public void Initialize(UIElement host, CompositionImage sourceElement, object payload)
{
_host = host;
_parent = host;
_payload = payload;
// Make a copy of the sourceElement's sprite so we can hand it off to the next page
SpriteVisual sourceSprite = sourceElement.SpriteVisual;
Compositor compositor = sourceSprite.Compositor;
_sprite = compositor.CreateSpriteVisual();
_sprite.Size = sourceSprite.Size;
_sprite.Brush = sourceElement.SurfaceBrush;
// We're going to use the backing surface, make sure it doesn't get released
sourceElement.SharedSurface = true;
// Determine the offset from the host to the source element used in the transition
GeneralTransform coordinate = sourceElement.TransformToVisual(_parent);
Point position = coordinate.TransformPoint(new Point(0, 0));
// Set the sprite to that offset relative to the host
_sprite.Offset = new Vector3((float)position.X, (float)position.Y, 0);
// Set the sprite as the content under the host
ElementCompositionPreview.SetElementChildVisual(_parent, _sprite);
}
public void Start(UIElement newParent, CompositionImage targetImage, ScrollViewer scrollViewer, UIElement animationTarget)
{
Visual transitionVisual = ElementCompositionPreview.GetElementChildVisual(_parent);
ElementCompositionPreview.SetElementChildVisual(_parent, null);
//
// We need to reparent the transition visual under the new parent. This is important to ensure
// it's propertly clipped, etc.
//
GeneralTransform coordinate = newParent.TransformToVisual(_parent);
Point position = coordinate.TransformPoint(new Point(0, 0));
Vector3 currentOffset = transitionVisual.Offset;
currentOffset.X -= (float)position.X;
currentOffset.Y -= (float)position.Y;
transitionVisual.Offset = currentOffset;
_parent = newParent;
_targetImage = targetImage;
// Move the transition visual to it's new parent
ElementCompositionPreview.SetElementChildVisual(_parent, transitionVisual);
// Hide the target Image now since the handoff visual is still transitioning
targetImage.Opacity = 0f;
// Load image if necessary
_imageLoaded = targetImage.IsContentLoaded;
if (!_imageLoaded)
{
targetImage.ImageOpened += CompositionImage_ImageOpened;
}
//
// Create a scoped batch around the animations. When the batch completes, we know the animations
// have finished and we can cleanup the transition related objects.
//
Compositor compositor = transitionVisual.Compositor;
_scopeBatch = compositor.CreateScopedBatch(CompositionBatchTypes.Animation);
//
// Determine the offset between the parent and the target UIElement. This will be used to calculate the
// target position we are animating to.
//
coordinate = targetImage.TransformToVisual(_parent);
position = coordinate.TransformPoint(new Point(0, 0));
TimeSpan totalDuration = TimeSpan.FromMilliseconds(1000);
Vector3KeyFrameAnimation offsetAnimation = compositor.CreateVector3KeyFrameAnimation();
if (scrollViewer != null)
{
CompositionPropertySet scrollProperties = ElementCompositionPreview.GetScrollViewerManipulationPropertySet(scrollViewer);
// Include the scroller offset as that is a factor
position.X += scrollViewer.HorizontalOffset;
position.Y += scrollViewer.VerticalOffset;
//
// Since the target position is relative to the target UIElement which can move, we need to construct
// an expression to bind the target's position to the end position of our animation.
//
string expression = "Vector3(scrollingProperties.Translation.X, scrollingProperties.Translation.Y, 0) + itemOffset";
offsetAnimation.InsertExpressionKeyFrame(1f, expression);
offsetAnimation.SetReferenceParameter("scrollingProperties", scrollProperties);
offsetAnimation.SetVector3Parameter("itemOffset", new Vector3((float)position.X, (float)position.Y, 0));
offsetAnimation.Duration = totalDuration;
}
else
{
offsetAnimation.InsertKeyFrame(1, new Vector3((float)position.X, (float)position.Y, 0));
offsetAnimation.Duration = totalDuration;
}
// Create size animation to change size of the visual
Vector2KeyFrameAnimation sizeAnimation = compositor.CreateVector2KeyFrameAnimation();
sizeAnimation.InsertKeyFrame(1f, new Vector2((float)targetImage.ActualWidth, (float)targetImage.ActualHeight));
sizeAnimation.Duration = totalDuration;
// Create the fade in animation for the other page content
if (animationTarget != null)
{
Visual fadeVisual = ElementCompositionPreview.GetElementVisual(animationTarget);
ScalarKeyFrameAnimation fadeIn = compositor.CreateScalarKeyFrameAnimation();
fadeIn.InsertKeyFrame(0f, 0.0f);
fadeIn.InsertKeyFrame(1f, 1.0f);
fadeIn.Duration = totalDuration;
fadeVisual.StartAnimation("Opacity", fadeIn);
}
//Start Animations
_sprite.StartAnimation("Size", sizeAnimation);
_sprite.StartAnimation("Offset", offsetAnimation);
//Scoped batch completed event
_scopeBatch.Completed += ScopeBatch_Completed;
_scopeBatch.End();
// Clear the flag
_animationCompleted = false;
}