media/base/data_source.h

// Copyright (c) 2012 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_DATA_SOURCE_H_
#define MEDIA_BASE_DATA_SOURCE_H_

#include <stdint.h>

#include "base/callback.h"
#include "base/compiler_specific.h"
#include "base/macros.h"
#include "media/base/media_export.h"

namespace media {

class MEDIA_EXPORT DataSource {
 public:
  using ReadCB = base::OnceCallback<void(int)>;

  enum { kReadError = -1, kAborted = -2 };

  DataSource();

  DataSource(const DataSource&) = delete;
  DataSource& operator=(const DataSource&) = delete;

  virtual ~DataSource();

  // Reads |size| bytes from |position| into |data|. And when the read is done
  // or failed, |read_cb| is called with the number of bytes read or
  // kReadError in case of error.
  virtual void Read(int64_t position,
                    int size,
                    uint8_t* data,
                    DataSource::ReadCB read_cb) = 0;

  // Stops the DataSource. Once this is called all future Read() calls will
  // return an error. This is a synchronous call and may be called from any
  // thread. Once called, the DataSource may no longer be used and should be
  // destructed shortly thereafter.
  virtual void Stop() = 0;

  // Similar to Stop(), but only aborts current reads and not future reads.
  virtual void Abort() = 0;

  // Returns true and the file size, false if the file size could not be
  // retrieved.
  virtual bool GetSize(int64_t* size_out) WARN_UNUSED_RESULT = 0;

  // Returns true if we are performing streaming. In this case seeking is
  // not possible.
  virtual bool IsStreaming() = 0;

  // Notify the DataSource of the bitrate of the media.
  // Values of |bitrate| <= 0 are invalid and should be ignored.
  virtual void SetBitrate(int bitrate) = 0;

  // Assume fully bufferred by default.
  virtual bool AssumeFullyBuffered() const;

  // By default this just returns GetSize().
  virtual int64_t GetMemoryUsage();
};

}  // namespace media

#endif  // MEDIA_BASE_DATA_SOURCE_H_