submodule/skia/docs/examples/skpaint_xfer.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(skpaint_xfer, 576, 640, false, 0) {
   5 static void draw_utf8_string(SkCanvas* c, const char* t, SkScalar x, SkScalar y,
   6                              const SkFont& f, const SkPaint& p) {
   7     c->drawTextBlob(SkTextBlob::MakeFromString(t, f).get(), x, y, p);
   8 }
   9
  10 void draw(SkCanvas* canvas) {
  11     SkBlendMode modes[] = {
  12         SkBlendMode::kClear,
  13         SkBlendMode::kSrc,
  14         SkBlendMode::kDst,
  15         SkBlendMode::kSrcOver,
  16         SkBlendMode::kDstOver,
  17         SkBlendMode::kSrcIn,
  18         SkBlendMode::kDstIn,
  19         SkBlendMode::kSrcOut,
  20         SkBlendMode::kDstOut,
  21         SkBlendMode::kSrcATop,
  22         SkBlendMode::kDstATop,
  23         SkBlendMode::kXor,
  24         SkBlendMode::kPlus,
  25         SkBlendMode::kModulate,
  26         SkBlendMode::kScreen,
  27         SkBlendMode::kOverlay,
  28         SkBlendMode::kDarken,
  29         SkBlendMode::kLighten,
  30         SkBlendMode::kColorDodge,
  31         SkBlendMode::kColorBurn,
  32         SkBlendMode::kHardLight,
  33         SkBlendMode::kSoftLight,
  34         SkBlendMode::kDifference,
  35         SkBlendMode::kExclusion,
  36         SkBlendMode::kMultiply,
  37         SkBlendMode::kHue,
  38         SkBlendMode::kSaturation,
  39         SkBlendMode::kColor,
  40         SkBlendMode::kLuminosity,
  41     };
  42     SkRect rect = SkRect::MakeWH(64.0f, 64.0f);
  43     SkPaint stroke, src, dst;
  44     stroke.setStyle(SkPaint::kStroke_Style);
  45     SkFont font(nullptr, 24);
  46     SkPoint srcPoints[2] = {
  47         SkPoint::Make(0.0f, 0.0f),
  48         SkPoint::Make(64.0f, 0.0f)
  49     };
  50     SkColor srcColors[2] = {
  51         SK_ColorMAGENTA & 0x00FFFFFF,
  52         SK_ColorMAGENTA};
  53     src.setShader(SkGradientShader::MakeLinear(
  54                 srcPoints, srcColors, nullptr, 2,
  55                 SkTileMode::kClamp, 0, nullptr));
  56
  57     SkPoint dstPoints[2] = {
  58         SkPoint::Make(0.0f, 0.0f),
  59         SkPoint::Make(0.0f, 64.0f)
  60     };
  61     SkColor dstColors[2] = {
  62         SK_ColorCYAN & 0x00FFFFFF,
  63         SK_ColorCYAN};
  64     dst.setShader(SkGradientShader::MakeLinear(
  65                 dstPoints, dstColors, nullptr, 2,
  66                 SkTileMode::kClamp, 0, nullptr));
  67     canvas->clear(SK_ColorWHITE);
  68     size_t N = sizeof(modes) / sizeof(modes[0]);
  69     size_t K = (N - 1) / 3 + 1;
  70     SkASSERT(K * 64 == 640);  // tall enough
  71     for (size_t i = 0; i < N; ++i) {
  72         SkAutoCanvasRestore autoCanvasRestore(canvas, true);
  73         canvas->translate(192.0f * (i / K), 64.0f * (i % K));
  74         const char* desc = SkBlendMode_Name(modes[i]);
  75         draw_utf8_string(canvas, desc, 68.0f, 30.0f, font, SkPaint());
  76         canvas->clipRect(SkRect::MakeWH(64.0f, 64.0f));
  77         canvas->drawColor(SK_ColorLTGRAY);
  78         (void)canvas->saveLayer(nullptr, nullptr);
  79         canvas->clear(SK_ColorTRANSPARENT);
  80         canvas->drawPaint(dst);
  81         src.setBlendMode(modes[i]);
  82         canvas->drawPaint(src);
  83         canvas->drawRect(rect, stroke);
  84     }
  85 }
  86 }  // END FIDDLE