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_RASTER_RASTER_SOURCE_H_
#define CC_RASTER_RASTER_SOURCE_H_

#include <stddef.h>

#include <memory>
#include <vector>

#include "base/macros.h"
#include "cc/cc_export.h"
#include "cc/debug/rendering_stats_instrumentation.h"
#include "cc/layers/recording_source.h"
#include "cc/paint/image_id.h"
#include "skia/ext/analysis_canvas.h"
#include "third_party/skia/include/core/SkPicture.h"
#include "ui/gfx/color_space.h"

namespace gfx {
class AxisTransform2d;
}  // namespace gfx

namespace cc {
class DisplayItemList;
class DrawImage;
class ImageProvider;

class CC_EXPORT RasterSource : public base::RefCountedThreadSafe<RasterSource> {
 public:
  struct CC_EXPORT PlaybackSettings {
    PlaybackSettings();
    PlaybackSettings(const PlaybackSettings&);
    PlaybackSettings(PlaybackSettings&&);
    ~PlaybackSettings();

    // If set to true, we should use LCD text.
    bool use_lcd_text = true;
    bool clear_canvas_before_raster = true;

    // The ImageProvider used to replace images during playback.
    ImageProvider* image_provider = nullptr;
  };

  // Helper function to apply a few common operations before passing the canvas
  // to the shorter version. This is useful for rastering into tiles.
  // canvas is expected to be backed by a tile, with a default state.
  // raster_transform will be applied to the display list, rastering the list
  // into the "content space".
  // canvas_bitmap_rect defines the extent of the tile in the content space,
  // i.e. contents in the rect will be cropped and translated onto the canvas.
  // canvas_playback_rect can be used to replay only part of the recording in,
  // the content space, so only a sub-rect of the tile gets rastered.
  void PlaybackToCanvas(SkCanvas* canvas,
                        const gfx::ColorSpace& target_color_space,
                        const gfx::Rect& canvas_bitmap_rect,
                        const gfx::Rect& canvas_playback_rect,
                        const gfx::AxisTransform2d& raster_transform,
                        const PlaybackSettings& settings) const;

  // Raster this RasterSource into the given canvas. Canvas states such as
  // CTM and clip region will be respected. This function will replace pixels
  // in the clip region without blending. It is assumed that existing pixels
  // may be uninitialized and will be cleared before playback.
  //
  // Virtual for testing.
  //
  // Note that this should only be called after the image decode controller has
  // been set, which happens during commit.
  virtual void PlaybackToCanvas(SkCanvas* canvas,
                                const gfx::ColorSpace& target_color_space,
                                const PlaybackSettings& settings) const;

  // Returns whether the given rect at given scale is of solid color in
  // this raster source, as well as the solid color value.
  bool PerformSolidColorAnalysis(gfx::Rect content_rect, SkColor* color) const;

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

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

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

  // Populate the given list with all images that may overlap the given
  // rect in layer space.
  void GetDiscardableImagesInRect(const gfx::Rect& layer_rect,
                                  std::vector<const DrawImage*>* images) const;

  // Return true iff this raster source can raster the given rect in layer
  // space.
  bool CoversRect(const gfx::Rect& layer_rect) const;

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

  // Valid rectangle in which everything is recorded and can be rastered from.
  virtual gfx::Rect RecordedViewport() const;

  // Tracing functionality.
  virtual void DidBeginTracing();
  virtual void AsValueInto(base::trace_event::TracedValue* array) const;
  virtual sk_sp<SkPicture> GetFlattenedPicture();
  virtual size_t GetMemoryUsage() const;

  const scoped_refptr<DisplayItemList>& GetDisplayItemList() const {
    return display_list_;
  }

  float recording_scale_factor() const { return recording_scale_factor_; }

  SkColor background_color() const { return background_color_; }

  base::flat_map<PaintImage::Id, PaintImage::DecodingMode>
  TakeDecodingModeMap();

 protected:
  // RecordingSource is the only class that can create a raster source.
  friend class RecordingSource;
  friend class base::RefCountedThreadSafe<RasterSource>;

  explicit RasterSource(const RecordingSource* other);
  virtual ~RasterSource();

  // These members are const as this raster source may be in use on another
  // thread and so should not be touched after construction.
  const scoped_refptr<DisplayItemList> display_list_;
  const size_t painter_reported_memory_usage_;
  const SkColor background_color_;
  const bool requires_clear_;
  const bool is_solid_color_;
  const SkColor solid_color_;
  const gfx::Rect recorded_viewport_;
  const gfx::Size size_;
  const bool clear_canvas_with_debug_color_;
  const int slow_down_raster_scale_factor_for_debug_;
  const float recording_scale_factor_;

 private:
  void RasterCommon(SkCanvas* canvas,
                    ImageProvider* image_provider = nullptr,
                    SkPicture::AbortCallback* callback = nullptr) const;

  void ClearCanvasForPlayback(SkCanvas* canvas) const;

  DISALLOW_COPY_AND_ASSIGN(RasterSource);
};

}  // namespace cc

#endif  // CC_RASTER_RASTER_SOURCE_H_