AppWidgetHost not updating widgets

Question

Can I use AppWidgetHost inside a Fragment? I can't get most widgets added to my AppWidgetHost to update. Here is my scenario..

LauncherActivity.java

• Very simple, just calling setContentView with a layout.

main.xml

• Contains a couple fragments, including one that has the AppWidgetHost in it.

CodeRedWidgetHostFragment.java

• onCreateView
  create instances of AppWidgetHost & AppWidgetManager
  create and setup my host view with a widget ID that I've stored in preferences

• onStart()
  appWidgetHost.startListening()

• onStop()
  appWidgetHost.stopListening()

When I get my instances of AppWidgetHost and AppWidgetManager I'm using getActivity() to get the Fragments hosting activity. I'm wondering if this is why my widgets aren't updating?

Some widgets actually do update, like the Analog Clock for example, however, the Youtube widget doesn't auto cycle through video thumbnails.

I should mention that I select the widget I want in my AppWidgetHost in another activity that stores the selected widget's id in SharedPreferences.

Here is the code for my Fragment class.

package com.brockoli.android.codered.widgethost;

import android.app.Fragment;
import android.appwidget.AppWidgetHost;
import android.appwidget.AppWidgetHostView;
import android.appwidget.AppWidgetManager;
import android.appwidget.AppWidgetProviderInfo;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import com.brockoli.android.codered.R;

public class CodeRedWidgetHostFragment extends Fragment {
private static final String TAG = CodeRedWidgetHostFragment.class.getSimpleName();

public static final String CODERED_WIDGET_ID = "CODERED_WIDGET_ID";

private SharedPreferences mSharedPrefsWidgets;

AppWidgetManager mAppWidgetManager;
AppWidgetHost mAppWidgetHost;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
    View parentView = inflater.inflate(R.layout.widget_host, null);

    mSharedPrefsWidgets = getActivity().getSharedPreferences("codered_widgets", 0);

    mAppWidgetManager = AppWidgetManager.getInstance(getActivity());
    mAppWidgetHost = new AppWidgetHost(getActivity(), R.id.APPWIDGET_HOST_ID);

    createWidget(parentView);

    return parentView;
}

@Override
public void onStart() {
    super.onStart();
    mAppWidgetHost.startListening();
}

@Override
public void onStop() {
    super.onStop();
    mAppWidgetHost.stopListening();
}


@Override
public void onResume() {
    super.onResume();
    createWidget(getView());
}

/**
 * Creates the widget and adds to our view layout.
 */
public void createWidget(View v) {
    if (v != null) {
        // Remove any existing widgets from the widget host
        ((ViewGroup) v).removeAllViews();
        int appWidgetId = mSharedPrefsWidgets.getInt(CODERED_WIDGET_ID, -1);
        if (appWidgetId > -1) {
            AppWidgetProviderInfo appWidgetInfo = mAppWidgetManager.getAppWidgetInfo(appWidgetId);
            AppWidgetHostView hostView = mAppWidgetHost.createView(getActivity(), appWidgetId, appWidgetInfo);
            hostView.setAppWidget(appWidgetId, appWidgetInfo);
            ((ViewGroup) v).addView(hostView);
            Log.i(TAG, "The widget size is: " + appWidgetInfo.minWidth + "*" + appWidgetInfo.minHeight);
        }   
    }
}
}

Answer 1

Building on Clemens answer, the AppWidgetHost should be alive during the entire lifecycle of your application. This means that regardless of Activity you should have an instance of AppWidgetHost and AppWidgetManager somewhere easily accessible to your app.

public class YourApp extends Application {

    private static final int HARDCODED_ID = 0; 

    private static AppWidgetHost appWidgetHost;
    private static AppWidgetManager appWidgetManager;

    @Override
    public void onCreate() {
        super.onCreate();

        appWidgetManager = AppWidgetManager.getInstance(getApplicationContext());
        appWidgetHost = new AppWidgetHost(getApplicationContext(), HARDCODED_ID);
        appWidgetHost.startListening();
    }

    @Override
    public void onTerminate() {
        super.onTerminate();

        appWidgetHost.stopListening();
        appWidgetHost = null;
    }

    public static AppWidgetHost getAppWidgetHost() { return appWidgetHost; }

    public static AppWidgetManager getAppWidgetManager() { return appWidgetManager; }

}

My current implementation has been updating correctly. Tested with many apps that need 'real-time' updates like my music player widget.

Please keep in mind, that application context was used to ensure that the context for AppWidgetHost and AppWidgetManager would always be available.

Also, newer widgets that use the AppCompat libraries within their widgets currently have a bug in com.android.support:appcompat-v7:23.1.1 dependencies. To avoid this use application context when calling the following.

AppWidgetHostView hostView = YourApp.getAppWidgetHost()
            .createView(context.getApplicationContexxt(), appWidgetId, info);

Answer 2

If some of your widgets do update, I believe your getActivity() might be the problem.

Try creating a reference in your fragment, like:

private Activity activity;

and set it in you onAttach()

@Override
public void onAttach(Activity activity) {
    super.onAttach(activity);
    this.activity = activity; 
}

This way, it should always point to your current hosting Activity.

Answer 3

I found the reason of the issue, for people that will be stuck in the future, here is the explaination:

AppwidgetManager is in fact a system service and you do not get new instance when calling AppwidgetManger.getInstance(Context context), but a reference to a single instance, which is the same anywhere else (across activities, services ..).

AppwidgetManger source:

public static AppWidgetManager getInstance(Context context) {
     return (AppWidgetManager) context.getSystemService(Context.APPWIDGET_SERVICE);
 }

So for me, my problem was that i had two activities, and each one get reference to AppwidgetManager, and per the doc, they was calling AppwidgetManger.startListening() in onStart() and onStopListening() in onStop().

But when i switched to second activity, here is what creates the bug:

• Activity1:onPause()
• Activity2:onCreate()
• Activity2:onStart() startListening()
• Activity1:onStop() stopListening()
• Activity1:onDestroy()
• Activity2:onResume()

So activity 2 correctly call startListening(), but in background, activity 1 is still alive and call stopListening() to the same AppwidgetManager instance.

Furthermore, you should change this

mAppWidgetHost = new AppWidgetHost(getActivity(), R.id.APPWIDGET_HOST_ID);

to

mAppWidgetHost = new AppWidgetHost(getActivity().getApplicationContext(), R.id.APPWIDGET_HOST_ID);

It will prevent system to keep reference to your activity and keep it away from GC (passing activity creates memory leak)

Answer 4

I've got the same problem and I haven't solved it (yet), but it seems to be a problem with AppWidgetHost. In my case the only way I get it to work is disabling stopListening() or recreating the AppWidgetHostViews in a new instance of AppWidgetHost… In your case it might help to recreate mAppWidgetHost in onStart() (or even onResume())…

Answer 5

Since you are writing a Launcher, I would recommend you to have a look at the official Android Launcher. In contrast to the documentation it utilizes the following mechanism:

@Override
protected void onCreate(final Bundle savedInstanceState) {
    super.onCreate();
    // ...
    appWidgetManager = AppWidgetManager.getInstance(this);
    appWidgetHost = new AppWidgetHost(this, HOST_WIDGET_ID);
    appWidgetHost.startListening();
}

@Override
protected void onDestroy() {
    super.onDestroy();
    // ...
    appWidgetHost.stopListening();
    appWidgetHost = null;
}

Be sure to remove all other instances of stopListening and startListening in your code.

Answer 6

You should call ViewGroup.removeAllViews() from parentView after you do mAppWidgetHost.stopListening().