xref: /aosp_15_r20/external/skia/docs/examples/Bitmap_readPixels.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_readPixels, 256, 128, false, 0) {
draw(SkCanvas * canvas)5 void draw(SkCanvas* canvas) {
6     const int width = 256;
7     const int height = 64;
8     SkImageInfo srcInfo = SkImageInfo::MakeN32Premul(width, height);
9     SkColor  gradColors[] = { 0xFFAA3300, 0x7F881122 };
10     SkPoint  gradPoints[] = { { 0, 0 }, { 256, 0 } };
11     SkPaint paint;
12     paint.setShader(SkGradientShader::MakeLinear(gradPoints, gradColors, nullptr,
13                     std::size(gradColors), SkTileMode::kClamp));
14     SkBitmap bitmap;
15     bitmap.allocPixels(srcInfo);
16     SkCanvas srcCanvas(bitmap);
17     srcCanvas.drawRect(SkRect::MakeWH(width, height), paint);
18     canvas->drawImage(bitmap.asImage(), 0, 0);
19     SkImageInfo dstInfo = srcInfo.makeColorType(kARGB_4444_SkColorType);
20     std::vector<int16_t> dstPixels;
21     dstPixels.resize(height * width);
22     bitmap.readPixels(dstInfo, &dstPixels.front(), width * 2, 0, 0);
23     SkPixmap dstPixmap(dstInfo, &dstPixels.front(), width * 2);
24     bitmap.installPixels(dstPixmap);
25     canvas->drawImage(bitmap.asImage(), 0, 64);
26 }
27 }  // END FIDDLE
28