laucher添加widget过程

 最近打算研究下android的widget相关问题，并把一些心得在此稍作记录，哈哈，等研究完成了，如果有必要的话，也会把改动的源码贴出来，以飨读者。今天先来看看launcher2中添加widget的流程。

    添加widget首先需要在laucher的空白处长按，所以首先定位在laucher的 public boolean onLongClick(View v) 中，看到：

 if (mWorkspace.allowLongPress()) {
     if (cellInfo.cell == null) {
         if (cellInfo.valid) {
             // User long pressed on empty space
             mWorkspace.setAllowLongPress(false);
             mWorkspace.performHapticFeedback(HapticFeedbackConstants.LONG_PRESS,
                     HapticFeedbackConstants.FLAG_IGNORE_VIEW_SETTING);
             showAddDialog(cellInfo);
         }
     } else {
         if (!(cellInfo.cell instanceof Folder)) {
             // User long pressed on an item
             mWorkspace.performHapticFeedback(HapticFeedbackConstants.LONG_PRESS,
                     HapticFeedbackConstants.FLAG_IGNORE_VIEW_SETTING);
             mWorkspace.startDrag(cellInfo);
         }
     }
 }

 

可以看到跳转到了showAddDialog(cellInfo)，寻找到：

 private void showAddDialog(CellLayout.CellInfo cellInfo) {
     mAddItemCellInfo = cellInfo;
     mWaitingForResult = true;
     showDialog(DIALOG_CREATE_SHORTCUT);
 }

 

可以看到他携带着DIALOG_CREATE_SHORTCUT参数创建了一个Dialog，携带参数跳入Launcher.java的父类Activity.java的showDialog()方法,最终到达Launcher.java的onCreateDialog(int id)方法,代码如下:

 @Override
 protected Dialog onCreateDialog(int id) {
     switch (id) {
         case DIALOG_CREATE_SHORTCUT:
             return new CreateShortcut().createDialog();
         case DIALOG_RENAME_FOLDER:
             return new RenameFolder().createDialog();
     }

     return super.onCreateDialog(id);
 }

 

跳转到了CreateShortcut()的createDialog()方法：

 Dialog createDialog() {
     mWaitingForResult = true;
     mAdapter = new AddAdapter(Launcher.this);
     final AlertDialog.Builder builder = new AlertDialog.Builder(Launcher.this);       builder.setTitle(getString(R.string.menu_item_add_item));
     builder.setAdapter(mAdapter, this);
     builder.setInverseBackgroundForced(true);
     AlertDialog dialog = builder.create();
     dialog.setOnCancelListener(this);
     dialog.setOnDismissListener(this);
     dialog.setOnShowListener(this);

     return dialog;
 }

这里可以看到一个  AddAdapter类，跳转去看看，这个就是定义长按后出现的对话框的内容：

 public static final int ITEM_SHORTCUT = 0;
     public static final int ITEM_APPWIDGET = 1;
     public static final int ITEM_LIVE_FOLDER = 2;
     public static final int ITEM_WALLPAPER = 3;

 

如果我们需要在原来的对话框中添加新的内容，那么首先需要修改的就是这里，我们回到之前的地方接着往下走，dialog响应的点击事件，public void onClick(DialogInterface dialog, int which) ：

 case AddAdapter.ITEM_APPWIDGET: {
                     int appWidgetId = Launcher.this.mAppWidgetHost.allocateAppWidgetId();
  //这里生成了一个appWidgetId，供后面绑定AppWidgetProvider使用
                     Intent pickIntent = new Intent(AppWidgetManager.ACTION_APPWIDGET_PICK);
  //新建一个intent，该intent是打开一个现实Widgets列表的activity,该activity对应类AppWidgetPickActivity
                 pickIntent.putExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, appWidgetId);
                     // start the pick activity
        //设置EXTRA_APPWIDGET_ID             startActivityForResult(pickIntent, REQUEST_PICK_APPWIDGET);
                     break;
                 }

 

 

这里看到点击widget条目之后，跳转打开一个新的pickIntent，其实际运行的为packages/apps/Settings/src/com/android/settings/AppWidgetPickActivity.java：

先在onCreate方法中创建了一个InstalledAppWidgets列表，该列表就是我们在界面上能见到的所有widgets。

在点击一个widgets,进入AppWidgetPickActivity.onClick事件监听，注意阅读该方法代码，它会进入else：

 if (intent.getExtras() != null) {
             // If there are any extras, it's because this entry is custom.
             // Don't try to bind it, just pass it back to the app.
             setResultData(RESULT_OK, intent);
         } else {
             try {
                 mAppWidgetManager.bindAppWidgetId(mAppWidgetId, intent.getComponent());
 //绑定选中的桌面组件与mAppWidgetId
         result = RESULT_OK;//设置返回结果为ok

 

activity执行结束后面都会进入launcher.onActivityResult,查看该函数方法有两个关键的case:

 case REQUEST_PICK_APPWIDGET:
      addAppWidget(data);
        break;
 case REQUEST_CREATE_APPWIDGET:
      completeAddAppWidget(data, mAddItemCellInfo);

 

 

接着跳转到launcher的addAppWidget(Intent data)里data为传递来的appWidgetId：

 void addAppWidget(Intent data) {
         // TODO: catch bad widget exception when sent
         int appWidgetId = data.getIntExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, -1);
         AppWidgetProviderInfo appWidget = mAppWidgetManager.getAppWidgetInfo(appWidgetId);
  //先判断是否有配置页
         if (appWidget.configure != null) {
             // Launch over to configure widget, if needed
             Intent intent = new Intent(AppWidgetManager.ACTION_APPWIDGET_CONFIGURE);
             intent.setComponent(appWidget.configure);
             intent.putExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, appWidgetId);
             startActivityForResultSafely(intent, REQUEST_CREATE_APPWIDGET);
         } else {
             // Otherwise just add it
             onActivityResult(REQUEST_CREATE_APPWIDGET, Activity.RESULT_OK, data);
         }
     }

 

通过onActivityResult(REQUEST_CREATE_APPWIDGET, Activity.RESULT_OK, data);跳转回launcher.onActivityResult的

 

 case REQUEST_CREATE_APPWIDGET:

          completeAddAppWidget(data, mAddItemCellInfo);

 

 

 @param data The intent describing the appWidgetId.
      * @param cellInfo The position on screen where to create the widget.
      */
     private void completeAddAppWidget(Intent data, CellLayout.CellInfo cellInfo)

 

在 completeAddAppWidget(data, mAddItemCellInfo)中完成widget的添加。

 

 private void completeAddAppWidget(Intent data, CellLayout.CellInfo cellInfo) {
         Bundle extras = data.getExtras();
         int appWidgetId = extras.getInt(AppWidgetManager.EXTRA_APPWIDGET_ID, -1);
         if (LOGD) Log.d(TAG, "dumping extras content=" + extras.toString());
  //由appWidgetId获取widget的信息，例如大小等
         AppWidgetProviderInfo appWidgetInfo = mAppWidgetManager.getAppWidgetInfo(appWidgetId);
         // Calculate the grid spans needed to fit this widget
         CellLayout layout = (CellLayout) mWorkspace.getChildAt(cellInfo.screen);
         int[] spans = layout.rectToCell(appWidgetInfo.minWidth, appWidgetInfo.minHeight);
         // Try finding open space on Launcher screen
         final int[] xy = mCellCoordinates;
         if (!findSlot(cellInfo, xy, spans[0], spans[1])) {
             if (appWidgetId != -1) mAppWidgetHost.deleteAppWidgetId(appWidgetId);
             return;
         }
         // Build Launcher-specific widget info and save to database
         LauncherAppWidgetInfo launcherInfo = new LauncherAppWidgetInfo(appWidgetId);
         launcherInfo.spanX = spans[0];
         launcherInfo.spanY = spans[1];
         LauncherModel.addItemToDatabase(this, launcherInfo,
                 LauncherSettings.Favorites.CONTAINER_DESKTOP,
                 mWorkspace.getCurrentScreen(), xy[0], xy[1], false);
         if (!mRestoring) {
             mDesktopItems.add(launcherInfo);
             // Perform actual inflation because we're live
             launcherInfo.hostView = mAppWidgetHost.createView(this, appWidgetId, appWidgetInfo);
             launcherInfo.hostView.setAppWidget(appWidgetId, appWidgetInfo);
             launcherInfo.hostView.setTag(launcherInfo);
             mWorkspace.addInCurrentScreen(launcherInfo.hostView, xy[0], xy[1],
                     launcherInfo.spanX, launcherInfo.spanY, isWorkspaceLocked());
         }