paint_utils.cc

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// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
 
#include "flutter/flow/paint_utils.h"
 
#include <stdlib.h>
 
#include "third_party/skia/include/core/SkBitmap.h"
#include "third_party/skia/include/core/SkImage.h"
 
namespace flutter {
 
namespace {
 
static std::shared_ptr<DlColorSource> CreateCheckerboardShader(SkColor c1,
                                                               SkColor c2,
                                                               int size) {
  SkBitmap bm;
  bm.allocN32Pixels(2 * size, 2 * size);
  bm.eraseColor(c1);
  bm.eraseArea(SkIRect::MakeLTRB(0, 0, size, size), c2);
  bm.eraseArea(SkIRect::MakeLTRB(size, size, 2 * size, 2 * size), c2);
  auto image = DlImage::Make(SkImages::RasterFromBitmap(bm));
  return DlColorSource::MakeImage(image, DlTileMode::kRepeat,
                                  DlTileMode::kRepeat,
                                  DlImageSampling::kNearestNeighbor);
}
 
}  // anonymous namespace
 
void DrawCheckerboard(DlCanvas* canvas, const DlRect& rect) {
  // Draw a checkerboard
  canvas->Save();
  canvas->ClipRect(rect, DlClipOp::kIntersect, false);
 
  // Secure random number generation isn't needed here.
  // NOLINTBEGIN(clang-analyzer-security.insecureAPI.rand)
  auto checkerboard_color =
      SkColorSetARGB(64, rand() % 256, rand() % 256, rand() % 256);
  // NOLINTEND(clang-analyzer-security.insecureAPI.rand)
 
  DlPaint paint;
  paint.setColorSource(
      CreateCheckerboardShader(checkerboard_color, 0x00000000, 12));
  canvas->DrawPaint(paint);
  canvas->Restore();
 
  // Stroke the drawn area
  DlPaint debug_paint;
  debug_paint.setStrokeWidth(8);
  debug_paint.setColor(DlColor(SkColorSetA(checkerboard_color, 255)));
  debug_paint.setDrawStyle(DlDrawStyle::kStroke);
  canvas->DrawRect(rect, debug_paint);
}
 
}  // namespace flutter