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* Copyright 2014 Google Inc. All Rights Reserved.
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* See the License for the specific language governing permissions and
* limitations under the License.
#include <string>
#include "base/memory/ref_counted.h"
#include "base/memory/scoped_ptr.h"
#include "base/optional.h"
#include "base/synchronization/waitable_event.h"
#include "base/threading/thread.h"
#include "base/threading/thread_checker.h"
#include "base/timer.h"
#include "cobalt/base/c_val_time_interval_timer.h"
#include "cobalt/render_tree/animations/animate_node.h"
#include "cobalt/render_tree/node.h"
#include "cobalt/renderer/backend/graphics_context.h"
#include "cobalt/renderer/rasterizer/rasterizer.h"
#include "cobalt/renderer/submission.h"
#include "cobalt/renderer/submission_queue.h"
namespace cobalt {
namespace renderer {
// Pipeline is a thread-safe class that setups up a rendering pipeline
// for processing render trees through a rasterizer. New render trees are
// submitted to the pipeline, from any thread, by calling Submit(). This
// pushes the submitted render tree through a rendering pipeline that eventually
// results in the render tree being submitted to the passed in rasterizer which
// can output the render tree to the display. A new thread is created which
// hosts the rasterizer submit calls. Render trees are rasterized as fast
// as the rasterizer will accept them, which is likely to be the display's
// refresh rate.
class Pipeline {
typedef base::Callback<scoped_ptr<rasterizer::Rasterizer>()>
typedef base::Callback<void(scoped_array<uint8>, const math::Size&)>
// Using the provided rasterizer creation function, a rasterizer will be
// created within the Pipeline on a separate rasterizer thread. Thus,
// the rasterizer created by the provided function should only reference
// thread safe objects.
Pipeline(const CreateRasterizerFunction& create_rasterizer_function,
const scoped_refptr<backend::RenderTarget>& render_target,
backend::GraphicsContext* graphics_context,
bool submit_even_if_render_tree_is_unchanged);
// Submit a new render tree to the renderer pipeline. After calling this
// method, the submitted render tree will be the one that is continuously
// animated and rendered by the rasterizer.
void Submit(const Submission& render_tree_submission);
// Clears the currently submitted render tree submission and waits for the
// pipeline to be flushed before returning.
void Clear();
// |render_tree_submission| will be rasterized into a new offscreen surface.
// The RGBA pixel data will be extracted from this surface, and |complete|
// will be called with the pixel data and the dimensions of the image.
void RasterizeToRGBAPixels(const Submission& render_tree_submission,
const RasterizationCompleteCallback& complete);
// Returns a thread-safe object from which one can produce renderer resources
// like images and fonts which can be referenced by render trees that are
// subsequently submitted to this pipeline.
render_tree::ResourceProvider* GetResourceProvider();
// All private data members should be accessed only on the rasterizer thread,
// with the exception of rasterizer_thread_ itself through which messages
// are posted.
// Called by Submit() to do the work of actually setting the newly submitted
// render tree. This method will be called on the rasterizer thread.
void SetNewRenderTree(const Submission& render_tree_submission);
// Clears the current render tree and calls the callback when this is done.
void ClearCurrentRenderTree(const base::Closure& clear_complete_callback);
// Called repeatedly (the rate is limited by the rasterizer, so likely it
// will be called every 1/60th of a second) on the rasterizer thread and
// results in the rasterization of the current tree and submission of it to
// the render target.
void RasterizeCurrentTree();
// Rasterize the animated |render_tree_submission| to |render_target|,
// applying the time_offset in the submission to the animations.
void RasterizeSubmissionToRenderTarget(
const Submission& render_tree_submission,
const scoped_refptr<backend::RenderTarget>& render_target);
// This method is executed on the rasterizer thread and is responsible for
// constructing the rasterizer.
void InitializeRasterizerThread(
const CreateRasterizerFunction& create_rasterizer_function);
// Shuts down the submission queue. This is done on the rasterizer thread
// and is separate from general shutdown because clearing out the submission
// queue may result in tasks being posted to the rasterizer thread (e.g.
// texture deletions).
void ShutdownSubmissionQueue();
// This method is executed on the rasterizer thread to shutdown anything that
// needs to be shutdown from there.
void ShutdownRasterizerThread();
void OnDumpCurrentRenderTree(const std::string&);
#endif // defined(ENABLE_DEBUG_CONSOLE)
// Render trees may contain a number of AnimateNodes (or none). In order
// to optimize for applying the animations on the rasterizer thread, this
// function searches the tree for AnimateNodes and collects all of their
// information into a single AnimateNode at the root of the returned
// render tree.
Submission CollectAnimations(const Submission& render_tree_submission);
base::WaitableEvent rasterizer_created_event_;
// The render_target that all submitted render trees will be rasterized to.
scoped_refptr<backend::RenderTarget> render_target_;
backend::GraphicsContext* graphics_context_;
// A timer that signals to the rasterizer to rasterize the next frame.
// The timer is setup with a period of 0ms so that it will submit as fast
// as possible, it is up to the rasterizer to pace the pipeline. The timer
// is used to manage the repeated posting of the rasterize task call and
// to make proper shutdown easier.
base::optional<base::Timer> rasterize_timer_;
// ThreadChecker for use by the rasterizer_thread_ defined below.
base::ThreadChecker rasterizer_thread_checker_;
// The thread that all rasterization will take place within.
base::Thread rasterizer_thread_;
// The rasterizer object that will run on the rasterizer_thread_ and is
// effectively the last stage of the pipeline, responsible for rasterizing
// the final render tree and submitting it to the render target.
scoped_ptr<rasterizer::Rasterizer> rasterizer_;
// A thread whose only purpose is to destroy submissions/render trees.
// This is important because destroying a render tree can take some time,
// and we would like to avoid spending this time on the renderer thread.
base::Thread submission_disposal_thread_;
// Manages a queue of render tree submissions that are to be rendered in
// the future.
base::optional<SubmissionQueue> submission_queue_;
// Keep track of the last render tree we rendered whose animations have
// expired so that if we see that we are asked to rasterize that render tree
// again, we know that we do not have to do anything.
scoped_refptr<render_tree::Node> last_rendered_expired_render_tree_;
// If true, we will submit the current render tree to the rasterizer every
// frame, even if it hasn't changed.
const bool submit_even_if_render_tree_is_unchanged_;
// Timers for tracking how frequently |RasterizeCurrentTree| is called and
// the amount of time spent in |RasterizeCurrentTree| each call.
base::CValTimeIntervalTimer<base::CValPublic> rasterize_current_tree_timer_;
// Dumps the current render tree to the console.
} // namespace renderer
} // namespace cobalt