Make it possible to opt out of accessibility support

This is only supported for winit with accesskit right now, with Qt it's always built-in. On macOS and Windows accessibility support is practically free. On Linux it pulls in zbus and async-io.
slint-ui · Jun 13, 2023 · d4f61f9 · d4f61f9
1 parent 0f0b275
commit d4f61f9
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Showing 10 changed files with 28 additions and 11 deletions.
diff --git a/api/cpp/CMakeLists.txt b/api/cpp/CMakeLists.txt
@@ -111,6 +111,7 @@ define_cargo_feature(backend-qt "Enable Qt based rendering backend" ON)
 
 define_cargo_feature(experimental "Enable experimental features (no compatibility guarantees)" OFF)
 define_cargo_feature(gettext "Enable support of translations using gettext" OFF)
+define_cargo_feature(accessibility "Enable integration with operating system provided accessibility APIs" ON)
 
 # Compat options
 option(SLINT_FEATURE_BACKEND_GL_ALL "This feature is an alias for SLINT_FEATURE_BACKEND_WINIT and SLINT_FEATURE_RENDERER_WINIT_FEMTOVG." OFF)

diff --git a/api/cpp/Cargo.toml b/api/cpp/Cargo.toml
@@ -36,6 +36,7 @@ renderer-winit-skia-opengl = ["i-slint-backend-selector/renderer-winit-skia-open
 renderer-winit-skia-vulkan = ["i-slint-backend-selector/renderer-winit-skia-vulkan"]
 renderer-winit-software = ["i-slint-backend-selector/renderer-winit-software"]
 gettext = ["i-slint-core/gettext-rs"]
+accessibility = ["i-slint-backend-selector/accessibility"]
 
 experimental = ["i-slint-renderer-skia", "raw-window-handle"]
 

diff --git a/api/rs/slint/Cargo.toml b/api/rs/slint/Cargo.toml
@@ -24,6 +24,7 @@ default = [
   "backend-winit",
   "renderer-winit-femtovg",
   "backend-qt",
+  "accessibility",
   "compat-1-0",
 ]
 
@@ -65,6 +66,12 @@ software-renderer-systemfonts = ["i-slint-core/software-renderer-systemfonts"]
 ## **Safety** : You must ensure that there is only one single thread that call into the Slint API
 unsafe-single-threaded = ["i-slint-core/unsafe-single-threaded"]
 
+## Enable integration with operating system provided accessibility APIs (default: enabled)
+##
+## Enabling this feature will try to expose the tree of UI elements to OS provided accessibility
+## APIs to support screen readers and other assistive technologies.
+accessibility = ["i-slint-backend-selector/accessibility"]
+
 #! ### Backends
 
 #! Slint needs a backend that will act as liaison between Slint and the OS.

diff --git a/internal/backends/selector/Cargo.toml b/internal/backends/selector/Cargo.toml
@@ -26,6 +26,7 @@ renderer-winit-skia-vulkan = ["i-slint-backend-winit/renderer-winit-skia-vulkan"
 renderer-winit-software = ["i-slint-backend-winit/renderer-winit-software"]
 
 rtti = ["i-slint-backend-winit?/rtti", "i-slint-backend-qt?/rtti"]
+accessibility = ["i-slint-backend-winit?/accessibility"]
 
 [dependencies]
 i-slint-core = { version = "=1.0.3", path = "../../../internal/core", default-features = false }

diff --git a/internal/backends/winit/Cargo.toml b/internal/backends/winit/Cargo.toml
@@ -26,6 +26,7 @@ renderer-winit-skia = ["i-slint-renderer-skia"]
 renderer-winit-skia-opengl = ["renderer-winit-skia", "i-slint-renderer-skia/opengl"]
 renderer-winit-skia-vulkan = ["renderer-winit-skia", "i-slint-renderer-skia/vulkan"]
 renderer-winit-software = ["softbuffer", "imgref", "rgb", "i-slint-core/software-renderer-systemfonts"]
+accessibility = ["accesskit", "accesskit_winit"]
 rtti = ["i-slint-core/rtti"]
 default = []
 
@@ -69,8 +70,8 @@ wasm-bindgen = { version = "0.2" }
 [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" }
+accesskit = { version = "0.11.0", optional = true }
+accesskit_winit = { version = "0.14.0", optional = true }
 
 [target.'cfg(target_os = "macos")'.dependencies]
 # For GL rendering

diff --git a/internal/backends/winit/build.rs b/internal/backends/winit/build.rs
@@ -7,5 +7,6 @@ fn main() {
     // Setup cfg aliases
     cfg_aliases! {
        enable_skia_renderer: { any(feature = "renderer-winit-skia", feature = "renderer-winit-skia-opengl", feature = "renderer-winit-skia-vulkan")},
+       enable_accesskit: { all(feature = "accessibility", not(target_arch = "wasm32")) },
     }
 }
diff --git a/internal/backends/winit/event_loop.rs b/internal/backends/winit/event_loop.rs
@@ -502,9 +502,9 @@ pub fn run() -> Result<(), corelib::platform::PlatformError> {
         match event {
             Event::WindowEvent { event, window_id } => {
                 if let Some(window) = window_by_id(window_id) {
-                    #[cfg(target_arch = "wasm32")]
+                    #[cfg(not(enable_accesskit))]
                     let process_event = true;
-                    #[cfg(not(target_arch = "wasm32"))]
+                    #[cfg(enable_accesskit)]
                     let process_event =
                         window.accesskit_adapter.on_event(&window.winit_window(), &event);
 

diff --git a/internal/backends/winit/lib.rs b/internal/backends/winit/lib.rs
@@ -53,7 +53,7 @@ mod renderer {
     pub(crate) mod sw;
 }
 
-#[cfg(not(target_arch = "wasm32"))]
+#[cfg(enable_accesskit)]
 mod accesskit;
 
 #[cfg(target_arch = "wasm32")]

diff --git a/internal/backends/winit/winitwindowadapter.rs b/internal/backends/winit/winitwindowadapter.rs
@@ -20,9 +20,9 @@ use crate::renderer::WinitCompatibleRenderer;
 use const_field_offset::FieldOffsets;
 
 use corelib::component::ComponentRc;
-#[cfg(not(target_arch = "wasm32"))]
+#[cfg(enable_accesskit)]
 use corelib::component::ComponentRef;
-#[cfg(not(target_arch = "wasm32"))]
+#[cfg(enable_accesskit)]
 use corelib::items::ItemRef;
 use corelib::items::{ItemRc, MouseCursor};
 
@@ -123,7 +123,7 @@ pub struct WinitWindowAdapter {
     #[cfg(target_arch = "wasm32")]
     virtual_keyboard_helper: RefCell<Option<super::wasm_input_helper::WasmInputHelper>>,
 
-    #[cfg(not(target_arch = "wasm32"))]
+    #[cfg(enable_accesskit)]
     pub accesskit_adapter: crate::accesskit::AccessKitAdapter,
 }
 
@@ -153,7 +153,7 @@ impl WinitWindowAdapter {
             renderer: Box::new(renderer),
             #[cfg(target_arch = "wasm32")]
             virtual_keyboard_helper: Default::default(),
-            #[cfg(not(target_arch = "wasm32"))]
+            #[cfg(enable_accesskit)]
             accesskit_adapter: crate::accesskit::AccessKitAdapter::new(
                 self_weak.clone(),
                 &*winit_window,
@@ -655,11 +655,11 @@ impl WindowAdapterSealed for WinitWindowAdapter {
     }
 
     fn handle_focus_change(&self, _old: Option<ItemRc>, _new: Option<ItemRc>) {
-        #[cfg(not(target_arch = "wasm32"))]
+        #[cfg(enable_accesskit)]
         self.accesskit_adapter.handle_focus_change(_new);
     }
 
-    #[cfg(not(target_arch = "wasm32"))]
+    #[cfg(enable_accesskit)]
     fn unregister_component<'a>(
         &self,
         _component: ComponentRef,

diff --git a/internal/interpreter/Cargo.toml b/internal/interpreter/Cargo.toml
@@ -81,6 +81,11 @@ renderer-winit-skia-vulkan = ["i-slint-backend-selector/renderer-winit-skia-vulk
 ## Must be used in combination with `backend-winit`, `backend-winit-x11`, or `backend-winit-wayland`.
 renderer-winit-software = ["i-slint-backend-selector/renderer-winit-software"]
 
+## Enable integration with operating system provided accessibility APIs (default: enabled)
+##
+## Enabling this feature will try to expose the tree of UI elements to OS provided accessibility
+## APIs to support screen readers and other assistive technologies.
+accessibility = ["i-slint-backend-selector/accessibility"]
 
 [dependencies]
 i-slint-compiler = { version = "=1.0.3", path = "../compiler" }