RenderObjectWithSingleChild mixin

Mixin for render objects that own a single render child.

Codifies the RenderProxyBox.child= idempotent setter pattern as the single ownership boundary for single-child render objects. Re-assigning the same child or one already adopted via adoptChild must be safe (no double adoption).

Superclass constraints

• RenderObject

Mixin applications

• RenderConstrainedBox
• RenderDecoratedBox
• RenderPadding
• RenderPositionedBox
• RenderProxyBox

Properties

children → List<RenderObject>

Child RenderObjects

final, inherited

debugNeedsLayout → bool

Whether this render object is waiting for layout.

no setter, inherited

debugNeedsPaint → bool

Whether this render object is waiting for paint.

no setter, inherited

hashCode → int

The hash code for this object.

no setter, inherited

height ↔ int

Height in terminal cells, assigned during layout.

getter/setter pair, inherited

parent ↔ RenderObject?

Parent RenderObject in the tree

getter/setter pair, inherited

pipelineOwner → PipelineOwner?

The pipeline owner this render object is attached to, if any.

no setter, inherited

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

width ↔ int

Width in terminal cells, assigned during layout.

getter/setter pair, inherited

x ↔ int

Horizontal position in terminal cells, relative to the parent.

getter/setter pair, inherited

y ↔ int

Vertical position in terminal cells, relative to the parent.

getter/setter pair, inherited

Methods

adoptChild(RenderObject child) → void

Add a child to this render object

inherited

attach(PipelineOwner owner) → void

Attach this render object and its existing children to owner.

inherited

detach() → void

Called when the render object is detached from the render tree.

inherited

dropChild(RenderObject child) → void

Remove a child from this render object

inherited

hitTest(HitTestResult result, Offset position) → bool

Hit-test this render object using position in local coordinates.

inherited

layout(Constraints constraints) → void

Entry point for layout.

inherited

markNeedsLayout() → void

Mark this render object as needing layout and paint.

inherited

markNeedsPaint() → void

Mark this render object as needing paint.

inherited

noSuchMethod(Invocation invocation) → dynamic

Invoked when a nonexistent method or property is accessed.

inherited

paint(PaintingContext context, Offset offset) → void

Paint protocol: record drawing commands at offset.

inherited

performLayout(Constraints constraints) → void

Layout protocol: given constraints, compute size and position.

inherited

setChild(RenderObject? child) → void

Replace this object's single render child.

toString() → String

A string representation of this object.

inherited

updateChild(RenderObject? current, RenderObject? next) → RenderObject?

Drop current and adopt next, returning next as the new child.

visitChildren(void visitor(RenderObject child)) → void

Visit all children with a callback

inherited

Operators

operator ==(Object other) → bool

The equality operator.

inherited