Add methods for iterating over children with linear instead of quadra…

…tic behavior

masonry/src/contexts.rs

@@ -477,6 +477,29 @@ impl<'w> QueryCtx<'w> {
             widget: child.item,
         }
     }
+
+    // TODO temporary until arena is more efficient (I think this might not always return the correct order of the children)?
+    /// To avoid quadratic behavior with manually iterating over children with [`Widget::children_ids`] by accessing these with [`Self::get`], this method allows to linearly iterate over all children.
+    pub fn children_iter(
+        self,
+    ) -> impl DoubleEndedIterator<Item = WidgetRef<'w, dyn Widget>> + ExactSizeIterator {
+        self.widget_children
+            .iter()
+            .zip(self.widget_state_children.iter())
+            .map(|(child, child_state)| {
+                let ctx = QueryCtx {
+                    global_state: self.global_state,
+                    widget_state_children: child_state.children,
+                    widget_children: child.children,
+                    widget_state: child_state.item,
+                };
+
+                WidgetRef {
+                    ctx,
+                    widget: child.item.as_dyn(),
+                }
+            })
+    }
 }
 
 // --- MARK: UPDATE FLAGS ---

masonry/src/tree_arena.rs

@@ -268,6 +268,12 @@ impl<'a, Item> ArenaRefChildren<'a, Item> {
             .map(|child| child.arena_ref(self.id, self.parents_map.parents_map))
     }
 
+    pub fn iter(self) -> impl DoubleEndedIterator<Item = ArenaRef<'a, Item>> + ExactSizeIterator {
+        self.children
+            .iter()
+            .map(move |child| child.arena_ref(self.id, self.parents_map.parents_map))
+    }
+
     /// Get the child of the item this handle is associated with, which has the given id.
     ///
     /// This is the same as [`get_child`](Self::get_child), except it consumes the

masonry/src/widget/widget.rs

@@ -342,8 +342,9 @@ pub(crate) fn find_widget_at_pos<'c>(
 
         // Assumes `Self::children_ids` is in increasing "z-order", picking the last child in case
         // of overlapping children.
-        for child_id in widget.children_ids().iter().rev() {
-            let child_ref = widget.ctx.get(*child_id);
+        // for child_id in widget.children_ids().iter().rev() {
+        //     let child_ref = widget.ctx.get(*child_id);
+        for child_ref in widget.ctx.children_iter().rev() {
             if let Some(child) = child_ref.widget.find_widget_at_pos(child_ref.ctx, pos) {
                 return Some(child);
             }