android Window Introduction

<span id="Label3"></p><span style="font-size:14px"><span style="font-size:14px">dialog is the Application class window whose subclasses are mostly changed to child windows<br>Popupwindow is the App class window that changes to a child window when it is displayed<br></span></span><p><p><span style="font-size:14px">Contextwindow is also the Application class window</span></p></p><p><p><span style="font-size:14px">Optionmenu is the Application class window</span><br></p></p><p><p></p></p><p><p><br></p></p><p><p><span style="font-size:14px; color:#FF0000">The root view of the App Class View is Decorview</span><br></p></p><span style="font-size:14px"><span style="font-size:14px">Menu Important Class Introduction:<br><span style="color:#FF0000"></span>Menu: A interface describes the interface that a menu should have. here the menu refers to the entire menu instead of an entry<br>Menubuilder is its true realization<br><span style="color:#FF0000">MenuItem</span>: A interface describes the action interface that a menu entry should have Menuitemimpl is the data that implements the entries saved in the class<br><span style="color:#FF0000">Contextmenubuilder</span>: There is a ArrayList (menuitemimpl) variable in this class that holds the entry information for the entire menu<br>Expands the menubuilder to increase the ContextMenu characteristics.<br><span style="color:#FF0000">Menudialoghelper</span>: Provides an action to display menu<br><br>ContextMenu Display Process:<br>Long press The->view class Performlongclick ()->showcontextmenu (), call Mparent.showcontextmenuforchild () at this point the root view is (DecorView)<br>That is, Decorview's showcontextmenuforchild ()->contextmenubuilder class, show (), calls the view Class's Createcontextmenu () in Show () method to create a detailed entry<br></span></span><p><p><span style="font-size:14px">Finally call the show () method of the Menudialoghelper class to complete the display</span></p></p><p><p><span style="font-size:14px"><br></span></p></p><p><p><span style="font-size:14px">3 Ways to create optionmenu:</span></p></p><p><p><span style="font-size:14px">The Preparepanel method of Phonewindow is called when the menu key is pressed</span></p></p><p><p><span style="font-size:14px"></span></p></p><pre name="code" class="java"> Public final Boolean Preparepanel (panelfeaturestate st, keyevent event) {//already prepared (isprepared'll be Reset to False Later) if (st.isprepared) return true; If (mpreparedpanel! = Null) && (mpreparedpanel! = St)) {//another Panel is prepared and possibly ope n, so close it closepanel (mpreparedpanel, false); } final Callback cb = Getcallback (); cb==activity if (cb! = Null) {//call oncreatepanelview to display a custom optionmenu St.createdpanelview = C B.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//invoke Activity's oncreateoptio Nmenu.Create a menu if (CB = = Null) | |!cb.oncreatepanelmenu (st.featureid, st.menu)) {//ditch th E menu created above St.menu = null; Return false; }}//Callback and return if the Callback does not want to show the Menu//onpreparepane L Custom Optionmenu if (!cb.onpreparepanel (st.featureid, st.createdpanelview, st.menu)) {return fals E }//Set the proper keymap keycharactermap Kmap = keycharactermap.load (event! = null? Event.getdevi CeId (): 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; }</pre>First look at a few concepts<p><p></p></p><p><p><span style="font-size:14px"></span></p></p><p><p><span style="font-size:14px"><br></span></p></p><p><p><span style="font-size:14px">Analyze the above code: you can see that there are 3 comments<br></span></p></p><p><p><span style="font-size:14px">There are 3 different ways to create a menu in these 3 notes</span></p></p><p><p><span style="font-size:14px">The callback here is the activity (activity implements the callback Interface)<br></span></p></p><p><p><span style="font-size:14px">1.<span style="color:#FF0000">Oncreatepanelview</span></span></p></p><p><p><span style="font-size:14px">Acitivity's</span> <span style="font-size:14px">Oncreatepanelview</span> <span style="font-size:14px">Method</span></p></p><p><p><span style="font-size:14px"></span></p></p><pre name="code" class="java"><pre name="code" class="java"> Public View Oncreatepanelview (int featureid) { return null; }</pre></pre>St.createdpanelview = Cb.oncreatepanelview (st.featureid);<p><p></p></p><p><p><span style="font-size:14px">By overriding <span style="font-size:14px">Oncreatepanelview</span> We can change the value of <span style="font-size:14px">Createdpanelview</span> to implement custom Optionmenu</span></p></p><p><p><span style="font-size:14px"><br></span></p></p><p><p><span style="font-size:14px">2.cb. <span style="color:#FF0000">Oncreatepanelmenu</span> (st.featureid, St.menu)</span></p></p><p><p><span style="font-size:14px"></span></p></p><pre name="code" class="java"><pre name="code" class="java">public boolean oncreatepanelmenu (int featureid, menu Menu) { if (featureid = = Window.feature_options_panel) { return Oncreateoptionsmenu (menu); } return false; }</pre></pre>Calling the Oncreateoptionmenu method here is also the most common way we create Optionmenu<br><p><p></p></p><p><p><span style="font-size:14px">This provides a menu object for us to operate on, and for background view, it uses the default</span></p></p><p><p><span style="font-size:14px">Look again:</span></p></p><pre name="code" class="java"><pre name="code" class="java">if (CB = = Null) | |!cb.oncreatepanelmenu (st.featureid, st.menu)) { //ditch The menu created above st.menu = null ; return false; }</pre></pre><br><p><p></p></p><p><p><span style="font-size:14px">Oncreatepanelmenu The default return value is False in the If statement, which is true</span></p></p><p><p><span style="font-size:14px">So execute St.menu = null;</span></p></p><p><p><span style="font-size:14px">So we rewrite <span style="font-size:14px">oncreatepanelmenu</span> Be sure to return to Ture</span></p></p><p><p><span style="font-size:14px">3.<span style="color:#FF0000">Onpreparepanel</span></span></p></p><p><p><span style="font-size:14px"></span></p></p><pre name="code" class="java"><pre name="code" class="java">public boolean Onpreparepanel (int featureid, view view, menu Menu) { if (featureid = = Window.feature_options_panel &am p;& menu = Null) { Boolean goforit = Onprepareoptionsmenu (menu); return Goforit && menu.hasvisibleitems (); } return true; }</pre></pre><br>Here we directly rewrite the target of Onpreparepanel for Createdpanelview (view) and menu (menu) to custom Optionmenu<br><p><p></p></p><p><p><br></p></p><p><p>android Window Introduction</p></p></span>