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_2, 256, 160, false, 0) {
draw(SkCanvas * canvas)5 void draw(SkCanvas* canvas) {
6 auto radiusToSigma = [](SkScalar radius) -> SkScalar {
7 static const SkScalar kBLUR_SIGMA_SCALE = 0.57735f;
8 return radius > 0 ? kBLUR_SIGMA_SCALE * radius + 0.5f : 0.0f;
9 };
10 SkBitmap alpha, bitmap;
11 bitmap.allocN32Pixels(100, 100);
12 SkCanvas offscreen(bitmap);
13 offscreen.clear(0);
14 SkPaint paint;
15 paint.setAntiAlias(true);
16 paint.setColor(SK_ColorBLUE);
17 paint.setStyle(SkPaint::kStroke_Style);
18 paint.setStrokeWidth(20);
19 offscreen.drawCircle(50, 50, 39, paint);
20 paint.setMaskFilter(SkMaskFilter::MakeBlur(kNormal_SkBlurStyle, radiusToSigma(25)));
21 SkIPoint offset;
22 bitmap.extractAlpha(&alpha, &paint, &offset);
23 paint.setColor(SK_ColorRED);
24 canvas->drawImage(bitmap.asImage(), 0, -offset.fY, SkSamplingOptions(), &paint);
25 canvas->drawImage(alpha.asImage(), 100 + offset.fX, 0, SkSamplingOptions(), &paint);
26 }
27 } // END FIDDLE
28