exo: Add Surface::SetBufferScale.

components/exo/surface.h

 // Copyright 2015 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 COMPONENTS_EXO_SURFACE_H_
 #define COMPONENTS_EXO_SURFACE_H_
 
 #include <list>
 #include <utility>
 
@@ skipping 37 matching lines @@
   void Damage(const gfx::Rect& rect);
 
   // Request notification when the next frame is displayed. Useful for
   // throttling redrawing operations, and driving animations.
   using FrameCallback = base::Callback<void(base::TimeTicks frame_time)>;
   void RequestFrameCallback(const FrameCallback& callback);
 
   // This sets the region of the surface that contains opaque content.
   void SetOpaqueRegion(const SkRegion& region);
 
+  // This sets the scaling factor used to interpret the contents of the buffer
+  // attached to the surface. Note that if the scale is larger than 1, then you
+  // have to attach a buffer that is larger (by a factor of scale in each
+  // dimension) than the desired surface size.
+  void SetBufferScale(float scale);
+
   // Functions that control sub-surface state. All sub-surface state is
   // double-buffered and will be applied when Commit() is called.
   void AddSubSurface(Surface* sub_surface);
   void RemoveSubSurface(Surface* sub_surface);
   void SetSubSurfacePosition(Surface* sub_surface, const gfx::Point& position);
   void PlaceSubSurfaceAbove(Surface* sub_surface, Surface* reference);
   void PlaceSubSurfaceBelow(Surface* sub_surface, Surface* sibling);
 
   // Surface state (damage regions, attached buffers, etc.) is double-buffered.
   // A Commit() call atomically applies all pending state, replacing the
@@ skipping 64 matching lines @@
   // |active_frame_callbacks_| when the effect of the Commit() is reflected in
   // the compositor's active layer tree. The callbacks fire once we're notified
   // that the compositor started drawing that active layer tree.
   std::list<FrameCallback> pending_frame_callbacks_;
   std::list<FrameCallback> frame_callbacks_;
   std::list<FrameCallback> active_frame_callbacks_;
 
   // The opaque region to take effect when Commit() is called.
   SkRegion pending_opaque_region_;
 
+  // The buffer scaling factor to take effect when Commit() is called.
+  float pending_buffer_scale_;
+
   // The stack of sub-surfaces to take effect when Commit() is called.
   // Bottom-most sub-surface at the front of the list and top-most sub-surface
   // at the back.
   using SubSurfaceEntry = std::pair<Surface*, gfx::Point>;
   using SubSurfaceEntryList = std::list<SubSurfaceEntry>;
   SubSurfaceEntryList pending_sub_surfaces_;
 
   // The buffer that is currently set as content of surface.
   base::WeakPtr<Buffer> current_buffer_;
 
@@ skipping 15 matching lines @@
 
   // Surface observer list. Surface does not own the observers.
   base::ObserverList<SurfaceObserver, true> observers_;
 
   DISALLOW_COPY_AND_ASSIGN(Surface);
 };
 
 }  // namespace exo
 
 #endif  // COMPONENTS_EXO_SURFACE_H_