blob: 59e5a62b6179dc284f51e3e140da07924e4ad982 [file] [log] [blame]
 /* * 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 #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/AnimTimer.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: bool onQuery(Sample::Event* evt) override { if (Sample::TitleQ(*evt)) { Sample::TitleR(evt, "Cusp"); return true; } return this->INHERITED::onQuery(evt); } 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(const AnimTimer& timer) override { curTime = timer.msec(); if (!start) { start = curTime; } return true; } private: typedef Sample INHERITED; }; DEF_SAMPLE( return new CuspView(); )