LayerTimelineVisibility class

Controls layer visibility based on Layer.startTime / Layer.endTime relative to the current video time.

The animation progress is derived directly from the video position so that seeking immediately reflects the correct transition state (e.g. seeking to the middle of a 5 s fade-in shows the layer at 50 %).

When Layer.animations is not empty, the transition is phase-aware: each animation drives a fade, slide, scale, wiggle, bounce, spin or flip during the layer's enter window ([startTime, startTime + duration]) and/or exit window ([endTime - duration, endTime]). Multiple animations are composed, so the enter and leave phases can use distinct animation types — something the single (child, animation) LayerTimelineConfigs.transitionBuilder cannot express. The slide effect is edge-aware: using canvasSize and layerCenter it pushes the layer just past the nearest canvas edge (rather than by its own size), so even an off-center layer leaves the visible area completely. A LayerAnimation.slideFrom point replaces that edge with a start position of the caller's own, measured like Layer.offset. The scale effect is anchored on the layer's visual center (via layerFractionalOffset) so that a combined slide + scale enters straight instead of drifting diagonally. A wiggle tilts the layer around the same center, and a bounce lifts it by a multiple of its height, measured on the box around the rotated layer as the exported image is. A spin turns it around that center too, and a flip squeezes it across the axis it turns around before anything turns it. A AnimationPhase.loop repeats for as long as the layer is visible. Text reveals are drawn by the text layer itself. When Layer.animations is empty, the legacy fade convenience driven by Layer.enterDuration / Layer.exitDuration and the LayerTimelineConfigs.transitionBuilder is used instead.

Layer.keyframes place the layer at every point of its time range. The widget's child is laid out at the layer's own placement, so the keyframed one is applied as the difference to it: the layer turns and scales around its visual center and moves by the difference in offset, and its opacity is the keyframes' own. The animations are composed on top of that, as the native renderer composes them on the keyframed placement, and so are the LayerKeyframe.effects between two keyframes while the playhead is there.

Inheritance

Constructors

LayerTimelineVisibility({Key? key, required Layer layer, required ValueNotifier<Duration> playTimeNotifier, required LayerTimelineConfigs configs, required Size canvasSize, required Offset layerCenter, Offset layerFractionalOffset = const Offset(-0.5, -0.5), required Widget child})
Creates a LayerTimelineVisibility.
const

Properties

canvasSize → Size
The size of the editor canvas (in canvas coordinates, origin top-left).
final
child → Widget
The layer widget to show/hide.
final
configs → LayerTimelineConfigs
Animation configuration for the enter/exit transition.
final
hashCode → int
The hash code for this object.
no setterinherited
key → Key?
Controls how one widget replaces another widget in the tree.
finalinherited
layer → Layer
The layer whose time range is evaluated.
final
layerCenter → Offset
The layer's center in canvas coordinates (origin top-left).
final
layerFractionalOffset → Offset
The fractional offset used to position the layer content within its layout box (defaults to Offset(-0.5, -0.5), centering the content).
final
playTimeNotifier → ValueNotifier<Duration>
Notifier that provides the current video playback position.
final
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited

Methods

createElement() → StatefulElement
Creates a StatefulElement to manage this widget's location in the tree.
inherited
createState() → State<LayerTimelineVisibility>
Creates the mutable state for this widget at a given location in the tree.
override
debugDescribeChildren() → List<DiagnosticsNode>
Returns a list of DiagnosticsNode objects describing this node's children.
inherited
debugFillProperties(DiagnosticPropertiesBuilder properties) → void
Add additional properties associated with the node.
inherited
noSuchMethod(Invocation invocation) → dynamic
Invoked when a nonexistent method or property is accessed.
inherited
toDiagnosticsNode({String? name, DiagnosticsTreeStyle? style}) → DiagnosticsNode
Returns a debug representation of the object that is used by debugging tools and by DiagnosticsNode.toStringDeep.
inherited
toString({DiagnosticLevel minLevel = DiagnosticLevel.info}) → String
A string representation of this object.
inherited
toStringDeep({String prefixLineOne = '', String? prefixOtherLines, DiagnosticLevel minLevel = DiagnosticLevel.debug, int wrapWidth = 65}) → String
Returns a string representation of this node and its descendants.
inherited
toStringShallow({String joiner = ', ', DiagnosticLevel minLevel = DiagnosticLevel.debug}) → String
Returns a one-line detailed description of the object.
inherited
toStringShort() → String
A short, textual description of this widget.
inherited

Operators

operator ==(Object other) → bool
The equality operator.
inherited