Implement asynchronous operation for RWHVP::CopyFromCompositingSurface on Mac

content/browser/renderer_host/compositing_iosurface_mac.h

 // Copyright (c) 2012 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 CONTENT_BROWSER_RENDERER_HOST_ACCELERATED_COMPOSITING_VIEW_MAC_H
 #define CONTENT_BROWSER_RENDERER_HOST_ACCELERATED_COMPOSITING_VIEW_MAC_H
 
 #import <Cocoa/Cocoa.h>
 #import <QuartzCore/CVDisplayLink.h>
 #include <QuartzCore/QuartzCore.h>
 
+#include "base/callback.h"
 #include "base/mac/scoped_cftyperef.h"
 #include "base/memory/scoped_nsobject.h"
 #include "base/synchronization/lock.h"
 #include "base/time.h"
 #include "base/timer.h"
 #include "ui/gfx/native_widget_types.h"
+#include "ui/gfx/rect.h"
 #include "ui/gfx/size.h"
 
 class IOSurfaceSupport;
 
 namespace gfx {
 class Rect;
 }
 
 namespace content {
 
@@ skipping 13 matching lines @@
   // Blit the IOSurface at the upper-left corner of the |view|. If |view| window
   // size is larger than the IOSurface, the remaining right and bottom edges
   // will be white. |scaleFactor| is 1 in normal views, 2 in HiDPI views.
   void DrawIOSurface(NSView* view, float scale_factor);
 
   // Copy the data of the "live" OpenGL texture referring to this IOSurfaceRef
   // into |out|. The copied region is specified with |src_pixel_subrect| and
   // the data is transformed so that it fits in |dst_pixel_size|.
   // |src_pixel_subrect| and |dst_pixel_size| are not in DIP but in pixel.
   // Caller must ensure that |out| is allocated with the size no less than
   // |4 * dst_pixel_size.width() * dst_pixel_size.height()| bytes.

[Nico, 2012/09/22 11:12:21]

Describe |callback|, mention that only one callback can be in flight at once.

-  bool CopyTo(const gfx::Rect& src_pixel_subrect,
+  void CopyTo(const gfx::Rect& src_pixel_subrect,
               const gfx::Size& dst_pixel_size,
-              void* out);
+              void* out,
+              const base::Callback<void(bool)>& callback);
 
   // Unref the IOSurface and delete the associated GL texture. If the GPU
   // process is no longer referencing it, this will delete the IOSurface.
   void UnrefIOSurface();
 
   // Call when globalFrameDidChange is received on the NSView.
   void GlobalFrameDidChange();
 
   // Disassociate the GL context with the NSView and unref the IOSurface. Do
   // this to switch to software drawing mode.
@@ skipping 71 matching lines @@
       // Texture coordinates are flipped vertically so they can be drawn on
       // a projection with a flipped y-axis (origin is top left).
       verts_[0].set_texcoord(tx1, ty2);
       verts_[1].set_texcoord(tx1, ty1);
       verts_[2].set_texcoord(tx2, ty1);
       verts_[3].set_texcoord(tx2, ty2);
     }
     SurfaceVertex verts_[4];
   };
 
+  // Keeps track of states and buffers for asynchronous readback of IOSurface.
+  struct CopyContext {
+    CopyContext();
+    ~CopyContext();
+
+    void Reset() {
+      started = false;
+      cycles_elapsed = 0;
+      frame_buffer = 0;
+      frame_buffer_texture = 0;
+      pixel_buffer = 0;
+      use_fence = false;
+      fence = 0;

[Nico, 2012/09/22 11:12:21]

you're not setting src_rect and dest_size to their empty values. I suppose
that's intentional?

+      out_buf = NULL;
+      callback.Reset();
+    }
+
+    bool started;
+    int cycles_elapsed;
+    GLuint frame_buffer;
+    GLuint frame_buffer_texture;
+    GLuint pixel_buffer;
+    bool use_fence;
+    GLuint fence;
+    gfx::Rect src_rect;
+    gfx::Size dest_size;
+    void* out_buf;
+    base::Callback<void(bool)> callback;
+  };
+
   CompositingIOSurfaceMac(IOSurfaceSupport* io_surface_support,
                           NSOpenGLContext* glContext,
                           CGLContextObj cglContext,
                           GLuint shader_program_blit_rgb,
                           GLint blit_rgb_sampler_location,
                           GLuint shader_program_white,
                           bool is_vsync_disabled,
                           CVDisplayLinkRef display_link);
 
   // Returns true if IOSurface is ready to render. False otherwise.
   bool MapIOSurfaceToTexture(uint64 io_surface_handle);
 
   void UnrefIOSurfaceWithContextCurrent();
 
   void DrawQuad(const SurfaceQuad& quad);
 
   // Called on display-link thread.
   void DisplayLinkTick(CVDisplayLinkRef display_link,
                        const CVTimeStamp* time);
 
   void CalculateVsyncParametersLockHeld(const CVTimeStamp* time);
 
   // Prevent from spinning on CGLFlushDrawable when it fails to throttle to
   // VSync frequency.
   void RateLimitDraws();
 
   void StartOrContinueDisplayLink();
   void StopDisplayLink();
 
+  void FinishCopy();
+  void CleanupResourcesForCopy();
+
   // Cached pointer to IOSurfaceSupport Singleton.
   IOSurfaceSupport* io_surface_support_;
 
   // GL context
   scoped_nsobject<NSOpenGLContext> glContext_;
   CGLContextObj cglContext_;  // weak, backed by |glContext_|.
 
   // IOSurface data.
   uint64 io_surface_handle_;
   base::mac::ScopedCFTypeRef<CFTypeRef> io_surface_;
 
   // The width and height of the io surface.
   gfx::Size pixel_io_surface_size_;  // In pixels.
   gfx::Size io_surface_size_;  // In view units.
 
   // The "live" OpenGL texture referring to this IOSurfaceRef. Note
   // that per the CGLTexImageIOSurface2D API we do not need to
   // explicitly update this texture's contents once created. All we
   // need to do is ensure it is re-bound before attempting to draw
   // with it.
   GLuint texture_;
 
+  CopyContext copy_context_;
+
+  // Timer for finishing a copy operation.
+  base::RepeatingTimer<CompositingIOSurfaceMac> copy_timer_;
+
   // Shader parameters.
   GLuint shader_program_blit_rgb_;
   GLint blit_rgb_sampler_location_;
   GLuint shader_program_white_;
 
   SurfaceQuad quad_;
 
   bool is_vsync_disabled_;
 
   // CVDisplayLink for querying Vsync timing info and throttling swaps.
@@ skipping 11 matching lines @@
 
   // Vsync timing data.
   base::TimeTicks vsync_timebase_;
   uint32 vsync_interval_numerator_;
   uint32 vsync_interval_denominator_;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_ACCELERATED_COMPOSITING_VIEW_MAC_H