private void ConfigSpringBasedTracker(UIElement element, double periodInMs,
float dampingRatio, float finalValue = 0.0f, double delayInMs = 0.0f)
{
ElementCompositionPreview.SetIsTranslationEnabled(element, true);
var tracker = InteractionTracker.Create(_compositor);
tracker.InteractionSources.Add(_interactionSource);
tracker.MaxPosition = new Vector3(Root.RenderSize.ToVector2(), 0.0f);
tracker.MinPosition = -tracker.MaxPosition;
var modifier = InteractionTrackerInertiaNaturalMotion.Create(_compositor);
var springAnimation = _compositor.CreateSpringScalarAnimation();
springAnimation.Period = TimeSpan.FromMilliseconds(periodInMs);
springAnimation.DampingRatio = dampingRatio;
springAnimation.FinalValue = finalValue;
// This will cause a black screen for a few seconds. Bug??
springAnimation.DelayTime = TimeSpan.FromMilliseconds(delayInMs);
modifier.Condition = _compositor.CreateExpressionAnimation("true");
modifier.NaturalMotion = springAnimation;
tracker.ConfigurePositionXInertiaModifiers(new InteractionTrackerInertiaModifier[] { modifier });
tracker.ConfigurePositionYInertiaModifiers(new InteractionTrackerInertiaModifier[] { modifier });
var imageVisual = ElementCompositionPreview.GetElementVisual(element);
imageVisual.StartAnimation("Translation", -tracker.GetReference().Position);
}
private void ActivateSpringForce()
{
#if SDKVERSION_15063
//
// On newer builds, use the Spring NaturalMotion
//
if (MainPage.RuntimeCapabilities.IsSdkVersionRuntimeSupported(RuntimeSupportedSDKs.SDKVERSION._15063))
{
var modifier = InteractionTrackerInertiaNaturalMotion.Create(_compositor);
var springAnimation = _compositor.CreateSpringScalarAnimation();
springAnimation.Period = TimeSpan.FromSeconds(.15);
springAnimation.DampingRatio = .4f;
springAnimation.FinalValue = 0.0f;
modifier.Condition = _compositor.CreateExpressionAnimation("true");
modifier.NaturalMotion = springAnimation;
_tracker.ConfigurePositionYInertiaModifiers(new InteractionTrackerInertiaModifier[] { modifier });
}
//
// On older builds, use a custom force that behaves like a spring
//
else
#endif
{
var dampingConstant = 5;
var springConstant = 20;
var modifier = InteractionTrackerInertiaMotion.Create(_compositor);
// Set the condition to true (always)
modifier.SetCondition((BooleanNode)true);
// Define a spring-like force, anchored at position 0.
var target = ExpressionValues.Target.CreateInteractionTrackerTarget();
modifier.SetMotion((-target.Position.Y * springConstant) - (dampingConstant * target.PositionVelocityInPixelsPerSecond.Y));
_tracker.ConfigurePositionYInertiaModifiers(new InteractionTrackerInertiaModifier[] { modifier });
}
}
