submodule/skia/docs/examples/50_percent_gray.cpp

   1 // Copyright 2020 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_SRGB(50_percent_gray, 530, 150, false, 0, 0, false) {
   5 static sk_sp<SkShader> make_bw_dither() {
   6     auto surf = SkSurface::MakeRasterN32Premul(2, 2);
   7     surf->getCanvas()->drawColor(SK_ColorWHITE);
   8     surf->getCanvas()->drawRect({0, 0, 1, 1}, SkPaint());
   9     surf->getCanvas()->drawRect({1, 1, 2, 2}, SkPaint());
  10     return surf->makeImageSnapshot()->makeShader(SkTileMode::kRepeat,
  11                                                  SkTileMode::kRepeat,
  12                                                  SkSamplingOptions(SkFilterMode::kLinear));
  13 }
  14
  15 void draw(SkCanvas* canvas) {
  16     canvas->drawColor(SK_ColorWHITE);
  17     SkFont font(nullptr, 12);
  18
  19     // BW Dither
  20     canvas->translate(5, 5);
  21     SkPaint p;
  22     p.setShader(make_bw_dither());
  23     canvas->drawRect({0, 0, 100, 100}, p);
  24     SkPaint black;
  25     canvas->drawString("BW Dither", 0, 125, font, black);
  26
  27     // Scaled BW Dither
  28     canvas->translate(105, 0);
  29     canvas->save();
  30     canvas->scale(0.5, 0.5);
  31     canvas->drawRect({0, 0, 200, 200}, p);
  32     canvas->restore();
  33     canvas->drawString("Scaled Dither", 0, 125, font, black);
  34
  35     // Blend black on to white
  36     canvas->translate(105, 0);
  37     p.setColor(0x80000000);
  38     p.setShader(nullptr);
  39     canvas->drawRect({0, 0, 100, 100}, p);
  40     p.setShader(nullptr);
  41     canvas->drawString("Blend", 0, 125, font, black);
  42
  43     // Opaque color (0xFFBCBCBC)
  44     canvas->translate(105, 0);
  45     p.setColor(0xFFBCBCBC);
  46     canvas->drawRect({0, 0, 100, 100}, p);
  47     canvas->drawString("0xFFBCBCBC", 0, 125, font, black);
  48
  49     // Opaque color (0xFF808080)
  50     canvas->translate(105, 0);
  51     p.setColor(0xFF808080);
  52     canvas->drawRect({0, 0, 100, 100}, p);
  53     canvas->drawString("0xFF808080", 0, 125, font, black);
  54 }
  55 }  // END FIDDLE