launcher widget 添加过程分析2

 

上篇讲到了Launcher中自定义了两个类：

LauncherAppWidgetHostView: 扩展了AppWidgetHostView，实现了对长按事件的处理

LauncherAppWidgetHost: 扩展了AppWidgetHost，这里只是重载了onCreateView，创建LauncherAppWidgetHostView的实例

24 /**

25  * Specific {@link AppWidgetHost} that creates our {@link LauncherAppWidgetHostView}

26  * which correctly captures all long-press events. This ensures that users can

27  * always pick up and move widgets.

28  */

29 public class LauncherAppWidgetHost extends AppWidgetHost {

30     public LauncherAppWidgetHost(Context context, int hostId) {

31         super(context, hostId);

32     }

33     

34     @Override

35     protected AppWidgetHostView onCreateView(Context context, int appWidgetId,

36             AppWidgetProviderInfo appWidget) {

37         return new LauncherAppWidgetHostView(context);

38     }

39 }

 

首先在Launcher.java中定义了如下两个变量

174     private AppWidgetManager mAppWidgetManager;

175     private LauncherAppWidgetHost mAppWidgetHost;

在onCreate函数中初始化，

224         mAppWidgetManager = AppWidgetManager.getInstance(this);

225         mAppWidgetHost = new LauncherAppWidgetHost(this, APPWIDGET_HOST_ID);

226         mAppWidgetHost.startListening();

上述代码，获取mAppWidgetManager的实例，并创建LauncherAppWidgetHost，以及监听

 

AppWidgetManager只是应用程序与底层Service之间的一个桥梁，是Android中标准的aidl实现方式

应用程序通过AppWidgetManager调用Service中的方法

frameworks/base / core / java / android / appwidget / AppWidgetManager.java

35 /**

36  * Updates AppWidget state; gets information about installed AppWidget providers and other

37  * AppWidget related state.

38  */

39 public class AppWidgetManager {

197    static WeakHashMap<Context, WeakReference<AppWidgetManager>> sManagerCache = new WeakHashMap();

198     static IAppWidgetService sService;

 

204     /**

205      * Get the AppWidgetManager instance to use for the supplied {@link android.content.Context

206      * Context} object.

207      */

208     public static AppWidgetManager getInstance(Context context) {

209         synchronized (sManagerCache) {

210             if (sService == null) {

211                 IBinder b = ServiceManager.getService(Context.APPWIDGET_SERVICE);

212                 sService = IAppWidgetService.Stub.asInterface(b);

213             }

214

215             WeakReference<AppWidgetManager> ref = sManagerCache.get(context);

216             AppWidgetManager result = null;

217             if (ref != null) {

218                 result = ref.get();

219             }

220             if (result == null) {

221                 result = new AppWidgetManager(context);

222                 sManagerCache.put(context, new WeakReference(result));

223             }

224             return result;

225         }

226     }

227

228     private AppWidgetManager(Context context) {

229         mContext = context;

230         mDisplayMetrics = context.getResources().getDisplayMetrics();

231     }

以上代码是设计模式中标准的单例模式

 

frameworks/base/ core / java / android / appwidget / AppWidgetHost.java

90     public AppWidgetHost(Context context, int hostId) {

91         mContext = context;

92         mHostId = hostId;

93         mHandler = new UpdateHandler(context.getMainLooper());

94         synchronized (sServiceLock) {

95             if (sService == null) {

96                 IBinder b = ServiceManager.getService(Context.APPWIDGET_SERVICE);

97                 sService = IAppWidgetService.Stub.asInterface(b);

98             }

99         }

100     }

可以看到AppWidgetHost有自己的HostId，Handler，和sService

93         mHandler = new UpdateHandler(context.getMainLooper());

这是啥用法呢？

参数为Looper，即消息处理放到此Looper的MessageQueue中，有哪些消息呢？

40     static final int HANDLE_UPDATE = 1;

41     static final int HANDLE_PROVIDER_CHANGED = 2;

 

48

49     class Callbacks extends IAppWidgetHost.Stub {

50         public void updateAppWidget(int appWidgetId, RemoteViews views) {

51             Message msg = mHandler.obtainMessage(HANDLE_UPDATE);

52             msg.arg1 = appWidgetId;

53             msg.obj = views;

54             msg.sendToTarget();

55         }

56

57         public void providerChanged(int appWidgetId, AppWidgetProviderInfo info) {

58             Message msg = mHandler.obtainMessage(HANDLE_PROVIDER_CHANGED);

59             msg.arg1 = appWidgetId;

60             msg.obj = info;

61             msg.sendToTarget();

62         }

63     }

64

65     class UpdateHandler extends Handler {

66         public UpdateHandler(Looper looper) {

67             super(looper);

68         }

69         

70         public void handleMessage(Message msg) {

71             switch (msg.what) {

72                 case HANDLE_UPDATE: {

73                     updateAppWidgetView(msg.arg1, (RemoteViews)msg.obj);

74                     break;

75                 }

76                 case HANDLE_PROVIDER_CHANGED: {

77                     onProviderChanged(msg.arg1, (AppWidgetProviderInfo)msg.obj);

78                     break;

79                 }

80             }

81         }

82     }

通过以上可以看到主要有两中类型的消息，HANDLE_UPDATE和HANDLE_PROVIDER_CHANGED

处理即通过自身定义的方法

231     /**

232      * Called when the AppWidget provider for a AppWidget has been upgraded to a new apk.

233      */

234     protected void onProviderChanged(int appWidgetId, AppWidgetProviderInfo appWidget) {

235         AppWidgetHostView v;

236         synchronized (mViews) {

237             v = mViews.get(appWidgetId);

238         }

239         if (v != null) {

240             v.updateAppWidget(null, AppWidgetHostView.UPDATE_FLAGS_RESET);

241         }

242     }

243

244     void updateAppWidgetView(int appWidgetId, RemoteViews views) {

245         AppWidgetHostView v;

246         synchronized (mViews) {

247             v = mViews.get(appWidgetId);

248         }

249         if (v != null) {

250             v.updateAppWidget(views, 0);

251         }

252     }

 

那么此消息是何时由谁发送的呢？

从以上的代码中看到AppWidgetHost定义了内部类Callback，扩展了类IAppWidgetHost.Stub，类Callback中负责发送以上消息

Launcher中会调用本类中的如下方法，

102     /**

103      * Start receiving onAppWidgetChanged calls for your AppWidgets.  Call this when your activity

104      * becomes visible, i.e. from onStart() in your Activity.

105      */

106     public void startListening() {

107         int[] updatedIds;

108         ArrayList<RemoteViews> updatedViews = new ArrayList<RemoteViews>();

109         

110         try {

111             if (mPackageName == null) {

112                 mPackageName = mContext.getPackageName();

113             }

114             updatedIds = sService.startListening(mCallbacks, mPackageName, mHostId, updatedViews);

115         }

116         catch (RemoteException e) {

117             throw new RuntimeException("system server dead?", e);

118         }

119

120         final int N = updatedIds.length;

121         for (int i=0; i<N; i++) {

122             updateAppWidgetView(updatedIds[i], updatedViews.get(i));

123         }

124     }

最终调用AppWidgetService中的方法startListening方法，并把mCallbacks传过去，由Service负责发送消息

 

Launcher中添加Widget

在Launcher中添加widget，有两种途径，通过Menu或者长按桌面的空白区域，都会弹出Dialog，让用户选择添加

如下代码是当用户选择

1999         /**

2000          * Handle the action clicked in the "Add to home" dialog.

2001          */

2002         public void onClick(DialogInterface dialog, int which) {

2003             Resources res = getResources();

2004             cleanup();

2005

2006             switch (which) {

2007                 case AddAdapter.ITEM_SHORTCUT: {

2008                     // Insert extra item to handle picking application

2009                     pickShortcut();

2010                     break;

2011                 }

2012

2013                 case AddAdapter.ITEM_APPWIDGET: {

2014                     int appWidgetId = Launcher.this.mAppWidgetHost.allocateAppWidgetId();

2015

2016                     Intent pickIntent = new Intent(AppWidgetManager.ACTION_APPWIDGET_PICK);

2017                     pickIntent.putExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, appWidgetId);

2018                     // start the pick activity

2019                     startActivityForResult(pickIntent, REQUEST_PICK_APPWIDGET);

2020                     break;

2021                 }

当用户在Dialog中选择AddAdapter.ITEM_APPWIDGET时，首先会通过AppWidgethost分配一个appWidgetId，并最终调到AppWidgetService中去

同时发送Intent，其中保存有刚刚分配的appWidgetId，AppWidgetManager.EXTRA_APPWIDGET_ID

139     /**

140      * Get a appWidgetId for a host in the calling process.

141      *

142      * @return a appWidgetId

143      */

144     public int allocateAppWidgetId() {

145         try {

146             if (mPackageName == null) {

147                 mPackageName = mContext.getPackageName();

148             }

149             return sService.allocateAppWidgetId(mPackageName, mHostId);

150         }

151         catch (RemoteException e) {

152             throw new RuntimeException("system server dead?", e);

153         }

154     }

 

2016                     Intent pickIntent = new Intent(AppWidgetManager.ACTION_APPWIDGET_PICK);

2017                     pickIntent.putExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, appWidgetId);

2018                     // start the pick activity

2019                     startActivityForResult(pickIntent, REQUEST_PICK_APPWIDGET);

这段代码之后，代码将会怎么执行呢，根据Log信息，可以看到代码将会执行到Setting应用中

packages/apps/Settings/ src / com / android / settings / AppWidgetPickActivity.java

此类将会通过AppWidgetService获取到当前系统已经安装的Widget，并显示出来

78     /**

79      * Create list entries for any custom widgets requested through

80      * {@link AppWidgetManager#EXTRA_CUSTOM_INFO}.

81      */

82     void putCustomAppWidgets(List<PickAdapter.Item> items) {

83         final Bundle extras = getIntent().getExtras();

84         

85         // get and validate the extras they gave us

86         ArrayList<AppWidgetProviderInfo> customInfo = null;

87         ArrayList<Bundle> customExtras = null;

88         try_custom_items: {

89             customInfo = extras.getParcelableArrayList(AppWidgetManager.EXTRA_CUSTOM_INFO);

90             if (customInfo == null || customInfo.size() == 0) {

91                 Log.i(TAG, "EXTRA_CUSTOM_INFO not present.");

92                 break try_custom_items;

93             }

94

95             int customInfoSize = customInfo.size();

96             for (int i=0; i<customInfoSize; i++) {

97                 Parcelable p = customInfo.get(i);

98                 if (p == null || !(p instanceof AppWidgetProviderInfo)) {

99                     customInfo = null;

100                     Log.e(TAG, "error using EXTRA_CUSTOM_INFO index=" + i);

101                     break try_custom_items;

102                 }

103             }

104

105             customExtras = extras.getParcelableArrayList(AppWidgetManager.EXTRA_CUSTOM_EXTRAS);

106             if (customExtras == null) {

107                 customInfo = null;

108                 Log.e(TAG, "EXTRA_CUSTOM_INFO without EXTRA_CUSTOM_EXTRAS");

109                 break try_custom_items;

110             }

111

112             int customExtrasSize = customExtras.size();

113             if (customInfoSize != customExtrasSize) {

114                 Log.e(TAG, "list size mismatch: EXTRA_CUSTOM_INFO: " + customInfoSize

115                         + " EXTRA_CUSTOM_EXTRAS: " + customExtrasSize);

116                 break try_custom_items;

117             }

118

119

120             for (int i=0; i<customExtrasSize; i++) {

121                 Parcelable p = customExtras.get(i);

122                 if (p == null || !(p instanceof Bundle)) {

123                     customInfo = null;

124                     customExtras = null;

125                     Log.e(TAG, "error using EXTRA_CUSTOM_EXTRAS index=" + i);

126                     break try_custom_items;

127                 }

128             }

129         }

130

131         if (LOGD) Log.d(TAG, "Using " + customInfo.size() + " custom items");

132         putAppWidgetItems(customInfo, customExtras, items);

133     }

从上述代码中可以看到，可以放置用户自己定义的伪Widget

关于伪widget，个人有如下想法：

早期Android版本中的Google Search Bar就属于伪Widget，其实就是把widget做到Launcher中，但是用户体验与真widget并没有区别，个人猜想HTC的sense就是这样实现的。

优点：是不需要进程间的通信，效率将会更高，并且也可以规避点Widget开发的种种限制

缺点：导致Launcher代码庞大，不易于维护

 

用户选择完之后，代码如下

135     /**

136      * {@inheritDoc}

137      */

138     @Override

139     public void onClick(DialogInterface dialog, int which) {

140         Intent intent = getIntentForPosition(which);

141         

142         int result;

143         if (intent.getExtras() != null) {

144             // If there are any extras, it's because this entry is custom.

145             // Don't try to bind it, just pass it back to the app.

146             setResultData(RESULT_OK, intent);

147         } else {

148             try {

149                 mAppWidgetManager.bindAppWidgetId(mAppWidgetId, intent.getComponent());

150                 result = RESULT_OK;

151             } catch (IllegalArgumentException e) {

152                 // This is thrown if they're already bound, or otherwise somehow

153                 // bogus.  Set the result to canceled, and exit.  The app *should*

154                 // clean up at this point.  We could pass the error along, but

155                 // it's not clear that that's useful -- the widget will simply not

156                 // appear.

157                 result = RESULT_CANCELED;

158             }

159             setResultData(result, null);

160         }

161         finish();

162     }

 

将会149                 mAppWidgetManager.bindAppWidgetId(mAppWidgetId, intent.getComponent());

如果此次添加的Widget是intent.getComponent()的第一个实例，将会发送如下广播

171     /**

172      * Sent when an instance of an AppWidget is added to a host for the first time.

173      * This broadcast is sent at boot time if there is a AppWidgetHost installed with

174      * an instance for this provider.

175      * 

176      * @see AppWidgetProvider#onEnabled AppWidgetProvider.onEnabled(Context context)

177      */

178    public static final String ACTION_APPWIDGET_ENABLED = "android.appwidget.action.APPWIDGET_ENABLED";

紧接着会发送UPDATE广播

135     /**

136      * Sent when it is time to update your AppWidget.

137      *

138      * <p>This may be sent in response to a new instance for this AppWidget provider having

139      * been instantiated, the requested {@link AppWidgetProviderInfo#updatePeriodMillis update interval}

140      * having lapsed, or the system booting.

141      *

142      * <p>

143      * The intent will contain the following extras:

144      * <table>

145      *   <tr>

146      *     <td>{@link #EXTRA_APPWIDGET_IDS}</td>

147      *     <td>The appWidgetIds to update.  This may be all of the AppWidgets created for this

148      *     provider, or just a subset.  The system tries to send updates for as few AppWidget

149      *     instances as possible.</td>

150      *  </tr>

151      * </table>

152      * 

153     * @see AppWidgetProvider#onUpdate AppWidgetProvider.onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds)

154      */

155    public static final String ACTION_APPWIDGET_UPDATE = "android.appwidget.action.APPWIDGET_UPDATE";

 待用户选择完要添加的widget之后，将会回到Launcher.java中的函数onActivityResult中

538                 case REQUEST_PICK_APPWIDGET:

539                     addAppWidget(data);

540                     break;

上述addAppWidget中做了哪些事情呢？

1174     void addAppWidget(Intent data) {

1175         // TODO: catch bad widget exception when sent

1176         int appWidgetId = data.getIntExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, -1);

1177         AppWidgetProviderInfo appWidget = mAppWidgetManager.getAppWidgetInfo(appWidgetId);

1178

1179         if (appWidget.configure != null) {

1180             // Launch over to configure widget, if needed

1181             Intent intent = new Intent(AppWidgetManager.ACTION_APPWIDGET_CONFIGURE);

1182             intent.setComponent(appWidget.configure);

1183             intent.putExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, appWidgetId);

1184

1185             startActivityForResultSafely(intent, REQUEST_CREATE_APPWIDGET);

1186         } else {

1187             // Otherwise just add it

1188             onActivityResult(REQUEST_CREATE_APPWIDGET, Activity.RESULT_OK, data);

1189         }

1190     }

首先获取appWidgetId，再通过AppWidgetManager获取AppWidgetProviderInfo，最后判断此Widget是否存在ConfigActivity，如果存在则启动ConfigActivity，否则直接调用函数onActivityResult

541                 case REQUEST_CREATE_APPWIDGET:

542                     completeAddAppWidget(data, mAddItemCellInfo);

543                     break;

通过函数completeAddAppWidget把此widget的信息插入到数据库中，并添加到桌面上

873     /**

874      * Add a widget to the workspace.

875      *

876      * @param data The intent describing the appWidgetId.

877      * @param cellInfo The position on screen where to create the widget.

878      */

879     private void completeAddAppWidget(Intent data, CellLayout.CellInfo cellInfo) {

880         Bundle extras = data.getExtras();

881         int appWidgetId = extras.getInt(AppWidgetManager.EXTRA_APPWIDGET_ID, -1);

882

883         if (LOGD) Log.d(TAG, "dumping extras content=" + extras.toString());

884

885         AppWidgetProviderInfo appWidgetInfo = mAppWidgetManager.getAppWidgetInfo(appWidgetId);

886

887         // Calculate the grid spans needed to fit this widget

888         CellLayout layout = (CellLayout) mWorkspace.getChildAt(cellInfo.screen);

889         int[] spans = layout.rectToCell(appWidgetInfo.minWidth, appWidgetInfo.minHeight);

890

891         // Try finding open space on Launcher screen

892         final int[] xy = mCellCoordinates;

893         if (!findSlot(cellInfo, xy, spans[0], spans[1])) {

894             if (appWidgetId != -1) mAppWidgetHost.deleteAppWidgetId(appWidgetId);

895             return;

896         }

897

898         // Build Launcher-specific widget info and save to database

899         LauncherAppWidgetInfo launcherInfo = new LauncherAppWidgetInfo(appWidgetId);

900         launcherInfo.spanX = spans[0];

901         launcherInfo.spanY = spans[1];

902

903         LauncherModel.addItemToDatabase(this, launcherInfo,

904                 LauncherSettings.Favorites.CONTAINER_DESKTOP,

905                 mWorkspace.getCurrentScreen(), xy[0], xy[1], false);

906

907         if (!mRestoring) {

908             mDesktopItems.add(launcherInfo);

909

910             // Perform actual inflation because we're live

911             launcherInfo.hostView = mAppWidgetHost.createView(this, appWidgetId, appWidgetInfo);

912

913             launcherInfo.hostView.setAppWidget(appWidgetId, appWidgetInfo);

914             launcherInfo.hostView.setTag(launcherInfo);

915

916             mWorkspace.addInCurrentScreen(launcherInfo.hostView, xy[0], xy[1],

917                     launcherInfo.spanX, launcherInfo.spanY, isWorkspaceLocked());

918         }

919     }

 

Launcher中删除widget

 长按一个widget，并拖入到DeleteZone中可实现删除

具体代码在DeleteZone中

92     public void onDrop(DragSource source, int x, int y, int xOffset, int yOffset,

93             DragView dragView, Object dragInfo) {

94         final ItemInfo item = (ItemInfo) dragInfo;

95

96         if (item.container == -1) return;

97

98         if (item.container == LauncherSettings.Favorites.CONTAINER_DESKTOP) {

99             if (item instanceof LauncherAppWidgetInfo) {

100                 mLauncher.removeAppWidget((LauncherAppWidgetInfo) item);

101             }

102         } else {

103             if (source instanceof UserFolder) {

104                 final UserFolder userFolder = (UserFolder) source;

105                 final UserFolderInfo userFolderInfo = (UserFolderInfo) userFolder.getInfo();

106                 // Item must be a ShortcutInfo otherwise it couldn't have been in the folder

107                 // in the first place.

108                 userFolderInfo.remove((ShortcutInfo)item);

109             }

110         }

111         if (item instanceof UserFolderInfo) {

112             final UserFolderInfo userFolderInfo = (UserFolderInfo)item;

113             LauncherModel.deleteUserFolderContentsFromDatabase(mLauncher, userFolderInfo);

114             mLauncher.removeFolder(userFolderInfo);

115         } else if (item instanceof LauncherAppWidgetInfo) {

116             final LauncherAppWidgetInfo launcherAppWidgetInfo = (LauncherAppWidgetInfo) item;

117             final LauncherAppWidgetHost appWidgetHost = mLauncher.getAppWidgetHost();

118             if (appWidgetHost != null) {

119                 appWidgetHost.deleteAppWidgetId(launcherAppWidgetInfo.appWidgetId);

120             }

121         }

122         LauncherModel.deleteItemFromDatabase(mLauncher, item);

123     }

删除时，判断删除的类型是否是AppWidget，如果是的话，要通过AppWidgetHost，删除AppWidetId，并最终从数据库中删除。