feat: Factor out core AT-SPI translation layer (#352)

Cargo.toml

@@ -3,6 +3,7 @@ resolver = "2"
 members = [
     "common",
     "consumer",
+    "platforms/atspi-common",
     "platforms/macos",
     "platforms/unix",
     "platforms/windows",
@@ -13,6 +14,7 @@ members = [
 default-members = [
     "common",
     "consumer",
+    "platforms/atspi-common",
     "platforms/winit",
     "bindings/c",
     "bindings/python",

platforms/atspi-common/Cargo.toml

@@ -0,0 +1,20 @@
+[package]
+name = "accesskit_atspi_common"
+version = "0.1.0"
+authors.workspace = true
+license.workspace = true
+description = "AccessKit UI accessibility infrastructure: core AT-SPI translation layer"
+categories.workspace = true
+keywords = ["gui", "ui", "accessibility"]
+repository.workspace = true
+readme = "README.md"
+edition.workspace = true
+rust-version.workspace = true
+
+[dependencies]
+accesskit = { version = "0.12.2", path = "../../common" }
+accesskit_consumer = { version = "0.17.0", path = "../../consumer" }
+atspi-common = { version = "0.3.0", default-features = false }
+serde = "1.0"
+thiserror = "1.0.39"
+zvariant = { version = "3", default-features = false }

platforms/atspi-common/src/action.rs

@@ -0,0 +1,14 @@
+// Copyright 2022 The AccessKit Authors. All rights reserved.
+// Licensed under the Apache License, Version 2.0 (found in
+// the LICENSE-APACHE file) or the MIT license (found in
+// the LICENSE-MIT file), at your option.
+
+use serde::{Deserialize, Serialize};
+use zvariant::Type;
+
+#[derive(Deserialize, Serialize, Type)]
+pub struct Action {
+    pub localized_name: String,
+    pub description: String,
+    pub key_binding: String,
+}

platforms/atspi-common/src/adapter.rs

@@ -0,0 +1,325 @@
+// Copyright 2022 The AccessKit Authors. All rights reserved.
+// Licensed under the Apache License, Version 2.0 (found in
+// the LICENSE-APACHE file) or the MIT license (found in
+// the LICENSE-MIT file), at your option.
+
+use accesskit::{ActionHandler, NodeId, Role, TreeUpdate};
+use accesskit_consumer::{DetachedNode, FilterResult, Node, Tree, TreeChangeHandler, TreeState};
+use atspi_common::{InterfaceSet, Live, State};
+use std::sync::{
+    atomic::{AtomicUsize, Ordering},
+    Arc, RwLock,
+};
+
+use crate::{
+    context::{AppContext, Context},
+    filters::{filter, filter_detached},
+    node::{NodeIdOrRoot, NodeWrapper, PlatformNode, PlatformRoot},
+    util::WindowBounds,
+    AdapterCallback, Event, ObjectEvent, WindowEvent,
+};
+
+struct AdapterChangeHandler<'a> {
+    adapter: &'a Adapter,
+}
+
+impl AdapterChangeHandler<'_> {
+    fn add_node(&mut self, node: &Node) {
+        let role = node.role();
+        let is_root = node.is_root();
+        let node = NodeWrapper::Node(node);
+        let interfaces = node.interfaces();
+        self.adapter.register_interfaces(node.id(), interfaces);
+        if is_root && role == Role::Window {
+            let adapter_index = self
+                .adapter
+                .context
+                .read_app_context()
+                .adapter_index(self.adapter.id)
+                .unwrap();
+            self.adapter.window_created(adapter_index, node.id());
+        }
+
+        let live = node.live();
+        if live != Live::None {
+            if let Some(name) = node.name() {
+                self.adapter
+                    .emit_object_event(node.id(), ObjectEvent::Announcement(name, live));
+            }
+        }
+    }
+
+    fn remove_node(&mut self, node: &DetachedNode) {
+        let role = node.role();
+        let is_root = node.is_root();
+        let node = NodeWrapper::DetachedNode(node);
+        if is_root && role == Role::Window {
+            self.adapter.window_destroyed(node.id());
+        }
+        self.adapter
+            .emit_object_event(node.id(), ObjectEvent::StateChanged(State::Defunct, true));
+        self.adapter
+            .unregister_interfaces(node.id(), node.interfaces());
+    }
+}
+
+impl TreeChangeHandler for AdapterChangeHandler<'_> {
+    fn node_added(&mut self, node: &Node) {
+        if filter(node) == FilterResult::Include {
+            self.add_node(node);
+        }
+    }
+
+    fn node_updated(&mut self, old_node: &DetachedNode, new_node: &Node) {
+        let filter_old = filter_detached(old_node);
+        let filter_new = filter(new_node);
+        if filter_new != filter_old {
+            if filter_new == FilterResult::Include {
+                self.add_node(new_node);
+            } else if filter_old == FilterResult::Include {
+                self.remove_node(old_node);
+            }
+        } else if filter_new == FilterResult::Include {
+            let old_wrapper = NodeWrapper::DetachedNode(old_node);
+            let new_wrapper = NodeWrapper::Node(new_node);
+            let old_interfaces = old_wrapper.interfaces();
+            let new_interfaces = new_wrapper.interfaces();
+            let kept_interfaces = old_interfaces & new_interfaces;
+            self.adapter
+                .unregister_interfaces(new_wrapper.id(), old_interfaces ^ kept_interfaces);
+            self.adapter
+                .register_interfaces(new_node.id(), new_interfaces ^ kept_interfaces);
+            let bounds = *self.adapter.context.read_root_window_bounds();
+            new_wrapper.notify_changes(&bounds, self.adapter, &old_wrapper);
+        }
+    }
+
+    fn focus_moved(
+        &mut self,
+        old_node: Option<&DetachedNode>,
+        new_node: Option<&Node>,
+        current_state: &TreeState,
+    ) {
+        if let Some(root_window) = root_window(current_state) {
+            if old_node.is_none() && new_node.is_some() {
+                self.adapter
+                    .window_activated(&NodeWrapper::Node(&root_window));
+            } else if old_node.is_some() && new_node.is_none() {
+                self.adapter
+                    .window_deactivated(&NodeWrapper::Node(&root_window));
+            }
+        }
+    }
+
+    fn node_removed(&mut self, node: &DetachedNode, _: &TreeState) {
+        if filter_detached(node) == FilterResult::Include {
+            self.remove_node(node);
+        }
+    }
+}
+
+static NEXT_ADAPTER_ID: AtomicUsize = AtomicUsize::new(0);
+
+pub struct AdapterIdToken(usize);
+
+impl AdapterIdToken {
+    pub fn next() -> Self {
+        let id = NEXT_ADAPTER_ID.fetch_add(1, Ordering::Relaxed);
+        Self(id)
+    }
+
+    pub fn id(&self) -> usize {
+        self.0
+    }
+}
+
+pub struct Adapter {
+    id: usize,
+    callback: Box<dyn AdapterCallback + Send + Sync>,
+    context: Arc<Context>,
+}
+
+impl Adapter {
+    pub fn new(
+        app_context: &Arc<RwLock<AppContext>>,
+        callback: Box<dyn AdapterCallback + Send + Sync>,
+        initial_state: TreeUpdate,
+        is_window_focused: bool,
+        root_window_bounds: WindowBounds,
+        action_handler: Box<dyn ActionHandler + Send>,
+    ) -> Self {
+        let id_token = AdapterIdToken::next();
+        Self::with_id(
+            id_token,
+            app_context,
+            callback,
+            initial_state,
+            is_window_focused,
+            root_window_bounds,
+            action_handler,
+        )
+    }
+
+    pub fn with_id(
+        id_token: AdapterIdToken,
+        app_context: &Arc<RwLock<AppContext>>,
+        callback: Box<dyn AdapterCallback + Send + Sync>,
+        initial_state: TreeUpdate,
+        is_window_focused: bool,
+        root_window_bounds: WindowBounds,
+        action_handler: Box<dyn ActionHandler + Send>,
+    ) -> Self {
+        let id = id_token.0;
+        let tree = Tree::new(initial_state, is_window_focused);
+        let context = Context::new(app_context, tree, action_handler, root_window_bounds);
+        context.write_app_context().push_adapter(id, &context);
+        let adapter = Self {
+            id,
+            callback,
+            context,
+        };
+        adapter.register_tree();
+        adapter
+    }
+
+    fn register_tree(&self) {
+        fn add_children(node: Node<'_>, to_add: &mut Vec<(NodeId, InterfaceSet)>) {
+            for child in node.filtered_children(&filter) {
+                let child_id = child.id();
+                let wrapper = NodeWrapper::Node(&child);
+                let interfaces = wrapper.interfaces();
+                to_add.push((child_id, interfaces));
+                add_children(child, to_add);
+            }
+        }
+
+        let mut objects_to_add = Vec::new();
+
+        let (adapter_index, root_id) = {
+            let tree = self.context.read_tree();
+            let tree_state = tree.state();
+            let mut app_context = self.context.write_app_context();
+            app_context.name = tree_state.app_name();
+            app_context.toolkit_name = tree_state.toolkit_name();
+            app_context.toolkit_version = tree_state.toolkit_version();
+            let adapter_index = app_context.adapter_index(self.id).unwrap();
+            let root = tree_state.root();
+            let root_id = root.id();
+            let wrapper = NodeWrapper::Node(&root);
+            objects_to_add.push((root_id, wrapper.interfaces()));
+            add_children(root, &mut objects_to_add);
+            (adapter_index, root_id)
+        };
+
+        for (id, interfaces) in objects_to_add {
+            self.register_interfaces(id, interfaces);
+            if id == root_id {
+                self.window_created(adapter_index, id);
+            }
+        }
+    }
+
+    pub fn platform_node(&self, id: NodeId) -> PlatformNode {
+        PlatformNode::new(&self.context, self.id, id)
+    }
+
+    pub fn platform_root(&self) -> PlatformRoot {
+        PlatformRoot::new(&self.context.app_context)
+    }
+
+    fn register_interfaces(&self, id: NodeId, new_interfaces: InterfaceSet) {
+        self.callback.register_interfaces(self, id, new_interfaces);
+    }
+
+    fn unregister_interfaces(&self, id: NodeId, old_interfaces: InterfaceSet) {
+        self.callback
+            .unregister_interfaces(self, id, old_interfaces);
+    }
+
+    pub(crate) fn emit_object_event(&self, target: NodeId, event: ObjectEvent) {
+        let target = NodeIdOrRoot::Node(target);
+        self.callback
+            .emit_event(self, Event::Object { target, event });
+    }
+
+    fn emit_root_object_event(&self, event: ObjectEvent) {
+        let target = NodeIdOrRoot::Root;
+        self.callback
+            .emit_event(self, Event::Object { target, event });
+    }
+
+    pub fn set_root_window_bounds(&self, new_bounds: WindowBounds) {
+        let mut bounds = self.context.root_window_bounds.write().unwrap();
+        *bounds = new_bounds;
+    }
+
+    pub fn update(&self, update: TreeUpdate) {
+        let mut handler = AdapterChangeHandler { adapter: self };
+        let mut tree = self.context.tree.write().unwrap();
+        tree.update_and_process_changes(update, &mut handler);
+    }
+
+    pub fn update_window_focus_state(&self, is_focused: bool) {
+        let mut handler = AdapterChangeHandler { adapter: self };
+        let mut tree = self.context.tree.write().unwrap();
+        tree.update_host_focus_state_and_process_changes(is_focused, &mut handler);
+    }
+
+    fn window_created(&self, adapter_index: usize, window: NodeId) {
+        self.emit_root_object_event(ObjectEvent::ChildAdded(adapter_index, window));
+    }
+
+    fn window_activated(&self, window: &NodeWrapper<'_>) {
+        self.callback.emit_event(
+            self,
+            Event::Window {
+                target: window.id(),
+                name: window.name().unwrap_or_default(),
+                event: WindowEvent::Activated,
+            },
+        );
+        self.emit_object_event(window.id(), ObjectEvent::StateChanged(State::Active, true));
+        self.emit_root_object_event(ObjectEvent::ActiveDescendantChanged(window.id()));
+    }
+
+    fn window_deactivated(&self, window: &NodeWrapper<'_>) {
+        self.callback.emit_event(
+            self,
+            Event::Window {
+                target: window.id(),
+                name: window.name().unwrap_or_default(),
+                event: WindowEvent::Deactivated,
+            },
+        );
+        self.emit_object_event(window.id(), ObjectEvent::StateChanged(State::Active, false));
+    }
+
+    fn window_destroyed(&self, window: NodeId) {
+        self.emit_root_object_event(ObjectEvent::ChildRemoved(window));
+    }
+
+    pub fn id(&self) -> usize {
+        self.id
+    }
+}
+
+fn root_window(current_state: &TreeState) -> Option<Node> {
+    const WINDOW_ROLES: &[Role] = &[Role::AlertDialog, Role::Dialog, Role::Window];
+    let root = current_state.root();
+    if WINDOW_ROLES.contains(&root.role()) {
+        Some(root)
+    } else {
+        None
+    }
+}
+
+impl Drop for Adapter {
+    fn drop(&mut self) {
+        let root_id = self.context.read_tree().state().root_id();
+        self.window_destroyed(root_id);
+        // Note: We deliberately do the following here, not in a Drop
+        // implementation on context, because AppContext owns a second
+        // strong reference to Context, and we need that to be released.
+        self.context.write_app_context().remove_adapter(self.id);
+    }
+}