ui/ozone/platform/dri/scanout_surface.h

   1 // Copyright 2014 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 UI_OZONE_PLATFORM_DRI_SCANOUT_SURFACE_H_
   6 #define UI_OZONE_PLATFORM_DRI_SCANOUT_SURFACE_H_
   7
   8 #include <stdint.h>
   9
  10 namespace gfx {
  11 class Size;
  12 }
  13
  14 namespace ui {
  15
  16 // ScanoutSurface is an interface for a surface that can be scanned out to a
  17 // monitor using the DRM/KMS API. Implementations will store the internal state
  18 // associated with the drawing surface. Implementations are also required to
  19 // performs all the needed operations to initialize and update the drawing
  20 // surface.
  21 //
  22 // The typical usage pattern is:
  23 // -----------------------------------------------------------------------------
  24 // HardwareDisplayController controller;
  25 // // Initialize controller
  26 //
  27 // ScanoutSurface* surface = new ScanoutSurfaceImpl(size);
  28 // surface.Initialize();
  29 // controller.BindSurfaceToController(surface);
  30 //
  31 // while (true) {
  32 //   DrawIntoSurface(surface);
  33 //   controller.SchedulePageFlip();
  34 //
  35 //   Wait for page flip event. The DRM page flip handler will call
  36 //   surface.SwapBuffers();
  37 // }
  38 //
  39 // delete surface;
  40 // -----------------------------------------------------------------------------
  41 // In the above example the wait consists of reading a DRM pageflip event from
  42 // the graphics card file descriptor. This is done by calling |drmHandleEvent|,
  43 // which will read and process the event. |drmHandleEvent| will call a callback
  44 // registered by |SchedulePageFlip| which will update the internal state.
  45 //
  46 // |SchedulePageFlip| can also be used to limit drawing to the screen's vsync
  47 // since page flips only happen on vsync. In a threaded environment a message
  48 // loop would listen on the graphics card file descriptor for an event and
  49 // |drmHandleEvent| would be called from the message loop. The event handler
  50 // would also be responsible for updating the renderer's state and signal that
  51 // it is OK to start drawing the next frame.
  52 class ScanoutSurface {
  53  public:
  54   virtual ~ScanoutSurface() {}
  55
  56   // Used to allocate all necessary buffers for this surface. If the
  57   // initialization succeeds, the device is ready to be used for drawing
  58   // operations.
  59   // Returns true if the initialization is successful, false otherwise.
  60   virtual bool Initialize() = 0;
  61
  62   // Swaps the back buffer with the front buffer.
  63   virtual void SwapBuffers() = 0;
  64
  65   // Returns the ID of the current backbuffer.
  66   virtual uint32_t GetFramebufferId() const = 0;
  67
  68   // Returns the handle of the current backbuffer.
  69   virtual uint32_t GetHandle() const = 0;
  70
  71   // Returns the surface size.
  72   virtual gfx::Size Size() const = 0;
  73 };
  74
  75 class ScanoutSurfaceGenerator {
  76  public:
  77   virtual ~ScanoutSurfaceGenerator() {}
  78
  79   virtual ScanoutSurface* Create(const gfx::Size& size) = 0;
  80 };
  81
  82 }  // namespace ui
  83
  84 #endif  // UI_OZONE_PLATFORM_DRI_SCANOUT_SURFACE_H_