skia2/samplecode/SampleFlutterAnimate.cpp

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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 "AnimTimer.h"
#include "Sample.h"
#include "SkCanvas.h"
#include "SkColorFilter.h"
#include "SkColorPriv.h"
#include "SkFont.h"
#include "SkImage.h"
#include "SkRandom.h"
#include "SkTime.h"
#include "SkTypeface.h"
#include "Timer.h"
#if SK_SUPPORT_GPU
#include "GrContext.h"
#endif
// Create an animation of a bunch of letters that rotate in place. This is intended to stress
// the glyph atlas and test that we don't see corruption or bad slowdowns.
class FlutterAnimateView : public Sample {
public:
FlutterAnimateView() : fCurrTime(0), fResetTime(0) {}
protected:
void onOnceBeforeDraw() override {
fTypeface = SkTypeface::MakeFromFile("/skimages/samplefont.ttf");
initChars();
}
bool onQuery(Sample::Event* evt) override {
if (Sample::TitleQ(*evt)) {
Sample::TitleR(evt, "FlutterAnimate");
return true;
}
return this->INHERITED::onQuery(evt);
}
void onDrawContent(SkCanvas* canvas) override {
SkFont font(fTypeface, 50);
SkPaint paint;
paint.setFilterQuality(kMedium_SkFilterQuality);
// rough center of each glyph
static constexpr auto kMidX = 35;
static constexpr auto kMidY = 50;
canvas->clear(SK_ColorWHITE);
for (int i = 0; i < kNumChars; ++i) {
canvas->save();
double rot = SkScalarInterp(fChars[i].fStartRotation, fChars[i].fEndRotation,
fCurrTime/kDuration);
canvas->translate(fChars[i].fPosition.fX + kMidX, fChars[i].fPosition.fY - kMidY);
canvas->rotate(SkRadiansToDegrees(rot));
canvas->translate(-35,+50);
canvas->drawString(fChars[i].fChar, 0, 0, font, paint);
canvas->restore();
}
}
bool onAnimate(const AnimTimer& timer) override {
fCurrTime = timer.secs() - fResetTime;
if (fCurrTime > kDuration) {
this->initChars();
fResetTime = timer.secs();
fCurrTime = 0;
}
return true;
}
private:
void initChars() {
for (int i = 0; i < kNumChars; ++i) {
char c = fRand.nextULessThan(26) + 65;
fChars[i].fChar[0] = c;
fChars[i].fChar[1] = '\0';
fChars[i].fPosition = SkPoint::Make(fRand.nextF()*748 + 10, fRand.nextF()*1004 + 10);
fChars[i].fStartRotation = fRand.nextF();
fChars[i].fEndRotation = fRand.nextF() * 20 - 10;
}
}
static constexpr double kDuration = 5.0;
double fCurrTime;
double fResetTime;
SkRandom fRand;
struct AnimatedChar {
char fChar[2];
SkPoint fPosition;
SkScalar fStartRotation;
SkScalar fEndRotation;
};
sk_sp<SkTypeface> fTypeface;
static constexpr int kNumChars = 40;
AnimatedChar fChars[kNumChars];
typedef Sample INHERITED;
};
//////////////////////////////////////////////////////////////////////////////
DEF_SAMPLE( return new FlutterAnimateView(); )