xref: /aosp_15_r20/external/skia/docs/examples/Pixmap_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(Pixmap_readPixels, 256, 128, false, 0) {
draw(SkCanvas * canvas)5  void draw(SkCanvas* canvas) {
6      std::vector<int32_t> pixels;
7      const int width = 256;
8      const int height = 64;
9      pixels.resize(height * width * 4);
10      SkImageInfo srcInfo = SkImageInfo::MakeN32Premul(width, height);
11      SkPixmap srcPixmap(srcInfo, (const void*) &pixels.front(), width * 4);
12      SkColor  gradColors[] = { 0xFFAA3300, 0x7F881122 };
13      SkPoint  gradPoints[] = { { 0, 0 }, { 256, 0 } };
14      SkPaint paint;
15      paint.setShader(SkGradientShader::MakeLinear(gradPoints, gradColors, nullptr,
16                      std::size(gradColors), SkTileMode::kClamp));
17      SkBitmap bitmap;
18      bitmap.installPixels(srcPixmap);
19      SkCanvas srcCanvas(bitmap);
20      srcCanvas.drawRect(SkRect::MakeWH(width, height), paint);
21      canvas->drawImage(bitmap.asImage(), 0, 0);
22      std::vector<int32_t> dstPixels;
23      dstPixels.resize(height * width * 2);
24      SkImageInfo dstInfo = srcInfo.makeColorType(kARGB_4444_SkColorType);
25      srcPixmap.readPixels(dstInfo, &dstPixels.front(), width * 2);
26      SkPixmap dstPixmap(dstInfo, &dstPixels.front(), width * 2);
27      bitmap.installPixels(dstPixmap);
28      canvas->drawImage(bitmap.asImage(), 0, 128);
29  }
30  }  // END FIDDLE
31