cc/resources/raster_source.h

// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CC_RESOURCES_RASTER_SOURCE_H_
#define CC_RESOURCES_RASTER_SOURCE_H_

#include <vector>

#include "base/memory/ref_counted.h"
#include "cc/base/cc_export.h"
#include "cc/debug/traced_value.h"
#include "skia/ext/refptr.h"
#include "third_party/skia/include/core/SkColor.h"
#include "third_party/skia/include/core/SkPixelRef.h"
#include "ui/gfx/geometry/rect.h"
#include "ui/gfx/geometry/size.h"

class SkCanvas;
class SkPicture;

namespace cc {

class Picture;

class CC_EXPORT RasterSource : public base::RefCountedThreadSafe<RasterSource> {
 public:
  struct CC_EXPORT SolidColorAnalysis {
    SolidColorAnalysis()
        : is_solid_color(false), solid_color(SK_ColorTRANSPARENT) {}
    ~SolidColorAnalysis() {}

    bool is_solid_color;
    SkColor solid_color;
  };

  // Raster a subrect of this RasterSource into the given canvas. It is
  // assumed that contents_scale has already been applied to this canvas.
  // Writes the total number of pixels rasterized and the time spent
  // rasterizing to the stats if the respective pointer is not nullptr.
  // It is assumed that the canvas passed here will only be rasterized by
  // this raster source via this call.
  virtual void PlaybackToCanvas(SkCanvas* canvas,
                                const gfx::Rect& canvas_rect,
                                float contents_scale) const = 0;

  // Similar to above, except that the canvas passed here can (or was already)
  // rasterized into by another raster source. That is, it is not safe to clear
  // the canvas or discard its underlying memory.
  virtual void PlaybackToSharedCanvas(SkCanvas* canvas,
                                      const gfx::Rect& canvas_rect,
                                      float contents_scale) const = 0;

  // Analyze to determine if the given rect at given scale is of solid color in
  // this raster source.
  virtual void PerformSolidColorAnalysis(
      const gfx::Rect& content_rect,
      float contents_scale,
      SolidColorAnalysis* analysis) const = 0;

  // Returns true iff the whole raster source is of solid color.
  virtual bool IsSolidColor() const = 0;

  // Returns the color of the raster source if it is solid color. The results
  // are unspecified if IsSolidColor returns false.
  virtual SkColor GetSolidColor() const = 0;

  // Returns the size of this raster source.
  virtual gfx::Size GetSize() const = 0;

  // Populate the given list with all SkPixelRefs that may overlap the given
  // rect at given scale.
  virtual void GatherPixelRefs(const gfx::Rect& content_rect,
                               float contents_scale,
                               std::vector<SkPixelRef*>* pixel_refs) const = 0;

  // Return true iff this raster source can raster the given rect at given
  // scale.
  virtual bool CoversRect(const gfx::Rect& content_rect,
                          float contents_scale) const = 0;

  // Returns true if this raster source has anything to rasterize.
  virtual bool HasRecordings() const = 0;

  // Informs the raster source that it should attempt to use distance field text
  // during rasterization.
  virtual void SetShouldAttemptToUseDistanceFieldText() = 0;

  // Return true iff this raster source would benefit from using distance
  // field text.
  virtual bool ShouldAttemptToUseDistanceFieldText() const = 0;

  // Tracing functionality.
  virtual void DidBeginTracing() = 0;
  virtual void AsValueInto(base::trace_event::TracedValue* array) const = 0;
  virtual skia::RefPtr<SkPicture> GetFlattenedPicture() = 0;
  virtual size_t GetPictureMemoryUsage() const = 0;

  // Return true if LCD anti-aliasing may be used when rastering text.
  virtual bool CanUseLCDText() const = 0;

 protected:
  friend class base::RefCountedThreadSafe<RasterSource>;

  RasterSource() {}
  virtual ~RasterSource() {}

 private:
  DISALLOW_COPY_AND_ASSIGN(RasterSource);
};

}  // namespace cc

#endif  // CC_RESOURCES_RASTER_SOURCE_H_