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- /*
- * Copyright 2018 Google Inc.
- *
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- */
- #include <string>
- #include "include/core/SkCanvas.h"
- #include "include/core/SkFont.h"
- #include "include/core/SkPath.h"
- #include "samplecode/Sample.h"
- #include "src/core/SkGeometry.h"
- #include "tools/timer/TimeUtils.h"
- // This draws an animation where every cubic has a cusp, to test drawing a circle
- // at the cusp point. Create a unit square. A cubic with its control points
- // at the four corners crossing over itself has a cusp.
- // Project the unit square through a random affine matrix.
- // Chop the cubic in two. One half of the cubic will have a cusp
- // (unless it was chopped exactly at the cusp point).
- // Running this looks mostly OK, but will occasionally draw something odd.
- // The odd parts don't appear related to the cusp code, but are old stroking
- // bugs that have not been fixed, yet.
- SkMSec start = 0;
- SkMSec curTime;
- bool first = true;
- // Create a path with one or two cubics, where one has a cusp.
- static SkPath cusp(const SkPoint P[4], SkPoint PP[7], bool& split, int speed, SkScalar phase) {
- SkPath path;
- path.moveTo(P[0]);
- SkScalar t = (curTime % speed) / SkIntToFloat(speed);
- t += phase;
- if (t > 1) {
- t -= 1;
- }
- if (0 <= t || t >= 1) {
- path.cubicTo(P[1], P[2], P[3]);
- split = false;
- } else {
- SkChopCubicAt(P, PP, t);
- path.cubicTo(PP[1], PP[2], PP[3]);
- path.cubicTo(PP[4], PP[5], PP[6]);
- split = true;
- }
- return path;
- }
- // Scale the animation counter to a value that oscillates from -scale to +scale.
- static SkScalar linearToLoop(int speed, SkScalar phase, SkScalar scale) {
- SkScalar loop;
- SkScalar linear = (curTime % speed) / SkIntToFloat(speed); // 0 to 1
- linear += phase;
- if (linear > 1) {
- linear -= 1;
- }
- if (linear < .25) {
- loop = linear * 4; // 0 to .25 ==> 0 to 1
- } else if (linear < .75) { // .25 to .75 ==> 1 to -1
- loop = (.5 - linear) * 4;
- } else { // .75 to 1 ==> -1 to 0
- loop = (linear - 1) * 4;
- }
- return loop * scale;
- }
- struct data {
- SkIPoint pt[4];
- } dat[] = {
- // When the animation looks funny, pause, and paste the last part of the stream in stdout here.
- // Enable the 1st #if to play the recorded stream backwards.
- // Enable the 2nd #if and replace the second 'i = ##' with the value of datCount that shows the bug.
- {{{0x43480000,0x43960000},{0x4318b999,0x4321570b},{0x432f999a,0x435a0a3d},{0x43311fff,0x43734cce},}},
- {{{0x43480000,0x43960000},{0x431d1ddf,0x4321ae13},{0x4331ddde,0x435c147c},{0x43334001,0x43719997},}},
- {{{0x43480000,0x43960000},{0x43218224,0x43220520},{0x43342223,0x435e1eba},{0x43356001,0x436fe666},}},
- {{{0x43480000,0x43960000},{0x4325a445,0x43225708},{0x43364444,0x43600a3c},{0x43376001,0x436e4ccc},}},
- {{{0x43480000,0x43960000},{0x432a0889,0x4322ae16},{0x43388889,0x4362147b},{0x43398000,0x436c999b},}},
- {{{0x43480000,0x43960000},{0x432e6ccd,0x43230523},{0x433acccd,0x43641eba},{0x433ba000,0x436ae66a},}},
- {{{0x43480000,0x43960000},{0x43328eef,0x4323570c},{0x433ceeee,0x43660a3c},{0x433da000,0x43694cd0},}},
- {{{0x43480000,0x43960000},{0x4336f333,0x4323ae13},{0x433f3333,0x4368147a},{0x433fc000,0x43679998},}},
- {{{0x43480000,0x43960000},{0x433b5777,0x43240520},{0x43417777,0x436a1eb9},{0x4341e000,0x4365e668},}},
- {{{0x43480000,0x43960000},{0x433f799a,0x4324570c},{0x4343999a,0x436c0a3e},{0x4343e000,0x43644cce},}},
- {{{0x43480000,0x43960000},{0x4343ddde,0x4324ae13},{0x4345dddf,0x436e147c},{0x43460000,0x43629996},}},
- {{{0x43480000,0x43960000},{0x43484222,0x4325051e},{0x43482222,0x43701eb9},{0x43481fff,0x4360e666},}},
- {{{0x43480000,0x43960000},{0x434c6446,0x43255709},{0x434a4444,0x43720a3e},{0x434a2002,0x435f4ccc},}},
- {{{0x43480000,0x43960000},{0x4350c888,0x4325ae16},{0x434c8889,0x4374147c},{0x434c3fff,0x435d999a},}},
- {{{0x43480000,0x43960000},{0x43552cce,0x43260521},{0x434ecccd,0x43761eb8},{0x434e6001,0x435be669},}},
- {{{0x43480000,0x43960000},{0x43594eee,0x4326570c},{0x4350eeef,0x43780a3d},{0x43505fff,0x435a4ccf},}},
- {{{0x43480000,0x43960000},{0x435db334,0x4326ae19},{0x43533333,0x437a147c},{0x43528001,0x4358999e},}},
- {{{0x43480000,0x43960000},{0x4361d555,0x43270002},{0x43555555,0x437bfffe},{0x43547fff,0x43570004},}},
- {{{0x43480000,0x43960000},{0x4366399a,0x4327570c},{0x4357999a,0x437e0a3f},{0x4356a001,0x43554ccd},}},
- {{{0x43480000,0x43960000},{0x436a9ddc,0x4327ae12},{0x4359ddde,0x43800a3e},{0x4358bffe,0x43539996},}},
- {{{0x43480000,0x43960000},{0x436f0222,0x4328051c},{0x435c2222,0x43810f5c},{0x435ae000,0x4351e664},}},
- };
- size_t datCount = SK_ARRAY_COUNT(dat);
- class CuspView : public Sample {
- public:
- CuspView() {}
- protected:
- SkString name() override { return SkString("Cusp"); }
- void onDrawContent(SkCanvas* canvas) override {
- SkPaint p;
- p.setAntiAlias(true);
- p.setStyle(SkPaint::kStroke_Style);
- p.setStrokeWidth(20);
- #if 0 // enable to play through the stream above backwards.
- SkPath path;
- int i;
- #if 0 // disable to draw only one problematic cubic
- i = --datCount;
- #else
- i = 14; // index into dat of problematic cubic
- #endif
- path.moveTo( SkBits2Float(dat[i].pt[0].fX), SkBits2Float(dat[i].pt[0].fY));
- path.cubicTo(SkBits2Float(dat[i].pt[1].fX), SkBits2Float(dat[i].pt[1].fY),
- SkBits2Float(dat[i].pt[2].fX), SkBits2Float(dat[i].pt[2].fY),
- SkBits2Float(dat[i].pt[3].fX), SkBits2Float(dat[i].pt[3].fY));
- #else
- SkPath path;
- SkRect rect;
- rect.setWH(100, 100);
- SkMatrix matrix;
- SkScalar vals[9];
- vals[0] = linearToLoop(3000, 0, 1);
- vals[1] = linearToLoop(4000, .25, 1.25);
- vals[2] = 200;
- vals[3] = linearToLoop(5000, .5, 1.5);
- vals[4] = linearToLoop(7000, .75, 1.75);
- vals[5] = 300;
- vals[6] = 0;
- vals[7] = 0;
- vals[8] = 1;
- matrix.set9(vals);
- SkPoint pts[4], pp[7];
- matrix.mapRectToQuad(pts, rect);
- std::swap(pts[1], pts[2]);
- bool split;
- path = cusp(pts, pp, split, 8000, .125);
- auto debugOutCubic = [](const SkPoint* pts) {
- return false; // comment out to capture stream of cusp'd cubics in stdout
- SkDebugf("{{");
- for (int i = 0; i < 4; ++i) {
- SkDebugf("{0x%08x,0x%08x},", SkFloat2Bits(pts[i].fX), SkFloat2Bits(pts[i].fY));
- }
- SkDebugf("}},\n");
- };
- if (split) {
- debugOutCubic(&pp[0]);
- debugOutCubic(&pp[4]);
- } else {
- debugOutCubic(&pts[0]);
- }
- #endif
- canvas->drawPath(path, p);
- // draw time to make it easier to guess when the bad cubic was drawn
- std::string timeStr = std::to_string((float) (curTime - start) / 1000.f);
- canvas->drawSimpleText(timeStr.c_str(), timeStr.size(), SkTextEncoding::kUTF8, 20, 20, SkFont(), SkPaint());
- SkDebugf("");
- }
- bool onAnimate(double nanos) override {
- curTime = TimeUtils::NanosToMSec(nanos);
- if (!start) {
- start = curTime;
- }
- return true;
- }
- private:
- typedef Sample INHERITED;
- };
- DEF_SAMPLE( return new CuspView(); )
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