/*
** Method Name: StartTaskSpawner()
** Parameters: None.
** Return Values: Void.
** Description: This method is used to spawn (start/create) a worker task that will continue to loop until the _StopFlag is changed to true.
** The task can be paused with the _PauseFlag. When operating in active mode it constantly generates lines and passes them to the UI thread's dispatcher.
** The task will allow lines to remain on the screen according to the _TailLength variable, lines beyond this value will be removed.
** After the line has been drawn the task sleeps for a time determined by the value of _SleepTimeInMilliSeconds.
** Also, a reference to the task will be placed into the list called TaskPool, so it can be referenced later.
*/
public void StartTaskSpawner()
{
LineGenerator myLineGenerator = new LineGenerator();
Brush ThreadColour = GetRandomBrushColour();
// Spawning the task (thread) that will perform the work of constantly generating new lines and sending them to the UI thread. Can be stopped via _StopFlag.
Task t = Task.Run(() =>
{
Queue <Line> LineQue = new Queue <Line>();
while (_StopFlag == false)
{
while (_PauseFlag == true)
{
Thread.Sleep(_SpawnTimeInMilliSeconds);
}
// I am putting this check in to ensure that no more lines are drawn once the stop flag has tripped.
if (_StopFlag == true)
{
break;
}
// This use of the dispatcher is necessary to have the UI thread access and told to draw the lines that we are generating.
ActiveCanvas.Dispatcher.BeginInvoke(System.Windows.Threading.DispatcherPriority.Send, (Action)(() =>
{
// Generate a new line.
Line myLine = new Line();
myLineGenerator.CalculateNewLinePoints(myLine);
myLine.Stroke = ThreadColour;
// Add the line to the collection of elements for the ActiveCanvas.
ActiveCanvas.Children.Add(myLine);
// Add the line to the que of lines.
LineQue.Enqueue(myLine);
// This code clears up the extra lines, once the desired number of tails has been reached.
while (LineQue.Count >= (_TailLength + 1))
{
ActiveCanvas.Children.Remove(LineQue.Dequeue());
}
}));
// This sleep command determines how fast the lines are generated, reducing the time here equals faster line generation.
Thread.Sleep(_SpawnTimeInMilliSeconds);
}
});
TaskPool.Add(t);
}
