/// <summary>
/// Returns an array of Wintab data packets from the packet queue.
/// </summary>
/// <param name="maxPkts_I">Specifies the maximum number of packets to return.</param>
/// <param name="remove_I">If true, returns data packets and removes them from the queue.</param>
/// <param name="numPkts_O">Number of packets actually returned.</param>
/// <returns>Returns the next maxPkts_I from the list. Note that if remove_I is false, then
/// repeated calls will return the same packets. If remove_I is true, then packets will be
/// removed and subsequent calls will get different packets (if any).</returns>
public WintabPacket[] GetDataPackets(UInt32 maxPkts_I, bool remove_I, ref UInt32 numPkts_O)
{
WintabPacket[] packets = null;
try {
CheckForValidHCTX("GetDataPackets");
if (maxPkts_I == 0)
{
throw new Exception("GetDataPackets - maxPkts_I is zero.");
}
// Packet array is used whether we're just looking or buying.
int size = (int)(maxPkts_I * Marshal.SizeOf(new WintabPacket()));
IntPtr buf = WMemUtils.AllocUnmanagedBuf(size);
if (remove_I)
{
// Return data packets and remove packets from queue.
numPkts_O = WNativeMethods.WTPacketsGet(m_context.HCtx, maxPkts_I, buf);
packets = WMemUtils.MarshalDataPackets(numPkts_O, buf);
//System.Diagnostics.Debug.WriteLine("GetDataPackets: numPkts_O: " + numPkts_O);
}
else
{
// Return data packets, but leave on queue. (Peek mode)
UInt32 pktIDOldest = 0;
UInt32 pktIDNewest = 0;
// Get oldest and newest packet identifiers in the queue. These will bound the
// packets that are actually returned.
if (WNativeMethods.WTQueuePacketsEx(m_context.HCtx, ref pktIDOldest, ref pktIDNewest))
{
UInt32 pktIDStart = pktIDOldest;
UInt32 pktIDEnd = pktIDNewest;
if (pktIDStart == 0)
{
throw new Exception("WTQueuePacketsEx reports zero start packet identifier");
}
if (pktIDEnd == 0)
{
throw new Exception("WTQueuePacketsEx reports zero end packet identifier");
}
// Peek up to the max number of packets specified.
UInt32 numFoundPkts = WNativeMethods.WTDataPeek(m_context.HCtx, pktIDStart, pktIDEnd, maxPkts_I, buf, ref numPkts_O);
System.Diagnostics.Debug.WriteLine("GetDataPackets: WTDataPeek - numFoundPkts: " + numFoundPkts + ", numPkts_O: " + numPkts_O);
if (numFoundPkts > 0 && numFoundPkts < numPkts_O)
{
throw new Exception("WTDataPeek reports more packets returned than actually exist in queue.");
}
packets = WMemUtils.MarshalDataPackets(numPkts_O, buf);
}
}
} catch (Exception ex) {
throw new Exception("FAILED GetPacketDataRange: " + ex.ToString());
}
return(packets);
}