Android-- Launcher拖拽事件详解

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转自：

http://blog.youkuaiyun.com/wdaming1986/article/details/7585649

http://blog.youkuaiyun.com/wdaming1986/article/details/7671318

 

最近研究ICS4.0的Launcher，发现4.0和2.3有稍微点区别，但是区别不是特别大，所以我就先整理一下Launcher启动的大致流程。Launcher其实是贯彻于手机的整个系统的，时时刻刻都在运行，要是Launcher不运行了，手机就得黑屏了。Launcher的LauncherMode=singletask，所以说不管Launcher启动了哪个应用，总有个Launcher的实例在堆栈中，并且位于栈底。点击Home键进入到Launcher，上篇Android的全局键（home键/长按耳机键）详解【android源码解析八】中有详细的介绍。大致思路其实就是启动launcher的时候，新启动一个task。大致先说这么多，先看截图：

大明原创，转载请标明出处：http://blog.youkuaiyun.com/wdaming1986/article/details/7585649

                                    

                                                                           图（1）

      上图是4.0的Launcher界面，下面我们分步来解析一下Launcher的启动过程。

     Step 0：首先要给大家介绍一下Launcher的数据库，这个数据库中存放着待机界面的图标，主屏底部的应用程序图标和桌面folder中各应用程序的图标，ICS4.0的folder中只能放应用程序的快捷方式，shortcut不能放到这个folder中，先看截图： 

                                                                        图（2）

       说说各字段的含义：

                title：表示桌面应用程序的名字，有的title为空，表示是widget的快捷方式；

             intent：表示启动这个图标的intent放到数据库中，当click的时候就会调用这个字段，启动相应的应用程序；

       container：表示应用程序的容器，folder的容器为整数，-100：表示在桌面的程序，-101：表示是主屏底部的程序；

           screen：表示在第几个屏，folder的screen都是0, container=-101的为0,1,3,4；2为allapp的按钮；

               cellX：表示在屏幕X轴的位置，（0,1,2,3），左上角为0点，往右依次增加；

               cellY：表示在屏幕Y轴的位置，（0,1,2,3），左上角为0点，往下依次增加；

              spallX：表示占X轴几个格；

              spallY：表示占Y轴几个格；

         itemType：应用程序用0表示，shortcut用1表示，folder用2表示，widget用4表示；

    appWidgetId：-1表示不是widget，数字大于0表示才是widget；

       isShortCut：值为0表示不是应用程序的ShortCut，值为1表示是应用程序的ShortCut；

         iconType：值为0表示图标的名字被定义为包名的资源id，值为1表示图标用bitmap保存；

                 icon：表示应用程序的图标，二进制的；显示为一张图片；

       说明：folder中的应用快捷方式绑定folder---->是用container的值绑定folder的id的；

        详细的讲解请参考LauncherSettings.java这个类，有数据库字段的详细讲解；

         手机是在第一次烧机完成后，数据库的值还没有，这时候launcher解析default_workspace.xml把这个值存到数据库中；所以说想定制什么样的开机桌面就在default_workspace.xml中做相应的配置，具体参照我前面的博客：

Android中源码Launcher主屏幕程序排列详解【安卓Launcher进化一】中有详细的介绍：

       i f (!convertDatabase(db)) {
                 // Populate favorites table with initial favorites
                loadFavorites(db, R.xml.default_workspace);
        }

      Step 1：开机后先启动LauncherApplication.java这个类的onCreate（）方法，下面看代码：  

   

[java] view plain copy print ?

1. @Override 
2. public void onCreate() { 
3.      super.onCreate(); 
4.  
5.      // set sIsScreenXLarge and sScreenDensity *before* creating icon cache 
6.      // 在创建图标缓存之前先设置sIsScreenXLarge和屏幕设备的分辨率 
7.      final int screenSize = getResources().getConfiguration().screenLayout & 
8.              Configuration.SCREENLAYOUT_SIZE_MASK; 
9.      sIsScreenLarge = screenSize == Configuration.SCREENLAYOUT_SIZE_LARGE || 
10.          screenSize == Configuration.SCREENLAYOUT_SIZE_XLARGE; 
11.      sScreenDensity = getResources().getDisplayMetrics().density; 
12.  
13.      // 实例化图标缓存区的对象 
14.      mIconCache = new IconCache(this); 
15.      // 实例化一个LauncherModel对象，这个类是保存Launcher的内存启动状态，更新Launcher的数据库的作用 
16.      mModel = new LauncherModel(this, mIconCache); 
17.  
18.      // Register intent receivers 
19.      // 注册监听，应用package增加，删除，改变的监听。 
20.      IntentFilter filter = new IntentFilter(Intent.ACTION_PACKAGE_ADDED); 
21.      filter.addAction(Intent.ACTION_PACKAGE_REMOVED); 
22.      filter.addAction(Intent.ACTION_PACKAGE_CHANGED); 
23.      filter.addDataScheme("package"); 
24.      registerReceiver(mModel, filter); 
25.      filter = new IntentFilter(); 
26.      // 注册application是否可用，语言改变，方向改变的监听。4.0支持横竖屏 
27.      filter.addAction(Intent.ACTION_EXTERNAL_APPLICATIONS_AVAILABLE); 
28.      filter.addAction(Intent.ACTION_EXTERNAL_APPLICATIONS_UNAVAILABLE); 
29.      filter.addAction(Intent.ACTION_LOCALE_CHANGED); 
30.      filter.addAction(Intent.ACTION_CONFIGURATION_CHANGED); 
31.      registerReceiver(mModel, filter); 
32.      filter = new IntentFilter(); 
33.      filter.addAction(SearchManager.INTENT_GLOBAL_SEARCH_ACTIVITY_CHANGED); 
34.      registerReceiver(mModel, filter); 
35.      filter = new IntentFilter(); 
36.      filter.addAction(SearchManager.INTENT_ACTION_SEARCHABLES_CHANGED); 
37.      registerReceiver(mModel, filter); 
38.  
39.      // Register for changes to the favorites 
40.      // 注册favorites应用程序数据库改变的监听 
41.      ContentResolver resolver = getContentResolver(); 
42.      resolver.registerContentObserver(LauncherSettings.Favorites.CONTENT_URI,true, 
43.              mFavoritesObserver); 
44. } 

   @Override    public void onCreate() {        super.onCreate();        // set sIsScreenXLarge and sScreenDensity *before* creating icon cache        // 在创建图标缓存之前先设置sIsScreenXLarge和屏幕设备的分辨率        final int screenSize = getResources().getConfiguration().screenLayout &                Configuration.SCREENLAYOUT_SIZE_MASK;        sIsScreenLarge = screenSize == Configuration.SCREENLAYOUT_SIZE_LARGE ||            screenSize == Configuration.SCREENLAYOUT_SIZE_XLARGE;        sScreenDensity = getResources().getDisplayMetrics().density;        // 实例化图标缓存区的对象        mIconCache = new IconCache(this);        // 实例化一个LauncherModel对象，这个类是保存Launcher的内存启动状态，更新Launcher的数据库的作用        mModel = new LauncherModel(this, mIconCache);        // Register intent receivers        // 注册监听，应用package增加，删除，改变的监听。        IntentFilter filter = new IntentFilter(Intent.ACTION_PACKAGE_ADDED);        filter.addAction(Intent.ACTION_PACKAGE_REMOVED);        filter.addAction(Intent.ACTION_PACKAGE_CHANGED);        filter.addDataScheme("package");        registerReceiver(mModel, filter);        filter = new IntentFilter();        // 注册application是否可用，语言改变，方向改变的监听。4.0支持横竖屏        filter.addAction(Intent.ACTION_EXTERNAL_APPLICATIONS_AVAILABLE);        filter.addAction(Intent.ACTION_EXTERNAL_APPLICATIONS_UNAVAILABLE);        filter.addAction(Intent.ACTION_LOCALE_CHANGED);        filter.addAction(Intent.ACTION_CONFIGURATION_CHANGED);        registerReceiver(mModel, filter);        filter = new IntentFilter();        filter.addAction(SearchManager.INTENT_GLOBAL_SEARCH_ACTIVITY_CHANGED);        registerReceiver(mModel, filter);        filter = new IntentFilter();        filter.addAction(SearchManager.INTENT_ACTION_SEARCHABLES_CHANGED);        registerReceiver(mModel, filter);        // Register for changes to the favorites        // 注册favorites应用程序数据库改变的监听        ContentResolver resolver = getContentResolver();        resolver.registerContentObserver(LauncherSettings.Favorites.CONTENT_URI, true,                mFavoritesObserver);    }

 

   

       Step 2：在LauncherApplication.java中onTerminate（）的方法，解除监听的绑定；

[java] view plain copy print ?

1. /**
2.     * There's no guarantee that this function is ever called.
3.     */ 
4.    @Override 
5.    public void onTerminate() { 
6.        super.onTerminate(); 
7.  
8.        unregisterReceiver(mModel); 
9.  
10.        ContentResolver resolver = getContentResolver(); 
11.        resolver.unregisterContentObserver(mFavoritesObserver); 
12.    } 

 /**     * There's no guarantee that this function is ever called.     */    @Override    public void onTerminate() {        super.onTerminate();        unregisterReceiver(mModel);        ContentResolver resolver = getContentResolver();        resolver.unregisterContentObserver(mFavoritesObserver);    }

     Step 3：Step1中的数据库mFavoritesObserver监听内部类如下：

[java] view plain copy print ?

1. /**
2.   * Receives notifications whenever the user favorites have changed.
3.   */ 
4. private final ContentObserver mFavoritesObserver =new ContentObserver(new Handler()) { 
5.      @Override 
6.      public void onChange(boolean selfChange) { 
7.          mModel.startLoader(LauncherApplication.this,false); 
8.      } 
9. }; 

   /**     * Receives notifications whenever the user favorites have changed.     */    private final ContentObserver mFavoritesObserver = new ContentObserver(new Handler()) {        @Override        public void onChange(boolean selfChange) {            mModel.startLoader(LauncherApplication.this, false);        }    };

 

      说明：mModel.startLoader（。。，。。）是开启一个线程，设置线程的优先级NORM_PRIORITY，开始load桌面图标对应的数据库，这个过程是和Launcher.onCreate()同时进行的；

   Step 4: 接着我们来看看mModel.startLoader(LauncherApplication.this, false)的方法：

[java] view plain copy print ?

1. public void startLoader(Context context,boolean isLaunching) { 
2.      synchronized (mLock) { 
3.          if (DEBUG_LOADERS) { 
4.              Log.d(TAG, "startLoader isLaunching=" + isLaunching); 
5.          } 
6.  
7.          // Don't bother to start the thread if we know it's not going to do anything 
8.          if (mCallbacks != null && mCallbacks.get() !=null) { 
9.              // If there is already one running, tell it to stop. 
10.              // also, don't downgrade isLaunching if we're already running 
11.              isLaunching = isLaunching || stopLoaderLocked(); 
12.              mLoaderTask = new LoaderTask(context, isLaunching); 
13.              sWorkerThread.setPriority(Thread.NORM_PRIORITY); 
14.              sWorker.post(mLoaderTask); 
15.          } 
16.      } 
17. } 

   public void startLoader(Context context, boolean isLaunching) {        synchronized (mLock) {            if (DEBUG_LOADERS) {                Log.d(TAG, "startLoader isLaunching=" + isLaunching);            }            // Don't bother to start the thread if we know it's not going to do anything            if (mCallbacks != null && mCallbacks.get() != null) {                // If there is already one running, tell it to stop.                // also, don't downgrade isLaunching if we're already running                isLaunching = isLaunching || stopLoaderLocked();                mLoaderTask = new LoaderTask(context, isLaunching);                sWorkerThread.setPriority(Thread.NORM_PRIORITY);                sWorker.post(mLoaderTask);            }        }    }

   Step 5：接着我们来看看LoaderTask.java的run（）方法：

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1. public void run() { 
2.     // Optimize for end-user experience: if the Launcher is up and // running with the 
3.     // All Apps interface in the foreground, load All Apps first. Otherwise, load the 
4.     // workspace first (default). 
5.     final Callbacks cbk = mCallbacks.get(); 
6.     final boolean loadWorkspaceFirst = cbk !=null ? (!cbk.isAllAppsVisible()) : true; 
7.  
8.     keep_running: { 
9.         // Elevate priority when Home launches for the first time to avoid 
10.         // starving at boot time. Staring at a blank home is not cool. 
11.         synchronized (mLock) { 
12.             if (DEBUG_LOADERS) Log.d(TAG,"Setting thread priority to " + 
13.                     (mIsLaunching ? "DEFAULT" :"BACKGROUND")); 
14.             android.os.Process.setThreadPriority(mIsLaunching 
15.                     ? Process.THREAD_PRIORITY_DEFAULT : Process.THREAD_PRIORITY_BACKGROUND); 
16.         } 
17.         if (loadWorkspaceFirst) { 
18.             if (DEBUG_LOADERS) Log.d(TAG,"step 1: loading workspace"); 
19.             loadAndBindWorkspace(); 
20.         } else { 
21.             if (DEBUG_LOADERS) Log.d(TAG,"step 1: special: loading all apps"); 
22.             loadAndBindAllApps(); 
23.         } 
24.  
25.         if (mStopped) { 
26.             break keep_running; 
27.         } 
28.  
29.         // Whew! Hard work done.  Slow us down, and wait until the UI thread has 
30.         // settled down. 
31.         synchronized (mLock) { 
32.             if (mIsLaunching) { 
33.                 if (DEBUG_LOADERS) Log.d(TAG,"Setting thread priority to BACKGROUND"); 
34.                 android.os.Process.setThreadPriority(Process.THREAD_PRIORITY_BACKGROUND); 
35.             } 
36.         } 
37.         waitForIdle(); 
38.  
39.         // second step 
40.         if (loadWorkspaceFirst) { 
41.             if (DEBUG_LOADERS) Log.d(TAG,"step 2: loading all apps"); 
42.             loadAndBindAllApps(); 
43.         } else { 
44.             if (DEBUG_LOADERS) Log.d(TAG,"step 2: special: loading workspace"); 
45.             loadAndBindWorkspace(); 
46.         } 
47.  
48.         // Restore the default thread priority after we are done loading items 
49.         synchronized (mLock) { 
50.             android.os.Process.setThreadPriority(Process.THREAD_PRIORITY_DEFAULT); 
51.         } 
52.     } 
53.  
54.  
55.     // Update the saved icons if necessary 
56.     if (DEBUG_LOADERS) Log.d(TAG, "Comparing loaded icons to database icons"); 
57.     for (Object key : sDbIconCache.keySet()) { 
58.         updateSavedIcon(mContext, (ShortcutInfo) key, sDbIconCache.get(key)); 
59.     } 
60.     sDbIconCache.clear(); 
61.  
62.     // Clear out this reference, otherwise we end up holding it until all of the 
63.     // callback runnables are done. 
64.     mContext = null; 
65.  
66.     synchronized (mLock) { 
67.         // If we are still the last one to be scheduled, remove ourselves. 
68.         if (mLoaderTask == this) { 
69.             mLoaderTask = null; 
70.         } 
71.     } 
72. } 
73.  
74. public void stopLocked() { 
75.     synchronized (LoaderTask.this) { 
76.         mStopped = true; 
77.         this.notify(); 
78.     } 
79. } 

        public void run() {            // Optimize for end-user experience: if the Launcher is up and // running with the            // All Apps interface in the foreground, load All Apps first. Otherwise, load the            // workspace first (default).            final Callbacks cbk = mCallbacks.get();            final boolean loadWorkspaceFirst = cbk != null ? (!cbk.isAllAppsVisible()) : true;            keep_running: {                // Elevate priority when Home launches for the first time to avoid                // starving at boot time. Staring at a blank home is not cool.                synchronized (mLock) {                    if (DEBUG_LOADERS) Log.d(TAG, "Setting thread priority to " +                            (mIsLaunching ? "DEFAULT" : "BACKGROUND"));                    android.os.Process.setThreadPriority(mIsLaunching                            ? Process.THREAD_PRIORITY_DEFAULT : Process.THREAD_PRIORITY_BACKGROUND);                }                if (loadWorkspaceFirst) {                    if (DEBUG_LOADERS) Log.d(TAG, "step 1: loading workspace");                    loadAndBindWorkspace();                } else {                    if (DEBUG_LOADERS) Log.d(TAG, "step 1: special: loading all apps");                    loadAndBindAllApps();                }                if (mStopped) {                    break keep_running;                }                // Whew! Hard work done.  Slow us down, and wait until the UI thread has                // settled down.                synchronized (mLock) {                    if (mIsLaunching) {                        if (DEBUG_LOADERS) Log.d(TAG, "Setting thread priority to BACKGROUND");                        android.os.Process.setThreadPriority(Process.THREAD_PRIORITY_BACKGROUND);                    }                }                waitForIdle();                // second step                if (loadWorkspaceFirst) {                    if (DEBUG_LOADERS) Log.d(TAG, "step 2: loading all apps");                    loadAndBindAllApps();                } else {                    if (DEBUG_LOADERS) Log.d(TAG, "step 2: special: loading workspace");                    loadAndBindWorkspace();                }                // Restore the default thread priority after we are done loading items                synchronized (mLock) {                    android.os.Process.setThreadPriority(Process.THREAD_PRIORITY_DEFAULT);                }            }            // Update the saved icons if necessary            if (DEBUG_LOADERS) Log.d(TAG, "Comparing loaded icons to database icons");            for (Object key : sDbIconCache.keySet()) {                updateSavedIcon(mContext, (ShortcutInfo) key, sDbIconCache.get(key));            }            sDbIconCache.clear();            // Clear out this reference, otherwise we end up holding it until all of the            // callback runnables are done.            mContext = null;            synchronized (mLock) {                // If we are still the last one to be scheduled, remove ourselves.                if (mLoaderTask == this) {                    mLoaderTask = null;                }            }        }        public void stopLocked() {            synchronized (LoaderTask.this) {                mStopped = true;                this.notify();            }        }

加载桌面图标对应的数据库的值，这些值能把这些图标显示在屏幕上。

    Step 6：LauncherApplication.onCreate()方法启动完成后，接着开始调用Launcher.java的onCreate()方法。代码如下：

[java] view plain copy print ?

1. @Override 
2. protected void onCreate(Bundle savedInstanceState) { 
3.     super.onCreate(savedInstanceState); 
4.     // 得到LauncherApplication的对象app 
5.     LauncherApplication app = ((LauncherApplication)getApplication()); 
6.     // 得到LauncherModel对象mModel,设置一个mCallbacks = new WeakReference<Callbacks>(callbacks)的 
7.     // 回调callbacks 
8.     mModel = app.setLauncher(this); 
9.     // 得到图标缓存的对象mIconCache 
10.     mIconCache = app.getIconCache(); 
11.     // 得到拖拽控制类DragController的对象 
12.     mDragController = new DragController(this); 
13.     // 得到一个LayoutInflater布局的对象 
14.     mInflater = getLayoutInflater(); 
15.  
16.     // 得到一个AppWidgetManager的对象 
17.     mAppWidgetManager = AppWidgetManager.getInstance(this); 
18.     // 得到LauncherAppWidgetHost的一个对象 
19.     mAppWidgetHost = new LauncherAppWidgetHost(this, APPWIDGET_HOST_ID); 
20.     // Start receiving onAppWidgetChanged calls for your AppWidgets. 
21.     mAppWidgetHost.startListening(); 
22.  
23.     if (PROFILE_STARTUP) { 
24.         android.os.Debug.startMethodTracing( 
25.                 Environment.getExternalStorageDirectory() +"/launcher"); 
26.     } 
27.  
28.     // 检查Locale的语言级别，mcc, mnc的改变 
29.     checkForLocaleChange(); 
30.     // 加载Launcher.xml布局文件 
31.     setContentView(R.layout.launcher); 
32.     // Launcher的布局的初始化 
33.     setupViews(); 
34.     // 第一次启动Android的展示设置向导, 
35.     // 这个SharedPreferences中存在 
36.     // <boolean name="cling.workspace.dismissed" value="true" /> 
37.     // 如果值为true，则不显示设置向导，为false，则显示设置向导。 
38.     showFirstRunWorkspaceCling(); 
39.  
40.     // 注册数据库观察者 
41.     registerContentObservers(); 
42.  
43.     lockAllApps(); 
44.  
45.     mSavedState = savedInstanceState; 
46.     restoreState(mSavedState); 
47.  
48.     // Update customization drawer _after_ restoring the states 
49.     if (mAppsCustomizeContent !=null) { 
50.         mAppsCustomizeContent.onPackagesUpdated(); 
51.     } 
52.  
53.     if (PROFILE_STARTUP) { 
54.         android.os.Debug.stopMethodTracing(); 
55.     } 
56.  
57.     if (!mRestoring) { 
58.         mModel.startLoader(this, true); 
59.     } 
60.  
61.     if (!mModel.isAllAppsLoaded()) { 
62.         ViewGroup appsCustomizeContentParent = (ViewGroup) mAppsCustomizeContent.getParent(); 
63.         mInflater.inflate(R.layout.apps_customize_progressbar, appsCustomizeContentParent); 
64.     } 
65.  
66.     // For handling default keys 
67.     mDefaultKeySsb = new SpannableStringBuilder(); 
68.     Selection.setSelection(mDefaultKeySsb, 0); 
69.  
70.     // 注册系统对话框消失的监听 
71.     IntentFilter filter = new IntentFilter(Intent.ACTION_CLOSE_SYSTEM_DIALOGS); 
72.     registerReceiver(mCloseSystemDialogsReceiver, filter); 
73.  
74.     boolean searchVisible = false; 
75.     boolean voiceVisible =false; 
76.     // If we have a saved version of these external icons, we load them up immediately 
77.     // 如果我们已经保存了外部图标的版本，我们立即加载它们 
78.     int coi = getCurrentOrientationIndexForGlobalIcons(); 
79.     if (sGlobalSearchIcon[coi] ==null || sVoiceSearchIcon[coi] == null || 
80.             sAppMarketIcon[coi] == null) { 
81.         updateAppMarketIcon(); 
82.         searchVisible = updateGlobalSearchIcon(); 
83.         voiceVisible = updateVoiceSearchIcon(searchVisible); 
84.     } 
85.     if (sGlobalSearchIcon[coi] !=null) { 
86.          updateGlobalSearchIcon(sGlobalSearchIcon[coi]); 
87.          searchVisible = true; 
88.     } 
89.     if (sVoiceSearchIcon[coi] !=null) { 
90.         updateVoiceSearchIcon(sVoiceSearchIcon[coi]); 
91.         voiceVisible = true; 
92.     } 
93.     if (sAppMarketIcon[coi] !=null) { 
94.         updateAppMarketIcon(sAppMarketIcon[coi]); 
95.     } 
96.     mSearchDropTargetBar.onSearchPackagesChanged(searchVisible, voiceVisible); 
97.  
98.     // On large interfaces, we want the screen to auto-rotate based on the current orientation 
99.     if (LauncherApplication.isScreenLarge() || Build.TYPE.contentEquals("eng")) { 
100.         setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_UNSPECIFIED); 
101.     } 
102. } 

    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        // 得到LauncherApplication的对象app        LauncherApplication app = ((LauncherApplication)getApplication());        // 得到LauncherModel对象mModel,设置一个mCallbacks = new WeakReference<Callbacks>(callbacks)的        // 回调callbacks        mModel = app.setLauncher(this);        // 得到图标缓存的对象mIconCache        mIconCache = app.getIconCache();        // 得到拖拽控制类DragController的对象        mDragController = new DragController(this);        // 得到一个LayoutInflater布局的对象        mInflater = getLayoutInflater();        // 得到一个AppWidgetManager的对象        mAppWidgetManager = AppWidgetManager.getInstance(this);        // 得到LauncherAppWidgetHost的一个对象        mAppWidgetHost = new LauncherAppWidgetHost(this, APPWIDGET_HOST_ID);        // Start receiving onAppWidgetChanged calls for your AppWidgets.        mAppWidgetHost.startListening();        if (PROFILE_STARTUP) {            android.os.Debug.startMethodTracing(                    Environment.getExternalStorageDirectory() + "/launcher");        }        // 检查Locale的语言级别，mcc, mnc的改变        checkForLocaleChange();        // 加载Launcher.xml布局文件        setContentView(R.layout.launcher);        // Launcher的布局的初始化        setupViews();        // 第一次启动Android的展示设置向导,        // 这个SharedPreferences中存在        // <boolean name="cling.workspace.dismissed" value="true" />        // 如果值为true，则不显示设置向导，为false，则显示设置向导。        showFirstRunWorkspaceCling();        // 注册数据库观察者        registerContentObservers();        lockAllApps();        mSavedState = savedInstanceState;        restoreState(mSavedState);        // Update customization drawer _after_ restoring the states        if (mAppsCustomizeContent != null) {            mAppsCustomizeContent.onPackagesUpdated();        }        if (PROFILE_STARTUP) {            android.os.Debug.stopMethodTracing();        }        if (!mRestoring) {            mModel.startLoader(this, true);        }        if (!mModel.isAllAppsLoaded()) {            ViewGroup appsCustomizeContentParent = (ViewGroup) mAppsCustomizeContent.getParent();            mInflater.inflate(R.layout.apps_customize_progressbar, appsCustomizeContentParent);        }        // For handling default keys        mDefaultKeySsb = new SpannableStringBuilder();        Selection.setSelection(mDefaultKeySsb, 0);        // 注册系统对话框消失的监听        IntentFilter filter = new IntentFilter(Intent.ACTION_CLOSE_SYSTEM_DIALOGS);        registerReceiver(mCloseSystemDialogsReceiver, filter);        boolean searchVisible = false;        boolean voiceVisible = false;        // If we have a saved version of these external icons, we load them up immediately        // 如果我们已经保存了外部图标的版本，我们立即加载它们        int coi = getCurrentOrientationIndexForGlobalIcons();        if (sGlobalSearchIcon[coi] == null || sVoiceSearchIcon[coi] == null ||                sAppMarketIcon[coi] == null) {            updateAppMarketIcon();            searchVisible = updateGlobalSearchIcon();            voiceVisible = updateVoiceSearchIcon(searchVisible);        }        if (sGlobalSearchIcon[coi] != null) {             updateGlobalSearchIcon(sGlobalSearchIcon[coi]);             searchVisible = true;        }        if (sVoiceSearchIcon[coi] != null) {            updateVoiceSearchIcon(sVoiceSearchIcon[coi]);            voiceVisible = true;        }        if (sAppMarketIcon[coi] != null) {            updateAppMarketIcon(sAppMarketIcon[coi]);        }        mSearchDropTargetBar.onSearchPackagesChanged(searchVisible, voiceVisible);        // On large interfaces, we want the screen to auto-rotate based on the current orientation        if (LauncherApplication.isScreenLarge() || Build.TYPE.contentEquals("eng")) {            setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_UNSPECIFIED);        }    }

    Step 7：其中LauncherModel这个类中有个回调接口，具体定义如下：

[java] view plain copy print ?

1. public interface Callbacks { 
2.        public boolean setLoadOnResume(); 
3.        public int getCurrentWorkspaceScreen(); 
4.        public void startBinding(); 
5.        public void bindItems(ArrayList<ItemInfo> shortcuts,int start, int end); 
6.        public void bindFolders(HashMap<Long,FolderInfo> folders); 
7.        public void finishBindingItems(); 
8.        public void bindAppWidget(LauncherAppWidgetInfo info); 
9.        public void bindAllApplications(ArrayList<ApplicationInfo> apps); 
10.        public void bindAppsAdded(ArrayList<ApplicationInfo> apps); 
11.        public void bindAppsUpdated(ArrayList<ApplicationInfo> apps); 
12.        public void bindAppsRemoved(ArrayList<ApplicationInfo> apps,boolean permanent); 
13.        public void bindPackagesUpdated(); 
14.        public boolean isAllAppsVisible(); 
15.        public void bindSearchablesChanged(); 
16.    } 

 public interface Callbacks {        public boolean setLoadOnResume();        public int getCurrentWorkspaceScreen();        public void startBinding();        public void bindItems(ArrayList<ItemInfo> shortcuts, int start, int end);        public void bindFolders(HashMap<Long,FolderInfo> folders);        public void finishBindingItems();        public void bindAppWidget(LauncherAppWidgetInfo info);        public void bindAllApplications(ArrayList<ApplicationInfo> apps);        public void bindAppsAdded(ArrayList<ApplicationInfo> apps);        public void bindAppsUpdated(ArrayList<ApplicationInfo> apps);        public void bindAppsRemoved(ArrayList<ApplicationInfo> apps, boolean permanent);        public void bindPackagesUpdated();        public boolean isAllAppsVisible();        public void bindSearchablesChanged();    }

 

对LauncherModel进行初始化的时候 mModel = app.setLauncher(this);---->mModel.initialize(launcher);----->

              public void initialize(Callbacks callbacks) {
                      synchronized (mLock) {
                              mCallbacks = new WeakReference<Callbacks>(callbacks);
                       }
               }

这个callbacks就是定义的接口回调，具体实现是在Launcher.java中定义的，启动Launcher的过程中，这些实现是异步来实现的。还有Launcher.java的onResume（）方法没有讲解，到这儿基本上Android的Launcher已经启动起来了，这个onResume（）我研究后再更新。

AndroidICS4.0版本的launcher拖拽的流程，基本和2.3的相似。就是比2.3写的封装的接口多了一些，比如删除类的写法就多了个类。等等。4.0的改变有一些，但是不是特别大。这个月一直在改动Launcher的缩略图的效果，4.0的缩略图的功能没有实现，还得从2.3的Launcher中摘出来。通过做这个缩略图对Launcher的模块有一点点了解，拿来分享一下Launcher拖拽的工作流程。有图有真相！

转载请标明出处：http://blog.youkuaiyun.com/wdaming1986/article/details/7671318

                （1）先来看看类之间的继承关系

                          

                                                         图（1）

                                                                                                                                               

              （2）再来看看Launcher拖拽流程的时序图

              

                                                                      图（2）

下面咱们分步来解析Launcher拖拽的详细过程：

step 1 ：先来看看Launcher.java这个类的onCreate（）方法中的setupViews（）方法中的一部分代码：

[java] view plain copy print ?

1. <strong> </strong><span style="color: rgb(0, 0, 0); font-size: 16px;">// Setup the workspace 
2.         mWorkspace.setHapticFeedbackEnabled(false); 
3.         mWorkspace.setOnLongClickListener(this); 
4.         mWorkspace.setup(dragController); 
5.         dragController.addDragListener(mWorkspace);</span> 

 // Setup the workspace        mWorkspace.setHapticFeedbackEnabled(false);        mWorkspace.setOnLongClickListener(this);        mWorkspace.setup(dragController);        dragController.addDragListener(mWorkspace);

Workspace设置长按事件的监听交给了Launcher.java这个类了。所以在主屏上长按事件会走到Launcher.java----->

onLongClick()这个方法中去；

step 2 ：接着我们来看看Launcher.java中onLongClick()的代码：

 

[java] view plain copy print ?

1. public boolean onLongClick(View v) { 
2.          ·············· 
3. // The hotseat touch handling does not go through Workspace, and we always allow long press 
4.         // on hotseat items. 
5.         final View itemUnderLongClick = longClickCellInfo.cell; 
6.         boolean allowLongPress = isHotseatLayout(v) || mWorkspace.allowLongPress(); 
7.         if (allowLongPress && !mDragController.isDragging()) { 
8.             if (itemUnderLongClick ==null) { 
9.                 // User long pressed on empty space 
10.                 mWorkspace.performHapticFeedback(HapticFeedbackConstants.LONG_PRESS, 
11.                         HapticFeedbackConstants.FLAG_IGNORE_VIEW_SETTING); 
12.                 startWallpaper(); 
13.             } else { 
14.                 if (!(itemUnderLongClickinstanceof Folder)) { 
15.                     // User long pressed on an item 
16.                     mWorkspace.startDrag(longClickCellInfo); 
17.                 } 
18.             } 
19.         } 
20.         return true; 
21.     } 

public boolean onLongClick(View v) {         ·············· // The hotseat touch handling does not go through Workspace, and we always allow long press        // on hotseat items.        final View itemUnderLongClick = longClickCellInfo.cell;        boolean allowLongPress = isHotseatLayout(v) || mWorkspace.allowLongPress();        if (allowLongPress && !mDragController.isDragging()) {            if (itemUnderLongClick == null) {                // User long pressed on empty space                mWorkspace.performHapticFeedback(HapticFeedbackConstants.LONG_PRESS,                        HapticFeedbackConstants.FLAG_IGNORE_VIEW_SETTING);                startWallpaper();            } else {                if (!(itemUnderLongClick instanceof Folder)) {                    // User long pressed on an item                    mWorkspace.startDrag(longClickCellInfo);                }            }        }        return true;    }

通过itemUnderLongClick == null 来判断，在屏幕上触发长按事件是否选中了shortcut或者widget。如果为空，就启动桌面的壁纸，else，就把拖拽事件往Workspace.java这个类传递。

Step 3 ：通过mWorkspace.startDrag(longClickCellInfo)，把长按事件传递给workspace来处理，具体来看代码：

[java] view plain copy print ?

1. void startDrag(CellLayout.CellInfo cellInfo) { 
2.      View child = cellInfo.cell; 
3.  
4.      // Make sure the drag was started by a long press as opposed to a long click. 
5.      if (!child.isInTouchMode()) { 
6.          return; 
7.      } 
8.  
9.      mDragInfo = cellInfo; 
10.      //隐藏拖拽的child 
11.      child.setVisibility(GONE); 
12.  
13.      child.clearFocus(); 
14.      child.setPressed(false); 
15.  
16.      final Canvas canvas = new Canvas(); 
17.  
18.      // We need to add extra padding to the bitmap to make room for the glow effect 
19.      final int bitmapPadding = HolographicOutlineHelper.MAX_OUTER_BLUR_RADIUS; 
20.  
21.      // The outline is used to visualize where the item will land if dropped 
22.      mDragOutline = createDragOutline(child, canvas, bitmapPadding); 
23.      beginDragShared(child, this); 
24. } 

   void startDrag(CellLayout.CellInfo cellInfo) {        View child = cellInfo.cell;        // Make sure the drag was started by a long press as opposed to a long click.        if (!child.isInTouchMode()) {            return;        }        mDragInfo = cellInfo;        //隐藏拖拽的child        child.setVisibility(GONE);        child.clearFocus();        child.setPressed(false);        final Canvas canvas = new Canvas();        // We need to add extra padding to the bitmap to make room for the glow effect        final int bitmapPadding = HolographicOutlineHelper.MAX_OUTER_BLUR_RADIUS;        // The outline is used to visualize where the item will land if dropped        mDragOutline = createDragOutline(child, canvas, bitmapPadding);        beginDragShared(child, this);    }

上面的代码主要做的工作是：把正在拖拽的这个view隐藏掉，在主屏幕上绘制一个蓝色的，大小和图标相似的一个边框，以表示能在主屏的这个位置放置。

Step 4 ：接着调用beginDragShared(child, this)这个方法，代码如下：

[java] view plain copy print ?

1. public void beginDragShared(View child, DragSource source) { 
2.     ··· ··· 
3. // Clear the pressed state if necessary 
4.         if (child instanceof BubbleTextView) { 
5.             BubbleTextView icon = (BubbleTextView) child; 
6.             icon.clearPressedOrFocusedBackground(); 
7.         } 
8.  
9.         mDragController.startDrag(b, dragLayerX, dragLayerY, source, child.getTag(), 
10.                 DragController.DRAG_ACTION_MOVE, dragVisualizeOffset, dragRect); 
11.         b.recycle(); 
12.     } 

 public void beginDragShared(View child, DragSource source) {    ··· ···// Clear the pressed state if necessary        if (child instanceof BubbleTextView) {            BubbleTextView icon = (BubbleTextView) child;            icon.clearPressedOrFocusedBackground();        }        mDragController.startDrag(b, dragLayerX, dragLayerY, source, child.getTag(),                DragController.DRAG_ACTION_MOVE, dragVisualizeOffset, dragRect);        b.recycle();    }

这个方法做的工作是：开始进行拖拽，绘制正在拖拽的图片，把拖拽的事件交给DragController来处理。

Step 5 ：接着来看看mDragController.startDrag(b, dragLayerX, dragLayerY, source, child.getTag(), DragController.DRAG_ACTION_MOVE, dragVisualizeOffset, dragRect)这个方法，代码如下：

[java] view plain copy print ?

1. public void startDrag(Bitmap b, int dragLayerX,int dragLayerY, 
2.             DragSource source, Object dragInfo, int dragAction, Point dragOffset, Rect dragRegion) { 
3. ··· ··· 
4. mDragObject.dragComplete = false; 
5.         mDragObject.xOffset = mMotionDownX - (dragLayerX + dragRegionLeft); 
6.         mDragObject.yOffset = mMotionDownY - (dragLayerY + dragRegionTop); 
7.         mDragObject.dragSource = source; 
8.         mDragObject.dragInfo = dragInfo; 
9. mVibrator.vibrate(VIBRATE_DURATION); 
10.  
11.         final DragView dragView = mDragObject.dragView =new DragView(mLauncher, b, registrationX, 
12.                 registrationY, 0, 0, b.getWidth(), b.getHeight()); 
13.  
14.         if (dragOffset != null) { 
15.             dragView.setDragVisualizeOffset(new Point(dragOffset)); 
16.         } 
17.         if (dragRegion !=null) { 
18.             dragView.setDragRegion(new Rect(dragRegion)); 
19.         } 
20.  
21.         dragView.show(mMotionDownX, mMotionDownY); 
22.         handleMoveEvent(mMotionDownX, mMotionDownY); 
23.     } 

 public void startDrag(Bitmap b, int dragLayerX, int dragLayerY,            DragSource source, Object dragInfo, int dragAction, Point dragOffset, Rect dragRegion) {··· ··· mDragObject.dragComplete = false;        mDragObject.xOffset = mMotionDownX - (dragLayerX + dragRegionLeft);        mDragObject.yOffset = mMotionDownY - (dragLayerY + dragRegionTop);        mDragObject.dragSource = source;        mDragObject.dragInfo = dragInfo;mVibrator.vibrate(VIBRATE_DURATION);        final DragView dragView = mDragObject.dragView = new DragView(mLauncher, b, registrationX,                registrationY, 0, 0, b.getWidth(), b.getHeight());        if (dragOffset != null) {            dragView.setDragVisualizeOffset(new Point(dragOffset));        }        if (dragRegion != null) {            dragView.setDragRegion(new Rect(dragRegion));        }        dragView.show(mMotionDownX, mMotionDownY);        handleMoveEvent(mMotionDownX, mMotionDownY);    }

这个方法的作用是：计算要拖拽的view的大小，显示在workspace上，dragView.show(mMotionDownX, mMotionDownY);这个show（）会根据手指的移动而移动的。然后在通过handleMoveEvent（）方法来分发拖拽的目标到底在哪个目标上。DropTarget一共有3个：workspace，ButtonDropTarget（删除类），Folder；他们分别实现了DropTarget这个接口。

下面来看看这个接口有一下几个方法：

 

[java] view plain copy print ?

1. boolean isDropEnabled(); 
2. void onDrop(DragObject dragObject); 
3.  
4.     void onDragEnter(DragObject dragObject); 
5.  
6.     void onDragOver(DragObject dragObject); 
7.  
8.     void onDragExit(DragObject dragObject); 
9. DropTarget getDropTargetDelegate(DragObject dragObject); 
10. boolean acceptDrop(DragObject dragObject); 
11.  
12.     // These methods are implemented in Views 
13.     void getHitRect(Rect outRect); 
14.     void getLocationInDragLayer(int[] loc); 
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