Widget not updated on launcher restart

问题:

I've got a widget which will update itself whenever there's a configuration change (such as screen orientation), and whenever the phone is unlocked. This process involves setting onClick handlers for the buttons on my widget. This works well, however I have found that there's a usage case which causes my app to not respond to onClick events. This particular case is whenever the launcher restarts itself.

Is there a way to detect when a launcher restarts, so I can update my widget manually? Or is there another way to ensure onClick handlers are not lost?

回答1:

Turns out I was spamming new RemoteViews() when I should have just called it once to produce the view, and then referred to that one instance when required. In my solution, I have a class variable which stores this single RemoteView instance, and a getter to access it.

回答2:

Proposal by @Glitch might not work for certain cases, especially app widget with ListView. This is because ListView will get very slow (Try to scroll the ListView) after appWidgetManager.notifyAppWidgetViewDataChanged(appWidgetId, list_id) had been called several time.

My guess is, the single RemoteView instance will keep all its executed instruction in a list. Over the time, the instruction list will grow. Every time appWidgetManager.notifyAppWidgetViewDataChanged(appWidgetId, list_id), the large instruction list will be executed all over again.

My proposed solution is as follow. However, I believe it will only work on certain device, as not all devices will receive same broadcast message during launcher restarting.

@SuppressLint("NewApi")
@Override
public void onReceive(Context context, Intent intent) {
    final String action = intent.getAction();

    if (action.equals("com.sec.android.widgetapp.APPWIDGET_RESIZE")) {
        // http://stackoverflow.com/questions/17396045/how-to-catch-widget-size-changes-on-devices-where-onappwidgetoptionschanged-not
        handleTouchWiz(context, intent);

        // Possible launcher restart.
        handleLauncherRestart(context, intent);
    } else if (action.equals("android.appwidget.action.APPWIDGET_UPDATE_OPTIONS")) {

        // Possible launcher restart.            
        handleLauncherRestart(context, intent);
    } 

    super.onReceive(context, intent);
}

private void handleLauncherRestart(Context context, Intent intent) {
    AppWidgetManager appWidgetManager = AppWidgetManager.getInstance(context);
    int appWidgetId = intent.getIntExtra(AppWidgetManager.EXTRA_APPWIDGET_ID,
            AppWidgetManager.INVALID_APPWIDGET_ID);
    updateAppWidget(context, appWidgetManager, appWidgetId);
}

private void handleTouchWiz(Context context, Intent intent) {
    AppWidgetManager appWidgetManager = AppWidgetManager.getInstance(context);

    int appWidgetId = intent.getIntExtra("widgetId", 0);
    int widgetSpanX = intent.getIntExtra("widgetspanx", 0);
    int widgetSpanY = intent.getIntExtra("widgetspany", 0);

    if (appWidgetId > 0 && widgetSpanX > 0 && widgetSpanY > 0) {
        Bundle newOptions = new Bundle();
        // We have to convert these numbers for future use
        // http://stackoverflow.com/questions/10008521/appwidget-size-calculation
        if (android.os.Build.VERSION.SDK_INT < android.os.Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
            newOptions.putInt(AppWidgetManager.OPTION_APPWIDGET_MIN_HEIGHT, widgetSpanY * 74 - 2);
            newOptions.putInt(AppWidgetManager.OPTION_APPWIDGET_MIN_WIDTH, widgetSpanX * 74 - 2);

        } else {
            newOptions.putInt(AppWidgetManager.OPTION_APPWIDGET_MIN_HEIGHT, widgetSpanY * 70 - 30);
            newOptions.putInt(AppWidgetManager.OPTION_APPWIDGET_MIN_WIDTH, widgetSpanX * 70 - 30);
        }

        onAppWidgetOptionsChanged(context, appWidgetManager, appWidgetId, newOptions);
    }
}