xref: /aosp_15_r20/external/skia/docs/examples/Bitmap_extractAlpha.cpp (revision c8dee2aa9b3f27cf6c858bd81872bdeb2c07ed17)
1 // Copyright 2019 Google LLC.
2 // Use of this source code is governed by a BSD-style license that can be found in the LICENSE file.
3 #include "tools/fiddle/examples.h"
4 REG_FIDDLE(Bitmap_extractAlpha, 256, 100, false, 0) {
draw(SkCanvas * canvas)5 void draw(SkCanvas* canvas) {
6     SkBitmap alpha, bitmap;
7     bitmap.allocN32Pixels(100, 100);
8     SkCanvas offscreen(bitmap);
9     offscreen.clear(0);
10     SkPaint paint;
11     paint.setAntiAlias(true);
12     paint.setColor(SK_ColorBLUE);
13     paint.setStyle(SkPaint::kStroke_Style);
14     paint.setStrokeWidth(20);
15     offscreen.drawCircle(50, 50, 39, paint);
16     bitmap.extractAlpha(&alpha);
17     paint.setColor(SK_ColorRED);
18     canvas->drawImage(bitmap.asImage(), 0, 0, SkSamplingOptions(), &paint);
19     canvas->drawImage(alpha.asImage(), 100, 0, SkSamplingOptions(), &paint);
20 }
21 }  // END FIDDLE
22