public void MouseUpHandler(object sender, MouseEventArgs e) { if (e.LeftButton == MouseButtonState.Released) { if (rectW != 0 && rectH != 0 && currentPoint.X != 0 && currentPoint.Y != 0) { if (rectW < 0) { currentPoint.X = currentPoint.X + rectW; rectW = -rectW; } if (rectH < 0) { currentPoint.Y = currentPoint.Y + rectH; rectH = -rectH; } RemoveTempMarker(); MainWindow mv = Application.Current.Windows.OfType <MainWindow>().FirstOrDefault(); tmpRect = DrawCanvas.Rect(currentPoint.X, currentPoint.Y, (int)rectW, (int)rectH, Brushes.Red, mv.CanvasResult, 0.3); currentPoint = default(Point); rectW = 0; rectH = 0; } } }