Calling OpenGL from the renderer process.

chrome/renderer/ggl/ggl.h

 // Copyright (c) 2010 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.
 
 // This API is consistent with other OpenGL setup APIs like window's WGL
 // and pepper's PGL. This API is used to manage OpenGL contexts in the Chrome
 // renderer process in a way that is consistent with other platforms. It is
 // a C style API to ease porting of existing OpenGL software to Chrome.
 
 #ifndef CHROME_RENDERER_GGL_GGL_H_
 #define CHROME_RENDERER_GGL_GGL_H_
 
+#include "gfx/native_widget_types.h"
+#include "gfx/size.h"
+
 class GpuChannelHost;
 
 namespace ggl {
 
 class Context;
 
 // These are the same error codes as used by EGL.
 enum Error {
   SUCCESS             = 0x3000,
   NOT_INITIALIZED     = 0x3001,
   BAD_CONTEXT         = 0x3006,
   CONTEXT_LOST        = 0x300E
 };
 
 // Initialize the GGL library. This must have completed before any other GGL
 // functions are invoked.
 bool Initialize();
 
 // Terminate the GGL library. This must be called after any other GGL functions
 // have completed.
 bool Terminate();
 
-// Create A GGL context for an offscreen 1 x 1 pbuffer.
-Context* CreateContext(GpuChannelHost* channel);
+// Create a GGL context that renders directly to a view.
+Context* CreateViewContext(GpuChannelHost* channel, gfx::NativeViewId view);
+
+// Create a GGL context that renders to an offscreen frame buffer. If parent is
+// not NULL, that context can access a copy of the created
+// context's frame buffer that is updated every time SwapBuffers is called. It
+// is not as general as shared contexts in other implementations of OpenGL. If
+// parent is not NULL, it must be used on the same thread as the parent. A child
+// context may not outlive its parent.
+Context* CreateOffscreenContext(GpuChannelHost* channel,
+                                Context* parent,
+                                const gfx::Size& size);
+
+// Resize an offscreen frame buffer. The resize occurs on the next call to
+// SwapBuffers. This is to avoid waiting until all pending GL calls have been
+// executed by the GPU process. Everything rendered up to the call to
+// SwapBuffers will be lost. A lost context will be reported if the resize
+// fails.
+void ResizeOffscreenContext(Context* context, const gfx::Size& size);
+
+// For an offscreen frame buffer context, return the texture ID with
+// respect to the parent context. Returns zero if context does not have a
+// parent.
+uint32 GetParentTextureId(Context* context);
 
 // Set the current GGL context for the calling thread.
 bool MakeCurrent(Context* context);
 
 // Get the calling thread's current GGL context.
 Context* GetCurrentContext();
 
-// Display everything that has been rendered since the last call.
+// For a view context, display everything that has been rendered since the
+// last call. For an offscreen context, resolve everything that has been
+// rendered since the last call to a copy that can be accessed by the parent
+// context.
 bool SwapBuffers();
 
 // Destroy the given GGL context.
 bool DestroyContext(Context* context);
 
 // Return the current GGL error.
 Error GetError();
 
 }  // namespace ggl
 
 #endif  // CHROME_RENDERER_GGL_GGL_H_