如何从 ExpressionAnimation 控制变量值？

Question

I'm using the AnimatedVisualPlayer within the Microsoft.UI.Xaml.Controls namespace. I want the progress of the animation that is playing back to be available as a double so that I can update the value of progress slider.

The AnimatedVisualPlayer provides a ProgressObject which is a Composition Object which you are supposed to bind to some property via an ExpressionAnimation . Rather then using this object to drive another animation, I would like to have the animations progress available as a value. Is there any simple way to achieve this?

This is what I have tried so far:

 internal void ProgressObjectToValue(CompositionObject ProgressObject)
    {
        var c = Window.Current.Compositor;

        SpriteVisual targetVisual = c.CreateSpriteVisual();

        ExpressionAnimation exp = c.CreateExpressionAnimation($"comp.Progress");

        exp.SetReferenceParameter("comp", ProgressObject);

        targetVisual.StartAnimation("Offset.X", exp);


        double progressValue = targetVisual.Offset.X;

With this, it seems the targetVisuals offset is not bound to the AnimatedVisualPlayer's progress. Thanks for any help you can provide!

Answer 1

I want the progress of the animation that is playing back to be available as a double so that I can update the value of progress slider.

Derive from AnimatedVisualPlayer TestUI project , we use the following to get progress value, during the testing, it always return 0 or 1 value.

var progressPropertySet = (CompositionPropertySet)Playback_Player.ProgressObject;
progressPropertySet.TryGetScalar("progress", out var value);
var progress = value.ToString();

For this scenario, we suggest you use timer to detect animation time, and use it to divide AnimatedVisualPlayer Duration property to get progress.