Struct FollowerLayer 

pub struct FollowerLayer { /* private fields */ }

A composited layer that applies a transformation matrix to its children such that they are positioned to match a LeaderLayer.

If any of the ancestors of this layer have a degenerate matrix (e.g. scaling by zero), then the FollowerLayer will not be able to transform its child to the coordinate space of the LeaderLayer.

A linked_offset property can be provided to further offset the child layer from the leader layer, for example if the child is to follow the linked layer at a distance rather than directly overlapping it.

Implementations

impl FollowerLayer

pub fn new(app: &mut App, link: Handle<LayerLink>) -> Handle<FollowerLayer>

Creates a follower layer.

The unlinked_offset, linked_offset, and show_when_unlinked properties must be non-null before the compositing phase of the pipeline.

pub fn link(self: Handle<Self>, app: &App) -> Handle<LayerLink>

The link to the LeaderLayer.

The same object should be provided to a LeaderLayer that is earlier in the layer tree. When this layer is composited, it will apply a transform that moves its children to match the position of the LeaderLayer.

pub fn set_link(self: Handle<Self>, app: &mut App, value: Handle<LayerLink>)

See link.

pub fn show_when_unlinked(self: Handle<Self>, app: &App) -> bool

Whether to show the layer’s contents when the link does not point to a LeaderLayer.

When the layer is linked, children layers are positioned such that they have the same global position as the linked LeaderLayer.

When the layer is not linked, then: if show_when_unlinked is true, children are positioned as if the FollowerLayer was a ContainerLayer; if it is false, then children are hidden.

The show_when_unlinked property must be non-null before the compositing phase of the pipeline.

pub fn set_show_when_unlinked(self: Handle<Self>, app: &mut App, value: bool)

See show_when_unlinked.

pub fn unlinked_offset(self: Handle<Self>, app: &App) -> Offset

Offset from parent in the parent’s coordinate system, used when the layer is not linked to a LeaderLayer.

The scene must be explicitly recomposited after this property is changed (as described at Layer).

The unlinked_offset property must be non-null before the compositing phase of the pipeline.

See also:

• linked_offset, for when the layers are linked.

pub fn set_unlinked_offset(self: Handle<Self>, app: &mut App, value: Offset)

See unlinked_offset.

pub fn linked_offset(self: Handle<Self>, app: &App) -> Offset

Offset from the origin of the leader layer to the origin of the child layers, used when the layer is linked to a LeaderLayer.

The scene must be explicitly recomposited after this property is changed (as described at Layer).

The linked_offset property must be non-null before the compositing phase of the pipeline.

See also:

• unlinked_offset, for when the layer is not linked.

pub fn set_linked_offset(self: Handle<Self>, app: &mut App, value: Offset)

See linked_offset.

pub fn get_last_transform(self: Handle<Self>, app: &App) -> Option<Matrix4>

The transform that was used during the last composition phase.

If the link was not linked to a LeaderLayer, or if this layer has a degenerate matrix applied, then this will be None.

This method returns a new Matrix4 instance each time it is invoked.

Trait Implementations

impl ContainerLayer for FollowerLayer

fn container_layer_data(self: Handle<Self>, app: &App) -> &ContainerLayerData

Mixin field access.

fn container_layer_data_mut( self: Handle<Self>, app: &mut App, ) -> &mut ContainerLayerData

See container_layer_data.

fn apply_transform( self: Handle<Self>, app: &App, child: Option<AnyLayer>, transform: &mut Matrix4, )

Applies the transform that would be applied when compositing the given child to the given matrix.

const AS_OFFSET: Option<fn() -> &'static OffsetLayerVTable> = None

The offset table when this type extends OffsetLayer; container_layer_accessors!(offset) sets it. Dart’s layer is OffsetLayer.

fn as_container_layer(self: Handle<Self>) -> AnyContainerLayer

Dart’s implicit upcast of a concrete layer to ContainerLayer.

fn fire_composition_callbacks( self: Handle<Self>, app: &mut App, include_children: bool, )

ContainerLayer._fireCompositionCallbacks.

fn supports_rasterization(self: Handle<Self>, app: &App) -> bool

ContainerLayer.supportsRasterization.

fn dispose(self: Handle<Self>, app: &mut App)

ContainerLayer.dispose.

fn find_annotations( self: Handle<Self>, app: &App, result: &mut AnnotationSearch, local_position: Offset, only_first: bool, ) -> bool

ContainerLayer.findAnnotations.

fn attach(self: Handle<Self>, app: &mut App, owner: HandleId)

ContainerLayer.attach.

fn detach(self: Handle<Self>, app: &mut App)

ContainerLayer.detach.

fn redepth_children(self: Handle<Self>, app: &mut App)

ContainerLayer.redepthChildren.

fn add_to_scene(self: Handle<Self>, app: &mut App, builder: &mut SceneBuilder)

ContainerLayer.addToScene.

impl Layer for FollowerLayer

fn always_needs_add_to_scene(self: Handle<Self>, _app: &App) -> bool

A FollowerLayer copies changes from a LeaderLayer that could be anywhere in the layer tree, and that leader layer could change without notifying the follower layer. Therefore a follower layer’s add_to_scene is always called.

const AS_CONTAINER: Option<fn() -> &'static ContainerLayerVTable>

The container table when this type extends ContainerLayer; layer_accessors!(container) sets it. Dart’s layer is ContainerLayer.

fn layer_data(self: Handle<Self>, app: &App) -> &LayerData

Dart’s base-class fields, held under the field layer ([layer_accessors!]).

fn layer_data_mut(self: Handle<Self>, app: &mut App) -> &mut LayerData

See layer_data.

fn supports_rasterization(self: Handle<Self>, app: &App) -> bool

Whether or not this layer, or any child layers, can be rasterized with Scene.toImage.

fn dispose(self: Handle<Self>, app: &mut App)

Clears any retained resources that this layer holds.

fn attach(self: Handle<Self>, app: &mut App, owner: HandleId)

Mark this layer as attached to the given owner.

fn detach(self: Handle<Self>, app: &mut App)

Mark this layer as detached from its owner.

fn redepth_children(self: Handle<Self>, app: &mut App)

Adjust the depth of this node’s children, if any.

fn find_annotations( self: Handle<Self>, app: &App, result: &mut AnnotationSearch, local_position: Offset, only_first: bool, ) -> bool

Search this layer and its subtree for annotations of the searched type at the location described by local_position.

fn add_to_scene(self: Handle<Self>, app: &mut App, builder: &mut SceneBuilder)

Override this method to upload this layer to the engine.

fn fire_composition_callbacks( self: Handle<Self>, app: &mut App, include_children: bool, )

Dart’s _fireCompositionCallbacks; ContainerLayer recurses into its children.

fn describe_clip_bounds(self: Handle<Self>, app: &App) -> Option<Rect>

Describes the clip that would be applied to contents of this layer, if any.