Skia Fiddle

Options

Width Height

check_box_outline_blank check_box Text Only [Use SkDebugf()]

check_box_outline_blank check_box sRGB

check_box_outline_blank check_box F16

check_box_outline_blank check_box Animation

check_box_outline_blank check_box Offscreen Render Target

Width Height Sample Count

check_box_outline_blank check_box Texturable

check_box_outline_blank check_box MipMap

This global is now defined:

GrBackendRenderTarget backEndRenderTarget;

GrBackendTexture backEndTextureRenderTarget;

Optional source image

check_box_outline_blank check_box MipMap

These globals are now defined:

SkBitmap source;
sk_sp<SkImage> image;
GrBackendTexture backEndTexture; // GPU Only.

Note:

Adding comments with SK_FOLD_START and SK_FOLD_END creates foldable code blocks.
These blocks will be folded by default and are useful for highlighting specific lines of code.
You can also use the keyboard shortcuts Ctrl+S and Ctrl+E in the code editor to set them.

xxxxxxxxxx
 
static const SkScalar size = 100;
static SkColor backdrop = 0xb0008000;
static SkColor       bg = 0xb0ff0000;
static SkColor       fg = 0xb00000ff;
​
// workaround for missing fiddle header
class SK_API SkArithmeticMode {
public:
    static sk_sp<SkXfermode> Make(SkScalar k1, SkScalar k2, SkScalar k3, SkScalar k4,
                                  bool enforcePMColor = true);
};
​
void blend_arithmetic(SkCanvas* c, SkColor bg, SkColor fg, SkScalar k) {
    SkAutoCanvasRestore acr(c, false);
    c->saveLayer(nullptr, nullptr);
​
    SkPaint p, layer_paint;
​
    p.setColor(bg);
    c->drawRect(SkRect::MakeWH(size, size / 2), p);
​
    layer_paint.setXfermode(SkArithmeticMode::Make(0.0f, k, 1.0 - k, 0.0));
    c->saveLayer(nullptr, &layer_paint);
​
    p.setColor(fg);
    c->drawRect(SkRect::MakeWH(size / 2, size), p);
}
​
void blend_kplus(SkCanvas* c, SkColor bg, SkColor fg, SkScalar k) {
    SkAutoCanvasRestore acr(c, false);
    c->saveLayer(nullptr, nullptr);
​
    SkPaint p, layer_paint;
    p.setColor(bg);
    c->saveLayerAlpha(nullptr, 255 * (1 - k));
    c->drawRect(SkRect::MakeWH(size, size / 2), p);
    c->restore();
​
    layer_paint.setXfermodeMode(SkXfermode::kPlus_Mode);
    layer_paint.setAlpha(255 * k);
    c->saveLayer(nullptr, &layer_paint);
​
    p.setColor(fg);
    c->drawRect(SkRect::MakeWH(size / 2, size), p);
}
​
void blend_modulate(SkCanvas* c, SkColor bg, SkColor fg, SkScalar k) {
    SkAutoCanvasRestore acr(c, false);
    c->saveLayer(nullptr, nullptr);
​
    SkPaint p;
    p.setColor(bg);
    c->saveLayerAlpha(nullptr, 255 * (1 - k));
    c->drawRect(SkRect::MakeWH(size, size / 2), p);
    c->restore();
​
​
    p.setColor(fg);
    c->saveLayerAlpha(nullptr, 255 * k);
    c->drawRect(SkRect::MakeWH(size / 2, size), p);
    c->restore();
}
​
void blend_srcover(SkCanvas* c, SkColor bg, SkColor fg, SkScalar k) {
    SkAutoCanvasRestore acr(c, false);
    c->saveLayer(nullptr, nullptr);
​
    SkPaint p;
    p.setColor(bg);
    c->drawRect(SkRect::MakeWH(size, size / 2), p);
​
    p.setColor(fg);
    p.setAlpha(p.getAlpha() * k);
    c->drawRect(SkRect::MakeWH(size / 2, size), p);
}
​
template<typename Func>
void drawRow(SkCanvas* c, Func f) {
    SkAutoCanvasRestore acr(c, true);
    c->translate(size * 0.1f, 0);
    for (int i = 0; i < 5; ++i) {
        {
             SkAutoCanvasRestore acr(c, true);
             c->clipRect(SkRect::MakeWH(size, size));
             c->drawColor(backdrop);
             f(c, bg, fg, 0.25f * i);
        }
        c->translate(size * 1.1f, 0);
    }
}
​
void draw(SkCanvas* canvas) {
    SkColor backdrop = 0xff008000;
​
    SkPaint p;
    p.setColor(backdrop);
    
    canvas->translate(0, size * 0.1f);
    drawRow(canvas, blend_arithmetic);
​
    canvas->translate(0, size * 1.1f);
    drawRow(canvas, blend_kplus);
​
    canvas->translate(0, size * 1.1f);
    drawRow(canvas, blend_modulate);
​
    canvas->translate(0, size * 1.1f);
    drawRow(canvas, blend_srcover);
}