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// HASH=092739b4cd5d732a27c07ced8ef45f01
5REG_FIDDLE(Bitmap_extractAlpha_2, 256, 160, false, 0) {
6void draw(SkCanvas* canvas) {
7    auto radiusToSigma = [](SkScalar radius) -> SkScalar {
8         static const SkScalar kBLUR_SIGMA_SCALE = 0.57735f;
9         return radius > 0 ? kBLUR_SIGMA_SCALE * radius + 0.5f : 0.0f;
10    };
11    SkBitmap alpha, bitmap;
12    bitmap.allocN32Pixels(100, 100);
13    SkCanvas offscreen(bitmap);
14    offscreen.clear(0);
15    SkPaint paint;
16    paint.setAntiAlias(true);
17    paint.setColor(SK_ColorBLUE);
18    paint.setStyle(SkPaint::kStroke_Style);
19    paint.setStrokeWidth(20);
20    offscreen.drawCircle(50, 50, 39, paint);
21    offscreen.flush();
22    paint.setMaskFilter(SkMaskFilter::MakeBlur(kNormal_SkBlurStyle, radiusToSigma(25)));
23    SkIPoint offset;
24    bitmap.extractAlpha(&alpha, &paint, &offset);
25    paint.setColor(SK_ColorRED);
26    canvas->drawImage(bitmap.asImage(), 0, -offset.fY, SkSamplingOptions(), &paint);
27    canvas->drawImage(alpha.asImage(), 100 + offset.fX, 0, SkSamplingOptions(), &paint);
28}
29}  // END FIDDLE
30