HDR: Do nonlinear blending in the compositor

cc/surfaces/surface_aggregator.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_SURFACES_SURFACE_AGGREGATOR_H_
 #define CC_SURFACES_SURFACE_AGGREGATOR_H_
 
 #include <map>
 #include <memory>
 #include <set>
@@ skipping 29 matching lines @@
   CompositorFrame Aggregate(const SurfaceId& surface_id);
   void ReleaseResources(const SurfaceId& surface_id);
   SurfaceIndexMap& previous_contained_surfaces() {
     return previous_contained_surfaces_;
   }
   void SetFullDamageForSurface(const SurfaceId& surface_id);
   void set_output_is_secure(bool secure) { output_is_secure_ = secure; }
 
   // Set the color spaces for the created RenderPasses, which is propagated
   // to the output surface.
-  void SetOutputColorSpace(const gfx::ColorSpace& output_color_space);
+  void SetOutputColorSpace(const gfx::ColorSpace& blending_color_space,
+                           const gfx::ColorSpace& output_color_space);
 
  private:
   struct ClipData {
     ClipData() : is_clipped(false) {}
     ClipData(bool is_clipped, const gfx::Rect& rect)
         : is_clipped(is_clipped), rect(rect) {}
 
     bool is_clipped;
     gfx::Rect rect;
   };
@@ skipping 39 matching lines @@
       const gfx::Transform& target_transform,
       const ClipData& clip_rect,
       RenderPass* dest_pass,
       const SurfaceId& surface_id);
   gfx::Rect PrewalkTree(const SurfaceId& surface_id,
                         bool in_moved_pixel_surface,
                         int parent_pass,
                         PrewalkResult* result);
   void CopyUndrawnSurfaces(PrewalkResult* prewalk);
   void CopyPasses(const CompositorFrame& frame, Surface* surface);
+  void AddColorConversionPass();
 
   // Remove Surfaces that were referenced before but aren't currently
   // referenced from the ResourceProvider.
   // Also notifies SurfaceAggregatorClient of newly added and removed
   // child surfaces.
   void ProcessAddedAndRemovedSurfaces();
 
   void PropagateCopyRequestPasses();
 
   int ChildIdForSurface(Surface* surface);
   gfx::Rect DamageRectForSurface(const Surface* surface,
                                  const RenderPass& source,
                                  const gfx::Rect& full_rect) const;
 
   SurfaceManager* manager_;
   ResourceProvider* provider_;
 
   // Every Surface has its own RenderPass ID namespace. This structure maps
   // each source (SurfaceId, RenderPass id) to a unified ID namespace that's
   // used in the aggregated frame. An entry is removed from the map if it's not
   // used for one output frame.
   using RenderPassIdAllocatorMap =
       std::map<std::pair<SurfaceId, int>, RenderPassInfo>;
   RenderPassIdAllocatorMap render_pass_allocator_map_;
   int next_render_pass_id_;
   const bool aggregate_only_damaged_;
   bool output_is_secure_;
+
+  // The color space for the root render pass. If this is different from
+  // |blending_color_space_|, then a final render pass to convert between
+  // the two will be added.
   gfx::ColorSpace output_color_space_;
+  // The color space in which blending is done, used for all non-root render
+  // passes.
+  gfx::ColorSpace blending_color_space_;
+  // The id for the final color conversion render pass.
+  int color_conversion_render_pass_id_ = 0;
 
   using SurfaceToResourceChildIdMap =
       std::unordered_map<SurfaceId, int, SurfaceIdHash>;
   SurfaceToResourceChildIdMap surface_id_to_resource_child_id_;
 
   // The following state is only valid for the duration of one Aggregate call
   // and is only stored on the class to avoid having to pass through every
   // function call.
 
   // This is the set of surfaces referenced in the aggregation so far, used to
@@ skipping 35 matching lines @@
   TransferableResourceArray* dest_resource_list_;
 
   base::WeakPtrFactory<SurfaceAggregator> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(SurfaceAggregator);
 };
 
 }  // namespace cc
 
 #endif  // CC_SURFACES_SURFACE_AGGREGATOR_H_