Struct WidgetTree 

pub struct WidgetTree { /* private fields */ }

The widget tree: a thin, typed wrapper over tree_arena::TreeArena.

Implementations

impl WidgetTree

pub fn new() -> Self

Create an empty tree.

pub fn insert_root(&mut self, pod: WidgetPod) -> WidgetId

Insert pod as a root of the tree, returning its id.

pub fn insert_child( &mut self, parent: WidgetId, pod: WidgetPod, ) -> Option<WidgetId>

Insert pod as a child of parent. Returns the child id, or None if parent is not in the tree.

Exercises the tree_arena 0.2.0 ArenaMut / ArenaMutList handles: a node’s value and its child list are borrowed disjointly, so this stays borrow-checker-clean.

pub fn pod(&self, id: WidgetId) -> Option<&WidgetPod>

Shared access to the pod with the given id, anywhere in the tree.

pub fn pod_mut(&mut self, id: WidgetId) -> Option<&mut WidgetPod>

Mutable access to the pod with the given id, anywhere in the tree.

pub fn roots(&self) -> Vec<WidgetId>

The tree’s root ids, in insertion order.

O(roots). Read-only; nothing here mutates the arena.

pub fn children(&self, id: WidgetId) -> Vec<WidgetId>

The children of id, in insertion order — empty if id has no children or is not in the tree.

O(depth) to find the parent, then O(children). Every id returned is live in the arena at call time.

pub fn inspect(&self) -> Vec<InspectNode>

A read-only snapshot of the whole retained tree in pre-order (a node precedes its descendants; siblings follow declaration order).

The walk covers both child mechanisms: the arena’s own children, then the ChildPods a widget publishes through Widget::visit_children — which is where nearly the whole hierarchy actually lives. A container that does not override that seam reads as a leaf.

O(nodes) — one pass, one HashSet of sibling ids per arena parent, no arena mutation and no bookkeeping left behind (a pod’s tooling id is assigned once, on its first visit, and reused). Bounds come from what the last layout pass recorded on each pod (WidgetPod::origin / WidgetPod::size, ChildPod::origin / ChildPod::size), accumulated into absolute window coordinates on the way down; call it after a layout pass or the rects are all zero-sized.

pub fn inspect_layout_dirty(&self) -> Vec<(WidgetId, bool)>

Per-node layout-dirty state for tooling and tests, read-only: one (id, layout_dirty) pair for every node WidgetTree::inspect reports, in exactly its pre-order and with exactly its ids, so the two zip.

A ChildPod reports ChildPod::is_layout_dirty — whether its next ChildPod::layout_child must lay it out whatever its constraints. An arena WidgetPod always reports false: it sits in no ChildPod, and the root lays it out on every pass unconditionally, so there is no skip state to report. Kept beside inspect rather than inside InspectNode so that plain struct’s shape — which consumers construct literally — does not change.

pub fn inspect_paint_dirty(&self) -> Vec<(WidgetId, bool)>

Per-node paint-dirty state for tooling and tests: the exact twin of WidgetTree::inspect_layout_dirty (same order, same ids) reporting ChildPod::is_paint_dirty. An arena WidgetPod reports false.

Trait Implementations

impl Default for WidgetTree

fn default() -> Self

Returns the “default value” for a type.