OpacityLayer class
A composited layer that makes its children partially transparent.
When debugging, setting debugDisableOpacityLayers to true will cause this layer to be skipped (directly replaced by its children). This can be helpful to track down the cause of performance problems.
Try to avoid an OpacityLayer with no children. Remove that layer if possible to save some tree walks.
- Inheritance
-
- Object
- Layer
- ContainerLayer
- OffsetLayer
- OpacityLayer
Constructors
- OpacityLayer({int? alpha, Offset offset = Offset.zero})
- Creates an opacity layer.
Properties
- alpha ↔ int?
-
The amount to multiply into the alpha channel.
getter/setter pair
- alwaysNeedsAddToScene → bool
-
Subclasses may override this to true to disable retained rendering.
no setterinherited
- attached → bool
-
Whether the layer tree containing this layer is attached to an owner.
no setterinherited
- debugCreator ↔ Object?
-
The object responsible for creating this layer.
getter/setter pairinherited
- debugDisposed → bool
-
If asserts are enabled, returns whether dispose has
been called since the last time any retained resources were created.
no setterinherited
- debugHandleCount → int
-
Returns the number of objects holding a LayerHandle to this layer.
no setterinherited
- debugSubtreeNeedsAddToScene → bool?
-
Whether this or any descendant layer in the subtree needs addToScene.
no setterinherited
- depth → int
-
The depth of this layer in the layer tree.
no setterinherited
- engineLayer ↔ EngineLayer?
-
Stores the engine layer created for this layer in order to reuse engine
resources across frames for better app performance.
getter/setter pairinherited
- firstChild → Layer?
-
The first composited layer in this layer's child list.
no setterinherited
- hasChildren → bool
-
Returns whether this layer has at least one child layer.
no setterinherited
- hashCode → int
-
The hash code for this object.
no setterinherited
- lastChild → Layer?
-
The last composited layer in this layer's child list.
no setterinherited
- nextSibling → Layer?
-
This layer's next sibling in the parent layer's child list.
no setterinherited
- offset ↔ Offset
-
Offset from parent in the parent's coordinate system.
getter/setter pairinherited
- owner → Object?
-
The owner for this layer (null if unattached).
no setterinherited
- parent → ContainerLayer?
-
This layer's parent in the layer tree.
no setterinherited
- previousSibling → Layer?
-
This layer's previous sibling in the parent layer's child list.
no setterinherited
- runtimeType → Type
-
A representation of the runtime type of the object.
no setterinherited
- subtreeHasCompositionCallbacks → bool
-
Whether the subtree rooted at this layer has any composition callback
observers.
no setterinherited
Methods
-
addChildrenToScene(
SceneBuilder builder) → void -
Uploads all of this layer's children to the engine.
inherited
-
addCompositionCallback(
CompositionCallback callback) → VoidCallback -
Adds a callback for when the layer tree that this layer is part of gets
composited, or when it is detached and will not be rendered again.
inherited
-
addToScene(
SceneBuilder builder) → void -
Override this method to upload this layer to the engine.
override
-
append(
Layer child) → void -
Adds the given layer to the end of this layer's child list.
inherited
-
applyTransform(
Layer? child, Matrix4 transform) → void -
Applies the transform that would be applied when compositing the given
child to the given matrix.
inherited
-
attach(
covariant Object owner) → void -
Mark this layer as attached to the given owner.
inherited
-
buildScene(
SceneBuilder builder) → Scene -
Consider this layer as the root and build a scene (a tree of layers)
in the engine.
inherited
-
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.
override
-
debugMarkClean(
) → void -
Mark that this layer is in sync with engine.
inherited
-
depthFirstIterateChildren(
) → List< Layer> -
Returns the descendants of this layer in depth first order.
inherited
-
describeClipBounds(
) → Rect? -
Describes the clip that would be applied to contents of this layer,
if any.
inherited
-
detach(
) → void -
Mark this layer as detached from its owner.
inherited
-
dispose(
) → void -
Clears any retained resources that this layer holds.
inherited
-
find<
S extends Object> (Offset localPosition) → S? -
Search this layer and its subtree for the first annotation of type
Sunder the point described bylocalPosition.inherited -
findAllAnnotations<
S extends Object> (Offset localPosition) → AnnotationResult< S> -
Search this layer and its subtree for all annotations of type
Sunder the point described bylocalPosition.inherited -
findAnnotations<
S extends Object> (AnnotationResult< S> result, Offset localPosition, {required bool onlyFirst}) → bool -
Search this layer and its subtree for annotations of type
Sat the location described bylocalPosition.inherited -
markNeedsAddToScene(
) → void -
Mark that this layer has changed and addToScene needs to be called.
inherited
-
noSuchMethod(
Invocation invocation) → dynamic -
Invoked when a nonexistent method or property is accessed.
inherited
-
redepthChild(
Layer child) → void -
Adjust the depth of the given
childto be greater than this node's own depth.inherited -
redepthChildren(
) → void -
Adjust the depth of this node's children, if any.
inherited
-
remove(
) → void -
Removes this layer from its parent layer's child list.
inherited
-
removeAllChildren(
) → void -
Removes all of this layer's children from its child list.
inherited
-
supportsRasterization(
) → bool -
Whether or not this layer, or any child layers, can be rasterized with
ui.Scene.toImage or ui.Scene.toImageSync.
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
-
toImage(
Rect bounds, {double pixelRatio = 1.0}) → Future< Image> -
Capture an image of the current state of this layer and its children.
inherited
-
toImageSync(
Rect bounds, {double pixelRatio = 1.0}) → Image -
Capture an image of the current state of this layer and its children.
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 brief description of this object, usually just the runtimeType and the
hashCode.
inherited
-
updateSubtreeNeedsAddToScene(
) → void -
Traverses the layer subtree starting from this layer and determines whether it needs addToScene.
inherited
Operators
-
operator ==(
Object other) → bool -
The equality operator.
inherited