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// Copyright (c) 2011 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.
// Transport texture is a mechanism to share a texture between renderer process
// and GPU process. This is useful when a texture is used in the renderer
// process but updated in the GPU process.
//
// BACKGROUND INFORMATION
//
// Renderer process uses command buffer to submit GLES2 commands to the GPU
// process for execution. When using a texture in the renderer process it is
// supposed to update the texture, for example by using glTexImage2D().
//
// However for some cases the texture needs to be updated in the GPU process.
// Objects other than command buffer in the GPU process will then need to
// access the texture ID.
//
// This class provides the following functions that solve the problems:
// 1. Textures be requested in the GPU process. The request is submitted
// to renderer process and textures are created in the command buffer
// context and eventually in the system context.
// 2. Textures are then create and used in the renderer process.
// 3. The corresponding texture ID in the GPU process can be obtained.
// 4. When texture is updated in the GPU process, notification can be received
// in the renderer process.
//
// THREAD SEMANTICS
//
// TransportTextureHost *must* be created on the render thread.
// After that methods of this object call be called on any thread.
//
// GLES2 commands are executed on Render Thread. IPC messages are sent and
// received on IO thread.
//
// USAGE
//
// --------------------------
// | In the renderer procss |
// --------------------------
//
// class TextureUpdateHandler {
// public:
// void OnTextureUpdate(int texture_id) {
// // Do something with the texture.
// }
// }
//
// TransportTextureHost factory_host;
// TextureUpdateHandler handler;
//
// void MyObjectInitDone() {
// std::vector<int> textures;
// factory_host.GetTextures(
// NewCallback(&handler, &TextureUpdateHandler::OnTextureUpdate),
// &textures);
// }
//
// void InitDone() {
// InitMyObjectInGPUProcess(factory_host.GetPeerId(),
// NewRunnableFunction(&MyObjectInitDone));
// }
//
// factory_host.Init(NewRunnableFunction(&InitDone));
//
// ----------------------
// | In the GPU process |
// ----------------------
//
// // When the transport texture factory id is known.
// TransportTexture* factory = gpu_channel->GetTransportTexture(id);
//
// void TextureCreateDone(vector<int> textures) {
// // Send message to renderer saying init is done.
// SendInitDone();
//
// UpdateTextureContent(textures[0]);
// factory->TextureUpdated(textures[0]);
// }
//
// // When init is requested from renderer.
// vector<int> textures;
//
// void OnInit() {
// factory->CreateTextures(3, 1024, 768, TransportTexture::RGB, &textures,
// NewRunnableFunction(&TextureCreateDone),
// textures);
// }
#ifndef CONTENT_RENDERER_TRANSPORT_TEXTURE_HOST_H_
#define CONTENT_RENDERER_TRANSPORT_TEXTURE_HOST_H_
#include <vector>
#include "base/basictypes.h"
#include "base/callback.h"
#include "base/memory/ref_counted.h"
#include "base/memory/scoped_ptr.h"
#include "base/task.h"
#include "ipc/ipc_channel.h"
class MessageLoop;
class RendererGLContext;
class TransportTextureService;
class TransportTextureHost
: public base::RefCountedThreadSafe<TransportTextureHost>,
public IPC::Channel::Listener {
public:
typedef Callback1<int>::Type TextureUpdateCallback;
// |io_message_loop| is where the IPC communication should happen.
// |render_message_loop| is where the GLES2 commands should be exeucted.
// |service| contains the route to this object.
// |sender| is used to send IPC messages to GPU process.
// |context| is the RendererGLContextt for generating textures.
// |context_route_id| is the route ID for the GpuChannelHost.
// |host_id| is the ID of this object in GpuChannelHost.
TransportTextureHost(MessageLoop* io_message_loop,
MessageLoop* render_message_loop,
TransportTextureService* service,
IPC::Message::Sender* sender,
RendererGLContext* context,
int32 context_route_id,
int32 host_id);
virtual ~TransportTextureHost();
// Initialize this object, this will cause a corresponding
// TransportTexture be created in the GPU process.
// |done_task| is called when initialization is completed.
void Init(Task* done_task);
// Destroy resources acquired by this object and in the GPU process.
//
// WARNING
//
// Call this method only after textures are not used in both the renderer
// and GPU process.
void Destroy();
// Get the list of textures generated through this factory.
// A callback must be provided to listen to texture update events. The
// callback will be called on the IO thread.
//
// Note that this method doesn't generate any textures, it simply return
// the list of textures generated.
void GetTextures(TextureUpdateCallback* callback,
std::vector<int>* textures);
// Return the peer ID of TransportTexture in the GPU process.
int GetPeerId();
// IPC::Channel::Listener.
virtual void OnChannelConnected(int32 peer_pid);
virtual void OnChannelError();
virtual bool OnMessageReceived(const IPC::Message& message);
private:
// Released all textures generated.
void ReleaseTexturesInternal();
// Send the texture IDs to the GPU process. This will copy the set of
// texture IDs.
void SendTexturesInternal(std::vector<int> textures);
// Send the destroy message to the GPU process.
void SendDestroyInternal();
////////////////////////////////////////////////////////////////////////////
// IPC Message Handlers
void OnTransportTextureCreated(int32 peer_id);
void OnCreateTextures(int32 n, uint32 width, uint32 height, int32 format);
void OnReleaseTextures();
void OnTextureUpdated(int texture_id);
MessageLoop* io_message_loop_;
MessageLoop* render_message_loop_;
scoped_refptr<TransportTextureService> service_;
IPC::Message::Sender* sender_;
RendererGLContext* context_;
int32 context_route_id_;
int32 host_id_;
int32 peer_id_;
scoped_ptr<Task> init_task_;
// A list of textures generated.
std::vector<int> textures_;
// Callback when a texture is updated.
scoped_ptr<TextureUpdateCallback> update_callback_;
DISALLOW_COPY_AND_ASSIGN(TransportTextureHost);
};
#endif // CONTENT_RENDERER_TRANSPORT_TEXTURE_HOST_H_
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