探祕widget之launcher添加widget的流程分析

                                By 何明桂（http://blog.csdn.net/hmg25） 轉載請註明出處

 

       最近打算研究下android的widget相關問題，並把一些心得在此稍作記錄，哈哈，等研究完成了，如果有必要的話，也會把改動的源碼貼出來，以饗讀者。今天先來看看launcher2中添加widget的流程。

    添加widget首先需要在laucher的空白處長按，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); } } }  

可以看到跳轉到了showAddDialog(cellInfo)，尋找到：

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

可以看到他攜帶着DIALOG_CREATE_SHORTCUT參數創建了一個Dialog，攜帶參數跳入Launcher.java的父類Activity.java的showDialog()方法,最終到達Launcher.java的onCreateDialog(int id)方法,代碼如下:

@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); }  

跳轉到了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; }

這裏可以看到一個  AddAdapter類，跳轉去看看，這個就是定義長按後出現的對話框的內容：

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; 

如果我們需要在原來的對話框中添加新的內容，那麼首先需要修改的就是這裏，我們回到之前的地方接着往下走，dialog響應的點擊事件，public void onClick(DialogInterface dialog, int which) ：

case AddAdapter.ITEM_APPWIDGET: { int appWidgetId = Launcher.this.mAppWidgetHost.allocateAppWidgetId(); //這裏生成了一個appWidgetId，供後面綁定AppWidgetProvider使用 Intent pickIntent = new Intent(AppWidgetManager.ACTION_APPWIDGET_PICK); //新建一個intent，該intent是打開一個現實Widgets列表的activity,該activity對應類AppWidgetPickActivity pickIntent.putExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, appWidgetId); // start the pick activity //設置EXTRA_APPWIDGET_ID startActivityForResult(pickIntent, REQUEST_PICK_APPWIDGET); break; }  

 

這裏看到點擊widget條目之後，跳轉打開一個新的pickIntent，其實際運行的爲packages/apps/Settings/src/com/android/settings/AppWidgetPickActivity.java：

先在onCreate方法中創建了一個InstalledAppWidgets列表，該列表就是我們在界面上能見到的所有widgets。

在點擊一個widgets,進入AppWidgetPickActivity.onClick事件監聽，注意閱讀該方法代碼，它會進入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()); //綁定選中的桌面組件與mAppWidgetId result = RESULT_OK;//設置返回結果爲ok 

activity執行結束後面都會進入launcher.onActivityResult,查看該函數方法有兩個關鍵的case:

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

 

接着跳轉到launcher的addAppWidget(Intent data)裏data爲傳遞來的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); //先判斷是否有配置頁 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); } }  

通過onActivityResult(REQUEST_CREATE_APPWIDGET, Activity.RESULT_OK, data);跳轉回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獲取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()); }