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// Copyright 2013 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 MEDIA_BASE_TEXT_RENDERER_H_
#define MEDIA_BASE_TEXT_RENDERER_H_
#include <map>
#include <memory>
#include <set>
#include "base/callback.h"
#include "base/macros.h"
#include "base/memory/weak_ptr.h"
#include "media/base/demuxer_stream.h"
#include "media/base/media_export.h"
#include "media/base/pipeline_status.h"
#include "media/base/text_ranges.h"
#include "media/base/text_track.h"
namespace base {
class SingleThreadTaskRunner;
}
namespace media {
class TextCue;
class TextTrackConfig;
// Receives decoder buffers from the upstream demuxer, decodes them to text
// cues, and then passes them onto the TextTrack object associated with each
// demuxer text stream.
class MEDIA_EXPORT TextRenderer {
public:
// |task_runner| is the thread on which TextRenderer will execute.
//
// |add_text_track_cb] is called when the demuxer requests (via its host)
// that a new text track be created.
TextRenderer(
const scoped_refptr<base::SingleThreadTaskRunner>& task_runner,
const AddTextTrackCB& add_text_track_cb);
// Stops all operations and fires all pending callbacks.
~TextRenderer();
// |ended_cb| is executed when all of the text tracks have reached
// end of stream, following a play request.
void Initialize(const base::Closure& ended_cb);
// Starts text track cue decoding and rendering.
void StartPlaying();
// Temporarily suspends decoding and rendering, executing |callback| when
// playback has been suspended.
void Pause(const base::Closure& callback);
// Discards any text data, executing |callback| when completed.
void Flush(const base::Closure& callback);
// Adds new |text_stream|, having the indicated |config|, to the text stream
// collection managed by this text renderer.
void AddTextStream(DemuxerStream* text_stream,
const TextTrackConfig& config);
// Removes |text_stream| from the text stream collection.
void RemoveTextStream(DemuxerStream* text_stream);
// Returns true if there are extant text tracks.
bool HasTracks() const;
private:
struct TextTrackState {
// To determine read progress.
enum ReadState {
kReadIdle,
kReadPending
};
explicit TextTrackState(std::unique_ptr<TextTrack> text_track);
~TextTrackState();
ReadState read_state;
std::unique_ptr<TextTrack> text_track;
TextRanges text_ranges_;
};
// Callback delivered by the demuxer |text_stream| when
// a read from the stream completes.
void BufferReady(DemuxerStream* text_stream,
DemuxerStream::Status status,
scoped_refptr<DecoderBuffer> input);
// Dispatches the decoded cue delivered on the demuxer's |text_stream|.
void CueReady(DemuxerStream* text_stream,
const scoped_refptr<TextCue>& text_cue);
// Dispatched when the AddTextTrackCB completes, after having created
// the TextTrack object associated with |text_stream|.
void OnAddTextTrackDone(DemuxerStream* text_stream,
std::unique_ptr<TextTrack> text_track);
// Utility function to post a read request on |text_stream|.
void Read(TextTrackState* state, DemuxerStream* text_stream);
scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
const AddTextTrackCB add_text_track_cb_;
// Callbacks provided during Initialize().
base::Closure ended_cb_;
// Callback provided to Pause().
base::Closure pause_cb_;
// Simple state tracking variable.
enum State {
kUninitialized,
kPausePending,
kPaused,
kPlaying,
kEnded
};
State state_;
std::map<DemuxerStream*, std::unique_ptr<TextTrackState>>
text_track_state_map_;
// Indicates how many read requests are in flight.
int pending_read_count_;
// Indicates which text streams have not delivered end-of-stream yet.
typedef std::set<DemuxerStream*> PendingEosSet;
PendingEosSet pending_eos_set_;
// NOTE: Weak pointers must be invalidated before all other member variables.
base::WeakPtrFactory<TextRenderer> weak_factory_{this};
DISALLOW_IMPLICIT_CONSTRUCTORS(TextRenderer);
};
} // namespace media
#endif // MEDIA_BASE_TEXT_RENDERER_H_