Android 音效流程分析
音效流程分析
音效事件起源
Android 平台所有view类型控件的touch，遥控器按键等事件在系统音效开启时，都可以触发按键音。
音效事件流程分析
从touch事件为例，整个流程如下图所示：
如图中所示，在touch事件触发后，onTouchEvent会被调用，接着performClick就会处理Click事件，
/**
* Call this view's OnClickListener, if it is defined. Performs all normal
* actions associated with clicking: reporting accessibility event, playing
* a sound, etc.
*
* @return True there was an assigned OnClickListener that was called, false
* otherwise is returned.
*/
public boolean performClick() {
sendAccessibilityEvent(AccessibilityEvent.TYPE_VIEW_CLICKED);
ListenerInfo li = mListenerInfo;
if (li != null && li.mOnClickListener != null) {
playSoundEffect(SoundEffectConstants.CLICK);
li.mOnClickListener.onClick(this);
return true;
}
return false;
}
/**
* Play a sound effect for this view.
*
* The framework will play sound effects for some built in actions, such as
* clicking, but you may wish to play these effects in your widget,
* for instance, for internal navigation.
*
*
The sound effect will only be played if sound effects are enabled by the user, and
* {@link #isSoundEffectsEnabled()} is true.
*
* @param soundConstant One of the constants defined in {@link SoundEffectConstants}
*/
public void playSoundEffect(int soundConstant) {
if (mAttachInfo == null || mAttachInfo.mRootCallbacks == null || !isSoundEffectsEnabled()) {
return;
}
mAttachInfo.mRootCallbacks.playSoundEffect(soundConstant);
}
在创建后，都会绑定到对应窗口Window,下面看一下函数dispatchAttachedToWindow
void dispatchAttachedToWindow(AttachInfo info, int visibility) {
//System.out.println("Attached! " + this);
mAttachInfo = info;
if (mOverlay != null) {
mOverlay.getOverlayView().dispatchAttachedToWindow(info, visibility);
}
mWindowAttachCount++;
// We will need to evaluate the drawable state at least once.
mPrivateFlags |= PFLAG_DRAWABLE_STATE_DIRTY;
if (mFloatingTreeObserver != null) {
info.mTreeObserver.merge(mFloatingTreeObserver);
mFloatingTreeObserver = null;
}
if ((mPrivateFlags&PFLAG_SCROLL_CONTAINER) != 0) {
mAttachInfo.mScrollContainers.add(this);
mPrivateFlags |= PFLAG_SCROLL_CONTAINER_ADDED;
}
performCollectViewAttributes(mAttachInfo, visibility);
onAttachedToWindow();
ListenerInfo li = mListenerInfo;
final CopyOnWriteArrayList listeners =
li != null ? li.mOnAttachStateChangeListeners : null;
if (listeners != null && listeners.size() > 0) {
// NOTE: because of the use of CopyOnWriteArrayList, we *must* use an iterator to
// perform the dispatching. The iterator is a safe guard against listeners that
// could mutate the list by calling the various add/remove methods. This prevents
// the array from being modified while we iterate it.
for (OnAttachStateChangeListener listener : listeners) {
listener.onViewAttachedToWindow(this);
}
}
int vis = info.mWindowVisibility;
if (vis != GONE) {
onWindowVisibilityChanged(vis);
}
if ((mPrivateFlags&PFLAG_DRAWABLE_STATE_DIRTY) != 0) {
// If nobody has evaluated the drawable state yet, then do it now.
refreshDrawableState();
}
needGlobalAttributesUpdate(false);
}
将ViewRootImpl.mAttachInfo设置下去，而此成员在ViewRootImpl构造函数中赋值。
public ViewRootImpl(Context context, Display display) {
mContext = context;
mWindowSession = WindowManagerGlobal.getWindowSession();
mDisplay = display;
mBasePackageName = context.getBasePackageName();
mDisplayAdjustments = display.getDisplayAdjustments();
mThread = Thread.currentThread();
mLocation = new WindowLeaked(null);
mLocation.fillInStackTrace();
mWidth = -1;
mHeight = -1;
mDirty = new Rect();
mTempRect = new Rect();
mVisRect = new Rect();
mWinFrame = new Rect();
mWindow = new W(this);
mTargetSdkVersion = context.getApplicationInfo().targetSdkVersion;
mViewVisibility = View.GONE;
mTransparentRegion = new Region();
mPreviousTransparentRegion = new Region();
mFirst = true; // true for the first time the view is added
mAdded = false;
mAccessibilityManager = AccessibilityManager.getInstance(context);
mAccessibilityInteractionConnectionManager =
new AccessibilityInteractionConnectionManager();
mAccessibilityManager.addAccessibilityStateChangeListener(
mAccessibilityInteractionConnectionManager);
mAttachInfo = new View.AttachInfo(mWindowSession, mWindow, display, this, mHandler, this);
mViewConfiguration = ViewConfiguration.get(context);
mDensity = context.getResources().getDisplayMetrics().densityDpi;
mNoncompatDensity = context.getResources().getDisplayMetrics().noncompatDensityDpi;
mFallbackEventHandler = PolicyManager.makeNewFallbackEventHandler(context);
mChoreographer = Choreographer.getInstance();
PowerManager powerManager = (PowerManager) context.getSystemService(Context.POWER_SERVICE);
mAttachInfo.mScreenOn = powerManager.isScreenOn();
loadSystemProperties();
}
再看AttachInfo构造函数，如下：
/**
* Creates a new set of attachment information with the specified
* events handler and thread.
*
* @param handler the events handler the view must use
*/
AttachInfo(IWindowSession session, IWindow window, Display display,
ViewRootImpl viewRootImpl, Handler handler, Callbacks effectPlayer) {
mSession = session;
mWindow = window;
mWindowToken = window.asBinder();
mDisplay = display;
mViewRootImpl = viewRootImpl;
mHandler = handler;
mRootCallbacks = effectPlayer;
}音频系统接管音效控制
从ViewRootImp的函数playSoundEffect
public void playSoundEffect(int effectId) {
checkThread();
if (mMediaDisabled) {
return;
}
try {
final AudioManager audioManager = getAudioManager();
switch (effectId) {
case SoundEffectConstants.CLICK:
audioManager.playSoundEffect(AudioManager.FX_KEY_CLICK);
return;
case SoundEffectConstants.NAVIGATION_DOWN:
audioManager.playSoundEffect(AudioManager.FX_FOCUS_NAVIGATION_DOWN);
return;
case SoundEffectConstants.NAVIGATION_LEFT:
audioManager.playSoundEffect(AudioManager.FX_FOCUS_NAVIGATION_LEFT);
return;
case SoundEffectConstants.NAVIGATION_RIGHT:
audioManager.playSoundEffect(AudioManager.FX_FOCUS_NAVIGATION_RIGHT);
return;
case SoundEffectConstants.NAVIGATION_UP:
audioManager.playSoundEffect(AudioManager.FX_FOCUS_NAVIGATION_UP);
return;
default:
throw new IllegalArgumentException("unknown effect id " + effectId +
" not defined in " + SoundEffectConstants.class.getCanonicalName());
}
} catch (IllegalStateException e) {
// Exception thrown by getAudioManager() when mView is null
Log.e(TAG, "FATAL EXCEPTION when attempting to play sound effect: " + e);
e.printStackTrace();
}
} private void onPlaySoundEffect(int effectType, int volume) {
synchronized (mSoundEffectsLock) {
onLoadSoundEffects();
if (mSoundPool == null) {
return;
}
float volFloat;
// use default if volume is not specified by caller
if (volume < 0) {
volFloat = (float)Math.pow(10, (float)sSoundEffectVolumeDb/20);
} else {
volFloat = (float) volume / 1000.0f;
}
if (SOUND_EFFECT_FILES_MAP[effectType][1] > 0) {
mSoundPool.play(SOUND_EFFECT_FILES_MAP[effectType][1],
volFloat, volFloat, 0, 0, 1.0f);
} else {
MediaPlayer mediaPlayer = new MediaPlayer();
try {
String filePath = Environment.getRootDirectory() + SOUND_EFFECTS_PATH +
SOUND_EFFECT_FILES.get(SOUND_EFFECT_FILES_MAP[effectType][0]);
mediaPlayer.setDataSource(filePath);
mediaPlayer.setAudioStreamType(AudioSystem.STREAM_SYSTEM);
mediaPlayer.prepare();
mediaPlayer.setVolume(volFloat);
mediaPlayer.setOnCompletionListener(new OnCompletionListener() {
public void onCompletion(MediaPlayer mp) {
cleanupPlayer(mp);
}
});
mediaPlayer.setOnErrorListener(new OnErrorListener() {
public boolean onError(MediaPlayer mp, int what, int extra) {
cleanupPlayer(mp);
return true;
}
});
mediaPlayer.start();
} catch (IOException ex) {
Log.w(TAG, "MediaPlayer IOException: "+ex);
} catch (IllegalArgumentException ex) {
Log.w(TAG, "MediaPlayer IllegalArgumentException: "+ex);
} catch (IllegalStateException ex) {
Log.w(TAG, "MediaPlayer IllegalStateException: "+ex);
}
}
}
}sSoundEffectVolumeDb 是音效使用的音量大小值，mSoundPool.play完成音效的播放功能。
音频系统音效全局控制
/**
* Plays a sound effect (Key clicks, lid open/close...)
* @param effectType The type of sound effect. One of
* {@link #FX_KEY_CLICK},
* {@link #FX_FOCUS_NAVIGATION_UP},
* {@link #FX_FOCUS_NAVIGATION_DOWN},
* {@link #FX_FOCUS_NAVIGATION_LEFT},
* {@link #FX_FOCUS_NAVIGATION_RIGHT},
* {@link #FX_KEYPRESS_STANDARD},
* {@link #FX_KEYPRESS_SPACEBAR},
* {@link #FX_KEYPRESS_DELETE},
* {@link #FX_KEYPRESS_RETURN},
* {@link #FX_KEYPRESS_INVALID},
* NOTE: This version uses the UI settings to determine
* whether sounds are heard or not.
*/
public void playSoundEffect(int effectType) {
if (effectType < 0 || effectType >= NUM_SOUND_EFFECTS) {
return;
}
if (!querySoundEffectsEnabled()) {
return;
}
//Ctv Patch Begin
effectTypeForHandler = effectType;
userHandler.removeCallbacks(queueRun);
userHandler.postDelayed(queueRun, 20);
/*IAudioService service = getService();
try {
service.playSoundEffect(effectType);
} catch (RemoteException e) {
Log.e(TAG, "Dead object in playSoundEffect"+e);
}*/
}
例如：Settings.System.putInt(mContext.getContentResolver(), Settings.System.SOUND_EFFECTS_ENABLED, 0/1) 关闭/开启