Extending Muzei with a FileProvider

MuzeiExtensionService.java

    public class MuzeiExtensionService extends MuzeiArtSource {
      
      private SubscriberManager mSubscriberManager;

      public MuzeiExtensionService() {
          super(MuzeiExtensionService.class.getName());
      }
  
      @Override
      public void onCreate() {
          super.onCreate();
          mSubscriberManager = SubscriberManager.obtain(this);
      }
      
      @Override
      protected void onSubscriberAdded(ComponentName subscriber) {
          super.onSubscriberAdded(subscriber);
          mSubscriberManager.add(subscriber.getPackageName());
      }
  
      @Override
      protected void onSubscriberRemoved(ComponentName subscriber) {
          super.onSubscriberRemoved(subscriber);
          mSubscriberManager.remove(subscriber.getPackageName());
      }
      
      @Override
      protected void onUpdate(int reason) {
      
        // obtain a Uri for from your FileProvider
        Uri wallpaper = FileProvider.getUriForFile(context, PROVIDER_AUTHORITY, wallpaperFile);
        
        // grant permission to the Uri so Muzei can retrieve it through your FileProvider
        // you can later revoke access to a Uri with Context.revokeUriPermission(Uri, int); 
        Set<String> subscribers = mSubscriberManager.subscribers();
        for (String subscriberPackage : subscribers)
                  getApplicationContext().grantUriPermission(subscriberPackage, wallpaper, Intent.FLAG_GRANT_READ_URI_PERMISSION);
  
        // publishArtwork ...
      }
      
       private static class SubscriberManager {

          private static final String NAME = "muzei";
          private static final String KEY = "subscribers";
  
          public static SubscriberManager obtain(Context context) {
              return new SubscriberManager(context);
          }
  
          private SharedPreferences preferences;
  
          private SubscriberManager(Context context) {
              preferences = context.getSharedPreferences(NAME, Context.MODE_PRIVATE);
          }
  
          public void add(String componentName) {
              Set<String> value = subscribers();
              value.add(componentName);
  
              save(value);
          }
  
          public void remove(String componentName) {
              Set<String> value = subscribers();
              value.remove(componentName);
  
              save(value);
          }
  
          public Set<String> subscribers() {
              return preferences.getStringSet(KEY, new TreeSet<String>());
          }
  
          private void save(Set<String> value) {
              SharedPreferences.Editor editor = preferences.edit();
              editor.putStringSet(KEY, value);
              editor.commit();
          }
  
      }
    
    }