Initial AccessKit support

This change adds initial accessibility support for the winit backend
through use of AccessKit.

helper_crates/vtable/src/vrc.rs

@@ -207,6 +207,23 @@ impl<VTable: VTableMetaDropInPlace + 'static> VRc<VTable, Dyn> {
     ) -> VRcMapped<VTable, MappedType> {
         VRcMapped { parent_strong: this.clone(), object: map_fn(Self::borrow_pin(&this)).get_ref() }
     }
+
+    /// Returns a raw pointer to the inner data structure that holds the reference counted object.
+    /// This pointer is only valid as long as a `VRc` remains alive.
+    pub fn as_raw_ptr(&self) -> *const core::ffi::c_void {
+        self.inner.as_ptr() as _
+    }
+
+    /// Transmutes a raw pointer to VRc's inner data structure back into a VRc. Use in combination
+    /// with `as_raw_ptr()`.
+    ///
+    /// Safety: This is highly unsafe. Don't use this unless you're absolutely certain that somebody
+    /// else is keeping the object alive via a VRc.
+    pub unsafe fn from_raw_ptr(raw_dyn: *const core::ffi::c_void) -> Self {
+        let inner: NonNull<VRcInner<'static, VTable, Dyn>> = core::mem::transmute(raw_dyn);
+        inner.as_ref().strong_ref.fetch_add(1, Ordering::SeqCst);
+        Self { inner }
+    }
 }
 impl<VTable: VTableMetaDropInPlace, X> VRc<VTable, X> {
     /// Create a Pinned reference to the inner.

internal/backends/winit/Cargo.toml

@@ -49,6 +49,7 @@ winit = { version = "=0.28.6", default-features = false }
 instant = "0.1"
 raw-window-handle = { version = "0.5", features = ["alloc"] }
 scopeguard =  { version = "1.1.0", default-features = false }
+send_wrapper = { workspace = true }
 
 # For the FemtoVG renderer
 i-slint-renderer-femtovg = { version = "=1.0.3", path = "../../renderers/femtovg", optional = true }
@@ -64,11 +65,12 @@ rgb = { version = "0.8.27", optional = true }
 [target.'cfg(target_arch = "wasm32")'.dependencies]
 web-sys = { version = "0.3", features=["HtmlInputElement", "HtmlCanvasElement", "Window", "Document", "Event", "KeyboardEvent", "InputEvent", "CompositionEvent", "DomStringMap", "ClipboardEvent", "DataTransfer"] }
 wasm-bindgen = { version = "0.2" }
-send_wrapper = { workspace = true }
 
 [target.'cfg(not(target_arch = "wasm32"))'.dependencies]
 glutin = { version = "0.30", optional = true, default-features = false, features = ["egl", "wgl"] }
 glutin-winit = { version = "0.3.0", optional = true, default-features = false, features = ["egl", "wgl"] }
+accesskit = { version = "0.11.0" }
+accesskit_winit = { version = "0.14.0" }
 
 [target.'cfg(target_os = "macos")'.dependencies]
 # For GL rendering

internal/backends/winit/event_loop.rs

@@ -502,8 +502,17 @@ pub fn run() -> Result<(), corelib::platform::PlatformError> {
         match event {
             Event::WindowEvent { event, window_id } => {
                 if let Some(window) = window_by_id(window_id) {
-                    *inner_event_loop_error.borrow_mut() =
-                        process_window_event(window, event, &mut cursor_pos, &mut pressed).err();
+                    #[cfg(target_arch = "wasm32")]
+                    let process_event = true;
+                    #[cfg(not(target_arch = "wasm32"))]
+                    let process_event =
+                        window.accesskit_adapter.on_event(&window.winit_window(), &event);
+
+                    if process_event {
+                        *inner_event_loop_error.borrow_mut() =
+                            process_window_event(window, event, &mut cursor_pos, &mut pressed)
+                                .err();
+                    }
                 };
             }
 

internal/backends/winit/winitwindowadapter.rs

@@ -20,7 +20,11 @@ use crate::renderer::WinitCompatibleRenderer;
 use const_field_offset::FieldOffsets;
 
 use corelib::component::ComponentRc;
-use corelib::items::MouseCursor;
+#[cfg(not(target_arch = "wasm32"))]
+use corelib::component::ComponentRef;
+#[cfg(not(target_arch = "wasm32"))]
+use corelib::items::ItemRef;
+use corelib::items::{ItemRc, MouseCursor};
 
 use corelib::layout::Orientation;
 use corelib::lengths::{LogicalLength, LogicalSize};
@@ -31,6 +35,9 @@ use corelib::{graphics::*, Coord};
 use i_slint_core as corelib;
 use once_cell::unsync::OnceCell;
 
+#[cfg(not(target_arch = "wasm32"))]
+mod accesskit;
+
 fn position_to_winit(pos: &corelib::api::WindowPosition) -> winit::dpi::Position {
     match pos {
         corelib::api::WindowPosition::Logical(pos) => {
@@ -118,6 +125,9 @@ pub struct WinitWindowAdapter {
 
     #[cfg(target_arch = "wasm32")]
     virtual_keyboard_helper: RefCell<Option<super::wasm_input_helper::WasmInputHelper>>,
+
+    #[cfg(not(target_arch = "wasm32"))]
+    pub accesskit_adapter: accesskit::AccessKitAdapter,
 }
 
 impl WinitWindowAdapter {
@@ -131,6 +141,8 @@ impl WinitWindowAdapter {
         )
         .and_then(|builder| R::new(builder))?;
 
+        let winit_window = Rc::new(winit_window);
+
         let self_rc = Rc::new_cyclic(|self_weak| Self {
             window: OnceCell::with_value(corelib::api::Window::new(self_weak.clone() as _)),
             #[cfg(target_arch = "wasm32")]
@@ -140,10 +152,12 @@ impl WinitWindowAdapter {
             dark_color_scheme: Default::default(),
             constraints: Default::default(),
             shown: Default::default(),
-            winit_window: Rc::new(winit_window),
+            winit_window: winit_window.clone(),
             renderer: Box::new(renderer),
             #[cfg(target_arch = "wasm32")]
             virtual_keyboard_helper: Default::default(),
+            #[cfg(not(target_arch = "wasm32"))]
+            accesskit_adapter: accesskit::AccessKitAdapter::new(self_weak.clone(), &*winit_window),
         });
 
         let id = self_rc.winit_window().id();
@@ -639,6 +653,20 @@ impl WindowAdapterSealed for WinitWindowAdapter {
     fn is_visible(&self) -> bool {
         self.winit_window().is_visible().unwrap_or(true)
     }
+
+    fn handle_focus_change(&self, _old: Option<ItemRc>, _new: Option<ItemRc>) {
+        #[cfg(not(target_arch = "wasm32"))]
+        self.accesskit_adapter.handle_focus_change(_new);
+    }
+
+    #[cfg(not(target_arch = "wasm32"))]
+    fn unregister_component<'a>(
+        &self,
+        _component: ComponentRef,
+        _: &mut dyn Iterator<Item = Pin<ItemRef<'a>>>,
+    ) {
+        self.accesskit_adapter.unregister_component(_component);
+    }
 }
 
 impl Drop for WinitWindowAdapter {