com.google.gwt.sample.mobilewebapp.client.ui.SoundEffects.java Source code

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Here is the source code for com.google.gwt.sample.mobilewebapp.client.ui.SoundEffects.java

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/*
 * Copyright 2011 Google Inc.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */
package com.google.gwt.sample.mobilewebapp.client.ui;

import com.google.gwt.dom.client.AudioElement;
import com.google.gwt.media.client.Audio;

/**
 * A bundle of sound effects that can be used in the application.
 */
public class SoundEffects {

    private static SoundEffects instance;
    private static boolean isSupported;

    /**
     * Get the singleton instance.
     * 
     * @return the singleton instance
     */
    public static SoundEffects get() {
        if (instance == null) {
            isSupported = Audio.isSupported();
            instance = new SoundEffects();
        }
        return instance;
    }

    private Audio error;

    /**
     * Construct using {@link #get()}.
     */
    private SoundEffects() {
    }

    /**
     * Play an error sound, if audio is supported.
     */
    public void playError() {
        prefetchError();
        playAudio(error);
    }

    /**
     * Prefetch the error sound.
     */
    public void prefetchError() {
        if (isSupported && error == null) {
            error = Audio.createIfSupported();
            error.addSource("audio/error.ogg", AudioElement.TYPE_OGG);
            error.addSource("audio/error.mp3", AudioElement.TYPE_MP3);
            error.addSource("audio/error.wav", AudioElement.TYPE_WAV);
            prefetchAudio(error);
        }
    }

    /**
     * Play an audio.
     * 
     * @param audio the audio to play, or null if not supported
     */
    private void playAudio(Audio audio) {
        if (audio == null) {
            return;
        }

        // Pause current progress.
        audio.pause();

        // Reset the source.
        // TODO(jlabanca): Is cache-control=private making the source unseekable?
        audio.setSrc(audio.getCurrentSrc());

        // Unmute because we muted in createAudioElement.
        audio.play();
    }

    /**
     * Prefetch an audio.
     * 
     * @param audio the audio to prefetch, or null if not supported
     */
    private void prefetchAudio(Audio audio) {
        if (audio != null) {
            audio.load();
        }
    }
}