RenderProxyBox class

A base class for render boxes that resemble their children.

A proxy box has a single child and mimics all the properties of that child by calling through to the child for each function in the render box protocol. For example, a proxy box determines its size by asking its child to layout with the same constraints and then matching the size.

A proxy box isn't useful on its own because you might as well just replace the proxy box with its child. However, RenderProxyBox is a useful base class for render objects that wish to mimic most, but not all, of the properties of their child.

See also:

Inheritance
Mixed in types
Implementers

Constructors

RenderProxyBox([RenderBox? child])
Creates a proxy render box.

Properties

alwaysNeedsCompositing → bool
Whether this render object always needs compositing.
no setterinherited
attached → bool
Whether the render tree this render object belongs to is attached to a PipelineOwner.
no setterinherited
child ↔ RenderBox?
The render object's unique child.
getter/setter pairinherited
constraints → BoxConstraints
The box constraints most recently received from the parent.
no setterinherited
debugCanParentUseSize → bool
Whether the parent render object is permitted to use this render object's size.
no setterinherited
debugCreator ↔ Object?
The object responsible for creating this render object.
getter/setter pairinherited
debugDisposed → bool?
Whether this has been disposed.
no setterinherited
debugDoingThisLayout → bool
Whether performLayout for this render object is currently running.
no setterinherited
debugDoingThisLayoutWithCallback → bool
Whether invokeLayoutCallback for this render object is currently running.
no setterinherited
debugDoingThisPaint → bool
Whether paint for this render object is currently running.
no setterinherited
debugDoingThisResize → bool
Whether performResize for this render object is currently running.
no setterinherited
debugLayer → ContainerLayer?
In debug mode, the compositing layer that this render object uses to repaint.
no setterinherited
debugLayoutParent → RenderObject?
The RenderObject that's expected to call layout on this RenderObject in its performLayout implementation.
no setterinherited
debugNeedsCompositedLayerUpdate → bool
Whether this render object's layer information is dirty.
no setterinherited
debugNeedsLayout → bool
Whether this render object's layout information is dirty.
no setterinherited
debugNeedsPaint → bool
Whether this render object's paint information is dirty.
no setterinherited
debugSemantics → SemanticsNode?
The semantics of this render object.
no setterinherited
depth → int
The depth of this render object in the render tree.
no setterinherited
hashCode → int
The hash code for this object.
no setterinherited
hasSize → bool
Whether this render object has undergone layout and has a size.
no setterinherited
isRepaintBoundary → bool
Whether this render object repaints separately from its parent.
no setterinherited
layer ↔ ContainerLayer?
The compositing layer that this render object uses to repaint.
getter/setter pairinherited
needsCompositing → bool
Whether we or one of our descendants has a compositing layer.
no setterinherited
owner → PipelineOwner?
The owner for this render object (null if unattached).
no setterinherited
paintBounds → Rect
Returns a rectangle that contains all the pixels painted by this box.
no setterinherited
parent → RenderObject?
The parent of this render object in the render tree.
no setterinherited
parentData ↔ ParentData?
Data for use by the parent render object.
getter/setter pairinherited
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited
semanticBounds → Rect
The bounding box, in the local coordinate system, of this object, for accessibility purposes.
no setterinherited
size ↔ Size
The size of this render box computed during layout.
getter/setter pairinherited
sizedByParent → bool
Whether the constraints are the only input to the sizing algorithm (in particular, child nodes have no impact).
no setterinherited

Methods

adoptChild(RenderObject child) → void
Called by subclasses when they decide a render object is a child.
inherited
applyPaintTransform(covariant RenderObject child, Matrix4 transform) → void
Multiply the transform from the parent's coordinate system to this box's coordinate system into the given transform.
inherited
assembleSemanticsNode(SemanticsNode node, SemanticsConfiguration config, Iterable<SemanticsNode> children) → void
Assemble the SemanticsNode for this RenderObject.
inherited
attach(PipelineOwner owner) → void
Mark this render object as attached to the given owner.
inherited
clearSemantics() → void
Removes all semantics from this render object and its descendants.
inherited
computeDistanceToActualBaseline(TextBaseline baseline) → double?
Returns the distance from the y-coordinate of the position of the box to the y-coordinate of the first given baseline in the box's contents, if any, or null otherwise.
inherited
computeDryBaseline(covariant BoxConstraints constraints, TextBaseline baseline) → double?
Computes the value returned by getDryBaseline.
inherited
computeDryLayout(covariant BoxConstraints constraints) → Size
Computes the value returned by getDryLayout. Do not call this function directly, instead, call getDryLayout.
inherited
computeMaxIntrinsicHeight(double width) → double
Computes the value returned by getMaxIntrinsicHeight. Do not call this function directly, instead, call getMaxIntrinsicHeight.
inherited
computeMaxIntrinsicWidth(double height) → double
Computes the value returned by getMaxIntrinsicWidth. Do not call this function directly, instead, call getMaxIntrinsicWidth.
inherited
computeMinIntrinsicHeight(double width) → double
Computes the value returned by getMinIntrinsicHeight. Do not call this function directly, instead, call getMinIntrinsicHeight.
inherited
computeMinIntrinsicWidth(double height) → double
Computes the value returned by getMinIntrinsicWidth. Do not call this function directly, instead, call getMinIntrinsicWidth.
inherited
computeSizeForNoChild(BoxConstraints constraints) → Size
Calculate the size the RenderProxyBox would have under the given BoxConstraints for the case where it does not have a child.
inherited
debugAdoptSize(Size value) → Size
Claims ownership of the given Size.
inherited
debugAssertDoesMeetConstraints() → void
Verify that the object's constraints are being met. Override this function in a subclass to verify that your state matches the constraints object. This function is only called when asserts are enabled (i.e. in debug mode) and only when needsLayout is false. If the constraints are not met, it should assert or throw an exception.
inherited
debugCannotComputeDryLayout({String? reason, FlutterError? error}) → bool
Called from computeDryLayout or computeDryBaseline within an assert if the given RenderBox subclass does not support calculating a dry layout.
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.
inherited
debugHandleEvent(PointerEvent event, HitTestEntry<HitTestTarget> entry) → bool
Implements the debugPaintPointersEnabled debugging feature.
inherited
debugPaint(PaintingContext context, Offset offset) → void
Override this method to paint debugging information.
inherited
debugPaintBaselines(PaintingContext context, Offset offset) → void
In debug mode, paints a line for each baseline.
inherited
debugPaintPointers(PaintingContext context, Offset offset) → void
In debug mode, paints a rectangle if this render box has counted more pointer downs than pointer up events.
inherited
debugPaintSize(PaintingContext context, Offset offset) → void
In debug mode, paints a border around this render box.
inherited
debugRegisterRepaintBoundaryPaint({bool includedParent = true, bool includedChild = false}) → void
Called, in debug mode, if isRepaintBoundary is true, when either the this render object or its parent attempt to paint.
inherited
debugResetSize() → void
If a subclass has a "size" (the state controlled by parentUsesSize, whatever it is in the subclass, e.g. the actual size property of RenderBox), and the subclass verifies that in debug mode this "size" property isn't used when debugCanParentUseSize isn't set, then that subclass should override debugResetSize to reapply the current values of debugCanParentUseSize to that state.
inherited
debugValidateChild(RenderObject child) → bool
Checks whether the given render object has the correct runtimeType to be a child of this render object.
inherited
describeApproximatePaintClip(covariant RenderObject child) → Rect?
Returns a rect in this object's coordinate system that describes the approximate bounding box of the clip rect that would be applied to the given child during the paint phase, if any.
inherited
describeForError(String name, {DiagnosticsTreeStyle style = DiagnosticsTreeStyle.shallow}) → DiagnosticsNode
Adds a debug representation of a RenderObject optimized for including in error messages.
inherited
describeSemanticsClip(covariant RenderObject? child) → Rect?
Returns a rect in this object's coordinate system that describes which SemanticsNodes produced by the child should be included in the semantics tree. SemanticsNodes from the child that are positioned outside of this rect will be dropped. Child SemanticsNodes that are positioned inside this rect, but outside of describeApproximatePaintClip will be included in the tree marked as hidden. Child SemanticsNodes that are inside of both rect will be included in the tree as regular nodes.
inherited
describeSemanticsConfiguration(SemanticsConfiguration config) → void
Report the semantics of this node, for example for accessibility purposes.
inherited
detach() → void
Mark this render object as detached from its PipelineOwner.
inherited
dispose() → void
Release any resources held by this render object.
inherited
dropChild(RenderObject child) → void
Called by subclasses when they decide a render object is no longer a child.
inherited
getDistanceToActualBaseline(TextBaseline baseline) → double?
Calls computeDistanceToActualBaseline and caches the result.
inherited
getDistanceToBaseline(TextBaseline baseline, {bool onlyReal = false}) → double?
Returns the distance from the y-coordinate of the position of the box to the y-coordinate of the first given baseline in the box's contents.
inherited
getDryBaseline(covariant BoxConstraints constraints, TextBaseline baseline) → double?
Returns the distance from the top of the box to the first baseline of the box's contents for the given constraints, or null if this RenderBox does not have any baselines.
inherited
getDryLayout(covariant BoxConstraints constraints) → Size
Returns the Size that this RenderBox would like to be given the provided BoxConstraints.
inherited
getMaxIntrinsicHeight(double width) → double
Returns the smallest height beyond which increasing the height never decreases the preferred width. The preferred width is the value that would be returned by getMinIntrinsicWidth for that height.
inherited
getMaxIntrinsicWidth(double height) → double
Returns the smallest width beyond which increasing the width never decreases the preferred height. The preferred height is the value that would be returned by getMinIntrinsicHeight for that width.
inherited
getMinIntrinsicHeight(double width) → double
Returns the minimum height that this box could be without failing to correctly paint its contents within itself, without clipping.
inherited
getMinIntrinsicWidth(double height) → double
Returns the minimum width that this box could be without failing to correctly paint its contents within itself, without clipping.
inherited
getTransformTo(RenderObject? target) → Matrix4
Applies the paint transform from this RenderObject to the target RenderObject.
inherited
globalToLocal(Offset point, {RenderObject? ancestor}) → Offset
Convert the given point from the global coordinate system in logical pixels to the local coordinate system for this box.
inherited
handleEvent(PointerEvent event, covariant HitTestEntry<HitTestTarget> entry) → void
Override this method to handle pointer events that hit this render object.
inherited
hitTest(BoxHitTestResult result, {required Offset position}) → bool
Determines the set of render objects located at the given position.
inherited
hitTestChildren(BoxHitTestResult result, {required Offset position}) → bool
Override this method to check whether any children are located at the given position.
inherited
hitTestSelf(Offset position) → bool
Override this method if this render object can be hit even if its children were not hit.
inherited
invokeLayoutCallback<T extends Constraints>(LayoutCallback<T> callback) → void
Allows mutations to be made to this object's child list (and any descendants) as well as to any other dirty nodes in the render tree owned by the same PipelineOwner as this object. The callback argument is invoked synchronously, and the mutations are allowed only during that callback's execution.
inherited
layout(Constraints constraints, {bool parentUsesSize = false}) → void
Compute the layout for this render object.
inherited
localToGlobal(Offset point, {RenderObject? ancestor}) → Offset
Convert the given point from the local coordinate system for this box to the global coordinate system in logical pixels.
inherited
markNeedsCompositedLayerUpdate() → void
Mark this render object as having changed a property on its composited layer.
inherited
markNeedsCompositingBitsUpdate() → void
Mark the compositing state for this render object as dirty.
inherited
markNeedsLayout() → void
Mark this render object's layout information as dirty, and either register this object with its PipelineOwner, or defer to the parent, depending on whether this object is a relayout boundary or not respectively.
inherited
markNeedsLayoutForSizedByParentChange() → void
Mark this render object's layout information as dirty (like markNeedsLayout), and additionally also handle any necessary work to handle the case where sizedByParent has changed value.
inherited
markNeedsPaint() → void
Mark this render object as having changed its visual appearance.
inherited
markNeedsSemanticsUpdate() → void
Mark this node as needing an update to its semantics description.
inherited
markParentNeedsLayout() → void
Mark this render object's layout information as dirty, and then defer to the parent.
inherited
noSuchMethod(Invocation invocation) → dynamic
Invoked when a nonexistent method or property is accessed.
inherited
paint(PaintingContext context, Offset offset) → void
Paint this render object into the given context at the given offset.
inherited
paintsChild(covariant RenderObject child) → bool
Whether the given child would be painted if paint were called.
inherited
performLayout() → void
Do the work of computing the layout for this render object.
inherited
performResize() → void
Updates the render objects size using only the constraints.
inherited
reassemble() → void
Cause the entire subtree rooted at the given RenderObject to be marked dirty for layout, paint, etc, so that the effects of a hot reload can be seen, or so that the effect of changing a global debug flag (such as debugPaintSizeEnabled) can be applied.
inherited
redepthChild(RenderObject child) → void
Adjust the depth of the given child to be greater than this node's own depth.
inherited
redepthChildren() → void
Adjust the depth of this node's children, if any.
inherited
replaceRootLayer(OffsetLayer rootLayer) → void
Replace the layer. This is only valid for the root of a render object subtree (whatever object scheduleInitialPaint was called on).
inherited
scheduleInitialLayout() → void
Bootstrap the rendering pipeline by scheduling the very first layout.
inherited
scheduleInitialPaint(ContainerLayer rootLayer) → void
Bootstrap the rendering pipeline by scheduling the very first paint.
inherited
scheduleInitialSemantics() → void
Bootstrap the semantics reporting mechanism by marking this node as needing a semantics update.
inherited
sendSemanticsEvent(SemanticsEvent semanticsEvent) → void
Sends a SemanticsEvent associated with this render object's SemanticsNode.
inherited
setupParentData(covariant RenderObject child) → void
Override to setup parent data correctly for your children.
inherited
showOnScreen({RenderObject? descendant, Rect? rect, Duration duration = Duration.zero, Curve curve = Curves.ease}) → void
Attempt to make (a portion of) this or a descendant RenderObject visible on screen.
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}) → String
Returns a description of the tree rooted at this node. If the prefix argument is provided, then every line in the output will be prefixed by that string.
inherited
toStringShallow({String joiner = ', ', DiagnosticLevel minLevel = DiagnosticLevel.debug}) → String
Returns a one-line detailed description of the render object. This description is often somewhat long.
inherited
toStringShort() → String
Returns a human understandable name.
inherited
updateCompositedLayer({required covariant OffsetLayer? oldLayer}) → OffsetLayer
Update the composited layer owned by this render object.
inherited
visitChildren(RenderObjectVisitor visitor) → void
Calls visitor for each immediate child of this render object.
inherited
visitChildrenForSemantics(RenderObjectVisitor visitor) → void
Called when collecting the semantics of this node.
inherited

Operators

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