Struct MultiChildLayoutChildren 

pub struct MultiChildLayoutChildren { /* private fields */ }

The children a MultiChildLayoutDelegate lays out, keyed by their MultiChildLayoutParentData::id.

Dart’s MultiChildLayoutDelegate._idToChild and, in debug builds, its _debugChildrenNeedingLayout. RenderCustomMultiChildLayoutBox builds one from its child list and hands it to MultiChildLayoutDelegate::perform_layout.

Implementations

impl MultiChildLayoutChildren

pub fn has_child(&self, child_id: &ChildLayoutId) -> bool

True if a non-None child was provided for the specified id.

Call this from MultiChildLayoutDelegate::perform_layout to determine which children are available, if the child list might vary.

This cannot be called from MultiChildLayoutDelegate::get_size as the size is not allowed to depend on the children.

pub fn layout_child( &mut self, app: &mut App, child_id: &ChildLayoutId, constraints: BoxConstraints, ) -> Size

Ask the child to update its layout within the limits specified by the constraints parameter. The child’s size is returned.

Call this from MultiChildLayoutDelegate::perform_layout to lay out each child. Every child must be laid out using this function exactly once each time MultiChildLayoutDelegate::perform_layout is called.

Panics

If there is no child with child_id, or, in a debug build, if that child was already laid out during this call.

pub fn position_child( &self, app: &mut App, child_id: &ChildLayoutId, offset: Offset, )

Specify the child’s origin relative to this origin.

Call this from MultiChildLayoutDelegate::perform_layout to position each child. If you do not call this for a child, its position will remain unchanged. Children initially have their position set to (0,0), i.e. the top left of the RenderCustomMultiChildLayoutBox.

Panics

If there is no child with child_id.