Calling OpenGL from the renderer process.

chrome/renderer/ggl/ggl.cc

 // 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.
 
 #include "build/build_config.h"
 
 #include "base/ref_counted.h"
 #include "base/singleton.h"
 #include "base/thread_local.h"
 #include "chrome/renderer/command_buffer_proxy.h"
@@ skipping 32 matching lines @@
   }
 
  private:
   DISALLOW_COPY_AND_ASSIGN(GLES2Initializer);
 };
 }  // namespace anonymous
 
 // Manages a GL context.
 class Context {
  public:
-  Context();
+  Context(GpuChannelHost* channel, Context* parent);
   ~Context();
 
   // Initialize a GGL context that can be used in association with a a GPU
   // channel acquired from a RenderWidget or RenderView.
-  bool Initialize(GpuChannelHost* channel);
+  bool Initialize(gfx::NativeViewId view, const gfx::Size& size);
+
+  // Asynchronously resizes an offscreen frame buffer.
+  void ResizeOffscreen(const gfx::Size& size);
+
+  // For an offscreen frame buffer context, return the frame buffer ID with
+  // respect to the parent.
+  uint32 parent_texture_id() const {
+    return parent_texture_id_;
+  }
 
   // Destroy all resources associated with the GGL context.
   void Destroy();
 
   // Make a GGL context current for the calling thread.
   static bool MakeCurrent(Context* context);
 
   // Display all content rendered since last call to SwapBuffers.
   // TODO(apatrick): support rendering to browser window. This function is
   // not useful at this point.
   bool SwapBuffers();
 
   // Get the current error code.
   Error GetError();
 
  private:
   scoped_refptr<GpuChannelHost> channel_;
+  Context* parent_;
+  uint32 parent_texture_id_;
   CommandBufferProxy* command_buffer_;
   gpu::gles2::GLES2CmdHelper* gles2_helper_;
   int32 transfer_buffer_id_;
   gpu::gles2::GLES2Implementation* gles2_implementation_;
 
   DISALLOW_COPY_AND_ASSIGN(Context);
 };
 
-Context::Context()
-    : channel_(NULL),
+Context::Context(GpuChannelHost* channel, Context* parent)
+    : channel_(channel),
+      parent_(parent),
+      parent_texture_id_(0),
       command_buffer_(NULL),
       gles2_helper_(NULL),
       transfer_buffer_id_(0),
       gles2_implementation_(NULL) {
+  DCHECK(channel);
 }
 
 Context::~Context() {
   Destroy();
 }
 
-bool Context::Initialize(GpuChannelHost* channel) {
-  DCHECK(channel);
+bool Context::Initialize(gfx::NativeViewId view, const gfx::Size& size) {
+  DCHECK(size.width() >= 0 && size.height() >= 0);
 
-  if (!channel->ready())
+  if (!channel_->ready())
     return false;
 
-  channel_ = channel;
-
   // Ensure the gles2 library is initialized first in a thread safe way.
   Singleton<GLES2Initializer>::get();
 
+  // Allocate a frame buffer ID with respect to the parent.
+  if (parent_) {
+    parent_->gles2_implementation_->MakeIds(1, &parent_texture_id_);
+  }
+
   // Create a proxy to a command buffer in the GPU process.
-  command_buffer_ = channel_->CreateCommandBuffer();
+  if (view) {
+    command_buffer_ = channel_->CreateViewCommandBuffer(view);
+  } else {
+    CommandBufferProxy* parent_command_buffer =
+        parent_ ? parent_->command_buffer_ : NULL;
+    command_buffer_ = channel_->CreateOffscreenCommandBuffer(
+        parent_command_buffer,
+        size,
+        parent_texture_id_);
+  }
   if (!command_buffer_) {
     Destroy();
     return false;
   }
 
   // Initiaize the command buffer.
   if (!command_buffer_->Initialize(kCommandBufferSize)) {
     Destroy();
     return false;
   }
@@ skipping 25 matching lines @@
   // Create the object exposing the OpenGL API.
   gles2_implementation_ = new gpu::gles2::GLES2Implementation(
       gles2_helper_,
       transfer_buffer.size,
       transfer_buffer.ptr,
       transfer_buffer_id_);
 
   return true;
 }
 
+void Context::ResizeOffscreen(const gfx::Size& size) {
+  DCHECK(size.width() > 0 && size.height() > 0);
+  command_buffer_->ResizeOffscreenFrameBuffer(size);
+}
+
 void Context::Destroy() {
+  if (parent_ && parent_texture_id_ != 0)
+    parent_->gles2_implementation_->FreeIds(1, &parent_texture_id_);
+
   delete gles2_implementation_;
   gles2_implementation_ = NULL;
 
   if (command_buffer_ && transfer_buffer_id_ != 0) {
     command_buffer_->DestroyTransferBuffer(transfer_buffer_id_);
     transfer_buffer_id_ = 0;
   }
 
   delete gles2_helper_;
   gles2_helper_ = NULL;
@@ skipping 41 matching lines @@
     return SUCCESS;
   } else {
     // All command buffer errors are unrecoverable. The error is treated as a
     // lost context: destroy the context and create another one.
     return CONTEXT_LOST;
   }
 }
 
 #endif  // ENABLE_GPU
 
-Context* CreateContext(GpuChannelHost* channel) {
+Context* CreateViewContext(GpuChannelHost* channel, gfx::NativeViewId view) {
 #if defined(ENABLE_GPU)
-  scoped_ptr<Context> context(new Context);
-  if (!context->Initialize(channel))
+  scoped_ptr<Context> context(new Context(channel, NULL));
+  if (!context->Initialize(view, gfx::Size()))
     return NULL;
 
   return context.release();
 #else
   return NULL;
 #endif
 }
 
+Context* CreateOffscreenContext(GpuChannelHost* channel,
+                                Context* parent,
+                                const gfx::Size& size) {
+#if defined(ENABLE_GPU)
+  scoped_ptr<Context> context(new Context(channel, parent));
+  if (!context->Initialize(NULL, size))
+    return NULL;
+
+  return context.release();
+#else
+  return NULL;
+#endif
+}
+
+void ResizeOffscreenContext(Context* context, const gfx::Size& size) {
+#if defined(ENABLE_GPU)
+  context->ResizeOffscreen(size);
+#endif
+}
+
+uint32 GetParentTextureId(Context* context) {
+#if defined(ENABLE_GPU)
+  return context->parent_texture_id();
+#else
+  return 0;
+#endif
+}
+
 bool MakeCurrent(Context* context) {
 #if defined(ENABLE_GPU)
   return Context::MakeCurrent(context);
 #else
   return false;
 #endif
 }
 
 Context* GetCurrentContext() {
 #if defined(ENABLE_GPU)
@@ skipping 36 matching lines @@
   if (!context)
     return BAD_CONTEXT;
 
   return context->GetError();
 #else
   return NOT_INITIALIZED;
 #endif
 }
 
 }  // namespace ggl