探秘 widget 之 launcher 添加 widget 的流程分析

鉴客 发布于 2011/09/25 07:08
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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)

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());
        }
    

原文出处:http://blog.csdn.net/hmg25/article/details/6439414

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ZhaoShenan
文章不错,有源码更好
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