NotificationMusic.java

package com.kure.musicplayer;

import android.app.Notification;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.app.Service;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.widget.RemoteViews;

import com.kure.musicplayer.activities.ActivityNowPlaying;
import com.kure.musicplayer.model.Song;

/**
 * Specific way to stick an on-going message on the system
 * with the current song I'm playing.
 *
 * This is a rather complicated set of functions because
 * it interacts with a great deal of the Android API.
 * Read with care.
 *
 * Thanks:
 *
 * - Gave me a complete example on how to add a custom
 *   action to a button click on the Notification:
 *   http://stackoverflow.com/a/21927248
 */
public class NotificationMusic extends NotificationSimple {

	/**
	 * Reference to the context that notified.
	 */
	Context context = null;

	/**
	 * Reference to the service we're attached to.
	 */
	Service service = null;

	/**
	 * Used to create and update the same notification.
	 */
	Notification.Builder notificationBuilder = null;

	/**
	 * Custom appearance of the notification, also updated.
	 */
	RemoteViews notificationView = null;

	/**
	 * Used to actually broadcast the notification.
	 * Depends on the Activity that originally called
	 * the nofitication.
	 */
	NotificationManager notificationManager = null;

	/**
	 * Sends a system notification with a song's information.
	 *
	 * If the user clicks the notification, will be redirected
	 * to the "Now Playing" Activity.
	 *
	 * If the user clicks on any of the buttons inside it,
	 * custom actions will be executed on the
	 * `NotificationButtonHandler` class.
	 *
	 * @param context Activity that calls this function.
	 * @param service Service that calls this function.
	 *                Required so the Notification can
	 *                run on the background.
	 * @param song    Song which we'll display information.
	 *
	 * @note By calling this function multiple times, it'll
	 *       update the old notification.
	 */
	public void notifySong(Context context, Service service, Song song) {

		if (this.context == null)
			this.context = context;
		if (this.service == null)
			this.service = service;



		// Intent that launches the "Now Playing" Activity
		Intent notifyIntent = new Intent(context, ActivityNowPlaying.class);
		notifyIntent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);

		// Letting the Intent be executed later by other application.
		PendingIntent pendingIntent = PendingIntent.getActivity
				(context,
				 0,
				 notifyIntent,
				 PendingIntent.FLAG_UPDATE_CURRENT);



		// Setting our custom appearance for the notification
		notificationView = new RemoteViews(kMP.packageName, R.layout.notification);

		// Manually settings the buttons and text
		// (ignoring the defaults on the XML)
		notificationView.setImageViewResource(R.id.notification_button_play, R.drawable.pause);
		notificationView.setImageViewResource(R.id.notification_button_skip, R.drawable.skip);
		notificationView.setTextViewText(R.id.notification_text_title, song.getTitle());
		notificationView.setTextViewText(R.id.notification_text_artist, song.getArtist());



		// On the notification we have two buttons - Play and Skip
		// Here we make sure the class `NotificationButtonHandler`
		// gets called when user selects one of those.
		//
		// First, building the play button and attaching it.
		Intent buttonPlayIntent = new Intent(context, NotificationPlayButtonHandler.class);
		buttonPlayIntent.putExtra("action", "togglePause");

		PendingIntent buttonPlayPendingIntent = PendingIntent.getBroadcast(context, 0, buttonPlayIntent, 0);
		notificationView.setOnClickPendingIntent(R.id.notification_button_play, buttonPlayPendingIntent);

		// And now, building and attaching the Skip button.
		Intent buttonSkipIntent = new Intent(context, NotificationSkipButtonHandler.class);
		buttonSkipIntent.putExtra("action", "skip");

		PendingIntent buttonSkipPendingIntent = PendingIntent.getBroadcast(context, 0, buttonSkipIntent, 0);
		notificationView.setOnClickPendingIntent(R.id.notification_button_skip, buttonSkipPendingIntent);



		// Finally... Actually creating the Notification
		notificationBuilder = new Notification.Builder(context);

		notificationBuilder.setContentIntent(pendingIntent)
		                   .setSmallIcon(R.drawable.ic_launcher_white)
		                   .setTicker("kMP: Playing '" + song.getTitle() + "' from '" + song.getArtist() + "'")
		                   .setOngoing(true)
		                   .setContentTitle(song.getTitle())
		                   .setContentText(song.getArtist())
		                   .setContent(notificationView);

		Notification notification = notificationBuilder.build();



		notificationManager = (NotificationManager)context.getSystemService(Context.NOTIFICATION_SERVICE);
//		notificationManager.notify(NOTIFICATION_ID, notification);

		// Sets the notification to run on the foreground.
		// (why not the former commented line?)
		service.startForeground(NOTIFICATION_ID, notification);
	}

	/**
	 * Called when user clicks the "play/pause" button on the on-going system Notification.
	 */
	public static class NotificationPlayButtonHandler extends BroadcastReceiver {
		@Override
		public void onReceive(Context context, Intent intent) {
			kMP.musicService.togglePlayback();
		}
	}

	/**
	 * Called when user clicks the "skip" button on the on-going system Notification.
	 */
	public static class NotificationSkipButtonHandler extends BroadcastReceiver {
		@Override
		public void onReceive(Context context, Intent intent) {
			kMP.musicService.next(true);
			kMP.musicService.playSong();
		}
	}

	/**
	 * Updates the Notification icon if the music is paused.
	 */
	public void notifyPaused(boolean isPaused) {
		if ((notificationView == null) || (notificationBuilder == null))
			return;

		int iconID = ((isPaused)?
	                  R.drawable.play :
	                  R.drawable.pause);

		notificationView.setImageViewResource(R.id.notification_button_play, iconID);

		notificationBuilder.setContent(notificationView);

//		notificationManager.notify(NOTIFICATION_ID, notificationBuilder.build());

		// Sets the notification to run on the foreground.
		// (why not the former commented line?)
		service.startForeground(NOTIFICATION_ID, notificationBuilder.build());
	}

	/**
	 * Cancels this notification.
	 */
	public void cancel() {
		service.stopForeground(true);

		notificationManager.cancel(NOTIFICATION_ID);
	}

	/**
	 * Cancels all sent notifications.
	 */
	public static void cancelAll(Context c) {
		NotificationManager manager = (NotificationManager)c.getSystemService(Context.NOTIFICATION_SERVICE);
		manager.cancelAll();
	}
}