

Example

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.

Parameters

`rect`	Rect to add as a closed contour
`dir`	Direction to wind added contour
`start`	initial corner of Rect to add

Example

The arrow is just after the initial corner and points towards the next corner appended to Path.

Parameters

`left`	smaller x-axis value of Rect
`top`	smaller y-axis value of Rect
`right`	larger x-axis value of Rect
`bottom`	larger y-axis value of Rect
`dir`	Direction to wind added contour

Example

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.

addOval

void addOval(const SkRect& oval, Direction dir = kCW Direction)

Adds 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.

Parameters

`oval`	bounds of ellipse added
`dir`	Direction to wind ellipse

Example

Parameters

`oval`	bounds of ellipse added
`dir`	Direction to wind ellipse
`start`	index of initial point of ellipse

Example

addCircle

void addCircle(SkScalar x, SkScalar y, SkScalar radius, Direction dir = kCW Direction)

Adds Circle centered at (x, y) of size radius to Path, appending kMove Verb, four kConic Verb, and kClose Verb. Circle begins at: (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.

Parameters

`x`	center of Circle
`y`	center of Circle
`radius`	distance from center to edge
`dir`	Direction to wind Circle

Example

addArc

void addArc(const SkRect& oval, SkScalar startAngle, SkScalar sweepAngle)

Appends 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.

Parameters

`oval`	bounds of ellipse containing Arc
`startAngle`	starting angle of Arc in degrees
`sweepAngle`	sweep, in degrees. Positive is clockwise; treated modulo 360

Example

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.

addRoundRect

void addRoundRect(const SkRect& rect, SkScalar rx, SkScalar ry, Direction dir = kCW Direction)

Appends 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.

Parameters

`rect`	bounds of Round Rect
`rx`	x-axis radius of rounded corners on the Round Rect
`ry`	y-axis radius of rounded corners on the Round Rect
`dir`	Direction to wind Round Rect

Example

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.

Parameters

`rect`	bounds of Round Rect
`radii`	array of 8 SkScalar values, a radius pair for each corner
`dir`	Direction to wind Round Rect

Example

addRRect

void addRRect(const SkRRect& rrect, Direction dir = kCW Direction)

Adds 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.

Parameters

`rrect`	bounds and radii of rounded rectangle
`dir`	Direction to wind Round Rect

Example

Parameters

`rrect`	bounds and radii of rounded rectangle
`dir`	Direction to wind Round Rect
`start`	index of initial point of Round Rect

Example

addPoly

void addPoly(const SkPoint pts[], int count, bool close)

Adds 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.

Parameters

`pts`	array of Line sharing end and start Point
`count`	length of Point array
`close`	true to add Line connecting Contour end and start

Example

Enum SkPath::AddPathMode

    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.

Constants

Const	Value	Description
`SkPath::kAppend_AddPathMode`	#Line # appended to destination unaltered ##	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.
`SkPath::kExtend_AddPathMode`	#Line # add line if prior Contour is not closed ##	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

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.

addPath

void addPath(const SkPath& src, SkScalar dx, SkScalar dy, AddPathMode mode = kAppend AddPathMode)

Appends 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.

Parameters

`src`	Path Verbs, Points, and Conic Weights to add
`dx`	offset added to src Point Array x-axis coordinates
`dy`	offset added to src Point Array y-axis coordinates
`mode`	kAppend AddPathMode or kExtend AddPathMode

Example

Parameters

`src`	Path Verbs, Points, and Conic Weights to add
`mode`	kAppend AddPathMode or kExtend AddPathMode

Example

Parameters

`src`	Path Verbs, Points, and Conic Weights to add
`matrix`	transform applied to src
`mode`	kAppend AddPathMode or kExtend AddPathMode

Example

reverseAddPath

void reverseAddPath(const SkPath& src)

Appends src to Path, from back to front. Reversed src always appends a new Contour to Path.

Parameters

src Path Verbs, Points, and Conic Weights to add

Example

offset

void offset(SkScalar dx, SkScalar dy, SkPath* dst) const

Offsets Point Array by (dx, dy). Offset Path replaces dst. If dst is nullptr, Path is replaced by offset data.

Parameters

`dx`	offset added to Point Array x-axis coordinates
`dy`	offset added to Point Array y-axis coordinates
`dst`	overwritten, translated copy of Path; may be nullptr

Example

Transform

Topic	Description
offset	translates Point Array
	offset(SkScalar dx, SkScalar dy, SkPath* dst) const
	offset(SkScalar dx, SkScalar dy)
transform	applies Matrix to Point Array and Weights
	transform(const SkMatrix& matrix, SkPath* dst) const
	transform(const SkMatrix& matrix)

void offset(SkScalar dx, SkScalar dy)

Offsets Point Array by (dx, dy). Path is replaced by offset data.

Parameters

`dx`	offset added to Point Array x-axis coordinates
`dy`	offset added to Point Array y-axis coordinates

Example

transform

void transform(const SkMatrix& matrix, SkPath* dst) const

Transforms 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.

Parameters

`matrix`	Matrix to apply to Path
`dst`	overwritten, transformed copy of Path; may be nullptr

Example

Parameters

matrix Matrix to apply to Path

Example

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.

getLastPt

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.

Parameters

lastPt storage for final Point in Point Array; may be nullptr

Return Value

true if Point Array contains one or more Points

Example

Example Output

last point: 35.2786, 52.9772

setLastPt

void setLastPt(SkScalar x, SkScalar y)

Sets Last Point to (x, y). If Point Array is empty, append kMove Verb to Verb Array and append (x, y) to Point Array.

Parameters

`x`	set x-axis value of Last Point
`y`	set y-axis value of Last Point

Example

Parameters

`p`	set value of Last Point

Example

Enum SkPath::SegmentMask

    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.

Constants

Const	Value	Description
`SkPath::kLine_SegmentMask`	1	Set if Verb Array contains kLine Verb.
`SkPath::kQuad_SegmentMask`	2	Set if Verb Array contains kQuad Verb. Note that conicTo may add a Quad.
`SkPath::kConic_SegmentMask`	4	Set if Verb Array contains kConic Verb.
`SkPath::kCubic_SegmentMask`	8	Set if Verb Array contains kCubic Verb.

Example

When conicTo has a weight of one, Quad is added to Path.

Example Output

Path kConic_SegmentMask is clear
Path kQuad_SegmentMask is set

getSegmentMasks

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 Value

SegmentMask bits or zero

Example

Example Output

mask quad set

contains

bool contains(SkScalar x, SkScalar y) const

Returns true if the point (x, y) is contained by Path, taking into account FillType.

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.

Parameters

`x`	x-axis value of containment test
`y`	y-axis value of containment test

Return Value

true if Point is in Path

Example

dump

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.

Parameters

`stream`	writable WStream receiving Path text representation; may be nullptr
`forceClose`	true if missing kClose Verb is output
`dumpAsHex`	true if SkScalar values are written as hexadecimal

Example

Example Output

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();

Example

Example Output

path.setFillType(SkPath::kWinding_FillType);
path.moveTo(0, 0);
path.lineTo(0.857143f, 0.666667f);
path is not equal to copy

dumpHex

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 bug reports against Skia .

Example

Example Output

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

writeToMemory

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.

Parameters

buffer storage for Path; may be nullptr

Return Value

size of storage required for Path; always a multiple of 4

Example

Example Output

path is equal to copy

serialize

sk sp<SkData> serialize() const

Writes 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 Value

Path data wrapped in Data buffer

Example

Example Output

path is equal to copy

readFromMemory

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.

Parameters

`buffer`	storage for Path
`length`	buffer size in bytes; must be multiple of 4

Return Value

number of bytes read, or zero on failure

Example

Example Output

length = 32; returned by readFromMemory = 0
length = 40; returned by readFromMemory = 36

Generation ID

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.

getGenerationID

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.

Fill Type does affect Generation ID on Android framework.

Return Value

non-zero, globally unique value

Example

Example Output

empty genID = 1
1st lineTo genID = 2
empty genID = 1
2nd lineTo genID = 3

isValid

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 Value

true if Path data is consistent

pathRefIsValid

bool pathRefIsValid() const

Deprecated.

soon

Class SkPath::Iter

Constructor

SkPath can be constructed or initialized by these functions, including C++ class constructors.

Topic	Description

Member_Function

SkPath member functions read and modify the structure properties.

Topic	Description

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;
};

Iterates through Verb Array, and associated Point Array and Conic Weight. Provides options to treat open Contours as closed, and to ignore degenerate data.

Example

Ignoring the actual Verbs and replacing them with Quads rounds the path of the glyph.

Iter

Iter()

Initializes Iter with an empty Path. next on Iter returns kDone Verb. Call setPath to initialize Iter at a later time.

Return Value

Iter of empty Path

Example

Example Output

iter is done
iter is done

Iter

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.

Parameters

`path`	Path to iterate
`forceClose`	true if open Contours generate kClose Verb

Return Value

Iter of path

Example

Example Output

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

Parameters

`path`	Path to iterate
`forceClose`	true if open Contours generate kClose Verb

Example

Example Output

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

Parameters

`pts`	storage for Point data describing returned Verb
`doConsumeDegenerates`	if true, skip degenerate Verbs
`exact`	skip zero length curves

Return Value

next Verb from Verb Array

Example

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.

Example Output

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

conicWeight

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 Value

Conic Weight for Conic Points returned by next

Example

Example Output

first verb is move
next verb is conic
conic points: {0,0}, {1,2}, {3,4}
conic weight: 0.5

isCloseLine

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 Value

true if last kLine Verb was generated by kClose Verb

Example

Example Output

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

isClosedContour

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 Value

true if Contour is closed

Example

Example Output

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

Class SkPath::RawIter

Constructor

SkPath can be constructed or initialized by these functions, including C++ class constructors.

Topic	Description

Member_Function

SkPath member functions read and modify the structure properties.

Topic	Description

    class RawIter {
    public:
        RawIter();
        RawIter(const SkPath& path);
        void setPath(const SkPath& path);
        Verb next(SkPoint pts[4]);
        Verb peek const;
        SkScalar conicWeight const;
    }

Iterates through Verb Array, and associated Point Array and Conic Weight. Verb Array, Point Array, and Conic Weight are returned unaltered.

RawIter

RawIter()

Initializes RawIter with an empty Path. next on RawIter returns kDone Verb. Call setPath to initialize SkPath::Iter at a later time.

Return Value

RawIter of empty Path

RawIter

RawIter(const SkPath& path)

Sets RawIter to return elements of Verb Array, Point Array, and Conic Weight in path.

Parameters

path Path to iterate

Return Value

RawIter of path

setPath

void setPath(const SkPath& path)

Sets SkPath::Iter to return elements of Verb Array, Point Array, and Conic Weight in path.

Parameters

path Path to iterate

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.

Parameters

pts storage for Point data describing returned Verb

Return Value

next Verb from Verb Array

Example

Example Output

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

Return Value

next Verb from Verb Array

Example

Example Output

#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

StdOut is not 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. see change 21340 (abandoned for now)

Return Value

Conic Weight for Conic Points returned by next

Example

Example Output

first verb is move
next verb is conic
conic points: {0,0}, {1,2}, {3,4}
conic weight: 0.5

start	Point
0	oval.centerX(), oval.fTop
1	oval.fRight, oval.centerY()
2	oval.centerX(), oval.fBottom
3	oval.fLeft, oval.centerY()

radii index	location
0	x-axis radius of top-left corner
1	y-axis radius of top-left corner
2	x-axis radius of top-right corner
3	y-axis radius of top-right corner
4	x-axis radius of bottom-right corner
5	y-axis radius of bottom-right corner
6	x-axis radius of bottom-left corner
7	y-axis radius of bottom-left corner

start	location
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

320 KiB Raw Blame History

SkPath Reference

Example

Example

Example

Example

Example

Overview

Constants

Example

Example Output

Constants

Example

See Also

SkPath

Return Value

Example

Example Output

See Also

SkPath

Parameters

Return Value

Example

Example Output

See Also

~SkPath

Example

See Also

operator=

Parameters

Return Value

Example

Example Output

See Also

operator==

Parameters

Return Value

Example

Example Output

operator!=

Parameters

Return Value

Example

Example Output

isInterpolatable

Parameters

Return Value

Example

Example Output

See Also

interpolate

Parameters

Return Value

Example

See Also

unique

Example

Constants

Example

See Also

getFillType

Return Value

Example

Example Output

See Also

setFillType

Parameters

Example

See Also

isInverseFillType

Return Value

Example

Example Output

See Also

toggleInverseFillType

Example

See Also

Constants

Example

See Also

320 KiB

Raw Blame History