标签:安卓
dialog是应用类窗口 其子类 大多会改为子窗口contextwindow也是应用类窗口
optionMenu是应用类窗口
应用类视图的根视图都是DecorView
->最终调用MenuDialogHelper类的show()方法 完成显示
创建optionMenu的3种方法:
当按下menu键时会调用phoneWindow的preparePanel方法
public final boolean preparePanel(PanelFeatureState st, KeyEvent event) { // Already prepared (isPrepared will be reset to false later) if (st.isPrepared) return true; if ((mPreparedPanel != null) && (mPreparedPanel != st)) { // Another Panel is prepared and possibly open, so close it closePanel(mPreparedPanel, false); } final Callback cb = getCallback(); //cb==activity if (cb != null) { //调用onCreatePanelView来显示一个自定义的optionMenu 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) { if (!initializePanelMenu(st) || (st.menu == null)) { return false; } // Call callback, and return if it doesn't want to display menu //调用activity的oncreateOptionMenu来创建一个Menu if ((cb == null) || !cb.onCreatePanelMenu(st.featureId, st.menu)) { // Ditch the menu created above st.menu = null; return false; } } // Callback and return if the callback does not want to show the menu //onPreparePanel自定义optionMenu if (!cb.onPreparePanel(st.featureId, st.createdPanelView, st.menu)) { return false; } // Set the proper keymap KeyCharacterMap kmap = KeyCharacterMap.load(event != null ? event.getDeviceId() : 0); st.qwertyMode = kmap.getKeyboardType() != KeyCharacterMap.NUMERIC; st.menu.setQwertyMode(st.qwertyMode); } // Set other state st.isPrepared = true; st.isHandled = false; mPreparedPanel = st; return true; }先看几个概念
分析上述代码 :可以看到有3处注释
在这3处注释中分别用了3种方式来创建一个menu
这里的CallBack就是Activity (activity实现了callback接口)
1.onCreatePanelView
acitivity的onCreatePanelView方法
public View onCreatePanelView(int featureId) { return null; }st.createdPanelView = cb.onCreatePanelView(st.featureId);
通过重写onCreatePanelView 我们可以更改createdPanelView 的值 从而实现自定义optionMenu
2.cb.onCreatePanelMenu(st.featureId, st.menu)
public boolean onCreatePanelMenu(int featureId, Menu menu) { if (featureId == Window.FEATURE_OPTIONS_PANEL) { return onCreateOptionsMenu(menu); } return false; }这里调用onCreateOptionMenu方法 也是我们创建OptionMenu最常用的方法
这里提供了一个menu对象 让我们来进行操作 而对于背景view则是使用默认的
再看:
if ((cb == null) || !cb.onCreatePanelMenu(st.featureId, st.menu)) { // Ditch the menu created above st.menu = null; return false; }
onCreatePanelMenu默认返回值是false 在if语句中也就是true
所以执行st.menu = null;
所以我们重写onCreatePanelMenu一定要返回ture
3.onPreparePanel
public boolean onPreparePanel(int featureId, View view, Menu menu) { if (featureId == Window.FEATURE_OPTIONS_PANEL && menu != null) { boolean goforit = onPrepareOptionsMenu(menu); return goforit && menu.hasVisibleItems(); } return true; }
标签:安卓
原文地址:http://blog.csdn.net/d342784178/article/details/45915753