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Respecify SkCanvas::drawArc, consolidate conversion to SkPath, add GM for oddball drawArcs

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Allows the arc to wind more than 360 degrees when useCenter is true, specs that nothing draws
if the oval is empty or the sweep angle is 0.
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2281653002

Review-Url: https://codereview.chromium.org/2281653002
This commit is contained in:
bsalomon 2016-08-25 12:29:23 -07:00 committed by Commit bot
parent 29b2563afb
commit 21af9ca1b1
8 changed files with 153 additions and 26 deletions
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85
gm/circulararcs.cpp
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@ -7,6 +7,7 @@
#include <functional>
#include "SkCanvas.h"
#include "SkDashPathEffect.h"
#include "gm.h"
static constexpr SkScalar kStarts[] = {0.f, 10.f, 30.f, 45.f, 90.f, 165.f, 180.f, 270.f};
@ -125,3 +126,87 @@ DEF_ARC_GM(stroke_and_fill_round) {
};
draw_arcs(canvas, setStroke);
}
DEF_SIMPLE_GM(circular_arcs_weird, canvas, 1000, 400) {
static constexpr SkScalar kS = 50;
struct Arc {
SkRect fOval;
SkScalar fStart;
SkScalar fSweep;
};
static const Arc noDrawArcs[] = {
// no sweep
{SkRect::MakeWH(kS, kS), 0, 0},
// empty rect in x
{SkRect::MakeWH(-kS, kS), 0, 90},
// empty rect in y
{SkRect::MakeWH(kS, -kS), 0, 90},
// empty rect in x and y
{SkRect::MakeWH( 0, 0), 0, 90},
};
static const Arc arcs[] = {
// large start
{SkRect::MakeWH(kS, kS), 810.f, 90.f},
// large negative start
{SkRect::MakeWH(kS, kS), -810.f, 90.f},
// exactly 360 sweep
{SkRect::MakeWH(kS, kS), 0.f, 360.f},
// exactly -360 sweep
{SkRect::MakeWH(kS, kS), 0.f, -360.f},
// exactly 540 sweep
{SkRect::MakeWH(kS, kS), 0.f, 540.f},
// exactly -540 sweep
{SkRect::MakeWH(kS, kS), 0.f, -540.f},
// generic large sweep and large start
{SkRect::MakeWH(kS, kS), 1125.f, 990.f},
};
SkTArray<SkPaint> paints;
// fill
paints.push_back();
// stroke
paints.push_back().setStyle(SkPaint::kStroke_Style);
paints.back().setStrokeWidth(kS / 6.f);
// hairline
paints.push_back().setStyle(SkPaint::kStroke_Style);
paints.back().setStrokeWidth(0.f);
// stroke and fill
paints.push_back().setStyle(SkPaint::kStrokeAndFill_Style);
paints.back().setStrokeWidth(kS / 6.f);
// dash effect
paints.push_back().setStyle(SkPaint::kStroke_Style);
paints.back().setStrokeWidth(kS / 6.f);
static constexpr SkScalar kDashIntervals[] = {kS / 15, 2 * kS / 15};
paints.back().setPathEffect(SkDashPathEffect::Make(kDashIntervals, 2, 0.f));
canvas->translate(kPad, kPad);
// This loop should draw nothing.
for (auto arc : noDrawArcs) {
for (auto paint : paints) {
paint.setAntiAlias(true);
canvas->drawArc(arc.fOval, arc.fStart, arc.fSweep, false, paint);
canvas->drawArc(arc.fOval, arc.fStart, arc.fSweep, true, paint);
}
}
SkPaint linePaint;
linePaint.setAntiAlias(true);
linePaint.setColor(SK_ColorRED);
SkScalar midX = SK_ARRAY_COUNT(arcs) * (kS + kPad) - kPad/2.f;
SkScalar height = paints.count() * (kS + kPad);
canvas->drawLine(midX, -kPad, midX, height, linePaint);
for (auto paint : paints) {
paint.setAntiAlias(true);
canvas->save();
for (auto arc : arcs) {
canvas->drawArc(arc.fOval, arc.fStart, arc.fSweep, false, paint);
canvas->translate(kS + kPad, 0.f);
}
for (auto arc : arcs) {
canvas->drawArc(arc.fOval, arc.fStart, arc.fSweep, true, paint);
canvas->translate(kS + kPad, 0.f);
}
canvas->restore();
canvas->translate(0, kS + kPad);
}
}

13
include/core/SkCanvas.h
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@ -737,14 +737,17 @@ public:
const SkPaint& paint);
/** Draw the specified arc, which will be scaled to fit inside the
specified oval. If the sweep angle is >= 360, then the oval is drawn
completely. Note that this differs slightly from SkPath::arcTo, which
treats the sweep angle mod 360.
specified oval. Sweep angles are not treated as modulo 360 and thus can
exceed a full sweep of the oval. Note that this differs slightly from
SkPath::arcTo, which treats the sweep angle mod 360. If the oval is empty
or the sweep angle is zero nothing is drawn. If useCenter is true the oval
center is inserted into the implied path before the arc and the path is
closed back to the, center forming a wedge. Otherwise, the implied path
contains just the arc and is not closed.
@param oval The bounds of oval used to define the shape of the arc.
@param startAngle Starting angle (in degrees) where the arc begins
@param sweepAngle Sweep angle (in degrees) measured clockwise.
@param useCenter true means include the center of the oval. For filling
this will draw a wedge. False means just use the arc.
@param useCenter true means include the center of the oval.
@param paint The paint used to draw the arc
*/
void drawArc(const SkRect& oval, SkScalar startAngle, SkScalar sweepAngle,

7
src/core/SkCanvas.cpp
View File

@ -3098,11 +3098,10 @@ void SkCanvas::drawArc(const SkRect& oval, SkScalar startAngle,
SkScalar sweepAngle, bool useCenter,
const SkPaint& paint) {
TRACE_EVENT0("disabled-by-default-skia", "SkCanvas::drawArc()");
if (SkScalarAbs(sweepAngle) >= SkIntToScalar(360)) {
this->drawOval(oval, paint);
} else {
this->onDrawArc(oval, startAngle, sweepAngle, useCenter, paint);
if (oval.isEmpty() || !sweepAngle) {
return;
}
this->onDrawArc(oval, startAngle, sweepAngle, useCenter, paint);
}
void SkCanvas::drawTextOnPathHV(const void* text, size_t byteLength,

13
src/core/SkDevice.cpp
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@ -16,6 +16,7 @@
#include "SkLatticeIter.h"
#include "SkMetaData.h"
#include "SkPatchUtils.h"
#include "SkPathPriv.h"
#include "SkPathMeasure.h"
#include "SkRasterClip.h"
#include "SkRSXform.h"
@ -74,16 +75,10 @@ SkPixelGeometry SkBaseDevice::CreateInfo::AdjustGeometry(const SkImageInfo& info
void SkBaseDevice::drawArc(const SkDraw& draw, const SkRect& oval, SkScalar startAngle,
SkScalar sweepAngle, bool useCenter, const SkPaint& paint) {
SkASSERT(SkScalarAbs(sweepAngle) >= 0.f && SkScalarAbs(sweepAngle) < 360.f);
SkPath path;
if (useCenter) {
path.moveTo(oval.centerX(), oval.centerY());
}
path.arcTo(oval, startAngle, sweepAngle, !useCenter);
if (useCenter) {
path.close();
}
path.setIsVolatile(true);
bool isFillNoPathEffect = SkPaint::kFill_Style == paint.getStyle() && !paint.getPathEffect();
SkPathPriv::CreateDrawArcPath(&path, oval, startAngle, sweepAngle, useCenter,
isFillNoPathEffect);
this->drawPath(draw, path, paint);
}

39
src/core/SkPath.cpp
View File

@ -3341,3 +3341,42 @@ bool SkPathPriv::IsSimpleClosedRect(const SkPath& path, SkRect* rect, SkPath::Di
}
return true;
}
void SkPathPriv::CreateDrawArcPath(SkPath* path, const SkRect& oval, SkScalar startAngle,
SkScalar sweepAngle, bool useCenter, bool isFillNoPathEffect) {
SkASSERT(!oval.isEmpty());
SkASSERT(sweepAngle);
path->reset();
path->setIsVolatile(true);
path->setFillType(SkPath::kWinding_FillType);
if (isFillNoPathEffect && SkScalarAbs(sweepAngle) >= 360.f) {
path->addOval(oval);
return;
}
if (useCenter) {
path->moveTo(oval.centerX(), oval.centerY());
}
// Arc to mods at 360 and drawArc is not supposed to.
bool forceMoveTo = !useCenter;
while (sweepAngle <= -360.f) {
path->arcTo(oval, startAngle, -180.f, forceMoveTo);
startAngle -= 180.f;
path->arcTo(oval, startAngle, -180.f, false);
startAngle -= 180.f;
forceMoveTo = false;
sweepAngle += 360.f;
}
while (sweepAngle >= 360.f) {
path->arcTo(oval, startAngle, 180.f, forceMoveTo);
startAngle += 180.f;
path->arcTo(oval, startAngle, 180.f, false);
startAngle += 180.f;
forceMoveTo = false;
sweepAngle -= 360.f;
}
path->arcTo(oval, startAngle, sweepAngle, forceMoveTo);
if (useCenter) {
path->close();
}
}

7
src/core/SkPathPriv.h
View File

@ -91,6 +91,13 @@ public:
*/
static bool IsSimpleClosedRect(const SkPath& path, SkRect* rect, SkPath::Direction* direction,
unsigned* start);
/**
* Creates a path from arc params using the semantics of SkCanvas::drawArc. This function
* assumes empty ovals and zero sweeps have already been filtered out.
*/
static void CreateDrawArcPath(SkPath* path, const SkRect& oval, SkScalar startAngle,
SkScalar sweepAngle, bool useCenter, bool isFillNoPathEffect);
};
#endif

10
src/gpu/GrDrawContext.cpp
View File

@ -1023,14 +1023,8 @@ void GrDrawContext::drawArc(const GrClip& clip,
}
}
SkPath path;
path.setIsVolatile(true);
if (useCenter) {
path.moveTo(oval.centerX(), oval.centerY());
}
path.arcTo(oval, startAngle, sweepAngle, !useCenter);
if (useCenter) {
path.close();
}
SkPathPriv::CreateDrawArcPath(&path, oval, startAngle, sweepAngle, useCenter,
style.isSimpleFill());
this->internalDrawPath(clip, paint, viewMatrix, path, style);
return;
}

5
src/gpu/GrOvalRenderer.cpp
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@ -2027,7 +2027,12 @@ GrDrawBatch* GrOvalRenderer::CreateArcBatch(GrColor color,
bool useCenter,
const GrStyle& style,
const GrShaderCaps* shaderCaps) {
SkASSERT(!oval.isEmpty());
SkASSERT(sweepAngle);
SkScalar width = oval.width();
if (SkScalarAbs(sweepAngle) >= 360.f) {
return nullptr;
}
if (!SkScalarNearlyEqual(width, oval.height()) || !circle_stays_circle(viewMatrix)) {
return nullptr;
}