Raster PictureLayerTiling with fractional translation

cc/raster/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 cc {
 class DisplayItemList;
 class DrawImage;
 class ImageDecodeCache;
+class ScaleTranslate2d;
 
 class CC_EXPORT RasterSource : public base::RefCountedThreadSafe<RasterSource> {
  public:
   struct CC_EXPORT PlaybackSettings {
     PlaybackSettings();
     PlaybackSettings(const PlaybackSettings&);
     PlaybackSettings(PlaybackSettings&&);
     ~PlaybackSettings();
 
     // If set to true, this indicates that the canvas has already been
@@ skipping 11 matching lines @@
     // during raster.
     // TODO(khushalsagar): Consolidate more settings for playback here? See
     // crbug.com/691076.
     ImageIdFlatSet images_to_skip;
   };
 
   static scoped_refptr<RasterSource> CreateFromRecordingSource(
       const RecordingSource* other,
       bool can_use_lcd_text);
 
-  // TODO(trchen): Deprecated.
+  // 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& canvas_color_space,
                         const gfx::Rect& canvas_bitmap_rect,
                         const gfx::Rect& canvas_playback_rect,
-                        float contents_scale,
+                        const ScaleTranslate2d& 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
@@ skipping 86 matching lines @@
                     SkPicture::AbortCallback* callback) const;
 
   void PrepareForPlaybackToCanvas(SkCanvas* canvas) const;
 
   DISALLOW_COPY_AND_ASSIGN(RasterSource);
 };
 
 }  // namespace cc
 
 #endif  // CC_RASTER_RASTER_SOURCE_H_