public override void Execute()
{
if (_undoCommand != null)
{
throw new InvalidOperationException("The command has already been executed.");
}
_parentCollection.Add(_graphic);
_undoCommand = new RemoveGraphicCommand(_graphic);
_parentCollection = null;
_graphic = null;
}
private void DoFlash(IPresentationImage image, SynchronizationContext syncContext)
{
if (!(image is IOverlayGraphicsProvider))
{
return;
}
GraphicCollection overlayGraphics = ((IOverlayGraphicsProvider)image).OverlayGraphics;
//Prevent multiple flash graphics per image.
var existing = overlayGraphics.OfType <FlashOverlayGraphic>().Where(g => g.Controller == this).FirstOrDefault();
if (existing != null)
{
return;
}
//Very little utility in flashing if nobody's looking at it.
if (syncContext == null)
{
return;
}
var flashOverlayGraphic = new FlashOverlayGraphic(this);
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);
}