submodule/skia/docs/examples/purplestamp.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(purplestamp, 256, 256, false, 0) {
   5 // purplestamp
   6
   7 // Whether to use a separate bitmap (with a color type) at all.
   8 bool drawWithRasterImage = true;
   9
  10 // This works with either kN32_SkColorType or kAlpha_8_SkColorType.
  11 // Applies only if drawWithRasterImage is true.
  12 SkColorType colorType = kN32_SkColorType;
  13
  14 void drawStamp(SkCanvas* canvas, int size) {
  15     canvas->save();
  16     canvas->clipRect(SkRect::MakeWH(size, size), SkClipOp::kIntersect, true);
  17
  18     canvas->clear(0x3F000000 /* translucent black */);
  19
  20     SkPaint paint;
  21     paint.setAntiAlias(true);
  22     paint.setColor(SK_ColorBLACK);
  23     canvas->drawRRect(
  24             SkRRect::MakeOval(SkRect::MakeXYWH(size / 4, size / 4, size / 2, size / 2)), paint);
  25
  26     paint.setStyle(SkPaint::kStroke_Style);
  27     paint.setStrokeWidth(20);
  28     canvas->drawRect(SkRect::MakeWH(size, size), paint);
  29
  30     canvas->restore();
  31 }
  32
  33 sk_sp<SkImage> stampImage(int size) {
  34     sk_sp<SkSurface> surface = SkSurface::MakeRaster(
  35             SkImageInfo::Make(size, size, colorType, kPremul_SkAlphaType));
  36     drawStamp(surface->getCanvas(), size);
  37     return surface->makeImageSnapshot();
  38 }
  39
  40 void draw(SkCanvas* canvas) {
  41     SkPaint paint;
  42     paint.setColorFilter(SkColorFilters::Blend(0xFF7F00FF, SkBlendMode::kSrcIn));
  43     paint.setAntiAlias(true);
  44
  45     SkSamplingOptions sampling(SkFilterMode::kLinear, SkMipmapMode::kLinear);
  46
  47     canvas->rotate(30);
  48     canvas->translate(60, 0);
  49
  50     int stampSize = 200;
  51     if (drawWithRasterImage) {
  52         canvas->drawImage(stampImage(stampSize), 0, 0, sampling, &paint);
  53     } else {
  54         canvas->saveLayer(nullptr, &paint);
  55         drawStamp(canvas, stampSize);
  56         canvas->restore();
  57     }
  58 }
  59 }  // END FIDDLE