private void DoFlash(IPresentationImage image, SynchronizationContext syncContext, string message)
{
if (!(image is IOverlayGraphicsProvider))
{
return;
}
GraphicCollection overlayGraphics = ((IOverlayGraphicsProvider)image).OverlayGraphics;
// Prevent multiple flash graphics per image.
var existing = overlayGraphics.OfType <FlashOverlayGraphic>().FirstOrDefault(g => g.Controller == this);
if (existing != null)
{
return;
}
// Very little utility in flashing if nobody's looking at it.
if (syncContext == null)
{
return;
}
var flashOverlayGraphic = new FlashOverlayGraphic(this, message);
overlayGraphics.Add(flashOverlayGraphic);
image.Draw();
ThreadPool.QueueUserWorkItem(
delegate
{
Thread.Sleep(FlashSpeed);
syncContext.Post(delegate
{
if (flashOverlayGraphic.IsDisposed)
{
return;
}
overlayGraphics.Remove(flashOverlayGraphic);
image.Draw();
}, null);
}, null);
}