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/*
* Copyright 2015 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "SkCanvas.h"
#include "SkGradientShader.h"
#include "gm.h"
// This GM reproduces what I think are overflow bugs in the CPU implementations of a
// couple xfermodes. I've marked non-obvious keys to reproducing the bug // Essential!
DEF_SIMPLE_GM(buggy_blend_modes, canvas, 800, 200) {
const auto tiling = SkShader::kClamp_TileMode;
const auto flags = SkGradientShader::kInterpolateColorsInPremul_Flag; // Essential!
SkAutoTUnref<SkShader> cyanH, magentaV;
{
SkPoint pts[] = { {0,0}, {200, 0} };
SkColor colors[] = { 0x00000000, 0xFF00FFFF };
cyanH.reset(
SkGradientShader::CreateLinear(pts, colors, nullptr, 2, tiling, flags, nullptr));
}
{
SkPoint pts[] = { {0,0}, {0, 200} };
SkColor colors[] = { 0x00000000, 0xFFFF00FF };
magentaV.reset(
SkGradientShader::CreateLinear(pts, colors, nullptr, 2, tiling, flags, nullptr));
}
SkXfermode::Mode modes[] = {
SkXfermode::kDarken_Mode, // Looks ok?
SkXfermode::kHardLight_Mode, // Definitely wrong.
SkXfermode::kLighten_Mode, // Definitely wrong.
SkXfermode::kOverlay_Mode, // Same code as kHardLight_Mode.
};
canvas->clear(SK_ColorWHITE);
for (auto mode : modes) {
canvas->saveLayer(nullptr, nullptr); // Essential!
SkPaint h, v;
h.setShader(cyanH);
v.setShader(magentaV);
v.setXfermodeMode(mode);
canvas->drawRect(SkRect::MakeWH(200,200), h);
canvas->drawRect(SkRect::MakeWH(200,200), v);
canvas->restore();
canvas->translate(200, 0);
}
}
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