chromecast/public/osd_plane.h

   1 // Copyright (c) 2015 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CHROMECAST_PUBLIC_OSD_PLANE_H_
   6 #define CHROMECAST_PUBLIC_OSD_PLANE_H_
   7
   8 namespace chromecast {
   9
  10 class OsdSurface;
  11 struct Rect;
  12 struct Size;
  13
  14 // Abstract graphics plane for OSD, to be implemented in platform-specific way.
  15 // Platform must composite this plane on top of main (GL-based) graphics plane.
  16 class OsdPlane {
  17  public:
  18   virtual ~OsdPlane() {}
  19
  20   // Creates a surface for offscreen drawing.
  21   virtual OsdSurface* CreateSurface(const Size& size) = 0;
  22
  23   // Sets a clip rectangle, client should call before drawing to back buffer
  24   // to specify the area they intend to draw on.  Platforms may reduce memory
  25   // usage by only allocating back buffer to cover this area.  Areas outside
  26   // clip rectangle must display as fully transparent.  In particular, setting
  27   // an empty clip rectangle and calling Flip should clear the plane.
  28   virtual void SetClipRectangle(const Rect& rect) = 0;
  29
  30   // Gets the current back buffer surface.  Valid until next call to Flip or
  31   // SetClipRectangle.
  32   virtual OsdSurface* GetBackBuffer() = 0;
  33
  34   // Presents current back buffer to screen.
  35   virtual void Flip() = 0;
  36 };
  37
  38 }  // namespace chromecast
  39
  40 #endif  // CHROMECAST_PUBLIC_OSD_PLANE_H