refactor!: Decouple in-tree focus from host window/view focus (#278)

Author: mwcampbell

bindings/c/examples/sdl/hello_world.c

@@ -76,8 +76,8 @@ void accesskit_sdl_adapter_init(struct accesskit_sdl_adapter *adapter,
   adapter->adapter = accesskit_macos_subclassing_adapter_for_window(
       (void *)wmInfo.info.cocoa.window, source, source_userdata, handler);
 #elif defined(UNIX)
-  adapter->adapter = accesskit_unix_adapter_new(app_name, "SDL", "2.0", source,
-                                                source_userdata, handler);
+  adapter->adapter = accesskit_unix_adapter_new(
+      app_name, "SDL", "2.0", source, source_userdata, false, handler);
 #elif defined(_WIN32)
   SDL_SysWMinfo wmInfo;
   SDL_VERSION(&wmInfo.version);
@@ -145,6 +145,24 @@ void accesskit_sdl_adapter_update_if_active(
 #endif
 }
 
+void accesskit_sdl_adapter_update_window_focus_state(
+    const struct accesskit_sdl_adapter *adapter, bool is_focused) {
+#if defined(__APPLE__)
+  accesskit_macos_queued_events *events =
+      accesskit_macos_subclassing_adapter_update_view_focus_state(
+          adapter->adapter, is_focused);
+  if (events != NULL) {
+    accesskit_macos_queued_events_raise(events);
+  }
+#elif defined(UNIX)
+  if (adapter->adapter != NULL) {
+    accesskit_unix_adapter_update_window_focus_state(adapter->adapter,
+                                                     is_focused);
+  }
+#endif
+  /* On Windows, the subclassing adapter takes care of this. */
+}
+
 void accesskit_sdl_adapter_update_root_window_bounds(
     const struct accesskit_sdl_adapter *adapter, SDL_Window *window) {
 #if defined(UNIX)
@@ -165,15 +183,13 @@ void accesskit_sdl_adapter_update_root_window_bounds(
 
 struct window_state {
   accesskit_node_id focus;
-  bool is_window_focused;
   const char *announcement;
   accesskit_node_class_set *node_classes;
   SDL_mutex *mutex;
 };
 
 void window_state_init(struct window_state *state) {
   state->focus = INITIAL_FOCUS;
-  state->is_window_focused = false;
   state->announcement = NULL;
   state->node_classes = accesskit_node_class_set_new();
   state->mutex = SDL_CreateMutex();
@@ -192,13 +208,6 @@ void window_state_unlock(struct window_state *state) {
   SDL_UnlockMutex(state->mutex);
 }
 
-void window_state_set_tree_update_focus(const struct window_state *state,
-                                        accesskit_tree_update *update) {
-  if (state->is_window_focused) {
-    accesskit_tree_update_set_focus(update, state->focus);
-  }
-}
-
 accesskit_node *window_state_build_root(const struct window_state *state) {
   accesskit_node_builder *builder =
       accesskit_node_builder_new(ACCESSKIT_ROLE_WINDOW);
@@ -218,10 +227,9 @@ accesskit_tree_update *window_state_build_initial_tree(
       build_button(BUTTON_1_ID, "Button 1", state->node_classes);
   accesskit_node *button_2 =
       build_button(BUTTON_2_ID, "Button 2", state->node_classes);
-  accesskit_tree_update *result = accesskit_tree_update_with_capacity(
-      (state->announcement != NULL) ? 4 : 3);
+  accesskit_tree_update *result = accesskit_tree_update_with_capacity_and_focus(
+      (state->announcement != NULL) ? 4 : 3, state->focus);
   accesskit_tree_update_set_tree(result, accesskit_tree_new(WINDOW_ID));
-  window_state_set_tree_update_focus(state, result);
   accesskit_tree_update_push_node(result, WINDOW_ID, root);
   accesskit_tree_update_push_node(result, BUTTON_1_ID, button_1);
   accesskit_tree_update_push_node(result, BUTTON_2_ID, button_2);
@@ -238,10 +246,10 @@ accesskit_tree_update *build_tree_update_for_button_press(void *userdata) {
   accesskit_node *announcement =
       build_announcement(state->announcement, state->node_classes);
   accesskit_node *root = window_state_build_root(state);
-  accesskit_tree_update *update = accesskit_tree_update_with_capacity(2);
+  accesskit_tree_update *update =
+      accesskit_tree_update_with_capacity_and_focus(2, state->focus);
   accesskit_tree_update_push_node(update, ANNOUNCEMENT_ID, announcement);
   accesskit_tree_update_push_node(update, WINDOW_ID, root);
-  accesskit_tree_update_set_focus(update, state->focus);
   return update;
 }
 
@@ -261,13 +269,15 @@ void window_state_press_button(struct window_state *state,
 
 accesskit_tree_update *build_tree_update_for_focus_update(void *userdata) {
   struct window_state *state = userdata;
-  accesskit_tree_update *update = accesskit_tree_update_new();
-  accesskit_tree_update_set_focus(update, state->focus);
+  accesskit_tree_update *update =
+      accesskit_tree_update_with_focus(state->focus);
   return update;
 }
 
-void window_state_update_focus(struct window_state *state,
-                               const struct accesskit_sdl_adapter *adapter) {
+void window_state_set_focus(struct window_state *state,
+                            const struct accesskit_sdl_adapter *adapter,
+                            accesskit_node_id focus) {
+  state->focus = focus;
   accesskit_sdl_adapter_update_if_active(
       adapter, build_tree_update_for_focus_update, state);
 }
@@ -345,17 +355,10 @@ int main(int argc, char *argv[]) {
                event.window.windowID == window_id) {
       switch (event.window.event) {
         case SDL_WINDOWEVENT_FOCUS_GAINED:
-          window_state_lock(&state);
-          state.is_window_focused = true;
-          window_state_update_focus(&state, &adapter);
-          window_state_unlock(&state);
-          continue;
+          accesskit_sdl_adapter_update_window_focus_state(&adapter, true);
           break;
         case SDL_WINDOWEVENT_FOCUS_LOST:
-          window_state_lock(&state);
-          state.is_window_focused = false;
-          window_state_update_focus(&state, &adapter);
-          window_state_unlock(&state);
+          accesskit_sdl_adapter_update_window_focus_state(&adapter, false);
           break;
         case SDL_WINDOWEVENT_MAXIMIZED:
         case SDL_WINDOWEVENT_MOVED:
@@ -370,12 +373,9 @@ int main(int argc, char *argv[]) {
       switch (event.key.keysym.sym) {
         case SDLK_TAB:
           window_state_lock(&state);
-          if (state.focus == BUTTON_1_ID) {
-            state.focus = BUTTON_2_ID;
-          } else {
-            state.focus = BUTTON_1_ID;
-          }
-          window_state_update_focus(&state, &adapter);
+          accesskit_node_id new_focus =
+              (state.focus == BUTTON_1_ID) ? BUTTON_2_ID : BUTTON_1_ID;
+          window_state_set_focus(&state, &adapter, new_focus);
           window_state_unlock(&state);
           break;
         case SDLK_SPACE:
@@ -391,8 +391,7 @@ int main(int argc, char *argv[]) {
       if (target == BUTTON_1_ID || target == BUTTON_2_ID) {
         window_state_lock(&state);
         if (event.user.code == SET_FOCUS_MSG) {
-          state.focus = target;
-          window_state_update_focus(&state, &adapter);
+          window_state_set_focus(&state, &adapter, target);
         } else if (event.user.code == DO_DEFAULT_ACTION_MSG) {
           window_state_press_button(&state, &adapter, target);
         }

bindings/c/examples/windows/hello_world.c

@@ -68,13 +68,6 @@ void window_state_free(struct window_state *state) {
   free(state);
 }
 
-void window_state_set_tree_update_focus(struct window_state *state,
-                                        accesskit_tree_update *update) {
-  if (state->is_window_focused) {
-    accesskit_tree_update_set_focus(update, state->focus);
-  }
-}
-
 accesskit_node *window_state_build_root(struct window_state *state) {
   accesskit_node_builder *builder =
       accesskit_node_builder_new(ACCESSKIT_ROLE_WINDOW);
@@ -93,10 +86,9 @@ accesskit_tree_update *window_state_build_initial_tree(
       build_button(BUTTON_1_ID, "Button 1", state->node_classes);
   accesskit_node *button_2 =
       build_button(BUTTON_2_ID, "Button 2", state->node_classes);
-  accesskit_tree_update *result = accesskit_tree_update_with_capacity(
-      (state->announcement != NULL) ? 4 : 3);
+  accesskit_tree_update *result = accesskit_tree_update_with_capacity_and_focus(
+      (state->announcement != NULL) ? 4 : 3, state->focus);
   accesskit_tree_update_set_tree(result, accesskit_tree_new(WINDOW_ID));
-  window_state_set_tree_update_focus(state, result);
   accesskit_tree_update_push_node(result, WINDOW_ID, root);
   accesskit_tree_update_push_node(result, BUTTON_1_ID, button_1);
   accesskit_tree_update_push_node(result, BUTTON_2_ID, button_2);
@@ -129,12 +121,24 @@ accesskit_windows_adapter *window_state_get_or_init_accesskit_adapter(
     accesskit_action_handler *action_handler =
         accesskit_action_handler_new(do_action, (void *)window);
     state->adapter = accesskit_windows_adapter_new(
-        window, initial_tree, action_handler, state->uia_init_marker);
+        window, initial_tree, state->is_window_focused, action_handler,
+        state->uia_init_marker);
     state->uia_init_marker = NULL;
     return state->adapter;
   }
 }
 
+void window_state_set_focus(struct window_state *state,
+                            accesskit_node_id focus) {
+  state->focus = focus;
+  if (state->adapter != NULL) {
+    accesskit_tree_update *update = accesskit_tree_update_with_focus(focus);
+    accesskit_windows_queued_events *events =
+        accesskit_windows_adapter_update(state->adapter, update);
+    accesskit_windows_queued_events_raise(events);
+  }
+}
+
 void window_state_press_button(struct window_state *state,
                                accesskit_node_id id) {
   const char *text;
@@ -148,10 +152,10 @@ void window_state_press_button(struct window_state *state,
     accesskit_node *announcement =
         build_announcement(text, state->node_classes);
     accesskit_node *root = window_state_build_root(state);
-    accesskit_tree_update *update = accesskit_tree_update_with_capacity(2);
+    accesskit_tree_update *update =
+        accesskit_tree_update_with_capacity_and_focus(2, state->focus);
     accesskit_tree_update_push_node(update, ANNOUNCEMENT_ID, announcement);
     accesskit_tree_update_push_node(update, WINDOW_ID, root);
-    window_state_set_tree_update_focus(state, update);
     accesskit_windows_queued_events *events =
         accesskit_windows_adapter_update(state->adapter, update);
     accesskit_windows_queued_events_raise(events);
@@ -162,14 +166,13 @@ struct window_state *get_window_state(HWND window) {
   return (struct window_state *)(GetWindowLongPtr(window, GWLP_USERDATA));
 }
 
-void update_focus(HWND window, bool is_window_focused) {
+void update_window_focus_state(HWND window, bool is_focused) {
   struct window_state *state = get_window_state(window);
-  state->is_window_focused = is_window_focused;
+  state->is_window_focused = is_focused;
   if (state->adapter != NULL) {
-    accesskit_tree_update *update = accesskit_tree_update_new();
-    window_state_set_tree_update_focus(state, update);
     accesskit_windows_queued_events *events =
-        accesskit_windows_adapter_update(state->adapter, update);
+        accesskit_windows_adapter_update_window_focus_state(state->adapter,
+                                                            is_focused);
     accesskit_windows_queued_events_raise(events);
   }
 }
@@ -220,19 +223,16 @@ LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam) {
     }
   } else if (msg == WM_SETFOCUS || msg == WM_EXITMENULOOP ||
              msg == WM_EXITSIZEMOVE) {
-    update_focus(hwnd, true);
+    update_window_focus_state(hwnd, true);
   } else if (msg == WM_KILLFOCUS || msg == WM_ENTERMENULOOP ||
              msg == WM_ENTERSIZEMOVE) {
-    update_focus(hwnd, false);
+    update_window_focus_state(hwnd, false);
   } else if (msg == WM_KEYDOWN) {
     if (wParam == VK_TAB) {
       struct window_state *state = get_window_state(hwnd);
-      if (state->focus == BUTTON_1_ID) {
-        state->focus = BUTTON_2_ID;
-      } else {
-        state->focus = BUTTON_1_ID;
-      }
-      update_focus(hwnd, true);
+      accesskit_node_id new_focus =
+          (state->focus == BUTTON_1_ID) ? BUTTON_2_ID : BUTTON_1_ID;
+      window_state_set_focus(state, new_focus);
     } else if (wParam == VK_SPACE) {
       struct window_state *window_state = get_window_state(hwnd);
       accesskit_node_id id = window_state->focus;
@@ -244,9 +244,7 @@ LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam) {
     accesskit_node_id id = (accesskit_node_id)lParam;
     if (id == BUTTON_1_ID || id == BUTTON_2_ID) {
       struct window_state *state = get_window_state(hwnd);
-      state->focus = id;
-      bool is_window_focused = state->is_window_focused;
-      update_focus(hwnd, is_window_focused);
+      window_state_set_focus(state, id);
     }
   } else if (msg == DO_DEFAULT_ACTION_MSG) {
     accesskit_node_id id = (accesskit_node_id)lParam;

bindings/c/src/common.rs

@@ -907,16 +907,24 @@ impl BoxCastPtr for tree_update {}
 
 impl tree_update {
     #[no_mangle]
-    pub extern "C" fn accesskit_tree_update_new() -> *mut tree_update {
-        let update = TreeUpdate::default();
+    pub extern "C" fn accesskit_tree_update_with_focus(focus: node_id) -> *mut tree_update {
+        let update = TreeUpdate {
+            nodes: vec![],
+            tree: None,
+            focus: focus.into(),
+        };
         BoxCastPtr::to_mut_ptr(update)
     }
 
     #[no_mangle]
-    pub extern "C" fn accesskit_tree_update_with_capacity(capacity: usize) -> *mut tree_update {
+    pub extern "C" fn accesskit_tree_update_with_capacity_and_focus(
+        capacity: usize,
+        focus: node_id,
+    ) -> *mut tree_update {
         let update = TreeUpdate {
             nodes: Vec::with_capacity(capacity),
-            ..Default::default()
+            tree: None,
+            focus: focus.into(),
         };
         BoxCastPtr::to_mut_ptr(update)
     }
@@ -954,13 +962,7 @@ impl tree_update {
     #[no_mangle]
     pub extern "C" fn accesskit_tree_update_set_focus(update: *mut tree_update, focus: node_id) {
         let update = mut_from_ptr(update);
-        update.focus = Some(focus.into());
-    }
-
-    #[no_mangle]
-    pub extern "C" fn accesskit_tree_update_clear_focus(update: *mut tree_update) {
-        let update = mut_from_ptr(update);
-        update.focus = None;
+        update.focus = focus.into();
     }
 }