es.deusto.weblab.client.ui.audio.AudioManager.java Source code

Introduction

Here is the source code for es.deusto.weblab.client.ui.audio.AudioManager.java

Source

/*
* Copyright (C) 2005 onwards University of Deusto
* All rights reserved.
*
* This software is licensed as described in the file COPYING, which
* you should have received as part of this distribution.
*
* This software consists of contributions made by many individuals, 
* listed below:
*
* Author: Luis Rodriguez <luis.rodriguez@opendeusto.es>
*
*/

package es.deusto.weblab.client.ui.audio;

import com.google.gwt.core.client.GWT;
import com.google.gwt.dom.client.AudioElement;
import com.google.gwt.dom.client.MediaElement;
import com.google.gwt.media.client.Audio;

import es.deusto.weblab.client.configuration.ConfigurationRetriever;

public class AudioManager {

    private static final String MP3_TYPE = "audio/mpeg;";
    private static final String OGG_TYPE = "audio/ogg; codecs=\"vorbis\"";
    private static final String WAV_TYPE = "audio/wav; codecs=\"1\"";

    private static final boolean SOUND_ENABLED_DEFAULT = false;
    private static final String SOUND_ENABLED_NAME = "sound.enabled";

    private static AudioManager instance = null;

    private ConfigurationRetriever configurationRetriever;

    /**
     * Constructs the AudioManager instance.
     * @param retriever ConfigurationRetriever which will be stored internally and
     * which makes it possible to access and modify globally the sound_enabled setting.
     * 
     * @see initialize
     */
    private AudioManager(ConfigurationRetriever retriever) {
        this.configurationRetriever = retriever;
    }

    /**
     * Constructs the only Audio Manager instance. Needs to be called before
     * being able to retrieve the AudioManager's instance.
     * It needs to be constructed explicitly because of the retriever
     * parameter the singleton requires.
     * 
     * @param retriever ConfigurationRetriever which will be stored internally
     * and which makes it possible to access and modify globally the sound_enabled
     * setting.
     * 
     * @throws RuntimeException If the singleton has already been initialized once
     * and hence an instance exists already.
     * 
     * @see getInstance
     */
    public static void initialize(ConfigurationRetriever retriever) {
        if (instance != null)
            throw new RuntimeException("AudioManager singleton has already been initialized");
        instance = new AudioManager(retriever);
    }

    /**
     * Retrieves the only instance of this class that may exist.
     * 
     * @return The one instance of the AudioManager class. Null if the singleton
     * has not been initialized yet.
     * 
     * @see initialize
     */
    public static AudioManager getInstance() {
        return AudioManager.instance;
    }

    /**
     * Checks whether sounds are enabled. If they are not, no sound at all
     * should ever be played.
     * @return True if sounds are enabled. False otherwise.
     */
    public boolean getSoundEnabled() {
        final boolean enabled = this.configurationRetriever.getBoolProperty(SOUND_ENABLED_NAME,
                SOUND_ENABLED_DEFAULT);
        return enabled;
    }

    /**
     * Enables or disables sound. 
     * @param enable True to enable, false to disable.
     */
    public void setSoundEnabled(boolean enable) {
        this.configurationRetriever.setBoolProperty(SOUND_ENABLED_NAME, enable);
    }

    /**
     * Helper method which will play a sound if certain conditions are met:
     * Sound is enabled.
     * Sound is supported.
     * File type is supported.
     * If they are not, calling this method will have no effect.
     * @param file File to play. The path should be relative to the module base URL. E.g. "/audio/foo.wav"
     * 
     * @return AudioElement being played, or null. May be used to modify the default behaviour, such
     * as enabling loop mode.
     */
    public AudioElement play(String file) {
        if (this.getSoundEnabled()) {
            final Audio audio = Audio.createIfSupported();
            if (audio != null) {
                final AudioElement elem = audio.getAudioElement();
                elem.setSrc(GWT.getModuleBaseURL() + file);
                elem.play();
                return elem;
            }
        }
        return null;
    }

    /**
     * Helper method which will play a sound if certain conditions are met:
     * Sound is enabled.
     * Sound is supported.
     * If they are not, calling this method will have no effect.
     * 
     * The file type is inferred by the web browser. If it supports OGG, it will use the ".ogg" extension. If it doesn't, but it
     * supports MP3, it will use ".mp3". It will also try WAV, and otherwise it will not work. Therefore, the audio files must be 
     * duplicated in these three formats to work. 
     * 
     * @param file File to play. The path should be relative to the module base URL. E.g. "/audio/foo" will select foo.ogg, foo.mp3 or foo.wav
     * 
     * @return AudioElement being played, or null. May be used to modify the default behaviour, such
     * as enabling loop mode.
     */
    public AudioElement playBest(String file) {
        if (this.getSoundEnabled()) {
            final Audio audio = Audio.createIfSupported();
            if (audio != null) {
                final AudioElement elem = audio.getAudioElement();

                // First try probably
                if (elem.canPlayType(OGG_TYPE).equals(MediaElement.CAN_PLAY_PROBABLY))
                    elem.setSrc(GWT.getModuleBaseURL() + file + ".ogg");
                else if (elem.canPlayType(MP3_TYPE).equals(MediaElement.CAN_PLAY_PROBABLY))
                    elem.setSrc(GWT.getModuleBaseURL() + file + ".mp3");
                else if (elem.canPlayType(WAV_TYPE).equals(MediaElement.CAN_PLAY_PROBABLY))
                    elem.setSrc(GWT.getModuleBaseURL() + file + ".wav");
                // Then maybe
                else if (elem.canPlayType(OGG_TYPE).equals(MediaElement.CAN_PLAY_MAYBE))
                    elem.setSrc(GWT.getModuleBaseURL() + file + ".ogg");
                else if (elem.canPlayType(MP3_TYPE).equals(MediaElement.CAN_PLAY_MAYBE))
                    elem.setSrc(GWT.getModuleBaseURL() + file + ".mp3");
                else if (elem.canPlayType(WAV_TYPE).equals(MediaElement.CAN_PLAY_MAYBE))
                    elem.setSrc(GWT.getModuleBaseURL() + file + ".wav");
                // Then fail
                else
                    return null;

                elem.play();
                return elem;
            }
        }
        return null;
    }

}