无法以编程方式在WPF中设置动画控件的宽度或高度（甚至无法通过Snoop设置）

Question

This may be animation related. I have a WPF control whose width and height I'm animating through several different storyboards. I create the storyboards and then call Begin() on them. I've provided code for how the storyboards look below.

I want to re-evaluate the control size on some event (eg window resize) so that it is different from the value that was animated. I attempt to handle this on SizeChanged manually (after the animation has run) by setting the Width and Height properties of my control. The debugger shows that those values are not set (the original values remain).

When I inspect the WPF through Snoop, the Width and Height rows are highlighted in a peach/orange color and trying to set the values through it again does not persist it (the original value is shown when I focus away. My guess is that my animation is somehow overriding manual changes to the property but I'm not sure if this is true or how to solve it.

Storyboard Class

public class MyAnimationClass
{
    private Storyboard _myStoryboard;
    private DoubleAnimation _animation1;
    private DoubleAnimation _animation2;
    private DoubleAnimation _animation3;

    private void InitializeStoryboard()
    {
        _myStoryboard = CreateMyStoryboard(out _animation1, out _animation2, out _animation3);
    }

    private Storyboard CreateMyStoryboard(out DoubleAnimation animation1, out DoubleAnimation animation2, out DoubleAnimation animation3)
    {
        var myStoryboard = new Storyboard();

        // create animations
        animation1 = new DoubleAnimation { Duration = new TimeSpan(0, 0, 0, 0, 250), From = 0, To = 0 };
        animation2 = new DoubleAnimation { BeginTime = new TimeSpan(), Duration = new TimeSpan(0, 0, 0, 0, 250), From = 35, To = 35 };
        animation3 = new DoubleAnimation { BeginTime = new TimeSpan(0, 0, 0, 0, 250), Duration = new TimeSpan(0, 0, 0, 0, 250), From = 35, To = 0 };

        Storyboard.SetTargetProperty(animation1, new PropertyPath(FrameworkElement.WidthProperty));
        Storyboard.SetTargetProperty(animation2, new PropertyPath(FrameworkElement.HeightProperty));
        Storyboard.SetTargetProperty(animation3, new PropertyPath(FrameworkElement.HeightProperty));

        myStoryboard.Children.Add(animation1);
        myStoryboard.Children.Add(animation2);
        myStoryboard.Children.Add(animation3);

        return myStoryboard;
    }

    public void Animate(Control controlToAnimate)
    {
        // ....

        var finalWidth = CalculateFinalWidth();
        var finalHeight = CalculateFinalHeight();

        _animation1.To = finalWidth;
        _animation3.To = finalHeight;
        _myStoryboard.Begin(controlToAnimate);
    }
}

When I want to animate something, I call Animate() on the instance of my MyAnimationClass class.

Thoughts?

Answer 1

This ended up being a pretty simple fix. The value wasn't changing because of FillBehavior controlling the property value. However, simply changing it to FillBehavior.Stop didn't solve my problem because when my non-animation code set width/height, the next time my animation ran it would animate to the width/height I wanted and then default back to the set height. This was solved by setting the width/height of the control after calculation and before animation:

public void Animate(Control controlToAnimate)
{
    // ....

    var finalWidth = CalculateFinalWidth();
    var finalHeight = CalculateFinalHeight();

    // set values here so after animation they stay
    controlToAnimate.Width = finalWidth;
    controlToAnimate.Height = finalHeight;

    _animation1.To = finalWidth;
    _animation3.To = finalHeight;
    _myStoryboard.Begin(controlToAnimate);
}