exo: Add support for subcompositor interface.

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>
 
 #include "base/callback.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
+#include "base/observer_list.h"
 #include "third_party/skia/include/core/SkRegion.h"
 #include "ui/compositor/compositor_observer.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/views/view.h"
 
 namespace base {
 namespace trace_event {
 class TracedValue;
 }
 }
 
 namespace exo {
 class Buffer;
 class SurfaceDelegate;
+class SurfaceObserver;
 
 // This class represents a rectangular area that is displayed on the screen.
 // It has a location, size and pixel contents.
 class Surface : public views::View, public ui::CompositorObserver {
  public:
   Surface();
   ~Surface() override;
 
   // Set a buffer as the content of this surface. A buffer can only be attached
   // to one surface at a time.
   void Attach(Buffer* buffer);
 
   // Describe the regions where the pending buffer is different from the
   // current surface contents, and where the surface therefore needs to be
   // repainted.
   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);
 
+  // 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
-  // current state.
+  // current state. Commit() is not guaranteed to be synchronous. See
+  // CommitSurfaceHierarchy() below.
   void Commit();
 
+  // This will synchronously commit all pending state of the surface and its
+  // descendants by recursively calling CommitSurfaceHierarchy() for each
+  // sub-surface with pending state.
+  void CommitSurfaceHierarchy();
+
+  // Returns true if surface is in synchronized mode.
+  bool IsSynchronized() const;
+
   // Set the surface delegate.
   void SetSurfaceDelegate(SurfaceDelegate* delegate);
 
+  // Returns true if surface has been assigned a surface delegate.
+  bool HasSurfaceDelegate() const;
+
+  // Surface does not own observers. It is the responsibility of the observer
+  // to remove itself when it is done observing.
+  void AddSurfaceObserver(SurfaceObserver* observer);
+  void RemoveSurfaceObserver(SurfaceObserver* observer);
+  bool HasSurfaceObserver(const SurfaceObserver* observer) const;
+
   // Returns a trace value representing the state of the surface.
   scoped_refptr<base::trace_event::TracedValue> AsTracedValue() const;
 
   bool HasPendingDamageForTesting() const { return !pending_damage_.IsEmpty(); }
 
   // Overridden from views::View:
   gfx::Size GetPreferredSize() const override;
 
   // Overridden from ui::CompositorObserver:
   void OnCompositingDidCommit(ui::Compositor* compositor) override;
   void OnCompositingStarted(ui::Compositor* compositor,
                             base::TimeTicks start_time) override;
   void OnCompositingEnded(ui::Compositor* compositor) override {}
   void OnCompositingAborted(ui::Compositor* compositor) override {}
   void OnCompositingLockStateChanged(ui::Compositor* compositor) override {}
   void OnCompositingShuttingDown(ui::Compositor* compositor) override;
 
  private:
+  bool needs_commit_surface_hierarchy() const {
+    return needs_commit_surface_hierarchy_;
+  }
+
+  bool has_contents() const { return has_contents_; }
+
   // The buffer that will become the content of surface when Commit() is called.
   base::WeakPtr<Buffer> pending_buffer_;
 
   // The damage region to schedule paint for when Commit() is called.
   // TODO(reveman): Use SkRegion here after adding a version of
   // ui::Layer::SchedulePaint that takes a SkRegion.
   gfx::Rect pending_damage_;
 
   // These lists contains the callbacks to notify the client when it is a good
   // time to start producing a new frame. These callbacks move to
   // |frame_callbacks_| when Commit() is called. Later they are moved to
   // |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 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_;
+
+  // This is true if a call to Commit() as been made but
+  // CommitSurfaceHierarchy() has not yet been called.
+  bool needs_commit_surface_hierarchy_;
+
+  // This is true when surface has some contents assigned to it.
+  bool has_contents_;
+
   // The compsitor being observer or null if not observing a compositor.
   ui::Compositor* compositor_;
 
   // This can be set to have some functions delegated. E.g. ShellSurface class
   // can set this to handle Commit() and apply any double buffered state it
   // maintains.
   SurfaceDelegate* delegate_;
 
+  // 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_