blob: 41aa4b9debc6b90fc29b2af6f728271bc8438dca [file] [log] [blame]
// Copyright 2020 Google LLC.
// Use of this source code is governed by a BSD-style license that can be found in the LICENSE file.
#include "tools/fiddle/examples.h"
// HASH=7d3751e82d1b6ec328ffa3d6f48ca831
REG_FIDDLE(Canvas_saveLayer_4, 256, 256, false, 3) {
void draw(SkCanvas* canvas) {
SkPaint pRed;
SkPaint pSolidBlue;
SkPaint pThirtyBlue;
SkPaint alpha;
// First row: Draw two opaque red rectangles into the 0th layer. Then draw two blue
// rectangles overlapping the red, one is solid, the other is 30% transparent.
canvas->drawRect(SkRect::MakeLTRB(10, 10, 60, 60), pRed);
canvas->drawRect(SkRect::MakeLTRB(150, 10, 200, 60), pRed);
canvas->drawRect(SkRect::MakeLTRB(30, 10, 80, 60), pSolidBlue);
canvas->drawRect(SkRect::MakeLTRB(170, 10, 220, 60), pThirtyBlue);
// Second row: Draw two opaque red rectangles into the 0th layer. Then save a new layer;
// when the 1st layer gets merged onto the 0th layer (i.e. when restore() is called), it will
// use the provided paint to do so. In this case, the paint is set to have 30% opacity, but
// it could also have things set like blend modes or image filters.
canvas->drawRect(SkRect::MakeLTRB(10, 70, 60, 120), pRed);
canvas->drawRect(SkRect::MakeLTRB(150, 70, 200, 120), pRed);
canvas->saveLayer(nullptr, &alpha);
// In the 1st layer, draw the same blue overlapping rectangles as in the first row. Notice in
// the final output, we have two different shades of purple. The layer's alpha made the
// opaque blue rectangle transparent, and it made the transparent blue rectangle even more so
canvas->drawRect(SkRect::MakeLTRB(30, 70, 80, 120), pSolidBlue);
canvas->drawRect(SkRect::MakeLTRB(170, 70, 220, 120), pThirtyBlue);
// Third row: save the layer first, before drawing the two red rectangle, followed by the
// overlapping blue rectangles. Notice that the blue overwrites the red in the same way as
// the first row because the alpha of the layer is not applied until the layer is restored.
canvas->saveLayer(nullptr, &alpha);
canvas->drawRect(SkRect::MakeLTRB(10, 130, 60, 180), pRed);
canvas->drawRect(SkRect::MakeLTRB(150, 130, 200, 180), pRed);
canvas->drawRect(SkRect::MakeLTRB(30, 130, 80, 180), pSolidBlue);
canvas->drawRect(SkRect::MakeLTRB(170, 130, 220, 180), pThirtyBlue);