private void AdornedElement_MouseMove(object sender, MouseEventArgs e)
{
if (dragging)
{
Point mousePosition = e.GetPosition(null);
Vector offset = mousePosition - dragStartMousePosition;
TranslateTransform transform = AdornedElement.RenderTransform as TranslateTransform;
transform.X = dragStartElementPosition.X + offset.X;
transform.Y = dragStartElementPosition.Y + offset.Y;
transform.X -= transform.X % CellSize;
transform.Y -= transform.Y % CellSize;
AdornedElement.InvalidateVisual();
}
}