static void InsertVisibilityVisualIntoTransformChain(
TranslationContext context,
float inProgress,
float outProgress,
ref ContainerVisual root)
{
// Implement the Visibility for the layer. Only needed if the layer becomes visible after
// the LottieComposition's in point, or it becomes invisible before the LottieComposition's out point.
if (inProgress > 0 || outProgress < 1)
{
// Insert a new node to control visibility at the top of the chain.
var visibilityNode = context.ObjectFactory.CreateContainerVisual();
visibilityNode.Children.Add(root);
root = visibilityNode;
var visibilityAnimation = context.ObjectFactory.CreateBooleanKeyFrameAnimation();
if (inProgress > 0)
{
// Set initial value to be non-visible.
visibilityNode.IsVisible = false;
visibilityAnimation.InsertKeyFrame(inProgress, true);
}
if (outProgress < 1)
{
visibilityAnimation.InsertKeyFrame(outProgress, false);
}
visibilityAnimation.Duration = context.LottieComposition.Duration;
Animate.WithKeyFrame(context, visibilityNode, "IsVisible", visibilityAnimation);
}
}
public static bool TryCreateContainerShapeTransformChain(
LayerContext context,
out CompositionContainerShape rootNode,
out CompositionContainerShape contentsNode)
{
// Create containers for the contents in the layer.
// The rootNode is the root for the layer. It may be the same object
// as the contentsNode if there are no inherited transforms and no visibility animation.
//
// +---------------+
// | ... |
// +---------------+
// ^
// |
// +-----------------+
// | visiblityNode |-- Optional visiblity node (only used if the visiblity is animated)
// +-----------------+
// ^
// |
// +-------------------+
// | rootTransformNode |--Transform (values are inherited from root ancestor of the transform tree)
// +-------------------+
// ^
// |
// + - - - - - - - - - - - - +
// | other transforms nodes |--Transform (values inherited from the transform tree)
// + - - - - - - - - - - - - +
// ^
// |
// +-------------------+
// | leafTransformNode |--Transform defined on the layer
// +-------------------+
// ^ ^
// | |
// +---------+ +---------+
// | content | | content | ...
// +---------+ +---------+
//
// Get the opacity of the layer.
var layerOpacity = Optimizer.TrimAnimatable(context, context.Layer.Transform.Opacity);
// Convert the layer's in point and out point into absolute progress (0..1) values.
var inProgress = context.InPointAsProgress;
var outProgress = context.OutPointAsProgress;
if (inProgress > 1 || outProgress <= 0 || inProgress >= outProgress || layerOpacity.IsAlways(LottieData.Opacity.Transparent))
{
// The layer is never visible. Don't create anything.
rootNode = null;
contentsNode = null;
return(false);
}
// Create the transforms chain.
TranslateTransformOnContainerShapeForLayer(context, context.Layer, out var transformsRoot, out contentsNode);
// Implement the Visibility for the layer. Only needed if the layer becomes visible after
// the LottieComposition's in point, or it becomes invisible before the LottieComposition's out point.
if (inProgress > 0 || outProgress < 1)
{
// Create a node to control visibility.
var visibilityNode = context.ObjectFactory.CreateContainerShape();
visibilityNode.Shapes.Add(transformsRoot);
rootNode = visibilityNode;
visibilityNode.SetDescription(context, () => $"Layer: {context.Layer.Name}");
// Animate between Scale(0,0) and Scale(1,1).
var visibilityAnimation = context.ObjectFactory.CreateVector2KeyFrameAnimation();
visibilityAnimation.SetName("ShapeVisibilityAnimation");
if (inProgress > 0)
{
// Set initial value to be non-visible (default is visible).
visibilityNode.Scale = Sn.Vector2.Zero;
visibilityAnimation.InsertKeyFrame(inProgress, Sn.Vector2.One, context.ObjectFactory.CreateHoldThenStepEasingFunction());
}
if (outProgress < 1)
{
visibilityAnimation.InsertKeyFrame(outProgress, Sn.Vector2.Zero, context.ObjectFactory.CreateHoldThenStepEasingFunction());
}
visibilityAnimation.Duration = context.Translation.LottieComposition.Duration;
Animate.WithKeyFrame(context, visibilityNode, nameof(visibilityNode.Scale), visibilityAnimation);
}
else
{
rootNode = transformsRoot;
}
return(true);
}
