VideoView源码分析

VideoView

基于Android4.4源码进行分析

简介

/*** Displays a video file.  The VideoView class* can load images from various sources (such as resources or content* providers), takes care of computing its measurement from the video so that* it can be used in any layout manager, and provides various display options* such as scaling and tinting.<p>** <em>Note: VideoView does not retain its full state when going into the* background.</em>  In particular, it does not restore the current play state,* play position, selected tracks, or any subtitle tracks added via* {@link #addSubtitleSource addSubtitleSource()}.  Applications should* save and restore these on their own in* {@link android.app.Activity#onSaveInstanceState} and* {@link android.app.Activity#onRestoreInstanceState}.<p>* Also note that the audio session id (from {@link #getAudioSessionId}) may* change from its previously returned value when the VideoView is restored.*/

关系

public class VideoView extends SurfaceViewimplements MediaPlayerControl

成员

播放器所有的状态

// all possible internal states
private static final int STATE_ERROR              = -1;
private static final int STATE_IDLE               = 0;
private static final int STATE_PREPARING          = 1;
private static final int STATE_PREPARED           = 2;
private static final int STATE_PLAYING            = 3;
private static final int STATE_PAUSED             = 4;
private static final int STATE_PLAYBACK_COMPLETED = 5;

记录播放器状态

// mCurrentState is a VideoView object's current state.
// mTargetState is the state that a method caller intends to reach.
// For instance, regardless the VideoView object's current state,
// calling pause() intends to bring the object to a target state
// of STATE_PAUSED.
private int mCurrentState = STATE_IDLE;
private int mTargetState  = STATE_IDLE;

主要功能部分

private SurfaceHolder mSurfaceHolder = null;// 显示图像
private MediaPlayer mMediaPlayer = null; // 声音、播放
private MediaController mMediaController; // 播放控制

其他

private int         mVideoWidth;  // 视频宽度 在onVideoSizeChanged() 和 onPrepared() 中可以得到具体大小
private int         mVideoHeight;  //视频高度
private int         mSurfaceWidth; // Surface宽度  在SurfaceHolder.Callback.surfaceChanged() 中可以得到具体大小
private int         mSurfaceHeight; // Surface高度
private int         mSeekWhenPrepared;  // recording the seek position while preparing

具体实现

构造方法

public VideoView(Context context) {super(context);initVideoView();
}public VideoView(Context context, AttributeSet attrs) {this(context, attrs, 0);initVideoView();
}public VideoView(Context context, AttributeSet attrs, int defStyle) {super(context, attrs, defStyle);initVideoView();
}

// 进行一些必要信息的初始化设置
private void initVideoView() {mVideoWidth = 0;mVideoHeight = 0;// 通过SurfaceHolder去控制SurfaceViewgetHolder().addCallback(mSHCallback);// Deprecated. this is ignored, this value is set automatically when needed.Android3.0以上会自动设置，但是为了兼容还需设置getHolder().setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);setFocusable(true);setFocusableInTouchMode(true);requestFocus();// 字幕相关，用不到mPendingSubtitleTracks = new Vector<Pair<InputStream, MediaFormat>>();mCurrentState = STATE_IDLE;mTargetState  = STATE_IDLE;
}

SurfaceHolder.Callback源码

SurfaceHolder.Callback mSHCallback = new SurfaceHolder.Callback()
{public void surfaceChanged(SurfaceHolder holder, int format,int w, int h){mSurfaceWidth = w;mSurfaceHeight = h;boolean isValidState =  (mTargetState == STATE_PLAYING);boolean hasValidSize = (mVideoWidth == w && mVideoHeight == h);if (mMediaPlayer != null && isValidState && hasValidSize) {if (mSeekWhenPrepared != 0) {seekTo(mSeekWhenPrepared);}// 如果当前已经是播放状态的话就调用mediaplaer.start() 方法，并且把当前状态以及目标状态进行改变start();}}public void surfaceCreated(SurfaceHolder holder){mSurfaceHolder = holder;// Surface创建后就开始调用播放openVideo();}public void surfaceDestroyed(SurfaceHolder holder){// after we return from this we can't use the surface any moremSurfaceHolder = null;if (mMediaController != null) mMediaController.hide();release(true);}
};

重写onMeasure()方法

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {int width = getDefaultSize(mVideoWidth, widthMeasureSpec);int height = getDefaultSize(mVideoHeight, heightMeasureSpec);// ....根据视频的宽高比进行处理， 为了更好的宽展，提供一些用户能自己选择的模式，一般会另外提供方法, 这部分代码可以先不看 startint width = getDefaultSize(mVideoWidth, widthMeasureSpec);int height = getDefaultSize(mVideoHeight, heightMeasureSpec);if (mVideoWidth > 0 && mVideoHeight > 0) {int widthSpecMode = MeasureSpec.getMode(widthMeasureSpec);int widthSpecSize = MeasureSpec.getSize(widthMeasureSpec);int heightSpecMode = MeasureSpec.getMode(heightMeasureSpec);int heightSpecSize = MeasureSpec.getSize(heightMeasureSpec);if (widthSpecMode == MeasureSpec.EXACTLY && heightSpecMode == MeasureSpec.EXACTLY) {// the size is fixedwidth = widthSpecSize;height = heightSpecSize;// for compatibility, we adjust size based on aspect ratioif ( mVideoWidth * height  < width * mVideoHeight ) {//Log.i("@@@", "image too wide, correcting");width = height * mVideoWidth / mVideoHeight;} else if ( mVideoWidth * height  > width * mVideoHeight ) {//Log.i("@@@", "image too tall, correcting");height = width * mVideoHeight / mVideoWidth;}} else if (widthSpecMode == MeasureSpec.EXACTLY) {// only the width is fixed, adjust the height to match aspect ratio if possiblewidth = widthSpecSize;height = width * mVideoHeight / mVideoWidth;if (heightSpecMode == MeasureSpec.AT_MOST && height > heightSpecSize) {// couldn't match aspect ratio within the constraintsheight = heightSpecSize;}} else if (heightSpecMode == MeasureSpec.EXACTLY) {// only the height is fixed, adjust the width to match aspect ratio if possibleheight = heightSpecSize;width = height * mVideoWidth / mVideoHeight;if (widthSpecMode == MeasureSpec.AT_MOST && width > widthSpecSize) {// couldn't match aspect ratio within the constraintswidth = widthSpecSize;}} else {// neither the width nor the height are fixed, try to use actual video sizewidth = mVideoWidth;height = mVideoHeight;if (heightSpecMode == MeasureSpec.AT_MOST && height > heightSpecSize) {// too tall, decrease both width and heightheight = heightSpecSize;width = height * mVideoWidth / mVideoHeight;}if (widthSpecMode == MeasureSpec.AT_MOST && width > widthSpecSize) {// too wide, decrease both width and heightwidth = widthSpecSize;height = width * mVideoHeight / mVideoWidth;}}} else {// no size yet, just adopt the given spec sizes}// endsetMeasuredDimension(width, height);
}

附上getDefaultSize()源码

/*** Utility to return a default size. Uses the supplied size if the* MeasureSpec imposed no constraints. Will get larger if allowed* by the MeasureSpec.** @param size Default size for this view* @param measureSpec Constraints imposed by the parent* @return The size this view should be.*/
public static int getDefaultSize(int size, int measureSpec) {int result = size;int specMode = MeasureSpec.getMode(measureSpec);int specSize = MeasureSpec.getSize(measureSpec);switch (specMode) {case MeasureSpec.UNSPECIFIED:result = size;break;case MeasureSpec.AT_MOST:case MeasureSpec.EXACTLY:result = specSize;break;}return result;
}

外部进行播放调用

public void setVideoPath(String path) {setVideoURI(Uri.parse(path));
}public void setVideoURI(Uri uri) {setVideoURI(uri, null);
}/*** @hide*/
public void setVideoURI(Uri uri, Map<String, String> headers) {mUri = uri;mHeaders = headers;mSeekWhenPrepared = 0;openVideo();requestLayout();invalidate();
}

openVide() 源码

private void openVideo() {if (mUri == null || mSurfaceHolder == null) {// not ready for playback just yet, will try again laterreturn;}// Tell the music playback service to pause// TODO: these constants need to be published somewhere in the framework.Intent i = new Intent("com.android.music.musicservicecommand");i.putExtra("command", "pause");mContext.sendBroadcast(i);// we shouldn't clear the target state, because somebody might have// called start() previously // 先把已经存在的MediaPlayer释放掉，然后重新创建一个, 不一定只在SetVideoPath() 中调用，在其他地方也会调用release(false);try {// 创建一个MediaPlayermMediaPlayer = new MediaPlayer();// TODO: create SubtitleController in MediaPlayer, but we need// a context for the subtitle renderersfinal Context context = getContext();final SubtitleController controller = new SubtitleController(context, mMediaPlayer.getMediaTimeProvider(), mMediaPlayer);controller.registerRenderer(new WebVttRenderer(context));mMediaPlayer.setSubtitleAnchor(controller, this);if (mAudioSession != 0) {mMediaPlayer.setAudioSessionId(mAudioSession);} else {mAudioSession = mMediaPlayer.getAudioSessionId();}// 设置一些必要的监听mMediaPlayer.setOnPreparedListener(mPreparedListener);mMediaPlayer.setOnVideoSizeChangedListener(mSizeChangedListener);mMediaPlayer.setOnCompletionListener(mCompletionListener);mMediaPlayer.setOnErrorListener(mErrorListener);mMediaPlayer.setOnInfoListener(mInfoListener);mMediaPlayer.setOnBufferingUpdateListener(mBufferingUpdateListener);mCurrentBufferPercentage = 0;// 让MediaPlayer进行播放mMediaPlayer.setDataSource(mContext, mUri, mHeaders);// 让SurfaceView进行画面显示mMediaPlayer.setDisplay(mSurfaceHolder);// 设置音频类型mMediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);// 播放时屏幕常亮mMediaPlayer.setScreenOnWhilePlaying(true);// Prepares the player for playback, asynchronously. After setting the datasource and the display surface, you need to either call prepare() or prepareAsync(). For streams, you should call prepareAsync(), // which returns immediately, rather than blocking until enough data has been buffered.mMediaPlayer.prepareAsync();for (Pair<InputStream, MediaFormat> pending: mPendingSubtitleTracks) {try {mMediaPlayer.addSubtitleSource(pending.first, pending.second);} catch (IllegalStateException e) {mInfoListener.onInfo(mMediaPlayer, MediaPlayer.MEDIA_INFO_UNSUPPORTED_SUBTITLE, 0);}}// we don't set the target state here either, but preserve the// target state that was there before.mCurrentState = STATE_PREPARING;// 如果已经调用过SetMediaController() 方法，这里会直接显示attachMediaController();} catch (IOException ex) {Log.w(TAG, "Unable to open content: " + mUri, ex);mCurrentState = STATE_ERROR;mTargetState = STATE_ERROR;mErrorListener.onError(mMediaPlayer, MediaPlayer.MEDIA_ERROR_UNKNOWN, 0);return;} catch (IllegalArgumentException ex) {Log.w(TAG, "Unable to open content: " + mUri, ex);mCurrentState = STATE_ERROR;mTargetState = STATE_ERROR;mErrorListener.onError(mMediaPlayer, MediaPlayer.MEDIA_ERROR_UNKNOWN, 0);return;} finally {mPendingSubtitleTracks.clear();}
}

release() 方法,在开始播放一个视频的时候会先调用该方法，然后重新创建一个，在SurfaceView销毁的时候也会调用该方法

/** release the media player in any state*/
private void release(boolean cleartargetstate) {if (mMediaPlayer != null) {mMediaPlayer.reset();mMediaPlayer.release();mMediaPlayer = null;mPendingSubtitleTracks.clear();mCurrentState = STATE_IDLE;if (cleartargetstate) {mTargetState  = STATE_IDLE;}}
}

外部停止播放调用

public void stopPlayback() {if (mMediaPlayer != null) {mMediaPlayer.stop();mMediaPlayer.release();mMediaPlayer = null;mCurrentState = STATE_IDLE;mTargetState  = STATE_IDLE;}
}

外部设置控制栏部分

public void setMediaController(MediaController controller) {if (mMediaController != null) {mMediaController.hide();}mMediaController = controller;attachMediaController();
}private void attachMediaController() {if (mMediaPlayer != null && mMediaController != null) {// setMediaPlayer(MediaPlayerControl player), 让MediaPlayer相应的控制部分调用本类中的实现方法mMediaController.setMediaPlayer(this);View anchorView = this.getParent() instanceof View ?(View)this.getParent() : this;// 创建Controller并且依据AnchorView的位置进行显示mMediaController.setAnchorView(anchorView);mMediaController.setEnabled(isInPlaybackState());}
}

MediaPlayer必要监听

OnVideoSizeChangedListener

MediaPlayer.OnVideoSizeChangedListener mSizeChangedListener =new MediaPlayer.OnVideoSizeChangedListener() {public void onVideoSizeChanged(MediaPlayer mp, int width, int height) {mVideoWidth = mp.getVideoWidth();mVideoHeight = mp.getVideoHeight();if (mVideoWidth != 0 && mVideoHeight != 0) {// 这个方法是设置Surface分辨率，而不是设置视频播放窗口的大小，视频播放窗口大小是由SurfaceView的布局控制，要分清Surface与SurfaceView的区别，Surface是Window中整个的一个控件(句柄),// 而SurfaceView是一个包含Surface的View，SurfaceView覆盖到Surface上(可以这样理解)，我们只能通过SurfaceView来看Surface中的内容,至于在SurfaceView显示之外的Surface我们是不可见的.getHolder().setFixedSize(mVideoWidth, mVideoHeight);requestLayout();}}
};

OnPreparedListener

MediaPlayer.OnPreparedListener mPreparedListener = new MediaPlayer.OnPreparedListener() {public void onPrepared(MediaPlayer mp) {mCurrentState = STATE_PREPARED;// Get the capabilities of the player for this streamMetadata data = mp.getMetadata(MediaPlayer.METADATA_ALL,MediaPlayer.BYPASS_METADATA_FILTER);if (data != null) {mCanPause = !data.has(Metadata.PAUSE_AVAILABLE)|| data.getBoolean(Metadata.PAUSE_AVAILABLE);mCanSeekBack = !data.has(Metadata.SEEK_BACKWARD_AVAILABLE)|| data.getBoolean(Metadata.SEEK_BACKWARD_AVAILABLE);mCanSeekForward = !data.has(Metadata.SEEK_FORWARD_AVAILABLE)|| data.getBoolean(Metadata.SEEK_FORWARD_AVAILABLE);} else {mCanPause = mCanSeekBack = mCanSeekForward = true;}if (mOnPreparedListener != null) {mOnPreparedListener.onPrepared(mMediaPlayer);}if (mMediaController != null) {mMediaController.setEnabled(true);}mVideoWidth = mp.getVideoWidth();mVideoHeight = mp.getVideoHeight();int seekToPosition = mSeekWhenPrepared;  // mSeekWhenPrepared may be changed after seekTo() callif (seekToPosition != 0) {seekTo(seekToPosition);}if (mVideoWidth != 0 && mVideoHeight != 0) {//Log.i("@@@@", "video size: " + mVideoWidth +"/"+ mVideoHeight);getHolder().setFixedSize(mVideoWidth, mVideoHeight);if (mSurfaceWidth == mVideoWidth && mSurfaceHeight == mVideoHeight) {// We didn't actually change the size (it was already at the size// we need), so we won't get a "surface changed" callback, so// start the video here instead of in the callback.if (mTargetState == STATE_PLAYING) {start();if (mMediaController != null) {mMediaController.show();}} else if (!isPlaying() &&(seekToPosition != 0 || getCurrentPosition() > 0)) {if (mMediaController != null) {// Show the media controls when we're paused into a video and make 'em stick.mMediaController.show(0);}}}} else {// We don't know the video size yet, but should start anyway.// The video size might be reported to us later.if (mTargetState == STATE_PLAYING) {start();}}}
};

OnCompletionListener

private MediaPlayer.OnCompletionListener mCompletionListener =new MediaPlayer.OnCompletionListener() {public void onCompletion(MediaPlayer mp) {mCurrentState = STATE_PLAYBACK_COMPLETED;mTargetState = STATE_PLAYBACK_COMPLETED;if (mMediaController != null) {mMediaController.hide();}if (mOnCompletionListener != null) {mOnCompletionListener.onCompletion(mMediaPlayer);}}
};

Touch以及Key的监听

@Override
public boolean onTouchEvent(MotionEvent ev) {if (isInPlaybackState() && mMediaController != null) {// 控制MediaController的显示与隐藏toggleMediaControlsVisiblity();}return false;
}

toggleMediaControlsVisiblity

private void toggleMediaControlsVisiblity() {if (mMediaController.isShowing()) {mMediaController.hide();} else {mMediaController.show();}
}

Key

@Override
public boolean onKeyDown(int keyCode, KeyEvent event)
{boolean isKeyCodeSupported = keyCode != KeyEvent.KEYCODE_BACK &&keyCode != KeyEvent.KEYCODE_VOLUME_UP &&keyCode != KeyEvent.KEYCODE_VOLUME_DOWN &&keyCode != KeyEvent.KEYCODE_VOLUME_MUTE &&keyCode != KeyEvent.KEYCODE_MENU &&keyCode != KeyEvent.KEYCODE_CALL &&keyCode != KeyEvent.KEYCODE_ENDCALL;if (isInPlaybackState() && isKeyCodeSupported && mMediaController != null) {if (keyCode == KeyEvent.KEYCODE_HEADSETHOOK ||keyCode == KeyEvent.KEYCODE_MEDIA_PLAY_PAUSE) {if (mMediaPlayer.isPlaying()) {pause();mMediaController.show();} else {start();mMediaController.hide();}return true;} else if (keyCode == KeyEvent.KEYCODE_MEDIA_PLAY) {if (!mMediaPlayer.isPlaying()) {start();mMediaController.hide();}return true;} else if (keyCode == KeyEvent.KEYCODE_MEDIA_STOP|| keyCode == KeyEvent.KEYCODE_MEDIA_PAUSE) {if (mMediaPlayer.isPlaying()) {pause();mMediaController.show();}return true;} else {toggleMediaControlsVisiblity();}}return super.onKeyDown(keyCode, event);
}

华丽丽的分割线上源码

/** Copyright (C) 2006 The Android Open Source Project** 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**      http://www.apache.org/licenses/LICENSE-2.0** Unless required by applicable law or agreed to in writing, software* distributed under the License is distributed on an "AS IS" BASIS,* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.* See the License for the specific language governing permissions and* limitations under the License.*//*** Displays a video file.  The VideoView class* can load images from various sources (such as resources or content* providers), takes care of computing its measurement from the video so that* it can be used in any layout manager, and provides various display options* such as scaling and tinting.<p>** <em>Note: VideoView does not retain its full state when going into the* background.</em>  In particular, it does not restore the current play state,* play position, selected tracks, or any subtitle tracks added via* {@link #addSubtitleSource addSubtitleSource()}.  Applications should* save and restore these on their own in* {@link android.app.Activity#onSaveInstanceState} and* {@link android.app.Activity#onRestoreInstanceState}.<p>* Also note that the audio session id (from {@link #getAudioSessionId}) may* change from its previously returned value when the VideoView is restored.*/
public class VideoView extends SurfaceViewimplements MediaPlayerControl, SubtitleController.Anchor {private String TAG = "VideoView";// settable by the clientprivate Uri         mUri;private Map<String, String> mHeaders;// all possible internal statesprivate static final int STATE_ERROR              = -1;private static final int STATE_IDLE               = 0;private static final int STATE_PREPARING          = 1;private static final int STATE_PREPARED           = 2;private static final int STATE_PLAYING            = 3;private static final int STATE_PAUSED             = 4;private static final int STATE_PLAYBACK_COMPLETED = 5;// mCurrentState is a VideoView object's current state.// mTargetState is the state that a method caller intends to reach.// For instance, regardless the VideoView object's current state,// calling pause() intends to bring the object to a target state// of STATE_PAUSED.private int mCurrentState = STATE_IDLE;private int mTargetState  = STATE_IDLE;// All the stuff we need for playing and showing a videoprivate SurfaceHolder mSurfaceHolder = null;private MediaPlayer mMediaPlayer = null;private int         mAudioSession;private int         mVideoWidth;private int         mVideoHeight;private int         mSurfaceWidth;private int         mSurfaceHeight;private MediaController mMediaController;private OnCompletionListener mOnCompletionListener;private MediaPlayer.OnPreparedListener mOnPreparedListener;private int         mCurrentBufferPercentage;private OnErrorListener mOnErrorListener;private OnInfoListener  mOnInfoListener;private int         mSeekWhenPrepared;  // recording the seek position while preparingprivate boolean     mCanPause;private boolean     mCanSeekBack;private boolean     mCanSeekForward;/** Subtitle rendering widget overlaid on top of the video. */private RenderingWidget mSubtitleWidget;/** Listener for changes to subtitle data, used to redraw when needed. */private RenderingWidget.OnChangedListener mSubtitlesChangedListener;public VideoView(Context context) {super(context);initVideoView();}public VideoView(Context context, AttributeSet attrs) {this(context, attrs, 0);initVideoView();}public VideoView(Context context, AttributeSet attrs, int defStyle) {super(context, attrs, defStyle);initVideoView();}@Overrideprotected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {//Log.i("@@@@", "onMeasure(" + MeasureSpec.toString(widthMeasureSpec) + ", "//        + MeasureSpec.toString(heightMeasureSpec) + ")");int width = getDefaultSize(mVideoWidth, widthMeasureSpec);int height = getDefaultSize(mVideoHeight, heightMeasureSpec);if (mVideoWidth > 0 && mVideoHeight > 0) {int widthSpecMode = MeasureSpec.getMode(widthMeasureSpec);int widthSpecSize = MeasureSpec.getSize(widthMeasureSpec);int heightSpecMode = MeasureSpec.getMode(heightMeasureSpec);int heightSpecSize = MeasureSpec.getSize(heightMeasureSpec);if (widthSpecMode == MeasureSpec.EXACTLY && heightSpecMode == MeasureSpec.EXACTLY) {// the size is fixedwidth = widthSpecSize;height = heightSpecSize;// for compatibility, we adjust size based on aspect ratioif ( mVideoWidth * height  < width * mVideoHeight ) {//Log.i("@@@", "image too wide, correcting");width = height * mVideoWidth / mVideoHeight;} else if ( mVideoWidth * height  > width * mVideoHeight ) {//Log.i("@@@", "image too tall, correcting");height = width * mVideoHeight / mVideoWidth;}} else if (widthSpecMode == MeasureSpec.EXACTLY) {// only the width is fixed, adjust the height to match aspect ratio if possiblewidth = widthSpecSize;height = width * mVideoHeight / mVideoWidth;if (heightSpecMode == MeasureSpec.AT_MOST && height > heightSpecSize) {// couldn't match aspect ratio within the constraintsheight = heightSpecSize;}} else if (heightSpecMode == MeasureSpec.EXACTLY) {// only the height is fixed, adjust the width to match aspect ratio if possibleheight = heightSpecSize;width = height * mVideoWidth / mVideoHeight;if (widthSpecMode == MeasureSpec.AT_MOST && width > widthSpecSize) {// couldn't match aspect ratio within the constraintswidth = widthSpecSize;}} else {// neither the width nor the height are fixed, try to use actual video sizewidth = mVideoWidth;height = mVideoHeight;if (heightSpecMode == MeasureSpec.AT_MOST && height > heightSpecSize) {// too tall, decrease both width and heightheight = heightSpecSize;width = height * mVideoWidth / mVideoHeight;}if (widthSpecMode == MeasureSpec.AT_MOST && width > widthSpecSize) {// too wide, decrease both width and heightwidth = widthSpecSize;height = width * mVideoHeight / mVideoWidth;}}} else {// no size yet, just adopt the given spec sizes}setMeasuredDimension(width, height);}@Overridepublic void onInitializeAccessibilityEvent(AccessibilityEvent event) {super.onInitializeAccessibilityEvent(event);event.setClassName(VideoView.class.getName());}@Overridepublic void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) {super.onInitializeAccessibilityNodeInfo(info);info.setClassName(VideoView.class.getName());}public int resolveAdjustedSize(int desiredSize, int measureSpec) {return getDefaultSize(desiredSize, measureSpec);}private void initVideoView() {mVideoWidth = 0;mVideoHeight = 0;getHolder().addCallback(mSHCallback);getHolder().setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);setFocusable(true);setFocusableInTouchMode(true);requestFocus();mPendingSubtitleTracks = new Vector<Pair<InputStream, MediaFormat>>();mCurrentState = STATE_IDLE;mTargetState  = STATE_IDLE;}public void setVideoPath(String path) {setVideoURI(Uri.parse(path));}public void setVideoURI(Uri uri) {setVideoURI(uri, null);}/*** @hide*/public void setVideoURI(Uri uri, Map<String, String> headers) {mUri = uri;mHeaders = headers;mSeekWhenPrepared = 0;openVideo();requestLayout();invalidate();}/*** Adds an external subtitle source file (from the provided input stream.)** Note that a single external subtitle source may contain multiple or no* supported tracks in it. If the source contained at least one track in* it, one will receive an {@link MediaPlayer#MEDIA_INFO_METADATA_UPDATE}* info message. Otherwise, if reading the source takes excessive time,* one will receive a {@link MediaPlayer#MEDIA_INFO_SUBTITLE_TIMED_OUT}* message. If the source contained no supported track (including an empty* source file or null input stream), one will receive a {@link* MediaPlayer#MEDIA_INFO_UNSUPPORTED_SUBTITLE} message. One can find the* total number of available tracks using {@link MediaPlayer#getTrackInfo()}* to see what additional tracks become available after this method call.** @param is     input stream containing the subtitle data.  It will be*               closed by the media framework.* @param format the format of the subtitle track(s).  Must contain at least*               the mime type ({@link MediaFormat#KEY_MIME}) and the*               language ({@link MediaFormat#KEY_LANGUAGE}) of the file.*               If the file itself contains the language information,*               specify "und" for the language.*/public void addSubtitleSource(InputStream is, MediaFormat format) {if (mMediaPlayer == null) {mPendingSubtitleTracks.add(Pair.create(is, format));} else {try {mMediaPlayer.addSubtitleSource(is, format);} catch (IllegalStateException e) {mInfoListener.onInfo(mMediaPlayer, MediaPlayer.MEDIA_INFO_UNSUPPORTED_SUBTITLE, 0);}}}private Vector<Pair<InputStream, MediaFormat>> mPendingSubtitleTracks;public void stopPlayback() {if (mMediaPlayer != null) {mMediaPlayer.stop();mMediaPlayer.release();mMediaPlayer = null;mCurrentState = STATE_IDLE;mTargetState  = STATE_IDLE;}}private void openVideo() {if (mUri == null || mSurfaceHolder == null) {// not ready for playback just yet, will try again laterreturn;}// Tell the music playback service to pause// TODO: these constants need to be published somewhere in the framework.Intent i = new Intent("com.android.music.musicservicecommand");i.putExtra("command", "pause");mContext.sendBroadcast(i);// we shouldn't clear the target state, because somebody might have// called start() previouslyrelease(false);try {mMediaPlayer = new MediaPlayer();// TODO: create SubtitleController in MediaPlayer, but we need// a context for the subtitle renderersfinal Context context = getContext();final SubtitleController controller = new SubtitleController(context, mMediaPlayer.getMediaTimeProvider(), mMediaPlayer);controller.registerRenderer(new WebVttRenderer(context));mMediaPlayer.setSubtitleAnchor(controller, this);if (mAudioSession != 0) {mMediaPlayer.setAudioSessionId(mAudioSession);} else {mAudioSession = mMediaPlayer.getAudioSessionId();}mMediaPlayer.setOnPreparedListener(mPreparedListener);mMediaPlayer.setOnVideoSizeChangedListener(mSizeChangedListener);mMediaPlayer.setOnCompletionListener(mCompletionListener);mMediaPlayer.setOnErrorListener(mErrorListener);mMediaPlayer.setOnInfoListener(mInfoListener);mMediaPlayer.setOnBufferingUpdateListener(mBufferingUpdateListener);mCurrentBufferPercentage = 0;mMediaPlayer.setDataSource(mContext, mUri, mHeaders);mMediaPlayer.setDisplay(mSurfaceHolder);mMediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);mMediaPlayer.setScreenOnWhilePlaying(true);mMediaPlayer.prepareAsync();for (Pair<InputStream, MediaFormat> pending: mPendingSubtitleTracks) {try {mMediaPlayer.addSubtitleSource(pending.first, pending.second);} catch (IllegalStateException e) {mInfoListener.onInfo(mMediaPlayer, MediaPlayer.MEDIA_INFO_UNSUPPORTED_SUBTITLE, 0);}}// we don't set the target state here either, but preserve the// target state that was there before.mCurrentState = STATE_PREPARING;attachMediaController();} catch (IOException ex) {Log.w(TAG, "Unable to open content: " + mUri, ex);mCurrentState = STATE_ERROR;mTargetState = STATE_ERROR;mErrorListener.onError(mMediaPlayer, MediaPlayer.MEDIA_ERROR_UNKNOWN, 0);return;} catch (IllegalArgumentException ex) {Log.w(TAG, "Unable to open content: " + mUri, ex);mCurrentState = STATE_ERROR;mTargetState = STATE_ERROR;mErrorListener.onError(mMediaPlayer, MediaPlayer.MEDIA_ERROR_UNKNOWN, 0);return;} finally {mPendingSubtitleTracks.clear();}}public void setMediaController(MediaController controller) {if (mMediaController != null) {mMediaController.hide();}mMediaController = controller;attachMediaController();}private void attachMediaController() {if (mMediaPlayer != null && mMediaController != null) {mMediaController.setMediaPlayer(this);View anchorView = this.getParent() instanceof View ?(View)this.getParent() : this;mMediaController.setAnchorView(anchorView);mMediaController.setEnabled(isInPlaybackState());}}MediaPlayer.OnVideoSizeChangedListener mSizeChangedListener =new MediaPlayer.OnVideoSizeChangedListener() {public void onVideoSizeChanged(MediaPlayer mp, int width, int height) {mVideoWidth = mp.getVideoWidth();mVideoHeight = mp.getVideoHeight();if (mVideoWidth != 0 && mVideoHeight != 0) {getHolder().setFixedSize(mVideoWidth, mVideoHeight);requestLayout();}}};MediaPlayer.OnPreparedListener mPreparedListener = new MediaPlayer.OnPreparedListener() {public void onPrepared(MediaPlayer mp) {mCurrentState = STATE_PREPARED;// Get the capabilities of the player for this streamMetadata data = mp.getMetadata(MediaPlayer.METADATA_ALL,MediaPlayer.BYPASS_METADATA_FILTER);if (data != null) {mCanPause = !data.has(Metadata.PAUSE_AVAILABLE)|| data.getBoolean(Metadata.PAUSE_AVAILABLE);mCanSeekBack = !data.has(Metadata.SEEK_BACKWARD_AVAILABLE)|| data.getBoolean(Metadata.SEEK_BACKWARD_AVAILABLE);mCanSeekForward = !data.has(Metadata.SEEK_FORWARD_AVAILABLE)|| data.getBoolean(Metadata.SEEK_FORWARD_AVAILABLE);} else {mCanPause = mCanSeekBack = mCanSeekForward = true;}if (mOnPreparedListener != null) {mOnPreparedListener.onPrepared(mMediaPlayer);}if (mMediaController != null) {mMediaController.setEnabled(true);}mVideoWidth = mp.getVideoWidth();mVideoHeight = mp.getVideoHeight();int seekToPosition = mSeekWhenPrepared;  // mSeekWhenPrepared may be changed after seekTo() callif (seekToPosition != 0) {seekTo(seekToPosition);}if (mVideoWidth != 0 && mVideoHeight != 0) {//Log.i("@@@@", "video size: " + mVideoWidth +"/"+ mVideoHeight);getHolder().setFixedSize(mVideoWidth, mVideoHeight);if (mSurfaceWidth == mVideoWidth && mSurfaceHeight == mVideoHeight) {// We didn't actually change the size (it was already at the size// we need), so we won't get a "surface changed" callback, so// start the video here instead of in the callback.if (mTargetState == STATE_PLAYING) {start();if (mMediaController != null) {mMediaController.show();}} else if (!isPlaying() &&(seekToPosition != 0 || getCurrentPosition() > 0)) {if (mMediaController != null) {// Show the media controls when we're paused into a video and make 'em stick.mMediaController.show(0);}}}} else {// We don't know the video size yet, but should start anyway.// The video size might be reported to us later.if (mTargetState == STATE_PLAYING) {start();}}}};private MediaPlayer.OnCompletionListener mCompletionListener =new MediaPlayer.OnCompletionListener() {public void onCompletion(MediaPlayer mp) {mCurrentState = STATE_PLAYBACK_COMPLETED;mTargetState = STATE_PLAYBACK_COMPLETED;if (mMediaController != null) {mMediaController.hide();}if (mOnCompletionListener != null) {mOnCompletionListener.onCompletion(mMediaPlayer);}}};private MediaPlayer.OnInfoListener mInfoListener =new MediaPlayer.OnInfoListener() {public  boolean onInfo(MediaPlayer mp, int arg1, int arg2) {if (mOnInfoListener != null) {mOnInfoListener.onInfo(mp, arg1, arg2);}return true;}};private MediaPlayer.OnErrorListener mErrorListener =new MediaPlayer.OnErrorListener() {public boolean onError(MediaPlayer mp, int framework_err, int impl_err) {Log.d(TAG, "Error: " + framework_err + "," + impl_err);mCurrentState = STATE_ERROR;mTargetState = STATE_ERROR;if (mMediaController != null) {mMediaController.hide();}/* If an error handler has been supplied, use it and finish. */if (mOnErrorListener != null) {if (mOnErrorListener.onError(mMediaPlayer, framework_err, impl_err)) {return true;}}/* Otherwise, pop up an error dialog so the user knows that* something bad has happened. Only try and pop up the dialog* if we're attached to a window. When we're going away and no* longer have a window, don't bother showing the user an error.*/if (getWindowToken() != null) {Resources r = mContext.getResources();int messageId;if (framework_err == MediaPlayer.MEDIA_ERROR_NOT_VALID_FOR_PROGRESSIVE_PLAYBACK) {messageId = com.android.internal.R.string.VideoView_error_text_invalid_progressive_playback;} else {messageId = com.android.internal.R.string.VideoView_error_text_unknown;}new AlertDialog.Builder(mContext).setMessage(messageId).setPositiveButton(com.android.internal.R.string.VideoView_error_button,new DialogInterface.OnClickListener() {public void onClick(DialogInterface dialog, int whichButton) {/* If we get here, there is no onError listener, so* at least inform them that the video is over.*/if (mOnCompletionListener != null) {mOnCompletionListener.onCompletion(mMediaPlayer);}}}).setCancelable(false).show();}return true;}};private MediaPlayer.OnBufferingUpdateListener mBufferingUpdateListener =new MediaPlayer.OnBufferingUpdateListener() {public void onBufferingUpdate(MediaPlayer mp, int percent) {mCurrentBufferPercentage = percent;}};/*** Register a callback to be invoked when the media file* is loaded and ready to go.** @param l The callback that will be run*/public void setOnPreparedListener(MediaPlayer.OnPreparedListener l){mOnPreparedListener = l;}/*** Register a callback to be invoked when the end of a media file* has been reached during playback.** @param l The callback that will be run*/public void setOnCompletionListener(OnCompletionListener l){mOnCompletionListener = l;}/*** Register a callback to be invoked when an error occurs* during playback or setup.  If no listener is specified,* or if the listener returned false, VideoView will inform* the user of any errors.** @param l The callback that will be run*/public void setOnErrorListener(OnErrorListener l){mOnErrorListener = l;}/*** Register a callback to be invoked when an informational event* occurs during playback or setup.** @param l The callback that will be run*/public void setOnInfoListener(OnInfoListener l) {mOnInfoListener = l;}SurfaceHolder.Callback mSHCallback = new SurfaceHolder.Callback(){public void surfaceChanged(SurfaceHolder holder, int format,int w, int h){mSurfaceWidth = w;mSurfaceHeight = h;boolean isValidState =  (mTargetState == STATE_PLAYING);boolean hasValidSize = (mVideoWidth == w && mVideoHeight == h);if (mMediaPlayer != null && isValidState && hasValidSize) {if (mSeekWhenPrepared != 0) {seekTo(mSeekWhenPrepared);}start();}}public void surfaceCreated(SurfaceHolder holder){mSurfaceHolder = holder;openVideo();}public void surfaceDestroyed(SurfaceHolder holder){// after we return from this we can't use the surface any moremSurfaceHolder = null;if (mMediaController != null) mMediaController.hide();release(true);}};/** release the media player in any state*/private void release(boolean cleartargetstate) {if (mMediaPlayer != null) {mMediaPlayer.reset();mMediaPlayer.release();mMediaPlayer = null;mPendingSubtitleTracks.clear();mCurrentState = STATE_IDLE;if (cleartargetstate) {mTargetState  = STATE_IDLE;}}}@Overridepublic boolean onTouchEvent(MotionEvent ev) {if (isInPlaybackState() && mMediaController != null) {toggleMediaControlsVisiblity();}return false;}@Overridepublic boolean onTrackballEvent(MotionEvent ev) {if (isInPlaybackState() && mMediaController != null) {toggleMediaControlsVisiblity();}return false;}@Overridepublic boolean onKeyDown(int keyCode, KeyEvent event){boolean isKeyCodeSupported = keyCode != KeyEvent.KEYCODE_BACK &&keyCode != KeyEvent.KEYCODE_VOLUME_UP &&keyCode != KeyEvent.KEYCODE_VOLUME_DOWN &&keyCode != KeyEvent.KEYCODE_VOLUME_MUTE &&keyCode != KeyEvent.KEYCODE_MENU &&keyCode != KeyEvent.KEYCODE_CALL &&keyCode != KeyEvent.KEYCODE_ENDCALL;if (isInPlaybackState() && isKeyCodeSupported && mMediaController != null) {if (keyCode == KeyEvent.KEYCODE_HEADSETHOOK ||keyCode == KeyEvent.KEYCODE_MEDIA_PLAY_PAUSE) {if (mMediaPlayer.isPlaying()) {pause();mMediaController.show();} else {start();mMediaController.hide();}return true;} else if (keyCode == KeyEvent.KEYCODE_MEDIA_PLAY) {if (!mMediaPlayer.isPlaying()) {start();mMediaController.hide();}return true;} else if (keyCode == KeyEvent.KEYCODE_MEDIA_STOP|| keyCode == KeyEvent.KEYCODE_MEDIA_PAUSE) {if (mMediaPlayer.isPlaying()) {pause();mMediaController.show();}return true;} else {toggleMediaControlsVisiblity();}}return super.onKeyDown(keyCode, event);}private void toggleMediaControlsVisiblity() {if (mMediaController.isShowing()) {mMediaController.hide();} else {mMediaController.show();}}@Overridepublic void start() {if (isInPlaybackState()) {mMediaPlayer.start();mCurrentState = STATE_PLAYING;}mTargetState = STATE_PLAYING;}@Overridepublic void pause() {if (isInPlaybackState()) {if (mMediaPlayer.isPlaying()) {mMediaPlayer.pause();mCurrentState = STATE_PAUSED;}}mTargetState = STATE_PAUSED;}public void suspend() {release(false);}public void resume() {openVideo();}@Overridepublic int getDuration() {if (isInPlaybackState()) {return mMediaPlayer.getDuration();}return -1;}@Overridepublic int getCurrentPosition() {if (isInPlaybackState()) {return mMediaPlayer.getCurrentPosition();}return 0;}@Overridepublic void seekTo(int msec) {if (isInPlaybackState()) {mMediaPlayer.seekTo(msec);mSeekWhenPrepared = 0;} else {mSeekWhenPrepared = msec;}}@Overridepublic boolean isPlaying() {return isInPlaybackState() && mMediaPlayer.isPlaying();}@Overridepublic int getBufferPercentage() {if (mMediaPlayer != null) {return mCurrentBufferPercentage;}return 0;}private boolean isInPlaybackState() {return (mMediaPlayer != null &&mCurrentState != STATE_ERROR &&mCurrentState != STATE_IDLE &&mCurrentState != STATE_PREPARING);}@Overridepublic boolean canPause() {return mCanPause;}@Overridepublic boolean canSeekBackward() {return mCanSeekBack;}@Overridepublic boolean canSeekForward() {return mCanSeekForward;}@Overridepublic int getAudioSessionId() {if (mAudioSession == 0) {MediaPlayer foo = new MediaPlayer();mAudioSession = foo.getAudioSessionId();foo.release();}return mAudioSession;}@Overrideprotected void onAttachedToWindow() {super.onAttachedToWindow();if (mSubtitleWidget != null) {mSubtitleWidget.onAttachedToWindow();}}@Overrideprotected void onDetachedFromWindow() {super.onDetachedFromWindow();if (mSubtitleWidget != null) {mSubtitleWidget.onDetachedFromWindow();}}@Overrideprotected void onLayout(boolean changed, int left, int top, int right, int bottom) {super.onLayout(changed, left, top, right, bottom);if (mSubtitleWidget != null) {measureAndLayoutSubtitleWidget();}}@Overridepublic void draw(Canvas canvas) {super.draw(canvas);if (mSubtitleWidget != null) {final int saveCount = canvas.save();canvas.translate(getPaddingLeft(), getPaddingTop());mSubtitleWidget.draw(canvas);canvas.restoreToCount(saveCount);}}/*** Forces a measurement and layout pass for all overlaid views.** @see #setSubtitleWidget(RenderingWidget)*/private void measureAndLayoutSubtitleWidget() {final int width = getWidth() - getPaddingLeft() - getPaddingRight();final int height = getHeight() - getPaddingTop() - getPaddingBottom();mSubtitleWidget.setSize(width, height);}/** @hide */@Overridepublic void setSubtitleWidget(RenderingWidget subtitleWidget) {if (mSubtitleWidget == subtitleWidget) {return;}final boolean attachedToWindow = isAttachedToWindow();if (mSubtitleWidget != null) {if (attachedToWindow) {mSubtitleWidget.onDetachedFromWindow();}mSubtitleWidget.setOnChangedListener(null);}mSubtitleWidget = subtitleWidget;if (subtitleWidget != null) {if (mSubtitlesChangedListener == null) {mSubtitlesChangedListener = new RenderingWidget.OnChangedListener() {@Overridepublic void onChanged(RenderingWidget renderingWidget) {invalidate();}};}setWillNotDraw(false);subtitleWidget.setOnChangedListener(mSubtitlesChangedListener);if (attachedToWindow) {subtitleWidget.onAttachedToWindow();requestLayout();}} else {setWillNotDraw(true);}invalidate();}/** @hide */@Overridepublic Looper getSubtitleLooper() {return Looper.getMainLooper();}
}

MediaPlayerControl

通过该接口来打通MediaController以及VideoView

“`java
public interface MediaPlayerControl {
void start();
void pause();
int getDuration();
int getCurrentPosition();
void seekTo(int pos);
boolean isPlaying();
int getBufferPercentage();
boolean canPause();
boolean canSeekBackward();
boolean canSeekForward();

/*** Get the audio session id for the player used by this VideoView. This can be used to* apply audio effects to the audio track of a video.* @return The audio session, or 0 if there was an error.*/
int     getAudioSessionId();

}
“`

MediaController

简介

/**
* A view containing controls for a MediaPlayer. Typically contains the
* buttons like "Play/Pause", "Rewind", "Fast Forward" and a progress
* slider. It takes care of synchronizing the controls with the state
* of the MediaPlayer.
* <p>
* The way to use this class is to instantiate it programatically.
* The MediaController will create a default set of controls
* and put them in a window floating above your application. Specifically,
* the controls will float above the view specified with setAnchorView().
* The window will disappear if left idle for three seconds and reappear
* when the user touches the anchor view.
* <p>
* Functions like show() and hide() have no effect when MediaController
* is created in an xml layout.
*
* MediaController will hide and
* show the buttons according to these rules:
* <ul>
* <li> The "previous" and "next" buttons are hidden until setPrevNextListeners()
*   has been called
* <li> The "previous" and "next" buttons are visible but disabled if
*   setPrevNextListeners() was called with null listeners
* <li> The "rewind" and "fastforward" buttons are shown unless requested
*   otherwise by using the MediaController(Context, boolean) constructor
*   with the boolean set to false
* </ul>
*/

关系

public class MediaController extends FrameLayout

成员

// 一些控制功能的接口
private MediaPlayerControl  mPlayer;
private Context             mContext;
// VideoView中调用setAnchorView()设置进来的View，MediaController显示的时候会感觉该AnchorView的位置进行显示
private View                mAnchor;
// MediaController最外层的根布局
private View                mRoot;// 通过Window的方式来显示MediaController，MediaController是一个填充屏幕的布局，但是背景是透明的
private WindowManager       mWindowManager;
private Window              mWindow;
private View                mDecor;
// 理解为当前整个MediaController的布局
private WindowManager.LayoutParams mDecorLayoutParams;
private ProgressBar         mProgress;
private TextView            mEndTime, mCurrentTime;
private boolean             mShowing;
private boolean             mDragging;
// 默认自动消失的时间
private static final int    sDefaultTimeout = 3000;
private static final int    FADE_OUT = 1;
private static final int    SHOW_PROGRESS = 2;
private boolean             mUseFastForward;
private boolean             mFromXml;
private boolean             mListenersSet;
private View.OnClickListener mNextListener, mPrevListener;
StringBuilder               mFormatBuilder;
Formatter                   mFormatter;
private ImageButton         mPauseButton;
private ImageButton         mFfwdButton;
private ImageButton         mRewButton;
private ImageButton         mNextButton;
private ImageButton         mPrevButton;

构造方法

public MediaController(Context context, AttributeSet attrs) {super(context, attrs);mRoot = this;mContext = context;mUseFastForward = true;mFromXml = true;
}@Override
public void onFinishInflate() {if (mRoot != null)initControllerView(mRoot);
}public MediaController(Context context, boolean useFastForward) {super(context);mContext = context;mUseFastForward = useFastForward;// 创建该MediaController的布局initFloatingWindowLayout();initFloatingWindow();
}public MediaController(Context context) {this(context, true);
}

initFloatingWindowLayout

// Allocate and initialize the static parts of mDecorLayoutParams. Must
// also call updateFloatingWindowLayout() to fill in the dynamic parts
// (y and width) before mDecorLayoutParams can be used.
private void initFloatingWindowLayout() {mDecorLayoutParams = new WindowManager.LayoutParams();WindowManager.LayoutParams p = mDecorLayoutParams;p.gravity = Gravity.TOP | Gravity.LEFT;p.height = LayoutParams.WRAP_CONTENT;p.x = 0;p.format = PixelFormat.TRANSLUCENT;p.type = WindowManager.LayoutParams.TYPE_APPLICATION_PANEL;p.flags |= WindowManager.LayoutParams.FLAG_ALT_FOCUSABLE_IM| WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL| WindowManager.LayoutParams.FLAG_SPLIT_TOUCH;p.token = null;p.windowAnimations = 0; // android.R.style.DropDownAnimationDown;
}

initFloatingWindow

private void initFloatingWindow() {// Android内核剖析 中有介绍mWindowManager = (WindowManager)mContext.getSystemService(Context.WINDOW_SERVICE);mWindow = PolicyManager.makeNewWindow(mContext);mWindow.setWindowManager(mWindowManager, null, null);mWindow.requestFeature(Window.FEATURE_NO_TITLE);// 通过WindowManager去add该Decor以及remove来实现MediaController的显示与隐藏mDecor = mWindow.getDecorView();mDecor.setOnTouchListener(mTouchListener);mWindow.setContentView(this);mWindow.setBackgroundDrawableResource(android.R.color.transparent);// While the media controller is up, the volume control keys should// affect the media stream typemWindow.setVolumeControlStream(AudioManager.STREAM_MUSIC);setFocusable(true);setFocusableInTouchMode(true);setDescendantFocusability(ViewGroup.FOCUS_AFTER_DESCENDANTS);requestFocus();
}

mTouchListener

private OnTouchListener mTouchListener = new OnTouchListener() {public boolean onTouch(View v, MotionEvent event) {if (event.getAction() == MotionEvent.ACTION_DOWN) {if (mShowing) {hide();}}return false;}
};

setMediaPlayer
VideoView调用setMediaController的时候会调用到该方法

public void setMediaPlayer(MediaPlayerControl player) {mPlayer = player;updatePausePlay();
}

setAnchorView
VideoView调用setMediaController的时候会调用到该方法

/*** Set the view that acts as the anchor for the control view.* This can for example be a VideoView, or your Activity's main view.* When VideoView calls this method, it will use the VideoView's parent* as the anchor.* @param view The view to which to anchor the controller when it is visible.*/
public void setAnchorView(View view) {if (mAnchor != null) {mAnchor.removeOnLayoutChangeListener(mLayoutChangeListener);}mAnchor = view;if (mAnchor != null) {mAnchor.addOnLayoutChangeListener(mLayoutChangeListener);}FrameLayout.LayoutParams frameParams = new FrameLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,ViewGroup.LayoutParams.MATCH_PARENT);removeAllViews();View v = makeControllerView();addView(v, frameParams);
}

mLayoutChangeListener

// This is called whenever mAnchor's layout bound changes
private OnLayoutChangeListener mLayoutChangeListener =new OnLayoutChangeListener() {public void onLayoutChange(View v, int left, int top, int right,int bottom, int oldLeft, int oldTop, int oldRight,int oldBottom) {// 更新布局updateFloatingWindowLayout();if (mShowing) {mWindowManager.updateViewLayout(mDecor, mDecorLayoutParams);}}
};

updateFloatingWindowLayout

// Update the dynamic parts of mDecorLayoutParams
// Must be called with mAnchor != NULL.
private void updateFloatingWindowLayout() {int [] anchorPos = new int[2];mAnchor.getLocationOnScreen(anchorPos);// we need to know the size of the controller so we can properly position it// within its spacemDecor.measure(MeasureSpec.makeMeasureSpec(mAnchor.getWidth(), MeasureSpec.AT_MOST),MeasureSpec.makeMeasureSpec(mAnchor.getHeight(), MeasureSpec.AT_MOST));WindowManager.LayoutParams p = mDecorLayoutParams;p.width = mAnchor.getWidth();p.x = anchorPos[0] + (mAnchor.getWidth() - p.width) / 2;p.y = anchorPos[1] + mAnchor.getHeight() - mDecor.getMeasuredHeight();
}

makeControllerView

/*** Create the view that holds the widgets that control playback.* Derived classes can override this to create their own.* @return The controller view.* @hide This doesn't work as advertised*/
protected View makeControllerView() {LayoutInflater inflate = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);mRoot = inflate.inflate(com.android.internal.R.layout.media_controller, null);// 对Controller中的一些按钮、功能进行事件设置initControllerView(mRoot);return mRoot;
}

touch事件处理

@Override
public boolean onTouchEvent(MotionEvent event) {show(sDefaultTimeout);return true;
}

进度的处理

seekBar的处理

// There are two scenarios that can trigger the seekbar listener to trigger:
//
// The first is the user using the touchpad to adjust the posititon of the
// seekbar's thumb. In this case onStartTrackingTouch is called followed by
// a number of onProgressChanged notifications, concluded by onStopTrackingTouch.
// We're setting the field "mDragging" to true for the duration of the dragging
// session to avoid jumps in the position in case of ongoing playback.
//
// The second scenario involves the user operating the scroll ball, in this
// case there WON'T BE onStartTrackingTouch/onStopTrackingTouch notifications,
// we will simply apply the updated position without suspending regular updates.
private OnSeekBarChangeListener mSeekListener = new OnSeekBarChangeListener() {public void onStartTrackingTouch(SeekBar bar) {show(3600000);mDragging = true;// By removing these pending progress messages we make sure// that a) we won't update the progress while the user adjusts// the seekbar and b) once the user is done dragging the thumb// we will post one of these messages to the queue again and// this ensures that there will be exactly one message queued up.mHandler.removeMessages(SHOW_PROGRESS);}public void onProgressChanged(SeekBar bar, int progress, boolean fromuser) {if (!fromuser) {// We're not interested in programmatically generated changes to// the progress bar's position.return;}long duration = mPlayer.getDuration();long newposition = (duration * progress) / 1000L;mPlayer.seekTo( (int) newposition);if (mCurrentTime != null)mCurrentTime.setText(stringForTime( (int) newposition));}public void onStopTrackingTouch(SeekBar bar) {mDragging = false;setProgress();updatePausePlay();show(sDefaultTimeout);// Ensure that progress is properly updated in the future,// the call to show() does not guarantee this because it is a// no-op if we are already showing.mHandler.sendEmptyMessage(SHOW_PROGRESS);}
};

SetProgress

private int setProgress() {if (mPlayer == null || mDragging) {return 0;}int position = mPlayer.getCurrentPosition();int duration = mPlayer.getDuration();if (mProgress != null) {if (duration > 0) {// use long to avoid overflowlong pos = 1000L * position / duration;mProgress.setProgress( (int) pos);}int percent = mPlayer.getBufferPercentage();mProgress.setSecondaryProgress(percent * 10);}if (mEndTime != null)mEndTime.setText(stringForTime(duration));if (mCurrentTime != null)mCurrentTime.setText(stringForTime(position));return position;
}

show

/*** Show the controller on screen. It will go away* automatically after 'timeout' milliseconds of inactivity.* @param timeout The timeout in milliseconds. Use 0 to show* the controller until hide() is called.*/
public void show(int timeout) {if (!mShowing && mAnchor != null) {// 先去设置一下进度setProgress();if (mPauseButton != null) {mPauseButton.requestFocus();}disableUnsupportedButtons();updateFloatingWindowLayout();mWindowManager.addView(mDecor, mDecorLayoutParams);mShowing = true;}updatePausePlay();// cause the progress bar to be updated even if mShowing// was already true.  This happens, for example, if we're// paused with the progress bar showing the user hits play.// 发送定期更新进度的消息mHandler.sendEmptyMessage(SHOW_PROGRESS);Message msg = mHandler.obtainMessage(FADE_OUT);if (timeout != 0) {mHandler.removeMessages(FADE_OUT);mHandler.sendMessageDelayed(msg, timeout);}
}

hide

/*** Remove the controller from the screen.*/
public void hide() {if (mAnchor == null)return;if (mShowing) {try {// 移除定期更新消息mHandler.removeMessages(SHOW_PROGRESS);mWindowManager.removeView(mDecor);} catch (IllegalArgumentException ex) {Log.w("MediaController", "already removed");}mShowing = false;}
}

上源码

/** Copyright (C) 2006 The Android Open Source Project** 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**      http://www.apache.org/licenses/LICENSE-2.0** Unless required by applicable law or agreed to in writing, software* distributed under the License is distributed on an "AS IS" BASIS,* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.* See the License for the specific language governing permissions and* limitations under the License.*/package android.widget;import android.content.Context;
import android.graphics.PixelFormat;
import android.media.AudioManager;
import android.os.Handler;
import android.os.Message;
import android.util.AttributeSet;
import android.util.Log;
import android.view.Gravity;
import android.view.KeyEvent;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.view.Window;
import android.view.WindowManager;
import android.view.accessibility.AccessibilityEvent;
import android.view.accessibility.AccessibilityNodeInfo;
import android.widget.SeekBar.OnSeekBarChangeListener;import com.android.internal.policy.PolicyManager;import java.util.Formatter;
import java.util.Locale;/*** A view containing controls for a MediaPlayer. Typically contains the* buttons like "Play/Pause", "Rewind", "Fast Forward" and a progress* slider. It takes care of synchronizing the controls with the state* of the MediaPlayer.* <p>* The way to use this class is to instantiate it programatically.* The MediaController will create a default set of controls* and put them in a window floating above your application. Specifically,* the controls will float above the view specified with setAnchorView().* The window will disappear if left idle for three seconds and reappear* when the user touches the anchor view.* <p>* Functions like show() and hide() have no effect when MediaController* is created in an xml layout.* * MediaController will hide and* show the buttons according to these rules:* <ul>* <li> The "previous" and "next" buttons are hidden until setPrevNextListeners()*   has been called* <li> The "previous" and "next" buttons are visible but disabled if*   setPrevNextListeners() was called with null listeners* <li> The "rewind" and "fastforward" buttons are shown unless requested*   otherwise by using the MediaController(Context, boolean) constructor*   with the boolean set to false* </ul>*/
public class MediaController extends FrameLayout {private MediaPlayerControl  mPlayer;private Context             mContext;private View                mAnchor;private View                mRoot;private WindowManager       mWindowManager;private Window              mWindow;private View                mDecor;private WindowManager.LayoutParams mDecorLayoutParams;private ProgressBar         mProgress;private TextView            mEndTime, mCurrentTime;private boolean             mShowing;private boolean             mDragging;private static final int    sDefaultTimeout = 3000;private static final int    FADE_OUT = 1;private static final int    SHOW_PROGRESS = 2;private boolean             mUseFastForward;private boolean             mFromXml;private boolean             mListenersSet;private View.OnClickListener mNextListener, mPrevListener;StringBuilder               mFormatBuilder;Formatter                   mFormatter;private ImageButton         mPauseButton;private ImageButton         mFfwdButton;private ImageButton         mRewButton;private ImageButton         mNextButton;private ImageButton         mPrevButton;public MediaController(Context context, AttributeSet attrs) {super(context, attrs);mRoot = this;mContext = context;mUseFastForward = true;mFromXml = true;}@Overridepublic void onFinishInflate() {if (mRoot != null)initControllerView(mRoot);}public MediaController(Context context, boolean useFastForward) {super(context);mContext = context;mUseFastForward = useFastForward;initFloatingWindowLayout();initFloatingWindow();}public MediaController(Context context) {this(context, true);}private void initFloatingWindow() {mWindowManager = (WindowManager)mContext.getSystemService(Context.WINDOW_SERVICE);mWindow = PolicyManager.makeNewWindow(mContext);mWindow.setWindowManager(mWindowManager, null, null);mWindow.requestFeature(Window.FEATURE_NO_TITLE);mDecor = mWindow.getDecorView();mDecor.setOnTouchListener(mTouchListener);mWindow.setContentView(this);mWindow.setBackgroundDrawableResource(android.R.color.transparent);// While the media controller is up, the volume control keys should// affect the media stream typemWindow.setVolumeControlStream(AudioManager.STREAM_MUSIC);setFocusable(true);setFocusableInTouchMode(true);setDescendantFocusability(ViewGroup.FOCUS_AFTER_DESCENDANTS);requestFocus();}// Allocate and initialize the static parts of mDecorLayoutParams. Must// also call updateFloatingWindowLayout() to fill in the dynamic parts// (y and width) before mDecorLayoutParams can be used.private void initFloatingWindowLayout() {mDecorLayoutParams = new WindowManager.LayoutParams();WindowManager.LayoutParams p = mDecorLayoutParams;p.gravity = Gravity.TOP | Gravity.LEFT;p.height = LayoutParams.WRAP_CONTENT;p.x = 0;p.format = PixelFormat.TRANSLUCENT;p.type = WindowManager.LayoutParams.TYPE_APPLICATION_PANEL;p.flags |= WindowManager.LayoutParams.FLAG_ALT_FOCUSABLE_IM| WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL| WindowManager.LayoutParams.FLAG_SPLIT_TOUCH;p.token = null;p.windowAnimations = 0; // android.R.style.DropDownAnimationDown;}// Update the dynamic parts of mDecorLayoutParams// Must be called with mAnchor != NULL.private void updateFloatingWindowLayout() {int [] anchorPos = new int[2];mAnchor.getLocationOnScreen(anchorPos);// we need to know the size of the controller so we can properly position it// within its spacemDecor.measure(MeasureSpec.makeMeasureSpec(mAnchor.getWidth(), MeasureSpec.AT_MOST),MeasureSpec.makeMeasureSpec(mAnchor.getHeight(), MeasureSpec.AT_MOST));WindowManager.LayoutParams p = mDecorLayoutParams;p.width = mAnchor.getWidth();p.x = anchorPos[0] + (mAnchor.getWidth() - p.width) / 2;p.y = anchorPos[1] + mAnchor.getHeight() - mDecor.getMeasuredHeight();}// This is called whenever mAnchor's layout bound changesprivate OnLayoutChangeListener mLayoutChangeListener =new OnLayoutChangeListener() {public void onLayoutChange(View v, int left, int top, int right,int bottom, int oldLeft, int oldTop, int oldRight,int oldBottom) {updateFloatingWindowLayout();if (mShowing) {mWindowManager.updateViewLayout(mDecor, mDecorLayoutParams);}}};private OnTouchListener mTouchListener = new OnTouchListener() {public boolean onTouch(View v, MotionEvent event) {if (event.getAction() == MotionEvent.ACTION_DOWN) {if (mShowing) {hide();}}return false;}};public void setMediaPlayer(MediaPlayerControl player) {mPlayer = player;updatePausePlay();}/*** Set the view that acts as the anchor for the control view.* This can for example be a VideoView, or your Activity's main view.* When VideoView calls this method, it will use the VideoView's parent* as the anchor.* @param view The view to which to anchor the controller when it is visible.*/public void setAnchorView(View view) {if (mAnchor != null) {mAnchor.removeOnLayoutChangeListener(mLayoutChangeListener);}mAnchor = view;if (mAnchor != null) {mAnchor.addOnLayoutChangeListener(mLayoutChangeListener);}FrameLayout.LayoutParams frameParams = new FrameLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,ViewGroup.LayoutParams.MATCH_PARENT);removeAllViews();View v = makeControllerView();addView(v, frameParams);}/*** Create the view that holds the widgets that control playback.* Derived classes can override this to create their own.* @return The controller view.* @hide This doesn't work as advertised*/protected View makeControllerView() {LayoutInflater inflate = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);mRoot = inflate.inflate(com.android.internal.R.layout.media_controller, null);initControllerView(mRoot);return mRoot;}private void initControllerView(View v) {mPauseButton = (ImageButton) v.findViewById(com.android.internal.R.id.pause);if (mPauseButton != null) {mPauseButton.requestFocus();mPauseButton.setOnClickListener(mPauseListener);}mFfwdButton = (ImageButton) v.findViewById(com.android.internal.R.id.ffwd);if (mFfwdButton != null) {mFfwdButton.setOnClickListener(mFfwdListener);if (!mFromXml) {mFfwdButton.setVisibility(mUseFastForward ? View.VISIBLE : View.GONE);}}mRewButton = (ImageButton) v.findViewById(com.android.internal.R.id.rew);if (mRewButton != null) {mRewButton.setOnClickListener(mRewListener);if (!mFromXml) {mRewButton.setVisibility(mUseFastForward ? View.VISIBLE : View.GONE);}}// By default these are hidden. They will be enabled when setPrevNextListeners() is called mNextButton = (ImageButton) v.findViewById(com.android.internal.R.id.next);if (mNextButton != null && !mFromXml && !mListenersSet) {mNextButton.setVisibility(View.GONE);}mPrevButton = (ImageButton) v.findViewById(com.android.internal.R.id.prev);if (mPrevButton != null && !mFromXml && !mListenersSet) {mPrevButton.setVisibility(View.GONE);}mProgress = (ProgressBar) v.findViewById(com.android.internal.R.id.mediacontroller_progress);if (mProgress != null) {if (mProgress instanceof SeekBar) {SeekBar seeker = (SeekBar) mProgress;seeker.setOnSeekBarChangeListener(mSeekListener);}mProgress.setMax(1000);}mEndTime = (TextView) v.findViewById(com.android.internal.R.id.time);mCurrentTime = (TextView) v.findViewById(com.android.internal.R.id.time_current);mFormatBuilder = new StringBuilder();mFormatter = new Formatter(mFormatBuilder, Locale.getDefault());installPrevNextListeners();}/*** Show the controller on screen. It will go away* automatically after 3 seconds of inactivity.*/public void show() {show(sDefaultTimeout);}/*** Disable pause or seek buttons if the stream cannot be paused or seeked.* This requires the control interface to be a MediaPlayerControlExt*/private void disableUnsupportedButtons() {try {if (mPauseButton != null && !mPlayer.canPause()) {mPauseButton.setEnabled(false);}if (mRewButton != null && !mPlayer.canSeekBackward()) {mRewButton.setEnabled(false);}if (mFfwdButton != null && !mPlayer.canSeekForward()) {mFfwdButton.setEnabled(false);}} catch (IncompatibleClassChangeError ex) {// We were given an old version of the interface, that doesn't have// the canPause/canSeekXYZ methods. This is OK, it just means we// assume the media can be paused and seeked, and so we don't disable// the buttons.}}/*** Show the controller on screen. It will go away* automatically after 'timeout' milliseconds of inactivity.* @param timeout The timeout in milliseconds. Use 0 to show* the controller until hide() is called.*/public void show(int timeout) {if (!mShowing && mAnchor != null) {setProgress();if (mPauseButton != null) {mPauseButton.requestFocus();}disableUnsupportedButtons();updateFloatingWindowLayout();mWindowManager.addView(mDecor, mDecorLayoutParams);mShowing = true;}updatePausePlay();// cause the progress bar to be updated even if mShowing// was already true.  This happens, for example, if we're// paused with the progress bar showing the user hits play.mHandler.sendEmptyMessage(SHOW_PROGRESS);Message msg = mHandler.obtainMessage(FADE_OUT);if (timeout != 0) {mHandler.removeMessages(FADE_OUT);mHandler.sendMessageDelayed(msg, timeout);}}public boolean isShowing() {return mShowing;}/*** Remove the controller from the screen.*/public void hide() {if (mAnchor == null)return;if (mShowing) {try {mHandler.removeMessages(SHOW_PROGRESS);mWindowManager.removeView(mDecor);} catch (IllegalArgumentException ex) {Log.w("MediaController", "already removed");}mShowing = false;}}private Handler mHandler = new Handler() {@Overridepublic void handleMessage(Message msg) {int pos;switch (msg.what) {case FADE_OUT:hide();break;case SHOW_PROGRESS:pos = setProgress();if (!mDragging && mShowing && mPlayer.isPlaying()) {msg = obtainMessage(SHOW_PROGRESS);sendMessageDelayed(msg, 1000 - (pos % 1000));}break;}}};private String stringForTime(int timeMs) {int totalSeconds = timeMs / 1000;int seconds = totalSeconds % 60;int minutes = (totalSeconds / 60) % 60;int hours   = totalSeconds / 3600;mFormatBuilder.setLength(0);if (hours > 0) {return mFormatter.format("%d:%02d:%02d", hours, minutes, seconds).toString();} else {return mFormatter.format("%02d:%02d", minutes, seconds).toString();}}private int setProgress() {if (mPlayer == null || mDragging) {return 0;}int position = mPlayer.getCurrentPosition();int duration = mPlayer.getDuration();if (mProgress != null) {if (duration > 0) {// use long to avoid overflowlong pos = 1000L * position / duration;mProgress.setProgress( (int) pos);}int percent = mPlayer.getBufferPercentage();mProgress.setSecondaryProgress(percent * 10);}if (mEndTime != null)mEndTime.setText(stringForTime(duration));if (mCurrentTime != null)mCurrentTime.setText(stringForTime(position));return position;}@Overridepublic boolean onTouchEvent(MotionEvent event) {show(sDefaultTimeout);return true;}@Overridepublic boolean onTrackballEvent(MotionEvent ev) {show(sDefaultTimeout);return false;}@Overridepublic boolean dispatchKeyEvent(KeyEvent event) {int keyCode = event.getKeyCode();final boolean uniqueDown = event.getRepeatCount() == 0&& event.getAction() == KeyEvent.ACTION_DOWN;if (keyCode ==  KeyEvent.KEYCODE_HEADSETHOOK|| keyCode == KeyEvent.KEYCODE_MEDIA_PLAY_PAUSE|| keyCode == KeyEvent.KEYCODE_SPACE) {if (uniqueDown) {doPauseResume();show(sDefaultTimeout);if (mPauseButton != null) {mPauseButton.requestFocus();}}return true;} else if (keyCode == KeyEvent.KEYCODE_MEDIA_PLAY) {if (uniqueDown && !mPlayer.isPlaying()) {mPlayer.start();updatePausePlay();show(sDefaultTimeout);}return true;} else if (keyCode == KeyEvent.KEYCODE_MEDIA_STOP|| keyCode == KeyEvent.KEYCODE_MEDIA_PAUSE) {if (uniqueDown && mPlayer.isPlaying()) {mPlayer.pause();updatePausePlay();show(sDefaultTimeout);}return true;} else if (keyCode == KeyEvent.KEYCODE_VOLUME_DOWN|| keyCode == KeyEvent.KEYCODE_VOLUME_UP|| keyCode == KeyEvent.KEYCODE_VOLUME_MUTE|| keyCode == KeyEvent.KEYCODE_CAMERA) {// don't show the controls for volume adjustmentreturn super.dispatchKeyEvent(event);} else if (keyCode == KeyEvent.KEYCODE_BACK || keyCode == KeyEvent.KEYCODE_MENU) {if (uniqueDown) {hide();}return true;}show(sDefaultTimeout);return super.dispatchKeyEvent(event);}private View.OnClickListener mPauseListener = new View.OnClickListener() {public void onClick(View v) {doPauseResume();show(sDefaultTimeout);}};private void updatePausePlay() {if (mRoot == null || mPauseButton == null)return;if (mPlayer.isPlaying()) {mPauseButton.setImageResource(com.android.internal.R.drawable.ic_media_pause);} else {mPauseButton.setImageResource(com.android.internal.R.drawable.ic_media_play);}}private void doPauseResume() {if (mPlayer.isPlaying()) {mPlayer.pause();} else {mPlayer.start();}updatePausePlay();}// There are two scenarios that can trigger the seekbar listener to trigger://// The first is the user using the touchpad to adjust the posititon of the// seekbar's thumb. In this case onStartTrackingTouch is called followed by// a number of onProgressChanged notifications, concluded by onStopTrackingTouch.// We're setting the field "mDragging" to true for the duration of the dragging// session to avoid jumps in the position in case of ongoing playback.//// The second scenario involves the user operating the scroll ball, in this// case there WON'T BE onStartTrackingTouch/onStopTrackingTouch notifications,// we will simply apply the updated position without suspending regular updates.private OnSeekBarChangeListener mSeekListener = new OnSeekBarChangeListener() {public void onStartTrackingTouch(SeekBar bar) {show(3600000);mDragging = true;// By removing these pending progress messages we make sure// that a) we won't update the progress while the user adjusts// the seekbar and b) once the user is done dragging the thumb// we will post one of these messages to the queue again and// this ensures that there will be exactly one message queued up.mHandler.removeMessages(SHOW_PROGRESS);}public void onProgressChanged(SeekBar bar, int progress, boolean fromuser) {if (!fromuser) {// We're not interested in programmatically generated changes to// the progress bar's position.return;}long duration = mPlayer.getDuration();long newposition = (duration * progress) / 1000L;mPlayer.seekTo( (int) newposition);if (mCurrentTime != null)mCurrentTime.setText(stringForTime( (int) newposition));}public void onStopTrackingTouch(SeekBar bar) {mDragging = false;setProgress();updatePausePlay();show(sDefaultTimeout);// Ensure that progress is properly updated in the future,// the call to show() does not guarantee this because it is a// no-op if we are already showing.mHandler.sendEmptyMessage(SHOW_PROGRESS);}};@Overridepublic void setEnabled(boolean enabled) {if (mPauseButton != null) {mPauseButton.setEnabled(enabled);}if (mFfwdButton != null) {mFfwdButton.setEnabled(enabled);}if (mRewButton != null) {mRewButton.setEnabled(enabled);}if (mNextButton != null) {mNextButton.setEnabled(enabled && mNextListener != null);}if (mPrevButton != null) {mPrevButton.setEnabled(enabled && mPrevListener != null);}if (mProgress != null) {mProgress.setEnabled(enabled);}disableUnsupportedButtons();super.setEnabled(enabled);}@Overridepublic void onInitializeAccessibilityEvent(AccessibilityEvent event) {super.onInitializeAccessibilityEvent(event);event.setClassName(MediaController.class.getName());}@Overridepublic void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) {super.onInitializeAccessibilityNodeInfo(info);info.setClassName(MediaController.class.getName());}private View.OnClickListener mRewListener = new View.OnClickListener() {public void onClick(View v) {int pos = mPlayer.getCurrentPosition();pos -= 5000; // millisecondsmPlayer.seekTo(pos);setProgress();show(sDefaultTimeout);}};private View.OnClickListener mFfwdListener = new View.OnClickListener() {public void onClick(View v) {int pos = mPlayer.getCurrentPosition();pos += 15000; // millisecondsmPlayer.seekTo(pos);setProgress();show(sDefaultTimeout);}};private void installPrevNextListeners() {if (mNextButton != null) {mNextButton.setOnClickListener(mNextListener);mNextButton.setEnabled(mNextListener != null);}if (mPrevButton != null) {mPrevButton.setOnClickListener(mPrevListener);mPrevButton.setEnabled(mPrevListener != null);}}public void setPrevNextListeners(View.OnClickListener next, View.OnClickListener prev) {mNextListener = next;mPrevListener = prev;mListenersSet = true;if (mRoot != null) {installPrevNextListeners();if (mNextButton != null && !mFromXml) {mNextButton.setVisibility(View.VISIBLE);}if (mPrevButton != null && !mFromXml) {mPrevButton.setVisibility(View.VISIBLE);}}}public interface MediaPlayerControl {void    start();void    pause();int     getDuration();int     getCurrentPosition();void    seekTo(int pos);boolean isPlaying();int     getBufferPercentage();boolean canPause();boolean canSeekBackward();boolean canSeekForward();/*** Get the audio session id for the player used by this VideoView. This can be used to* apply audio effects to the audio track of a video.* @return The audio session, or 0 if there was an error.*/int     getAudioSessionId();}
}

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