/// <summary>Returns the current RTT encoding as an XML element, and then immediately starts a new RTT fragment</summary>
public XmlElement GetEncodedRTT()
{
XmlElement rttEncoded = rtt;
rttEncoded.SetAttribute("xmlns", RealTimeText.NAMESPACE);
if (newMsg)
{
// The first RTT element of a new message always has event='new'
// (i.e. This rtt element contains the first character of real time text)
rttEncoded.SetAttribute("event", "new");
newMsg = false;
seq = (uint)random.Next(1000000); // Generates up to a 6-digit random number. XEP-0301 recommends randomization, and keeping numbers compact for bandwidth savings
if (redundancy)
{
redundancyClock.Reset();
redundancyClock.Start();
}
}
else
{
// Error recovery/fault tolerance: Automatic retransmission
if (redundancy &&
(redundancyClock.ElapsedMilliseconds > redundancyInterval))
{
fullMessageTransmit = true;
redundancyClock.Reset();
redundancyClock.Start();
}
// Automatic and/or manually forced message retransmission
if (fullMessageTransmit)
{
rttEncoded.SetAttribute("event", "reset");
if ((messagePrevious.CursorPos != -1) &&
(messagePrevious.CursorPos != messagePrevious.Text.Length))
{
// For clients supporting an optional remote cursor position, a blank INSERT TEXT <t/> elements sets the cursor position.
XmlElement resetPos = rttEncoded.OwnerDocument.CreateElement("t");
resetPos.SetAttribute("p", messagePrevious.CursorPos.ToString());
rtt.PrependChild(resetPos);
}
if (messagePrevious.Text.Length > 0)
{
// Retransmission of full message text in an INSERT TEXT <t/> element.
XmlElement resetText = rttEncoded.OwnerDocument.CreateElement("t");
resetText.InnerText = messagePrevious.Text;
rtt.PrependChild(resetText);
}
}
}
rttEncoded.SetAttribute("seq", seq.ToString());
seq++;
fullMessageTransmit = false;
messagePrevious = message.Clone();
// Create new RTT element for next message.
rtt = doc.CreateElement(RealTimeText.ROOT);
if (DEBUG_CONSOLE_XML) Console.WriteLine("outgoing rtt: " + rttEncoded.OuterXml.ToString());
return rttEncoded;
}
/// <summary>Encodes RTT fragment for the specified text. This encoder compares this text to the previous state of text, and generates a compact RTT code for this text</summary>
/// <param name="text">Current state of message text</param>
/// <param name="cursorPos">Current position index within text, for optional remote cursor</param>
public void Encode(string text, int cursorPos)
{
if (text == null) text = message.Text;
bool textChanged = (text != message.Text);
bool posChanged = (cursorPos != -1) && (cursorPos != message.CursorPos);
if (textChanged || posChanged)
{
// If necessary, generate the 'w' interval action element
if (message.KeyIntervalsEnabled)
{
if (!rtt.HasChildNodes) delayCalculator.Start(); // Delay calculator starts on first rtt element.
int milliseconds = delayCalculator.GetMillisecondsSinceLastCall();
if (milliseconds > 0)
{
if (milliseconds > transmitInterval) milliseconds = transmitInterval; // Limit delays to maximum interval.
RealTimeText.AppendElement.WaitInterval(rtt, milliseconds);
}
}
// Encode the text differences since last message, into action elements.
RealTimeText.Message newMessage = new RealTimeText.Message(text, cursorPos);
RealTimeText.EncodeRawRTT(rtt, message, newMessage);
message.Text = text;
message.CursorPos = cursorPos;
}
}