C++ SourceBuffer::removedFromMediaSource方法代码示例

//.........这里部分代码省略.........
            audioTracks->remove(track);
        }

        // 5.4 If the removed enabled audio track flag equals true, then queue a task to fire a simple event
        // named change at the HTMLMediaElement audioTracks list.
        if (removedEnabledAudioTrack)
            mediaElement()->audioTracks().scheduleChangeEvent();
    }

    // 6. Let SourceBuffer videoTracks list equal the VideoTrackList object returned by sourceBuffer.videoTracks.
    RefPtr<VideoTrackList> videoTracks = buffer.videoTracks();

    // 7. If the SourceBuffer videoTracks list is not empty, then run the following steps:
    if (videoTracks->length()) {
        // 7.1 Let HTMLMediaElement videoTracks list equal the VideoTrackList object returned by the videoTracks
        // attribute on the HTMLMediaElement.
        // 7.2 Let the removed selected video track flag equal false.
        bool removedSelectedVideoTrack = false;

        // 7.3 For each VideoTrack object in the SourceBuffer videoTracks list, run the following steps:
        while (videoTracks->length()) {
            auto& track = *videoTracks->lastItem();

            // 7.3.1 Set the sourceBuffer attribute on the VideoTrack object to null.
            track.setSourceBuffer(nullptr);

            // 7.3.2 If the selected attribute on the VideoTrack object is true, then set the removed selected
            // video track flag to true.
            if (track.selected())
                removedSelectedVideoTrack = true;

            // 7.3.3 Remove the VideoTrack object from the HTMLMediaElement videoTracks list.
            // 7.3.4 Queue a task to fire a trusted event named removetrack, that does not bubble and is not
            // cancelable, and that uses the TrackEvent interface, at the HTMLMediaElement videoTracks list.
            if (mediaElement())
                mediaElement()->removeVideoTrack(track);

            // 7.3.5 Remove the VideoTrack object from the SourceBuffer videoTracks list.
            // 7.3.6 Queue a task to fire a trusted event named removetrack, that does not bubble and is not
            // cancelable, and that uses the TrackEvent interface, at the SourceBuffer videoTracks list.
            videoTracks->remove(track);
        }

        // 7.4 If the removed selected video track flag equals true, then queue a task to fire a simple event
        // named change at the HTMLMediaElement videoTracks list.
        if (removedSelectedVideoTrack)
            mediaElement()->videoTracks().scheduleChangeEvent();
    }

    // 8. Let SourceBuffer textTracks list equal the TextTrackList object returned by sourceBuffer.textTracks.
    RefPtr<TextTrackList> textTracks = buffer.textTracks();

    // 9. If the SourceBuffer textTracks list is not empty, then run the following steps:
    if (textTracks->length()) {
        // 9.1 Let HTMLMediaElement textTracks list equal the TextTrackList object returned by the textTracks
        // attribute on the HTMLMediaElement.
        // 9.2 Let the removed enabled text track flag equal false.
        bool removedEnabledTextTrack = false;

        // 9.3 For each TextTrack object in the SourceBuffer textTracks list, run the following steps:
        while (textTracks->length()) {
            auto& track = *textTracks->lastItem();

            // 9.3.1 Set the sourceBuffer attribute on the TextTrack object to null.
            track.setSourceBuffer(nullptr);

            // 9.3.2 If the mode attribute on the TextTrack object is set to "showing" or "hidden", then
            // set the removed enabled text track flag to true.
            if (track.mode() == TextTrack::Mode::Showing || track.mode() == TextTrack::Mode::Hidden)
                removedEnabledTextTrack = true;

            // 9.3.3 Remove the TextTrack object from the HTMLMediaElement textTracks list.
            // 9.3.4 Queue a task to fire a trusted event named removetrack, that does not bubble and is not
            // cancelable, and that uses the TrackEvent interface, at the HTMLMediaElement textTracks list.
            if (mediaElement())
                mediaElement()->removeTextTrack(track);

            // 9.3.5 Remove the TextTrack object from the SourceBuffer textTracks list.
            // 9.3.6 Queue a task to fire a trusted event named removetrack, that does not bubble and is not
            // cancelable, and that uses the TrackEvent interface, at the SourceBuffer textTracks list.
            textTracks->remove(track);
        }
        
        // 9.4 If the removed enabled text track flag equals true, then queue a task to fire a simple event
        // named change at the HTMLMediaElement textTracks list.
        if (removedEnabledTextTrack)
            mediaElement()->textTracks().scheduleChangeEvent();
    }
    
    
    // 10. If sourceBuffer is in activeSourceBuffers, then remove sourceBuffer from activeSourceBuffers ...
    m_activeSourceBuffers->remove(buffer);
    
    // 11. Remove sourceBuffer from sourceBuffers and fire a removesourcebuffer event
    // on that object.
    m_sourceBuffers->remove(buffer);
    
    // 12. Destroy all resources for sourceBuffer.
    buffer.removedFromMediaSource();
}