| public SendAndReceive ( byte request, byte responseBuffer ) : int | ||
| request | byte | Array of bytes (command) to send to SRV-1 Blackfin robot/camera. |
| responseBuffer | byte | Buffer to read response into. |
| return | int | |
public int SendAndReceive( byte[] request, byte[] responseBuffer )
{
lock ( sync )
{
if ( socket == null )
{
// handle error
throw new NotConnectedException( "Not connected to SRV-1." );
}
lock ( communicationQueue )
{
communicationQueue.Enqueue( new CommunicationRequest( request, responseBuffer ) );
}
requestIsAvailable.Set( );
// waiting for reply
replyIsAvailable.WaitOne( );
// no reply since we got disconnect request from user - background thread is exiting
if ( lastRequestWithReply == null )
return 0;
// get number of bytes read
int bytesRead = lastRequestWithReply.BytesRead;
// clean the last reply
lastRequestWithReply = null;
if ( bytesRead == -1 )
{
// handle error
throw new ConnectionLostException( "Connection lost or communicaton failure." );
}
if ( bytesRead == -2 )
{
// handle error
throw new IndexOutOfRangeException( "Response buffer is too small." );
}
return bytesRead;
}
}
/// <summary>
/// Worker thread.
/// </summary>
///
private void WorkerThread( )
{
System.Diagnostics.Stopwatch stopWatch = new System.Diagnostics.Stopwatch( );
// buffer to read stream into
byte[] buffer = new byte[bufferSize];
while (!stopEvent.WaitOne(0, false))
{
try
{
stopWatch.Reset( );
stopWatch.Start( );
int bytesRead = communicator.SendAndReceive(new byte[] { (byte)'I' }, buffer);
bytesReceived += bytesRead;
if (bytesRead > 10)
{
// check for image reply signature
if (
(buffer[0] == (byte)'#') &&
(buffer[1] == (byte)'#') &&
(buffer[2] == (byte)'I') &&
(buffer[3] == (byte)'M') &&
(buffer[4] == (byte)'J'))
{
// extract image size
int imageSize = System.BitConverter.ToInt32(buffer, 6);
if (!stopEvent.WaitOne(0, false))
{
try
{
// decode image from memory stream
Bitmap bitmap = (Bitmap)Bitmap.FromStream(new MemoryStream(buffer, 10, imageSize));
framesReceived++;
// let subscribers know if there are any
if (NewFrame != null)
{
NewFrame(this, new NewFrameEventArgs(bitmap));
}
bitmap.Dispose( );
}
catch
{
}
// wait for a while ?
if (frameInterval > 0)
{
// get download duration
stopWatch.Stop( );
// miliseconds to sleep
int msec = frameInterval - (int)stopWatch.ElapsedMilliseconds;
while ((msec > 0) && (stopEvent.WaitOne(0, false) == false))
{
// sleeping ...
Thread.Sleep((msec < 100) ? msec : 100);
msec -= 100;
}
}
}
}
}
}
catch
{
if (VideoSourceError != null)
{
VideoSourceError(this, new VideoSourceErrorEventArgs("Failed receiving video frame from SRV-1."));
}
}
}
stopWatch.Stop( );
if (PlayingFinished != null)
{
PlayingFinished(this, ReasonToFinishPlaying.StoppedByUser);
}
}