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/*
* Copyright 2012 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "gm.h"
#include "SkCanvas.h"
#include "SkGradientShader.h"
#include "SkGraphics.h"
#include "SkShader.h"
#include "SkString.h"
#include "SkXfermode.h"
static sk_sp<SkShader> make_shader(SkXfermode::Mode mode) {
SkPoint pts[2];
SkColor colors[2];
pts[0].set(0, 0);
pts[1].set(SkIntToScalar(100), 0);
colors[0] = SK_ColorRED;
colors[1] = SK_ColorBLUE;
auto shaderA = SkGradientShader::MakeLinear(pts, colors, nullptr, 2, SkShader::kClamp_TileMode);
pts[0].set(0, 0);
pts[1].set(0, SkIntToScalar(100));
colors[0] = SK_ColorBLACK;
colors[1] = SkColorSetARGB(0x80, 0, 0, 0);
auto shaderB = SkGradientShader::MakeLinear(pts, colors, nullptr, 2, SkShader::kClamp_TileMode);
return SkShader::MakeComposeShader(std::move(shaderA), std::move(shaderB),
SkXfermode::Make(mode));
}
class ComposeShaderGM : public skiagm::GM {
public:
ComposeShaderGM() {
fShader = make_shader(SkXfermode::kDstIn_Mode);
}
protected:
SkString onShortName() override {
return SkString("composeshader");
}
SkISize onISize() override {
return SkISize::Make(120, 120);
}
void onDraw(SkCanvas* canvas) override {
SkPaint paint;
paint.setColor(SK_ColorGREEN);
canvas->drawRectCoords(0, 0, SkIntToScalar(100), SkIntToScalar(100), paint);
paint.setShader(fShader);
canvas->drawRectCoords(0, 0, SkIntToScalar(100), SkIntToScalar(100), paint);
}
protected:
sk_sp<SkShader> fShader;
private:
typedef GM INHERITED ;
};
class ComposeShaderAlphaGM : public skiagm::GM {
public:
ComposeShaderAlphaGM() {}
protected:
SkString onShortName() override {
return SkString("composeshader_alpha");
}
SkISize onISize() override {
return SkISize::Make(750, 220);
}
void onDraw(SkCanvas* canvas) override {
sk_sp<SkShader> shaders[] = {
make_shader(SkXfermode::kDstIn_Mode),
make_shader(SkXfermode::kSrcOver_Mode),
};
SkPaint paint;
paint.setColor(SK_ColorGREEN);
const SkRect r = SkRect::MakeXYWH(5, 5, 100, 100);
for (size_t y = 0; y < SK_ARRAY_COUNT(shaders); ++y) {
canvas->save();
for (int alpha = 0xFF; alpha > 0; alpha -= 0x28) {
paint.setAlpha(0xFF);
paint.setShader(nullptr);
canvas->drawRect(r, paint);
paint.setAlpha(alpha);
paint.setShader(shaders[y]);
canvas->drawRect(r, paint);
canvas->translate(r.width() + 5, 0);
}
canvas->restore();
canvas->translate(0, r.height() + 5);
}
}
private:
typedef GM INHERITED ;
};
// creates a square bitmap with red background and a green circle in the center
static void draw_color_bm(SkBitmap* bm, int length) {
SkPaint paint;
paint.setColor(SK_ColorGREEN);
bm->allocN32Pixels(length, length);
bm->eraseColor(SK_ColorRED);
SkCanvas canvas(*bm);
canvas.drawCircle(SkIntToScalar(length/2), SkIntToScalar(length/2), SkIntToScalar(length/2),
paint);
}
// creates a square alpha8 bitmap with transparent background and an opaque circle in the center
static void draw_alpha8_bm(SkBitmap* bm, int length) {
SkPaint circlePaint;
circlePaint.setColor(SK_ColorBLACK);
bm->allocPixels(SkImageInfo::MakeA8(length, length));
bm->eraseColor(SK_ColorTRANSPARENT);
SkCanvas canvas(*bm);
canvas.drawCircle(SkIntToScalar(length/2), SkIntToScalar(length/2), SkIntToScalar(length/4),
circlePaint);
}
// creates a linear gradient shader
static sk_sp<SkShader> make_linear_gradient_shader(int length) {
SkPoint pts[2];
SkColor colors[2];
pts[0].set(0, 0);
pts[1].set(SkIntToScalar(length), 0);
colors[0] = SK_ColorBLUE;
colors[1] = SkColorSetARGB(0, 0, 0, 0xFF);
return SkGradientShader::MakeLinear(pts, colors, nullptr, 2, SkShader::kClamp_TileMode);
}
class ComposeShaderBitmapGM : public skiagm::GM {
public:
ComposeShaderBitmapGM() {}
protected:
void onOnceBeforeDraw() override {
draw_color_bm(&fColorBitmap, squareLength);
draw_alpha8_bm(&fAlpha8Bitmap, squareLength);
SkMatrix s;
s.reset();
fColorBitmapShader = SkShader::MakeBitmapShader(fColorBitmap, SkShader::kRepeat_TileMode,
SkShader::kRepeat_TileMode, &s);
fAlpha8BitmapShader = SkShader::MakeBitmapShader(fAlpha8Bitmap, SkShader::kRepeat_TileMode,
SkShader::kRepeat_TileMode, &s);
fLinearGradientShader = make_linear_gradient_shader(squareLength);
}
SkString onShortName() override {
return SkString("composeshader_bitmap");
}
SkISize onISize() override {
return SkISize::Make(7 * (squareLength + 5), 2 * (squareLength + 5));
}
void onDraw(SkCanvas* canvas) override {
auto xfer(SkXfermode::Make(SkXfermode::kDstOver_Mode));
sk_sp<SkShader> shaders[] = {
// gradient should appear over color bitmap
SkShader::MakeComposeShader(fLinearGradientShader, fColorBitmapShader, xfer),
// gradient should appear over alpha8 bitmap colorized by the paint color
SkShader::MakeComposeShader(fLinearGradientShader, fAlpha8BitmapShader, xfer),
};
SkPaint paint;
paint.setColor(SK_ColorYELLOW);
const SkRect r = SkRect::MakeXYWH(0, 0, SkIntToScalar(squareLength),
SkIntToScalar(squareLength));
for (size_t y = 0; y < SK_ARRAY_COUNT(shaders); ++y) {
canvas->save();
for (int alpha = 0xFF; alpha > 0; alpha -= 0x28) {
paint.setAlpha(alpha);
paint.setShader(shaders[y]);
canvas->drawRect(r, paint);
canvas->translate(r.width() + 5, 0);
}
canvas->restore();
canvas->translate(0, r.height() + 5);
}
}
private:
/** This determines the length and width of the bitmaps used in the ComposeShaders. Values
* above 20 may cause an SkASSERT to fail in SkSmallAllocator. However, larger values will
* work in a release build. You can change this parameter and then compile a release build
* to have this GM draw larger bitmaps for easier visual inspection.
*/
static const int squareLength = 20;
SkBitmap fColorBitmap;
SkBitmap fAlpha8Bitmap;
sk_sp<SkShader> fColorBitmapShader;
sk_sp<SkShader> fAlpha8BitmapShader;
sk_sp<SkShader> fLinearGradientShader;
typedef GM INHERITED;
};
//////////////////////////////////////////////////////////////////////////////
DEF_GM( return new ComposeShaderGM; )
DEF_GM( return new ComposeShaderAlphaGM; )
DEF_GM( return new ComposeShaderBitmapGM; )
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