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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 "Sample.h"
#include "SkAnimTimer.h"
#include "SkCanvas.h"
#include "SkGeometry.h"
#include "SkPath.h"
#include <string>
// 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->drawString(timeStr.c_str(), 20, 20, SkPaint());
SkDebugf("");
}
bool onAnimate(const SkAnimTimer& timer) override {
curTime = timer.msec();
if (!start) {
start = curTime;
}
return true;
}
private:
typedef Sample INHERITED;
};
DEF_SAMPLE( return new CuspView(); )
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