WPF: Measure/Arrange gets called only once during animation

Question

I'm working on a custom grid-like panel where one element can be zoomed. First, all elements have the same size. If one should be zoomed, it gets twice its previous size and the rest of the elements fill the remaining space uniformly (so, all elements except the ones in the same row or column with the zoomed element get smaller height and width, the ones in the same row get a smaller width and zoomed height, etc.).

Everything worked fine until I added animations for the zoom.

I'm calculating the size of each element in the measure pass and at first I was measuring each element with its calculated size. The elements itself have NaN as size until they get zoomed. I'm zooming them by setting them to their final size and then start doubleanimations from old to new.

However when I added animations, measure and arrange were only called for the first animation step. And when I tried to measure the elements with availableSize or an infinite size the animation worked fine but the elements didn't proper resize in the dimensions where they got smaller.

Does anyone know how to solve either one of those behaviors?

Regards Tobias

Edit: Code for animations:

        Size normalSize = GetNormalElementSize(new Size(ActualWidth, ActualHeight));

        DoubleAnimation widthAnimation = new DoubleAnimation
        {
            From = normalSize.Width,
            To = normalSize.Width * 2,
            Duration = TimeSpan.FromMilliseconds(750),
            EasingFunction = new QuadraticEase { EasingMode = EasingMode.EaseInOut }
        };

        DoubleAnimation heightAnimation = new DoubleAnimation
        {
            From = normalSize.Height,
            To = normalSize.Height * 2,
            Duration = TimeSpan.FromMilliseconds(750),
            EasingFunction = new QuadraticEase { EasingMode = EasingMode.EaseInOut }
        };

        ZoomedElement.Height = normalSize.Height;
        ZoomedElement.Width = normalSize.Width;

        Storyboard.SetTargetProperty(widthAnimation, new PropertyPath(FrameworkElement.WidthProperty));
        Storyboard.SetTarget(widthAnimation, ZoomedElement);
        Storyboard.SetTargetProperty(heightAnimation, new PropertyPath(FrameworkElement.HeightProperty));
        Storyboard.SetTarget(heightAnimation, ZoomedElement);

        Storyboard zoomStoryboard = new Storyboard();
        zoomStoryboard.Children.Add(heightAnimation);
        zoomStoryboard.Children.Add(widthAnimation);
        zoomStoryboard.CurrentTimeInvalidated += zoomStoryboard_CurrentTimeInvalidated;
        zoomStoryboard.Begin();

Answer 1

I guess you are using RenderTransformation, try LayoutTransformation instead.