Main.java

package com.shc.gwtal.examples.client;

import com.google.gwt.animation.client.AnimationScheduler;
import com.google.gwt.core.client.EntryPoint;
import com.google.gwt.core.client.GWT;
import com.google.gwt.event.dom.client.KeyCodes;
import com.google.gwt.typedarrays.shared.ArrayBuffer;
import com.google.gwt.user.client.ui.Button;
import com.google.gwt.user.client.ui.FlowPanel;
import com.google.gwt.user.client.ui.Label;
import com.google.gwt.user.client.ui.RootPanel;
import com.google.gwt.user.client.ui.TextBox;
import com.google.gwt.xhr.client.XMLHttpRequest;
import com.shc.gwtal.client.openal.AL;
import com.shc.gwtal.client.openal.AL10;
import com.shc.gwtal.client.openal.ALContext;
import com.shc.gwtal.client.openal.AudioDecoder;
import com.shc.gwtal.client.webaudio.AudioBuffer;
import com.shc.gwtal.client.webaudio.AudioContext;
import com.shc.gwtal.client.webaudio.AudioContextException;
import com.shc.gwtal.client.webaudio.nodes.AudioBufferSourceNode;

public class Main implements EntryPoint
{
    private AudioBuffer           webBuffer;
    private AudioBufferSourceNode sourceNode;

    private boolean openALLooping = false;

    private int alSource;

    private float alPitch = 1.0f;

    @Override
    public void onModuleLoad()
    {
        // Test media support in browser
        GWT.log("MP3: " + AudioDecoder.isSupported(AudioDecoder.FileFormat.MP3));
        GWT.log("WAV: " + AudioDecoder.isSupported(AudioDecoder.FileFormat.WAV));
        GWT.log("OGG: " + AudioDecoder.isSupported(AudioDecoder.FileFormat.OGG));
        GWT.log("WEBM: " + AudioDecoder.isSupported(AudioDecoder.FileFormat.WEBM));

        String url = Resources.INSTANCE.music().getSafeUri().asString();

        // Create an XMLHttpRequest to load the file from URL
        XMLHttpRequest request = XMLHttpRequest.create();
        request.setResponseType(XMLHttpRequest.ResponseType.ArrayBuffer);

        request.open("GET", url);

        // Attach a state change listener to check for the loading of the file
        request.setOnReadyStateChange((r) ->
        {
            if (request.getReadyState() == XMLHttpRequest.DONE)
            {
                try
                {
                    ArrayBuffer data = request.getResponseArrayBuffer();

                    createWebAudioAPIExample(data);
                    createOpenALExample(data);
                }
                catch (AudioContextException e)
                {
                    e.printStackTrace();
                }
            }
        });

        // Send the request so browser starts loading the file
        request.send();
    }

    private void createOpenALExample(ArrayBuffer data) throws AudioContextException
    {
        ALContext context = ALContext.create();
        AL.setCurrentContext(context);

        alSource = AL10.alGenSources();

        FlowPanel panel = new FlowPanel();
        panel.add(new Label("OpenAL example: "));

        Button playButton = new Button("Play");
        playButton.addClickHandler(event -> AL10.alSourcePlay(alSource));
        playButton.setEnabled(false);

        Button stopButton = new Button("Stop");
        stopButton.addClickHandler(event -> AL10.alSourceStop(alSource));

        Button pauseButton = new Button("Pause");
        pauseButton.addClickHandler(event -> AL10.alSourcePause(alSource));

        Button loopButton = new Button("Looping: Off");
        loopButton.addClickHandler(event -> {
            openALLooping = !openALLooping;
            AL10.alSourcei(alSource, AL10.AL_LOOPING, openALLooping ? AL10.AL_TRUE : AL10.AL_FALSE);

            loopButton.setText("Looping: " + (openALLooping ? "On" : "Off"));
        });

        TextBox pitchBox = new TextBox();
        pitchBox.setValue("" + alPitch);
        pitchBox.addKeyDownHandler(event -> {
            if (event.getNativeKeyCode() == KeyCodes.KEY_ENTER)
                try
                {
                    alPitch = Float.parseFloat(pitchBox.getValue());
                }
                catch (Exception e)
                {
                    GWT.log(e.getMessage());
                }
        });

        panel.add(playButton);
        panel.add(stopButton);
        panel.add(pauseButton);
        panel.add(loopButton);
        panel.add(new Label("Pitch: "));
        panel.add(pitchBox);

        AudioDecoder.decodeAudio
                (
                        data,

                        // On success, set the buffer on the source, and start the animation loop
                        alBufferID ->
                        {
                            AL10.alSourcei(alSource, AL10.AL_BUFFER, alBufferID);
                            playButton.setEnabled(true);

                            AnimationScheduler.get().requestAnimationFrame(this::openalTimeStep);
                        },

                        GWT::log // Log with GWT on error
                );

        RootPanel.get().add(panel);
    }

    private void openalTimeStep(double timestamp)
    {
        float pos = (float) Math.sin(timestamp / 2);
        AL10.alSource3f(alSource, AL10.AL_POSITION, pos, 0, 0);
        AL10.alSourcef(alSource, AL10.AL_PITCH, alPitch);

        int error = AL10.alGetError();

        if (error != AL10.AL_NO_ERROR)
            GWT.log("OpenAL error: " + error + ": " + AL10.alGetString(error));

        AnimationScheduler.get().requestAnimationFrame(this::openalTimeStep);
    }

    private void createWebAudioAPIExample(ArrayBuffer data) throws AudioContextException
    {
        // Create an audio context
        AudioContext context = AudioContext.create();

        context.setOnStateChange(() ->
        {
            GWT.log(context.getState().getJsState());
        });

        FlowPanel panel = new FlowPanel();

        panel.add(new Label("WebAudioAPI example: "));

        // Create the play button
        Button playButton = new Button("Play");
        playButton.addClickHandler((e) ->
        {
            // Stop if already playing
            if (sourceNode != null)
            {
                sourceNode.stop();
                sourceNode = null;
            }

            // Create the source node
            sourceNode = context.createBufferSource();
            sourceNode.setBuffer(webBuffer);

            // Connect to the destination and play
            sourceNode.connect(context.getDestination());
            sourceNode.start();
        });
        playButton.setEnabled(false);

        // Create the stop button
        Button stopButton = new Button("Stop");
        stopButton.addClickHandler((e) ->
        {
            if (sourceNode != null)
            {
                sourceNode.stop();
                sourceNode = null;
            }
        });

        // Add the buttons to the panel
        panel.add(playButton);
        panel.add(stopButton);

        // Add the panel to the document
        RootPanel.get().add(panel);

        // Decode using the context
        context.decodeAudioData(data, decodedData -> {
            webBuffer = decodedData;
            playButton.setEnabled(true);
        });
    }
}