tenant.openagents/omega

1//! Accessibility support, provided by [AccessKit][accesskit].
2//!
3//! There are user-facing guide-level docs [here](crate::_accessibility).
4//!
5//! ## Architecture
6//!
7//! ```text
8//!                              ┌────────────────────────────────┐   ┌─────────────────────┐
9//!                           ┌─▶│ AccessKit Adapter (MacOS)      │◀─▶│ MacOS System APIs   │
10//!                           │  └────────────────────────────────┘   └─────────────────────┘
11//!                           │
12//! ┌──────┐   ┌───────────┐  │  ┌────────────────────────────────┐   ┌─────────────────────┐
13//! │ GPUI │◀─▶│ AccessKit │◀─┼─▶│ AccessKit Adapter (Windows)    │◀─▶│ Windows System APIs │
14//! └──────┘   └───────────┘  │  └────────────────────────────────┘   └─────────────────────┘
15//!                           │
16//!                           │  ┌────────────────────────────────┐   ┌─────────────────────┐
17//!                           └─▶│ AccessKit Adapter (Linux)      │◀─▶│ dbus                │
18//!                              └────────────────────────────────┘   └─────────────────────┘
19//! ```
20//!
21//! In order for GPUI apps to be usable for people using assistive technology,
22//! we must do a few things:
23//! - Inform the system when the UI changes meaningfully. This includes:
24//!   - Reporting new/removed/changed UI elements
25//!   - *Not* reporting irrelevant UI changes, e.g. an invisible `div()` being
26//!     added.
27//!   - Reporting the appearance and capabilities of each UI element. For example:
28//!     - What does this piece of text say?
29//!     - How far along is this progress bar?
30//!     - Can this node be focused?
31//!     - Can this node have a value directly assigned? (e.g. a slider)
32//! - Allowing the system to interact with the UI by dispatching actions to
33//!   nodes. Note that AccessKit has its own [`Action`] type, which is not the
34//!   [`crate::Action`] trait.
35//! - Activate and deactivate accessibility features when requested by the
36//!   system.
37//!
38//! Activating and deactivating at the right time is trivial, so I won't go into
39//! detail here. The other two are almost orthogonal in implementation.
40//!
41//! The state for both lives in the [`A11y`] struct in this module.
42//!
43//! ### Reporting UI changes
44//!
45//! Every frame, we build a [`TreeUpdate`] and send it to the platform-specific
46//! adapter. A [`TreeUpdate`] is a representation of a subset of the UI tree.
47//! When the adapter receives the update, it diffs it against the previous
48//! update, and calls platform-specific APIs to inform screen readers about the
49//! changes. Nodes may have been created, destroyed, or updated.
50//!
51//! Each node has an ID, and this ID *should* be stable across frames. If a
52//! node's ID changes, then, from AccessKit's point of view, it is a different
53//! node.
54//!
55//! We derive the node ID from the [`GlobalElementId`] in
56//! [`GlobalElementId::accesskit_node_id`]. Nodes without [`GlobalElementId`]s
57//! cannot produce an AccessKit [`NodeId`], and so are not included in the
58//! accessibility tree. We try to warn when using accessibility APIs on
59//! [`div()`] without setting an ID.
60//!
61//! This all happens in [`Drawable::prepaint`]. The [`A11y`] struct maintains a
62//! stack of nodes during prepainting, which we can use to calculate the
63//! [`NodeId`]s, and record parent-child relationships. Once all [`Element`]s in
64//! a frame have been prepainted, we send the resulting [`TreeUpdate`] object to
65//! the adapter and the screen reader can announce the changes.
66//!
67//! #### Synthetic children
68//!
69//! Additionally, some nodes can register "synthetic children" using
70//! [`Element::a11y_synthetic_children`]. Normally, one accesskit node is pushed
71//! for every [`Element`] with a role and id. However, sometimes a single
72//! element may want to produce many accesskit nodes. These extra nodes are
73//! referred to as "synthetic children" of the element providing a non-default
74//! [`Element::a11y_synthetic_children`] implementation.
75//!
76//! The user is provided a builder-style API using [`A11ySubtreeBuilder`], which
77//! allows them to create push nodes that are children of the current node, as
78//! well as modify the current node itself.
79//!
80//! GPUI calls this callback *after* prepainting (and just before popping the
81//! corresponding element), since this step may need prepaint information to be
82//! available. In the future, we may want to add prepaint information more
83//! generally to [`Element::write_a11y_info`], but for now that's not necessary.
84//!
85//! ### Responding to actions
86//!
87//! On adapter creation, we provide a callback to the adapter, which can be used
88//! to dispatch actions. This callback forwards to [`A11y::action_listeners`], a
89//! mapping from [`NodeId`]s to action handlers (basically just `Box<dyn
90//! Fn()>`).
91//!
92//! This is populated in:
93//! - [`Window::on_a11y_action`], which is called by:
94//! - [`Interactivity::paint`], which is called by:
95//! - [`StatefulInteractiveElement::on_a11y_action`], which is a public-facing API
96//!
97//! These are cleared at the start of a frame, and re-populated during painting.
98//!
99//! [`NodeId`]: accesskit::NodeId
100
101use crate::*;
102
103pub(crate) mod debug;
104
105use crate::{App, Bounds, FocusId, Pixels, SharedString, Window};
106use accesskit::{Action, NodeId, TreeUpdate};
107use collections::{FxHashMap, FxHashSet};
108use smallvec::SmallVec;
109use std::hash::{Hash, Hasher};
110use std::sync::{
111    Arc,
112    atomic::{AtomicBool, Ordering},
113};
114
115/// The fixed AccessKit node ID used for the root of every window's a11y tree.
116pub(crate) const ROOT_NODE_ID: NodeId = NodeId(0);
117
118/// A listener for an accessibility action on a specific node.
119pub(crate) type A11yActionListener =
120    Box<dyn FnMut(Option<&accesskit::ActionData>, &mut Window, &mut App) + 'static>;
121
122/// Per-window accessibility state.
123///
124/// Manages the AccessKit tree that is built each frame and the mappings
125/// needed to dispatch incoming action requests back to the right elements.
126pub(crate) struct A11y {
127    /// Whether accessibility has been [forcibly disabled] for this window.
128    ///
129    /// [forcibly disabled]: crate::Application::new_inaccessible
130    force_disabled: bool,
131    /// Whether a11y features have been requested by the system.
132    ///
133    /// Updated by AccessKit using callbacks provided to the adapter. Can change
134    /// halfway through a frame.
135    active_flag: Arc<AtomicBool>,
136    /// Whether a11y features are active for *this specific frame*.
137    ///
138    /// At the start of each frame, we load [`Self::active_flag`] (using
139    /// [`Self::sync_active_flag`]) and use this to determine whether we
140    /// should construct a [`TreeUpdate`] for this frame. It's important that
141    /// this value is stable within a frame, because the builder API exposed by
142    /// this type maintains a stack of nodes and each must be pushed and popped
143    /// exactly once.
144    ///
145    /// At the end of the frame, we re-call [`Self::sync_active_flag`] to
146    /// determine whether we should actually send the finished [`TreeUpdate`].
147    active_this_frame: bool,
148    pub(crate) nodes: A11yNodeBuilder,
149    pub(crate) focus_ids: FxHashMap<NodeId, FocusId>,
150    pub(crate) node_bounds: FxHashMap<NodeId, Bounds<Pixels>>,
151    pub(crate) action_listeners: FxHashMap<NodeId, Vec<(Action, A11yActionListener)>>,
152    /// The window's title, used to label the root node so assistive
153    /// technology can tell windows apart.
154    window_title: Option<SharedString>,
155    /// The focus id we most recently reported as having no accessibility node,
156    /// used to log at most once per focus change rather than every frame.
157    last_focus_without_node: Option<FocusId>,
158    /// Retains the last tree update (and, in debug builds, per-node provenance)
159    /// so it can be dumped via [`crate::Window::debug_a11y_tree_json`].
160    debug: debug::A11yDebug,
161    /// Maps a view's [`EntityId`] to its `Render` type name
162    #[cfg(debug_assertions)]
163    pub(crate) view_type_names: FxHashMap<EntityId, &'static str>,
164}
165
166impl A11y {
167    pub(crate) fn new(
168        active_flag: Arc<AtomicBool>,
169        force_disabled: bool,
170        window_title: Option<SharedString>,
171    ) -> Self {
172        Self {
173            force_disabled,
174            active_flag,
175            active_this_frame: false,
176            nodes: A11yNodeBuilder::new(),
177            focus_ids: FxHashMap::default(),
178            node_bounds: FxHashMap::default(),
179            action_listeners: FxHashMap::default(),
180            window_title,
181            last_focus_without_node: None,
182            debug: debug::A11yDebug::default(),
183            #[cfg(debug_assertions)]
184            view_type_names: FxHashMap::default(),
185        }
186    }
187
188    /// Logs (once per focus change) that the focused element is not exposed to
189    /// assistive technology because it has no accessibility node. When this
190    /// happens, screen readers fall back to announcing the whole window instead
191    /// of the focused element. The fix is to give the element both an
192    /// `.id(...)` and a `.role(...)`.
193    pub(crate) fn note_focus_without_node(&mut self, focus_id: FocusId, reason: &str) {
194        if self.last_focus_without_node != Some(focus_id) {
195            self.last_focus_without_node = Some(focus_id);
196            log::info!(
197                "a11y: focused element ({focus_id:?}) has no accessibility node \
198                 ({reason}); assistive technology will announce the whole window \
199                 instead. Give it both an `.id(...)` and a `.role(...)` to expose it."
200            );
201        }
202    }
203
204    pub(crate) fn set_window_title(&mut self, title: impl Into<SharedString>) {
205        self.window_title = Some(title.into());
206    }
207
208    /// Ensures that [`Self::is_active`] returns up to date information.
209    ///
210    /// See the docs for [`Self::active_flag`] and [`Self::active_this_frame`]
211    /// for more commentary.
212    pub(crate) fn sync_active_flag(&mut self) {
213        self.active_this_frame = !self.force_disabled && self.active_flag.load(Ordering::SeqCst);
214    }
215
216    pub(crate) fn is_active(&self) -> bool {
217        self.active_this_frame
218    }
219
220    pub(crate) fn set_focusable(&mut self, node_id: NodeId, focus_id: FocusId) {
221        self.focus_ids.insert(node_id, focus_id);
222    }
223
224    /// Report `node_id` as the currently-focused node, if it is present in the
225    /// tree.
226    ///
227    /// Must only be called once per frame.
228    pub(crate) fn set_focus(&mut self, node_id: NodeId) {
229        // A focused node must have been registered as focusable this frame.
230        if !self.focus_ids.contains_key(&node_id) {
231            if cfg!(debug_assertions) {
232                panic!("set_focus called for a node that was not registered with set_focusable");
233            } else {
234                log::warn!(
235                    "a11y: set_focus called for a node that was not registered with \
236                     set_focusable ({node_id:?})"
237                );
238            }
239        }
240        if self.nodes.has_node(node_id) {
241            // The focused element is properly exposed; reset the dedup so a
242            // later focus on a node-less element logs again.
243            self.last_focus_without_node = None;
244            self.nodes.set_focus(node_id);
245        } else {
246            // The element registered a focus handle and an id, but never got a
247            // node because it has no role.
248            if let Some(focus_id) = self.focus_ids.get(&node_id).copied() {
249                self.note_focus_without_node(focus_id, "it has an id but no role");
250            }
251        }
252    }
253
254    pub(crate) fn set_active_descendant(&mut self, node_id: NodeId) {
255        // The active descendant must be a descendant of the focused container,
256        // not the focused node itself.
257        if self.nodes.node_is_focused(node_id) {
258            if cfg!(debug_assertions) {
259                panic!("set_active_descendant called on the focused node");
260            } else {
261                log::warn!("a11y: set_active_descendant called on the focused node ({node_id:?})");
262            }
263            return;
264        }
265        if self.nodes.has_node(node_id) && self.nodes.focus_is_ancestor_of_current() {
266            self.nodes.set_active_descendant(node_id);
267        }
268    }
269
270    /// Clear per-frame state and push the root node to start a new frame.
271    pub(crate) fn begin_frame(&mut self) {
272        self.focus_ids.clear();
273        self.node_bounds.clear();
274        self.action_listeners.clear();
275        self.nodes.begin_frame(self.window_title.as_ref());
276    }
277
278    /// Finalize the tree and produce a [`TreeUpdate`] for the platform adapter.
279    pub(crate) fn end_frame(&mut self, frame: debug::FrameDebugInfo) -> TreeUpdate {
280        let update = self.nodes.finalize();
281        self.debug.capture(
282            &update,
283            self.nodes.focus,
284            self.nodes.active_descendant,
285            self.window_title.as_ref(),
286            frame,
287        );
288        #[cfg(debug_assertions)]
289        self.debug.capture_node_info(&self.nodes.node_info);
290        update
291    }
292
293    pub(crate) fn debug_tree_json(&self) -> Option<String> {
294        self.debug.to_json()
295    }
296}
297
298/// Builder API for synthetic children. See the docs for
299/// [`Element::a11y_synthetic_children`].
300pub struct A11ySubtreeBuilder<'a> {
301    parent_id: NodeId,
302    nodes: &'a mut A11yNodeBuilder,
303    /// Provenance of the real element whose `a11y_synthetic_children` is
304    /// running.
305    #[cfg(debug_assertions)]
306    creator: debug::NodeCreator,
307}
308
309impl<'a> A11ySubtreeBuilder<'a> {
310    pub(crate) fn new(parent_id: NodeId, nodes: &'a mut A11yNodeBuilder) -> Self {
311        Self {
312            parent_id,
313            nodes,
314            #[cfg(debug_assertions)]
315            creator: debug::NodeCreator::default(),
316        }
317    }
318
319    #[cfg(debug_assertions)]
320    pub(crate) fn with_creator(mut self, creator: debug::NodeCreator) -> Self {
321        self.creator = creator;
322        self
323    }
324
325    /// Derive a [`NodeId`] for a synthetic child.
326    ///
327    /// The generated ID is based on the hash of `key`, as well as the parent's
328    /// ID. This means that `key`s must be unique within the same
329    /// [`Element::a11y_synthetic_children`] call, but may be duplicated across
330    /// different calls.
331    pub fn synthetic_node_id(&self, key: impl Hash) -> NodeId {
332        let mut hasher = std::hash::DefaultHasher::default();
333        self.parent_id.0.hash(&mut hasher);
334        key.hash(&mut hasher);
335        NodeId(hasher.finish())
336    }
337
338    /// Append a synthetic leaf node as a child of this element's node.
339    ///
340    /// Returns `false` if a node with this id is already present in the tree,
341    /// in which case the node is discarded.
342    pub fn push_child(&mut self, id: NodeId, node: accesskit::Node) -> bool {
343        let pushed = self.nodes.push_leaf(id, node);
344        #[cfg(debug_assertions)]
345        if pushed {
346            self.nodes.record_node_info(
347                id,
348                debug::NodeDebugInfo {
349                    synthetic: true,
350                    view: self.creator.view,
351                    element_id: self.creator.element_id.clone(),
352                    source_location: self.creator.source_location,
353                },
354            );
355        }
356        pushed
357    }
358
359    /// A mutable reference to the parent node.
360    pub fn parent_node(&mut self) -> &mut accesskit::Node {
361        self.nodes
362            .current_node_mut()
363            .expect("A11ySubtreeBuilder exists only while its element's node is on the stack")
364    }
365}
366
367pub(crate) struct A11yNodeBuilder {
368    ids_stack: SmallVec<[NodeId; 16]>,
369    nodes_stack: SmallVec<[accesskit::Node; 16]>,
370    /// This is the exact type required by accesskit, so we can't just make it a
371    /// `HashMap<NodeId, Node>` to remove the need for `seen_ids`
372    all_nodes: Vec<(NodeId, accesskit::Node)>,
373    seen_ids: FxHashSet<NodeId>,
374    /// The node that GPUI considers focused. Note that this may be different to
375    /// what is reported to accesskit - see [`Self::active_descendant`]
376    focus: Option<NodeId>,
377    /// If a node calls `.aria_active_descendant()`, AND an ancestor is focused,
378    /// override it as the focused node. This supports the "active descendant"
379    /// pattern, which allows a focused container to act as if a descendant is
380    /// focused.
381    active_descendant: Option<NodeId>,
382    #[cfg(debug_assertions)]
383    node_info: FxHashMap<NodeId, debug::NodeDebugInfo>,
384}
385
386impl A11yNodeBuilder {
387    fn new() -> Self {
388        Self {
389            ids_stack: SmallVec::new(),
390            nodes_stack: SmallVec::new(),
391            all_nodes: Vec::new(),
392            seen_ids: FxHashSet::default(),
393            focus: None,
394            active_descendant: None,
395            #[cfg(debug_assertions)]
396            node_info: FxHashMap::default(),
397        }
398    }
399
400    /// Records provenance for a node already pushed this frame. Debug builds only.
401    #[cfg(debug_assertions)]
402    pub(crate) fn record_node_info(&mut self, id: NodeId, info: debug::NodeDebugInfo) {
403        self.node_info.insert(id, info);
404    }
405
406    #[must_use]
407    fn can_push(&mut self, id: NodeId) -> bool {
408        debug_assert!(!self.ids_stack.is_empty(), "node pushed before push_root");
409
410        if !self.seen_ids.insert(id) {
411            debug_assert!(
412                false,
413                "Duplicate a11y node id: {id:?}. In a release build, this node would be silently discarded from the a11y tree."
414            );
415            return false;
416        }
417
418        true
419    }
420
421    /// Push a new node onto the stack. It becomes a child of the current
422    /// top-of-stack node.
423    ///
424    /// Returns `true` if the node was successfully pushed.
425    pub(crate) fn push(&mut self, id: NodeId, node: accesskit::Node) -> bool {
426        if !self.can_push(id) {
427            return false;
428        }
429
430        if let Some(parent) = self.nodes_stack.last_mut() {
431            parent.push_child(id);
432        }
433        self.ids_stack.push(id);
434        self.nodes_stack.push(node);
435        true
436    }
437
438    /// Add a leaf node as a child of the current top-of-stack node, without
439    /// pushing it onto the stack. Semantically equivalent to a [`Self::push`]
440    /// followed by a [`Self::pop`].
441    ///
442    /// Returns `true` if the node was successfully pushed.
443    pub(crate) fn push_leaf(&mut self, id: NodeId, node: accesskit::Node) -> bool {
444        if !self.can_push(id) {
445            return false;
446        }
447
448        if let Some(parent) = self.nodes_stack.last_mut() {
449            parent.push_child(id);
450        }
451        self.all_nodes.push((id, node));
452        true
453    }
454
455    pub(crate) fn current_node_mut(&mut self) -> Option<&mut accesskit::Node> {
456        self.nodes_stack.last_mut()
457    }
458
459    /// Pop the current node off the stack and finalize it into the all_nodes
460    /// list.
461    pub(crate) fn pop(&mut self) {
462        debug_assert!(self.ids_stack.len() > 1, "pop would remove the root node");
463
464        if let (Some(id), Some(node)) = (self.ids_stack.pop(), self.nodes_stack.pop()) {
465            self.all_nodes.push((id, node));
466        }
467    }
468
469    /// Push the root node to start a new frame.
470    fn begin_frame(&mut self, window_title: Option<&SharedString>) {
471        self.all_nodes.clear();
472        self.ids_stack.clear();
473        self.nodes_stack.clear();
474        self.seen_ids.clear();
475        #[cfg(debug_assertions)]
476        self.node_info.clear();
477        let mut root_node = accesskit::Node::new(accesskit::Role::Window);
478        if let Some(title) = window_title {
479            root_node.set_label(title.to_string());
480        }
481
482        self.ids_stack.push(ROOT_NODE_ID);
483        self.nodes_stack.push(root_node);
484        self.focus = None;
485        self.active_descendant = None;
486    }
487
488    /// Returns whether a node with the given ID has been pushed in this frame.
489    pub(crate) fn has_node(&self, id: NodeId) -> bool {
490        id == ROOT_NODE_ID || self.seen_ids.contains(&id)
491    }
492
493    /// Returns whether `id` is the node currently reported as focused.
494    pub(crate) fn node_is_focused(&self, id: NodeId) -> bool {
495        self.focus == Some(id)
496    }
497
498    pub(crate) fn focus_is_ancestor_of_current(&self) -> bool {
499        let Some(focus) = self.focus else {
500            return false;
501        };
502
503        // The current node is on top of the stack; everything below it is an
504        // ancestor.
505        let ancestor_count = self.ids_stack.len().saturating_sub(1);
506        self.ids_stack[..ancestor_count].contains(&focus)
507    }
508
509    pub(crate) fn set_active_descendant(&mut self, id: NodeId) {
510        if self
511            .active_descendant
512            .is_some_and(|existing| existing != id)
513        {
514            if cfg!(debug_assertions) {
515                panic!("active descendant claimed by multiple nodes in one frame");
516            } else {
517                log::warn!(
518                    "a11y: multiple nodes claimed the active descendant this frame; \
519                     using last-wins ({id:?})"
520                );
521            }
522        }
523        self.active_descendant = Some(id);
524    }
525
526    pub(crate) fn set_focus(&mut self, id: NodeId) {
527        if self.focus.is_some() {
528            if cfg!(debug_assertions) {
529                panic!("set_focus called more than once in a single frame");
530            } else {
531                log::warn!(
532                    "a11y: set_focus called more than once in a single frame; \
533                     using last-wins ({id:?})"
534                );
535            }
536        }
537        self.focus = Some(id);
538    }
539
540    fn finalize(&mut self) -> TreeUpdate {
541        // Stack should contain only the root node
542        debug_assert_eq!(self.ids_stack.len(), 1);
543        debug_assert_eq!(self.ids_stack[0], ROOT_NODE_ID);
544
545        if self.ids_stack.len() != 1 {
546            log::error!(
547                "a11y: Stack imbalance at end of frame: expected 1 (root), got {}. \
548                 Some elements may have pushed without popping.",
549                self.ids_stack.len()
550            );
551        }
552
553        // Pop remaining nodes (should just be the root).
554        while !self.ids_stack.is_empty() {
555            if let (Some(id), Some(node)) = (self.ids_stack.pop(), self.nodes_stack.pop()) {
556                self.all_nodes.push((id, node));
557            }
558        }
559
560        let focus = match self.active_descendant {
561            Some(id) if self.has_node(id) => id,
562            Some(id) => {
563                if cfg!(debug_assertions) {
564                    panic!("active_descendant set to {id:?}, which is not in the tree");
565                } else {
566                    log::warn!("active_descendant set to {id:?}, which is not in the tree");
567                    self.focus.unwrap_or(ROOT_NODE_ID)
568                }
569            }
570
571            _ => self.focus.unwrap_or(ROOT_NODE_ID),
572        };
573
574        let nodes = std::mem::take(&mut self.all_nodes);
575        let update = TreeUpdate {
576            nodes,
577            tree: Some(accesskit::Tree::new(ROOT_NODE_ID)),
578            tree_id: accesskit::TreeId::ROOT,
579            focus,
580        };
581
582        Self::repair_tree_update(update)
583    }
584
585    /// Accesskit panics on invalid [`TreeUpdate`]s. This function defensively
586    /// checks invariants that accesskit panics on, and tries to fix them.
587    fn repair_tree_update(mut update: TreeUpdate) -> TreeUpdate {
588        let node_ids: FxHashSet<NodeId> = update.nodes.iter().map(|(id, _)| *id).collect();
589
590        // Focus must point to a node in the tree.
591        if !node_ids.contains(&update.focus) {
592            log::error!(
593                "a11y: Focused node {:?} is not in the tree ({} nodes). \
594                 Falling back to root. This is a bug in the a11y tree builder.",
595                update.focus,
596                update.nodes.len()
597            );
598            update.focus = ROOT_NODE_ID;
599        }
600
601        // Every child reference must point to a node in the update.
602        for (id, node) in &mut update.nodes {
603            let has_invalid_child = node
604                .children()
605                .iter()
606                .any(|child_id| !node_ids.contains(child_id));
607            if has_invalid_child {
608                let children = node.children();
609                let invalid_count = children
610                    .iter()
611                    .filter(|child_id| !node_ids.contains(child_id))
612                    .count();
613                log::error!(
614                    "a11y: Node {:?} references {} children not present in the tree. \
615                     Stripping invalid child references.",
616                    id,
617                    invalid_count
618                );
619                let valid: Vec<NodeId> = children
620                    .iter()
621                    .copied()
622                    .filter(|child_id| node_ids.contains(child_id))
623                    .collect();
624                node.set_children(valid);
625            }
626        }
627
628        update
629    }
630}
631
632#[cfg(test)]
633mod tests {
634    // Import specific items rather than glob-importing `super`, which would pull
635    // in gpui's own `test` attribute macro and shadow the standard one.
636    use super::{A11y, A11yNodeBuilder, ROOT_NODE_ID};
637    use crate::FocusId;
638    use accesskit::{NodeId, Role};
639    use std::sync::{Arc, atomic::AtomicBool};
640
641    fn test_node() -> accesskit::Node {
642        accesskit::Node::new(Role::GenericContainer)
643    }
644
645    fn new_builder() -> A11yNodeBuilder {
646        let mut builder = A11yNodeBuilder::new();
647        builder.begin_frame(None);
648        builder
649    }
650
651    fn new_a11y() -> A11y {
652        let mut a11y = A11y::new(Arc::new(AtomicBool::new(true)), false, None);
653        a11y.begin_frame();
654        a11y
655    }
656
657    #[test]
658    fn active_descendant_honored_when_container_focused() {
659        let mut builder = new_builder();
660        let container = NodeId(1);
661        let item = NodeId(2);
662
663        assert!(builder.push(container, test_node()));
664        builder.set_focus(container);
665        assert!(builder.push(item, test_node()));
666
667        // The item is on top of the stack; the focused container is its
668        // ancestor, so the claim is honored.
669        assert!(builder.focus_is_ancestor_of_current());
670        builder.set_active_descendant(item);
671
672        builder.pop(); // item
673        builder.pop(); // container
674        let update = builder.finalize();
675        assert_eq!(update.focus, item);
676    }
677
678    #[test]
679    fn active_descendant_honored_for_deep_descendant() {
680        let mut builder = new_builder();
681        let container = NodeId(1);
682        let group = NodeId(2);
683        let item = NodeId(3);
684
685        assert!(builder.push(container, test_node()));
686        builder.set_focus(container);
687        assert!(builder.push(group, test_node()));
688        assert!(builder.push(item, test_node()));
689
690        // The item is a grandchild of the focused container; depth doesn't
691        // matter, the focused ancestor is still on the stack.
692        assert!(builder.focus_is_ancestor_of_current());
693        builder.set_active_descendant(item);
694
695        builder.pop(); // item
696        builder.pop(); // group
697        builder.pop(); // container
698        let update = builder.finalize();
699        assert_eq!(update.focus, item);
700    }
701
702    #[test]
703    fn active_descendant_ignored_when_focus_in_other_subtree() {
704        let mut builder = new_builder();
705        let focused_container = NodeId(1);
706        let focused_leaf = NodeId(2);
707        let other_container = NodeId(3);
708        let other_item = NodeId(4);
709
710        // First subtree holds real focus.
711        assert!(builder.push(focused_container, test_node()));
712        assert!(builder.push(focused_leaf, test_node()));
713        builder.set_focus(focused_leaf);
714        builder.pop(); // focused_leaf
715        builder.pop(); // focused_container
716
717        // Second subtree: its item would claim the active descendant, but the
718        // focus is not on any of its ancestors, so the gate rejects it.
719        assert!(builder.push(other_container, test_node()));
720        assert!(builder.push(other_item, test_node()));
721        assert!(!builder.focus_is_ancestor_of_current());
722        builder.pop(); // other_item
723        builder.pop(); // other_container
724
725        let update = builder.finalize();
726        assert_eq!(update.focus, focused_leaf);
727    }
728
729    #[test]
730    fn active_descendant_ignored_when_nothing_focused() {
731        let mut builder = new_builder();
732        let container = NodeId(1);
733        let item = NodeId(2);
734
735        assert!(builder.push(container, test_node()));
736        assert!(builder.push(item, test_node()));
737
738        // Nothing is focused (focus defaults to the root window node), so the
739        // gate rejects the claim.
740        assert!(!builder.focus_is_ancestor_of_current());
741        builder.pop();
742        builder.pop();
743
744        let update = builder.finalize();
745        assert_eq!(update.focus, ROOT_NODE_ID);
746    }
747
748    #[test]
749    fn regular_focus_used_when_no_active_descendant() {
750        let mut builder = new_builder();
751        let focused = NodeId(1);
752
753        assert!(builder.push(focused, test_node()));
754        builder.set_focus(focused);
755        builder.pop();
756
757        let update = builder.finalize();
758        assert_eq!(update.focus, focused);
759    }
760
761    #[test]
762    fn focus_is_ancestor_excludes_self_and_non_ancestors() {
763        let mut builder = new_builder();
764        let container = NodeId(1);
765        let item = NodeId(2);
766
767        assert!(builder.push(container, test_node()));
768        builder.set_focus(container);
769
770        // With the focused container itself on top, it is not its own (strict)
771        // ancestor, so the gate is false.
772        assert!(!builder.focus_is_ancestor_of_current());
773
774        assert!(builder.push(item, test_node()));
775        // Now the focused container is a strict ancestor of the item on top.
776        assert!(builder.focus_is_ancestor_of_current());
777
778        builder.pop();
779        builder.pop();
780    }
781
782    // The double-claim guard panics only in debug builds; in release it falls
783    // back to last-wins with a warning.
784    #[test]
785    #[cfg_attr(
786        debug_assertions,
787        should_panic(expected = "active descendant claimed by multiple nodes")
788    )]
789    fn multiple_active_descendant_claims_panic_in_debug() {
790        let mut builder = new_builder();
791        builder.set_active_descendant(NodeId(1));
792        builder.set_active_descendant(NodeId(2));
793    }
794
795    // Setting focus twice in one frame means two elements both claimed window
796    // focus; that panics in debug and falls back to last-wins in release.
797    #[test]
798    #[cfg_attr(
799        debug_assertions,
800        should_panic(expected = "set_focus called more than once")
801    )]
802    fn setting_focus_twice_panics_in_debug() {
803        let mut builder = new_builder();
804        builder.set_focus(NodeId(1));
805        builder.set_focus(NodeId(2));
806    }
807
808    // Focusing a node that was never registered as focusable is a bug: panic in
809    // debug, warn in release.
810    #[test]
811    #[cfg_attr(
812        debug_assertions,
813        should_panic(expected = "was not registered with set_focusable")
814    )]
815    fn set_focus_without_set_focusable() {
816        let mut a11y = new_a11y();
817        let node = NodeId(1);
818        assert!(a11y.nodes.push(node, test_node()));
819        // set_focusable was never called for `node`.
820        a11y.set_focus(node);
821    }
822
823    // The focused node cannot also be its own active descendant: panic in
824    // debug, warn in release.
825    #[test]
826    #[cfg_attr(debug_assertions, should_panic(expected = "on the focused node"))]
827    fn set_active_descendant_on_focused_node() {
828        let mut a11y = new_a11y();
829        let node = NodeId(1);
830        assert!(a11y.nodes.push(node, test_node()));
831        a11y.set_focusable(node, FocusId::default());
832        a11y.set_focus(node);
833        a11y.set_active_descendant(node);
834    }
835
836    // Two sibling children of a focused container both claim the active
837    // descendant (both pass the focus gate). The second claim is a bug: panic
838    // in debug, last-wins + warn in release.
839    #[test]
840    #[cfg_attr(
841        debug_assertions,
842        should_panic(expected = "active descendant claimed by multiple nodes")
843    )]
844    fn two_siblings_claiming_active_descendant() {
845        let mut a11y = new_a11y();
846        let container = NodeId(1);
847        let first = NodeId(2);
848        let second = NodeId(3);
849
850        assert!(a11y.nodes.push(container, test_node()));
851        a11y.set_focusable(container, FocusId::default());
852        a11y.set_focus(container);
853
854        assert!(a11y.nodes.push(first, test_node()));
855        a11y.set_active_descendant(first);
856        a11y.nodes.pop(); // first
857
858        assert!(a11y.nodes.push(second, test_node()));
859        a11y.set_active_descendant(second);
860        a11y.nodes.pop(); // second
861
862        a11y.nodes.pop(); // container
863    }
864
865    // Node A is focused; node C (a child of the unfocused node B) claims the
866    // active descendant. The final tree must still report A as focused.
867    #[test]
868    fn active_descendant_in_unfocused_subtree_keeps_real_focus() {
869        let mut a11y = new_a11y();
870        let a = NodeId(1);
871        let b = NodeId(2);
872        let c = NodeId(3);
873
874        assert!(a11y.nodes.push(a, test_node()));
875        a11y.set_focusable(a, FocusId::default());
876        a11y.set_focus(a);
877        a11y.nodes.pop(); // a
878
879        assert!(a11y.nodes.push(b, test_node()));
880        assert!(a11y.nodes.push(c, test_node()));
881        a11y.set_active_descendant(c);
882        a11y.nodes.pop(); // c
883        a11y.nodes.pop(); // b
884
885        let update = a11y.end_frame(Default::default());
886        assert_eq!(update.focus, a);
887    }
888}
889