core/java/android/webkit/HTML5Audio.java

/*
 * Copyright (C) 2010 The Android Open Source Project
 *
 * 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 android.webkit;

import android.media.MediaPlayer;
import android.media.MediaPlayer.OnBufferingUpdateListener;
import android.media.MediaPlayer.OnCompletionListener;
import android.media.MediaPlayer.OnErrorListener;
import android.media.MediaPlayer.OnPreparedListener;
import android.media.MediaPlayer.OnSeekCompleteListener;
import android.os.Handler;
import android.os.Message;
import android.util.Log;

import java.io.IOException;
import java.util.Timer;
import java.util.TimerTask;

/**
 * <p>HTML5 support class for Audio.
 */
class HTML5Audio extends Handler
                 implements MediaPlayer.OnBufferingUpdateListener,
                            MediaPlayer.OnCompletionListener,
                            MediaPlayer.OnErrorListener,
                            MediaPlayer.OnPreparedListener,
                            MediaPlayer.OnSeekCompleteListener {
    // Logging tag.
    private static final String LOGTAG = "HTML5Audio";

    private MediaPlayer mMediaPlayer;

    // The C++ MediaPlayerPrivateAndroid object.
    private int mNativePointer;

    private static int IDLE        =  0;
    private static int INITIALIZED =  1;
    private static int PREPARED    =  2;
    private static int STARTED     =  4;
    private static int COMPLETE    =  5;
    private static int PAUSED      =  6;
    private static int STOPPED     = -2;
    private static int ERROR       = -1;

    private int mState = IDLE;

    private String mUrl;
    private boolean mAskToPlay = false;

    // Timer thread -> UI thread
    private static final int TIMEUPDATE = 100;

    // The spec says the timer should fire every 250 ms or less.
    private static final int TIMEUPDATE_PERIOD = 250;  // ms
    // The timer for timeupate events.
    // See http://www.whatwg.org/specs/web-apps/current-work/#event-media-timeupdate
    private Timer mTimer;
    private final class TimeupdateTask extends TimerTask {
        public void run() {
            HTML5Audio.this.obtainMessage(TIMEUPDATE).sendToTarget();
        }
    }

    @Override
    public void handleMessage(Message msg) {
        switch (msg.what) {
            case TIMEUPDATE: {
                try {
                    if (mState != ERROR && mMediaPlayer.isPlaying()) {
                        int position = mMediaPlayer.getCurrentPosition();
                        nativeOnTimeupdate(position, mNativePointer);
                    }
                } catch (IllegalStateException e) {
                    mState = ERROR;
                }
            }
        }
    }

    // event listeners for MediaPlayer
    // Those are called from the same thread we created the MediaPlayer
    // (i.e. the webviewcore thread here)

    // MediaPlayer.OnBufferingUpdateListener
    public void onBufferingUpdate(MediaPlayer mp, int percent) {
        nativeOnBuffering(percent, mNativePointer);
    }

    // MediaPlayer.OnCompletionListener;
    public void onCompletion(MediaPlayer mp) {
        resetMediaPlayer();
        mState = IDLE;
        nativeOnEnded(mNativePointer);
    }

    // MediaPlayer.OnErrorListener
    public boolean onError(MediaPlayer mp, int what, int extra) {
        mState = ERROR;
        resetMediaPlayer();
        mState = IDLE;
        return false;
    }

    // MediaPlayer.OnPreparedListener
    public void onPrepared(MediaPlayer mp) {
        mState = PREPARED;
        if (mTimer != null) {
            mTimer.schedule(new TimeupdateTask(),
                            TIMEUPDATE_PERIOD, TIMEUPDATE_PERIOD);
        }
        nativeOnPrepared(mp.getDuration(), 0, 0, mNativePointer);
        if (mAskToPlay) {
            mAskToPlay = false;
            play();
        }
    }

    // MediaPlayer.OnSeekCompleteListener
    public void onSeekComplete(MediaPlayer mp) {
        nativeOnTimeupdate(mp.getCurrentPosition(), mNativePointer);
    }


    /**
     * @param nativePtr is the C++ pointer to the MediaPlayerPrivate object.
     */
    public HTML5Audio(int nativePtr) {
        // Save the native ptr
        mNativePointer = nativePtr;
        resetMediaPlayer();
    }

    private void resetMediaPlayer() {
        if (mMediaPlayer == null) {
            mMediaPlayer = new MediaPlayer();
        } else {
            mMediaPlayer.reset();
        }
        mMediaPlayer.setOnBufferingUpdateListener(this);
        mMediaPlayer.setOnCompletionListener(this);
        mMediaPlayer.setOnErrorListener(this);
        mMediaPlayer.setOnPreparedListener(this);
        mMediaPlayer.setOnSeekCompleteListener(this);

        if (mTimer != null) {
            mTimer.cancel();
        }
        mTimer = new Timer();
        mState = IDLE;
    }

    private void setDataSource(String url) {
        mUrl = url;
        try {
            if (mState != IDLE) {
                resetMediaPlayer();
            }
            mMediaPlayer.setDataSource(url);
            mState = INITIALIZED;
            mMediaPlayer.prepareAsync();
        } catch (IOException e) {
            Log.e(LOGTAG, "couldn't load the resource: " + url + " exc: " + e);
            resetMediaPlayer();
        }
    }

    private void play() {
        if ((mState == ERROR || mState == IDLE) && mUrl != null) {
            resetMediaPlayer();
            setDataSource(mUrl);
            mAskToPlay = true;
        }

        if (mState >= PREPARED) {
            mMediaPlayer.start();
            mState = STARTED;
        }
    }

    private void pause() {
        if (mState == STARTED) {
            if (mTimer != null) {
                mTimer.purge();
            }
            mMediaPlayer.pause();
            mState = PAUSED;
        }
    }

    private void seek(int msec) {
        if (mState >= PREPARED) {
            mMediaPlayer.seekTo(msec);
        }
    }

    private void teardown() {
        mMediaPlayer.release();
        mState = ERROR;
        mNativePointer = 0;
    }

    private float getMaxTimeSeekable() {
        return mMediaPlayer.getDuration() / 1000.0f;
    }

    private native void nativeOnBuffering(int percent, int nativePointer);
    private native void nativeOnEnded(int nativePointer);
    private native void nativeOnPrepared(int duration, int width, int height, int nativePointer);
    private native void nativeOnTimeupdate(int position, int nativePointer);
}