b6474dd1a5
Path measure cannot use the same code approach for quadratics and cubics. Subdividing cubics repeatedly does not result in subdivided t values, e.g. a quarter circle cubic divided in half twice does not have a t value equivalent to 1/4. Instead, always compute the cubic segment from a pair of t values. When finding the length of the cubic through recursive measures, it is enough to carry the point at a given t to the next subdivision. (Chrome suppression has landed already.) R=reed@google.com GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1602153002 Review URL: https://codereview.chromium.org/1602153002
79 lines
2.7 KiB
C++
79 lines
2.7 KiB
C++
/*
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* Copyright 2016 Google Inc.
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*
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#include "gm.h"
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#include "SkPath.h"
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#include "SkDashPathEffect.h"
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int dash1[] = { 1, 1 };
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int dash2[] = { 1, 3 };
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int dash3[] = { 1, 1, 3, 3 };
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int dash4[] = { 1, 3, 2, 4 };
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struct DashExample {
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int* pattern;
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int length;
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} dashExamples[] = {
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{ dash1, SK_ARRAY_COUNT(dash1) },
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{ dash2, SK_ARRAY_COUNT(dash2) },
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{ dash3, SK_ARRAY_COUNT(dash3) },
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{ dash4, SK_ARRAY_COUNT(dash4) }
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};
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DEF_SIMPLE_GM(dashcircle, canvas, 900, 1200) {
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SkPaint refPaint;
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refPaint.setAntiAlias(true);
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refPaint.setColor(0xFFbf3f7f);
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refPaint.setStyle(SkPaint::kStroke_Style);
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refPaint.setStrokeWidth(1);
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const SkScalar radius = 125;
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SkRect oval = SkRect::MakeLTRB(-radius - 20, -radius - 20, radius + 20, radius + 20);
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SkPath circle;
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circle.addCircle(0, 0, radius);
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SkScalar circumference = radius * SK_ScalarPI * 2;
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int wedges[] = { 6, 12, 36 };
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canvas->translate(radius + 20, radius + 20);
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for (int wedge : wedges) {
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SkScalar arcLength = 360.f / wedge;
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canvas->save();
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for (const DashExample& dashExample : dashExamples) {
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SkPath refPath;
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int dashUnits = 0;
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for (int index = 0; index < dashExample.length; ++index) {
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dashUnits += dashExample.pattern[index];
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}
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SkScalar unitLength = arcLength / dashUnits;
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SkScalar angle = 0;
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for (int index = 0; index < wedge; ++index) {
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for (int i2 = 0; i2 < dashExample.length; i2 += 2) {
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SkScalar span = dashExample.pattern[i2] * unitLength;
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refPath.moveTo(0, 0);
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refPath.arcTo(oval, angle, span, false);
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refPath.close();
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angle += span + (dashExample.pattern[i2 + 1]) * unitLength;
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}
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}
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canvas->drawPath(refPath, refPaint);
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SkPaint p;
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p.setAntiAlias(true);
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p.setStyle(SkPaint::kStroke_Style);
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p.setStrokeWidth(10);
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SkScalar intervals[4];
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int intervalCount = dashExample.length;
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SkScalar dashLength = circumference / wedge / dashUnits;
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for (int index = 0; index < dashExample.length; ++index) {
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intervals[index] = dashExample.pattern[index] * dashLength;
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}
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p.setPathEffect(SkDashPathEffect::Create(intervals, intervalCount, 0))->unref();
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canvas->drawPath(circle, p);
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canvas->translate(0, radius * 2 + 50);
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}
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canvas->restore();
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canvas->translate(radius * 2 + 50, 0);
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}
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}
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