exo: Add support for alpha_compositing interface to wayland bindings.

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 <memory>
 #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 "third_party/skia/include/core/SkXfermode.h"
 #include "ui/aura/window.h"
 #include "ui/aura/window_observer.h"
 #include "ui/compositor/compositor_observer.h"
 #include "ui/gfx/geometry/rect.h"
 
 namespace base {
 namespace trace_event {
 class TracedValue;
 }
 }
@@ skipping 54 matching lines @@
   void PlaceSubSurfaceAbove(Surface* sub_surface, Surface* reference);
   void PlaceSubSurfaceBelow(Surface* sub_surface, Surface* sibling);
 
   // This sets the surface viewport for scaling.
   void SetViewport(const gfx::Size& viewport);
 
   // This sets the only visible on secure output flag, preventing it from
   // appearing in screenshots or from being viewed on non-secure displays.
   void SetOnlyVisibleOnSecureOutput(bool only_visible_on_secure_output);
 
+  // This sets the blend mode that will be used when drawing the surface.
+  void SetBlendMode(SkXfermode::Mode blend_mode);

[Daniele Castagna, 2016/05/09 23:34:19]

nit: You can drop "This". Comments are usually imperative. I see the same "This
does" above though, so it can probably stay the same.

[reveman, 2016/05/10 14:05:19]

"This" all over place in this file so I'm going to keep it consistent and maybe
change it in a follow up.

+
+  // This sets the alpha value that will be applied to the whole surface.
+  void SetAlpha(float alpha);
+
   // Surface state (damage regions, attached buffers, etc.) is double-buffered.
   // A Commit() call atomically applies all pending state, replacing the
   // 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();
@@ skipping 90 matching lines @@
   using SubSurfaceEntry = std::pair<Surface*, gfx::Point>;
   using SubSurfaceEntryList = std::list<SubSurfaceEntry>;
   SubSurfaceEntryList pending_sub_surfaces_;
 
   // The viewport to take effect when Commit() is called.
   gfx::Size pending_viewport_;
 
   // The secure output visibility state to take effect when Commit() is called.
   bool pending_only_visible_on_secure_output_;
 
+  // The blend mode state to take effect when Commit() is called.
+  SkXfermode::Mode pending_blend_mode_;

[Daniele Castagna, 2016/05/09 23:34:19]

Would it make sense to group all the pending state in a struct?

[reveman, 2016/05/10 14:05:19]

It might. I'll consider it for a follow up change.

+
+  // The alpha state to take effect when Commit() is called.
+  float pending_alpha_;
+
   // The buffer that is currently set as content of surface.
   base::WeakPtr<Buffer> current_buffer_;
 
   // The active input region used for hit testing.
   SkRegion input_region_;
 
   // This is true if a call to Commit() as been made but
   // CommitSurfaceHierarchy() has not yet been called.
   bool needs_commit_surface_hierarchy_;
 
@@ 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_