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