如何在动画中显示从下到上的窗口?

static int screenWidth = (int)SystemParameters.WorkArea.Width;
static int screenHeight = (int)SystemParameters.WorkArea.Height;

int heightAvail = ((screenHeight - intHeight) / 2);
int widthAvail = ((screenWidth - intWidth) / 2);
DoubleAnimation animation = new DoubleAnimation(widthAvail, widthAvail, TimeSpan.FromMilliseconds(300));
DoubleAnimation animationT = new DoubleAnimation(1920, heightAvail, TimeSpan.FromMilliseconds(300));
objUIElement.BeginAnimation(Window.LeftProperty, animation);
objUIElement.BeginAnimation(Window.TopProperty, animationT);
static int screenWidth = (int)SystemParameters.