Android4.1 Open Menu的过程
1. PhoneWindow.onKeyDown()
1. onKeyDownPanel.
当Menu键按下去之后，会产生一个KeyEvent，是keyDown事件，如果Activity没有处理这个Menu Down事件，就会由PhonwWindow默认onKeyDown处理。
在onKeyDown中只要就是调用了onKeyDownPanel把事件传递给对应的panel。
protected boolean onKeyDown(int featureId, int keyCode, KeyEvent event) {
switch (keyCode) {
... ...
case KeyEvent.KEYCODE_MENU: {
onKeyDownPanel((featureId < 0) ? FEATURE_OPTIONS_PANEL : featureId, event);
return true;
}
... ...
}
return false;
}
1.1 PhoneWindow.onKeyDownPanel(int featureId, KeyEvent event)
1. getPanelState()
根据featureId获得对应的PanelFeatureState，PanelFeatureState用来保存一个panel对象，比如option menu是对应一个PanelFeatureState 和 featureId。
2. preparePanel()
由于是第一次得到PanelFeatureState，st.isOpen返回false，所以就去preparePanel。
public final boolean onKeyDownPanel(int featureId, KeyEvent event) {
final int keyCode = event.getKeyCode();
if (event.getRepeatCount() == 0) {
// The panel key was pushed, so set the chording key
mPanelChordingKey = keyCode;
PanelFeatureState st = getPanelState(featureId, true);
if (!st.isOpen) {
return preparePanel(st, event);
}
}
return false;
}
1.1.1 PhoneWindow. getPanelState(int featureId, boolean required, PanelFeatureState convertPanelState)
这个getPanelState也很简单，如果存在与featureId对应的PanelFeatureState就直接返回，没有的就new一个新的。也就是如果如果我们再当前Activity中，如果是第一次按menu的话，应该是不存在FEATURE_OPTIONS_PANEL相对应的PanelFeatureState。于是就会new一个新的出来。
private PanelFeatureState getPanelState(int featureId, boolean required,
PanelFeatureState convertPanelState) {
PanelFeatureState[] ar;
if ((ar = mPanels) == null || ar.length <= featureId) {
PanelFeatureState[] nar = new PanelFeatureState[featureId + 1];
if (ar != null) {
System.arraycopy(ar, 0, nar, 0, ar.length);
}
mPanels = ar = nar;
}
PanelFeatureState st = ar[featureId];
if (st == null) {
ar[featureId] = st = (convertPanelState != null)
? convertPanelState
: new PanelFeatureState(featureId);
}
return st;
}
1. 通过Callback（Activity）的onCreatePanelView去创建一个panel，用户可以复写这个方法， 如果用户没有复写，则st.createPanelView = null。
2. initializePanelMenu(), 初始化st中的MenuBuilder，用于以后创建Menu。
3. 调用cb.onPreparePanel，就会调用Activity的onPreaparePanel方法，而在onPreparePanel中会调用onPrepareOptionsMenu去完成 option menu的prepare工作。完成之后把st中的状态设置一下。 st.isPrepared = true; st.isHandled = false; mPreparedPanel = st;
public final boolean preparePanel(PanelFeatureState st, KeyEvent event) {
final Callback cb = getCallback();
if (cb != null) {
st.createdPanelView = cb.onCreatePanelView(st.featureId);
}
if (st.createdPanelView == null) {
// Init the panel state's menu--return false if init failed
if (st.menu == null || st.refreshMenuContent) {
if (st.menu == null) {
if (!initializePanelMenu(st) || (st.menu == null)) {
return false;
}
}
if (mActionBar != null) {
if (mActionMenuPresenterCallback == null) {
mActionMenuPresenterCallback = new ActionMenuPresenterCallback();
}
mActionBar.setMenu(st.menu, mActionMenuPresenterCallback);
}
st.menu.stopDispatchingItemsChanged();
st.refreshMenuContent = false;
}
// Callback and return if the callback does not want to show the menu
// Preparing the panel menu can involve a lot of manipulation;
// don't dispatch change events to presenters until we're done.
st.menu.stopDispatchingItemsChanged();
if (!cb.onPreparePanel(st.featureId, st.createdPanelView, st.menu)) {
if (mActionBar != null) {
// The app didn't want to show the menu for now but it still exists.
// Clear it out of the action bar.
mActionBar.setMenu(null, mActionMenuPresenterCallback);
}
st.menu.startDispatchingItemsChanged();
return false;
}
... ...
}
// Set other state
st.isPrepared = true;
st.isHandled = false;
mPreparedPanel = st;
return true;
}
2. PhoneWindow.onKeyUp()
跟KeyDown对应，按键起来之后会有一个up事件。而Menu的up事件也是又PhoneWindow来处理。
1. onKeyUpPanel
protected boolean onKeyUp(int featureId, int keyCode, KeyEvent event) {
... ...
case KeyEvent.KEYCODE_MENU: {
onKeyUpPanel(featureId < 0 ? FEATURE_OPTIONS_PANEL : featureId,
event);
return true;
}
... ...
}
2.1 PhoneWindow.onKeyUpPanel(int featureId, KeyEvent event)
1. 如果panel在前面的down事件中已经prepare成功了，调用 openPanel(st, event);去打开option menu。并且把 playSoundEffect 设为 true;
PS: 会打出Event log。
2.
public final void onKeyUpPanel(int featureId, KeyEvent event) {
// The panel key was released, so clear the chording key
if (mPanelChordingKey != 0) {
... ...
boolean playSoundEffect = false;
final PanelFeatureState st = getPanelState(featureId, true);
if (featureId == FEATURE_OPTIONS_PANEL && mActionBar != null &&
mActionBar.isOverflowReserved()) {
if (mActionBar.getVisibility() == View.VISIBLE) {
if (!mActionBar.isOverflowMenuShowing()) {
if (!isDestroyed() && preparePanel(st, event)) {
playSoundEffect = mActionBar.showOverflowMenu();
}
} else {
playSoundEffect = mActionBar.hideOverflowMenu();
}
}
} else {
if (st.isOpen || st.isHandled) {
// Play the sound effect if the user closed an open menu (and not if
// they just released a menu shortcut)
playSoundEffect = st.isOpen;
// Close menu
closePanel(st, true);
} else if (st.isPrepared) {
boolean show = true;
if (st.refreshMenuContent) {
// Something may have invalidated the menu since we prepared it.
// Re-prepare it to refresh.
st.isPrepared = false;
show = preparePanel(st, event);
}
if (show) {
// Write 'menu opened' to event log
EventLog.writeEvent(50001, 0);
// Show menu
openPanel(st, event);
playSoundEffect = true;
}
}
}
if (playSoundEffect) {
AudioManager audioManager = (AudioManager) getContext().getSystemService(
Context.AUDIO_SERVICE);
if (audioManager != null) {
audioManager.playSoundEffect(AudioManager.FX_KEY_CLICK);
} else {
Log.w(TAG, "Couldn't get audio manager");
}
}
}
}
2.1.1 PhoneWindow.openPanel(PanelFeatureState st, KeyEvent event)
在打开panel之前，会对平台的屏幕进行检测，如果发现不是手机，就直接返回。
1. initializePanelDecor(PanelFeatureState st) //初始化对应panel的DecorView； 如果menu没有item的话，就直接return
2. initializePanelContent(PanelFeatureState st)， //初始化Panel的MenuView，并赋给st.shownPanelView；
3. 把st.shownPanelView寄到decorView中，然后通过wm.addView(st.decorView, lp);把新建出来的option menu的decorView加到WMS中。
这样option menu就显示出来了。
private void openPanel(PanelFeatureState st, KeyEvent event) {
Callback cb = getCallback();
if ((cb != null) && (!cb.onMenuOpened(st.featureId, st.menu))) {
// Callback doesn't want the menu to open, reset any state
closePanel(st, true);
return;
}
final WindowManager wm = getWindowManager();
int width = WRAP_CONTENT;
if (st.decorView == null || st.refreshDecorView) {
if (st.decorView == null) {
// Initialize the panel decor, this will populate st.decorView
if (!initializePanelDecor(st) || (st.decorView == null))
return;
} else if (st.refreshDecorView && (st.decorView.getChildCount() > 0)) {
// Decor needs refreshing, so remove its views
st.decorView.removeAllViews();
}
// This will populate st.shownPanelView
if (!initializePanelContent(st) || !st.hasPanelItems()) {
return;
}
ViewGroup.LayoutParams lp = st.shownPanelView.getLayoutParams();
if (lp == null) {
lp = new ViewGroup.LayoutParams(WRAP_CONTENT, WRAP_CONTENT);
}
int backgroundResId;
if (lp.width == ViewGroup.LayoutParams.MATCH_PARENT) {
// If the contents is fill parent for the width, set the
// corresponding background
backgroundResId = st.fullBackground;
width = MATCH_PARENT;
} else {
// Otherwise, set the normal panel background
backgroundResId = st.background;
}
st.decorView.setWindowBackground(getContext().getResources().getDrawable(
backgroundResId));
ViewParent shownPanelParent = st.shownPanelView.getParent();
if (shownPanelParent != null && shownPanelParent instanceof ViewGroup) {
((ViewGroup) shownPanelParent).removeView(st.shownPanelView);
}
st.decorView.addView(st.shownPanelView, lp);
/*
* Give focus to the view, if it or one of its children does not
* already have it.
*/
if (!st.shownPanelView.hasFocus()) {
st.shownPanelView.requestFocus();
}
} else if (!st.isInListMode()) {
width = MATCH_PARENT;
} else if (st.createdPanelView != null) {
// If we already had a panel view, carry width=MATCH_PARENT through
// as we did above when it was created.
ViewGroup.LayoutParams lp = st.createdPanelView.getLayoutParams();
if (lp != null && lp.width == ViewGroup.LayoutParams.MATCH_PARENT) {
width = MATCH_PARENT;
}
}
st.isOpen = true;
st.isHandled = false;
WindowManager.LayoutParams lp = new WindowManager.LayoutParams(
width, WRAP_CONTENT,
st.x, st.y, WindowManager.LayoutParams.TYPE_APPLICATION_ATTACHED_DIALOG,
WindowManager.LayoutParams.FLAG_ALT_FOCUSABLE_IM
| WindowManager.LayoutParams.FLAG_SPLIT_TOUCH,
st.decorView.mDefaultOpacity);
if (st.isCompact) {
lp.gravity = getOptionsPanelGravity();
sRotationWatcher.addWindow(this);
} else {
lp.gravity = st.gravity;
}
lp.windowAnimations = st.windowAnimations;
wm.addView(st.decorView, lp);
// Log.v(TAG, "Adding main menu to window manager.");
}
2.1.1.1 PhoneWindow.initializePanelDecor(PanelFeatureState st)
new出一个DecorView并且赋值给st.decorView。
protected boolean initializePanelDecor(PanelFeatureState st) {
st.decorView = new DecorView(getContext(), st.featureId);
st.gravity = Gravity.CENTER | Gravity.BOTTOM;
st.setStyle(getContext());
return true;
}
2.1.1.2 PhoneWindow. initializePanelContent(PanelFeatureState st)
//初始化Panel的MenuView，并赋给st.shownPanelView；
protected boolean initializePanelContent(PanelFeatureState st) {
if (st.createdPanelView != null) {
st.shownPanelView = st.createdPanelView;
return true;
}
if (st.menu == null) {
return false;
}
if (mPanelMenuPresenterCallback == null) {
mPanelMenuPresenterCallback = new PanelMenuPresenterCallback();
}
MenuView menuView = st.isInListMode()
? st.getListMenuView(getContext(), mPanelMenuPresenterCallback)
: st.getIconMenuView(getContext(), mPanelMenuPresenterCallback);
st.shownPanelView = (View) menuView;
if (st.shownPanelView != null) {
// Use the menu View's default animations if it has any
final int defaultAnimations = menuView.getWindowAnimations();
if (defaultAnimations != 0) {
st.windowAnimations = defaultAnimations;
}
return true;
} else {
return false;
}
}