/*
* 11/19/04 1.0 moved to LGPL.
* 29/01/00 Initial version. mdm@techie.com
*-----------------------------------------------------------------------
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Library General Public License as published
* by the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*----------------------------------------------------------------------
*/
package javazoom.jl.player;
import javazoom.jl.decoder.Decoder;
import javazoom.jl.decoder.JavaLayerException;
/**
* The <code>AudioDeviceBase</code> class provides a simple thread-safe
* implementation of the <code>AudioDevice</code> interface. Template methods
* are provided for subclasses to override and in doing so provide the
* implementation for the main operations of the <code>AudioDevice</code>
* interface.
*
* @since 0.0.8
* @author Mat McGowan
*/
/*
* REVIEW: It is desirable to be able to use the decoder whe
* in the implementation of open(), but the decoder
* has not yet read a frame, and so much of the
* desired information (sample rate, channels etc.)
* are not available.
*/
public abstract class AudioDeviceBase implements AudioDevice
{
private boolean open = false;
private Decoder decoder = null;
/**
* Opens this audio device.
*
* @param decoder
* The decoder that will provide audio data to this audio device.
*/
public synchronized void open(Decoder decoder) throws JavaLayerException
{
if (!isOpen())
{
this.decoder = decoder;
openImpl();
setOpen(true);
}
}
/**
* Template method to provide the implementation for the opening of the
* audio device.
*/
protected void openImpl() throws JavaLayerException
{
}
/**
* Sets the open state for this audio device.
*/
protected void setOpen(boolean open)
{
this.open = open;
}
/**
* Determines if this audio device is open or not.
*
* @return <code>true</code> if the audio device is open, <code>false</code>
* if it is not.
*/
public synchronized boolean isOpen()
{
return open;
}
/**
* Closes this audio device. If the device is currently playing audio,
* playback is stopped immediately without flushing any buffered audio data.
*/
public synchronized void close()
{
if (isOpen())
{
closeImpl();
setOpen(false);
decoder = null;
}
}
/**
* Template method to provide the implementation for closing the audio
* device.
*/
protected void closeImpl()
{
}
/**
* Writes audio data to this audio device. Audio data is assumed to be in
* the output format of the decoder. This method may return before the data
* has actually been sounded by the device if the device buffers audio
* samples.
*
* @param samples
* The samples to write to the audio device.
* @param offs
* The offset into the array of the first sample to write.
* @param len
* The number of samples from the array to write.
* @throws JavaLayerException
* if the audio data could not be written to the audio device.
* If the audio device is not open, this method does nthing.
*/
public void write(short[] samples, int offs, int len)
throws JavaLayerException
{
if (isOpen())
{
writeImpl(samples, offs, len);
}
}
/**
* Template method to provide the implementation for writing audio samples
* to the audio device.
*/
protected void writeImpl(short[] samples, int offs, int len)
throws JavaLayerException
{
}
/**
* Waits for any buffered audio samples to be played by the audio device.
* This method should only be called prior to closing the device.
*/
public void flush()
{
if (isOpen())
{
flushImpl();
}
}
/**
* Template method to provide the implementation for flushing any buffered
* audio data.
*/
protected void flushImpl()
{
}
/**
* Retrieves the decoder that provides audio data to this audio device.
*
* @return The associated decoder.
*/
protected Decoder getDecoder()
{
return decoder;
}
}