xref: /aosp_15_r20/external/skia/docs/examples/Image_readPixels_2.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(Image_readPixels_2, 256, 256, false, 3) {
draw(SkCanvas * canvas)5 void draw(SkCanvas* canvas) {
6     std::vector<int32_t> srcPixels;
7     int rowBytes = image->width() * 4;
8     int quarterWidth = image->width() / 4;
9     int quarterHeight = image->height() / 4;
10     srcPixels.resize(image->height() * rowBytes);
11     for (int y = 0; y < 4; ++y) {
12         for (int x = 0; x < 4; ++x) {
13             SkPixmap pixmap(SkImageInfo::MakeN32Premul(quarterWidth, quarterHeight),
14                     &srcPixels.front() + x * image->height() * quarterWidth +
15                     y * quarterWidth, rowBytes);
16             image->readPixels(nullptr, pixmap, x * quarterWidth, y * quarterHeight);
17         }
18     }
19     canvas->scale(.5f, .5f);
20     SkBitmap bitmap;
21     bitmap.installPixels(SkImageInfo::MakeN32Premul(image->width(), image->height()),
22                              &srcPixels.front(), rowBytes);
23     canvas->drawImage(bitmap.asImage(), 0, 0);
24 }
25 }  // END FIDDLE
26