private static void Element_MouseWheel(object sender, MouseWheelEventArgs e)
{
var element = sender as FrameworkElement;
var parent = element.Parent as FrameworkElement;
var transforms = (element.RenderTransform as TransformGroup).Children;
var translate = transforms.GetTranslate();
var scale = transforms.GetScale();
//ZoomSpeed
var zoom = e.Delta > 0 ? .2 : -.2;
var relative = e.GetPosition(element);
var absolute = e.GetAbsolutePosition(element);
//必須是scale先，translate後
var ToScale = Math.Clamp(scale.ScaleX + zoom, GetMaximum(element), 1);
var ToX = Math.Clamp(absolute.X - relative.X * ToScale, 0, element.ActualWidth * (1 - ToScale));
var ToY = Math.Clamp(absolute.Y - relative.Y * ToScale, 0, element.ActualHeight * (1 - ToScale));
scale.BeginAnimation(ScaleTransform.ScaleXProperty, ToScale, WheelTime);
scale.BeginAnimation(ScaleTransform.ScaleYProperty, ToScale, WheelTime);
translate.BeginAnimation(TranslateTransform.XProperty, ToX, WheelTime);
translate.BeginAnimation(TranslateTransform.YProperty, ToY, WheelTime);
}