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AccessibilityBridgeMac.mm
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1 // Copyright 2013 The Flutter Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #import "flutter/shell/platform/darwin/macos/framework/Source/AccessibilityBridgeMac.h"
6
7 #import "flutter/shell/platform/darwin/macos/framework/Source/FlutterEngine_Internal.h"
8 #import "flutter/shell/platform/darwin/macos/framework/Source/FlutterPlatformNodeDelegateMac.h"
9 #import "flutter/shell/platform/darwin/macos/framework/Source/FlutterTextInputSemanticsObject.h"
10 #import "flutter/shell/platform/darwin/macos/framework/Source/FlutterViewController_Internal.h"
11 #include "flutter/shell/platform/embedder/embedder.h"
12
13 namespace flutter {
14
15 // Native mac notifications fired. These notifications are not publicly documented.
16 static NSString* const kAccessibilityLoadCompleteNotification = @"AXLoadComplete";
17 static NSString* const kAccessibilityInvalidStatusChangedNotification = @"AXInvalidStatusChanged";
18 static NSString* const kAccessibilityLiveRegionCreatedNotification = @"AXLiveRegionCreated";
19 static NSString* const kAccessibilityLiveRegionChangedNotification = @"AXLiveRegionChanged";
20 static NSString* const kAccessibilityExpandedChanged = @"AXExpandedChanged";
21 static NSString* const kAccessibilityMenuItemSelectedNotification = @"AXMenuItemSelected";
22
23 AccessibilityBridgeMac::AccessibilityBridgeMac(__weak FlutterEngine* flutter_engine,
24 __weak FlutterViewController* view_controller)
25 : flutter_engine_(flutter_engine), view_controller_(view_controller) {}
26
27 void AccessibilityBridgeMac::OnAccessibilityEvent(
28 ui::AXEventGenerator::TargetedEvent targeted_event) {
29 if (!view_controller_.viewLoaded || !view_controller_.view.window) {
30 // Don't need to send accessibility events if the there is no view or window.
31 return;
32 }
33 ui::AXNode* ax_node = targeted_event.node;
34 std::vector<AccessibilityBridgeMac::NSAccessibilityEvent> events =
35 MacOSEventsFromAXEvent(targeted_event.event_params.event, *ax_node);
36 for (const AccessibilityBridgeMac::NSAccessibilityEvent& event : events) {
37 if (event.user_info != nil) {
38 DispatchMacOSNotificationWithUserInfo(event.target, event.name, event.user_info);
39 } else {
40 DispatchMacOSNotification(event.target, event.name);
41 }
42 }
43 }
44
45 std::vector<AccessibilityBridgeMac::NSAccessibilityEvent>
46 AccessibilityBridgeMac::MacOSEventsFromAXEvent(ui::AXEventGenerator::Event event_type,
47 const ui::AXNode& ax_node) const {
48 // Gets the native_node with the node_id.
49 NSCAssert(flutter_engine_, @"Flutter engine should not be deallocated");
50 auto platform_node_delegate = GetFlutterPlatformNodeDelegateFromID(ax_node.id()).lock();
51 NSCAssert(platform_node_delegate, @"Event target must exist in accessibility bridge.");
52 auto mac_platform_node_delegate =
53 std::static_pointer_cast<FlutterPlatformNodeDelegateMac>(platform_node_delegate);
54 gfx::NativeViewAccessible native_node = mac_platform_node_delegate->GetNativeViewAccessible();
55
56 std::vector<AccessibilityBridgeMac::NSAccessibilityEvent> events;
57 switch (event_type) {
58 case ui::AXEventGenerator::Event::ACTIVE_DESCENDANT_CHANGED:
59 if (ax_node.data().role == ax::mojom::Role::kTree) {
60 events.push_back({
61 .name = NSAccessibilitySelectedRowsChangedNotification,
62 .target = native_node,
63 .user_info = nil,
64 });
65 } else if (ax_node.data().role == ax::mojom::Role::kTextFieldWithComboBox) {
66 // Even though the selected item in the combo box has changed, don't
67 // post a focus change because this will take the focus out of
68 // the combo box where the user might be typing.
69 events.push_back({
70 .name = NSAccessibilitySelectedChildrenChangedNotification,
71 .target = native_node,
72 .user_info = nil,
73 });
74 }
75 // In all other cases, this delegate should post
76 // |NSAccessibilityFocusedUIElementChangedNotification|, but this is
77 // handled elsewhere.
78 break;
79 case ui::AXEventGenerator::Event::LOAD_COMPLETE:
80 events.push_back({
81 .name = kAccessibilityLoadCompleteNotification,
82 .target = native_node,
83 .user_info = nil,
84 });
85 break;
86 case ui::AXEventGenerator::Event::INVALID_STATUS_CHANGED:
87 events.push_back({
88 .name = kAccessibilityInvalidStatusChangedNotification,
89 .target = native_node,
90 .user_info = nil,
91 });
92 break;
93 case ui::AXEventGenerator::Event::SELECTED_CHILDREN_CHANGED:
94 if (ui::IsTableLike(ax_node.data().role)) {
95 events.push_back({
96 .name = NSAccessibilitySelectedRowsChangedNotification,
97 .target = native_node,
98 .user_info = nil,
99 });
100 } else {
101 // VoiceOver does not read anything if selection changes on the
102 // currently focused object, and the focus did not move. Fire a
103 // selection change if the focus did not change.
104 NSAccessibilityElement* native_accessibility_node = (NSAccessibilityElement*)native_node;
105 if (native_accessibility_node.accessibilityFocusedUIElement &&
106 ax_node.data().HasState(ax::mojom::State::kMultiselectable) &&
107 !HasPendingEvent(ui::AXEventGenerator::Event::ACTIVE_DESCENDANT_CHANGED) &&
108 !HasPendingEvent(ui::AXEventGenerator::Event::FOCUS_CHANGED)) {
109 // Don't fire selected children change, it will sometimes override
110 // announcement of current focus.
111 break;
112 }
113 events.push_back({
114 .name = NSAccessibilitySelectedChildrenChangedNotification,
115 .target = native_node,
116 .user_info = nil,
117 });
118 }
119 break;
120 case ui::AXEventGenerator::Event::DOCUMENT_SELECTION_CHANGED: {
121 id focused = mac_platform_node_delegate->GetFocus();
122 if ([focused isKindOfClass:[FlutterTextField class]]) {
123 // If it is a text field, the selection notifications are handled by
124 // the FlutterTextField directly. Only need to make sure it is the
125 // first responder.
126 FlutterTextField* native_text_field = (FlutterTextField*)focused;
127 if (native_text_field == mac_platform_node_delegate->GetFocus()) {
128 [native_text_field startEditing];
129 }
130 break;
131 }
132 // This event always fires at root
133 events.push_back({
134 .name = NSAccessibilitySelectedTextChangedNotification,
135 .target = native_node,
136 .user_info = nil,
137 });
138 // WebKit fires a notification both on the focused object and the page
139 // root.
140 const ui::AXTreeData& tree_data = GetAXTreeData();
141 int32_t focus = tree_data.focus_id;
142 if (focus == ui::AXNode::kInvalidAXID || focus != tree_data.sel_anchor_object_id) {
143 break; // Just fire a notification on the root.
144 }
145 auto focus_node = GetFlutterPlatformNodeDelegateFromID(focus).lock();
146 if (!focus_node) {
147 break; // Just fire a notification on the root.
148 }
149 events.push_back({
150 .name = NSAccessibilitySelectedTextChangedNotification,
151 .target = focus_node->GetNativeViewAccessible(),
152 .user_info = nil,
153 });
154 break;
155 }
156 case ui::AXEventGenerator::Event::CHECKED_STATE_CHANGED:
157 events.push_back({
158 .name = NSAccessibilityValueChangedNotification,
159 .target = native_node,
160 .user_info = nil,
161 });
162 break;
163 case ui::AXEventGenerator::Event::VALUE_CHANGED: {
164 if (ax_node.data().role == ax::mojom::Role::kTextField) {
165 // If it is a text field, the value change notifications are handled by
166 // the FlutterTextField directly. Only need to make sure it is the
167 // first responder.
168 id native_text_field = mac_platform_node_delegate->GetNativeViewAccessible();
169 FML_DCHECK([native_text_field isKindOfClass:FlutterTextField.class]);
170 id focused = mac_platform_node_delegate->GetFocus();
171 if (!focused || native_text_field == focused) {
172 [(FlutterTextField*)native_text_field startEditing];
173 }
174 break;
175 }
176 events.push_back({
177 .name = NSAccessibilityValueChangedNotification,
178 .target = native_node,
179 .user_info = nil,
180 });
181 if (ax_node.data().HasState(ax::mojom::State::kEditable)) {
182 events.push_back({
183 .name = NSAccessibilityValueChangedNotification,
184 .target = RootDelegate()->GetNativeViewAccessible(),
185 .user_info = nil,
186 });
187 }
188 break;
189 }
190 case ui::AXEventGenerator::Event::LIVE_REGION_CREATED:
191 events.push_back({
192 .name = kAccessibilityLiveRegionCreatedNotification,
193 .target = native_node,
194 .user_info = nil,
195 });
196 break;
197 case ui::AXEventGenerator::Event::ALERT: {
198 events.push_back({
199 .name = kAccessibilityLiveRegionCreatedNotification,
200 .target = native_node,
201 .user_info = nil,
202 });
203 // VoiceOver requires a live region changed notification to actually
204 // announce the live region.
205 auto live_region_events =
206 MacOSEventsFromAXEvent(ui::AXEventGenerator::Event::LIVE_REGION_CHANGED, ax_node);
207 events.insert(events.end(), live_region_events.begin(), live_region_events.end());
208 break;
209 }
210 case ui::AXEventGenerator::Event::LIVE_REGION_CHANGED: {
211 // Uses native VoiceOver support for live regions.
212 events.push_back({
213 .name = kAccessibilityLiveRegionChangedNotification,
214 .target = native_node,
215 .user_info = nil,
216 });
217 break;
218 }
219 case ui::AXEventGenerator::Event::ROW_COUNT_CHANGED:
220 events.push_back({
221 .name = NSAccessibilityRowCountChangedNotification,
222 .target = native_node,
223 .user_info = nil,
224 });
225 break;
226 case ui::AXEventGenerator::Event::EXPANDED: {
227 NSAccessibilityNotificationName mac_notification;
228 if (ax_node.data().role == ax::mojom::Role::kRow ||
229 ax_node.data().role == ax::mojom::Role::kTreeItem) {
230 mac_notification = NSAccessibilityRowExpandedNotification;
231 } else {
232 mac_notification = kAccessibilityExpandedChanged;
233 }
234 events.push_back({
235 .name = mac_notification,
236 .target = native_node,
237 .user_info = nil,
238 });
239 break;
240 }
241 case ui::AXEventGenerator::Event::COLLAPSED: {
242 NSAccessibilityNotificationName mac_notification;
243 if (ax_node.data().role == ax::mojom::Role::kRow ||
244 ax_node.data().role == ax::mojom::Role::kTreeItem) {
245 mac_notification = NSAccessibilityRowCollapsedNotification;
246 } else {
247 mac_notification = kAccessibilityExpandedChanged;
248 }
249 events.push_back({
250 .name = mac_notification,
251 .target = native_node,
252 .user_info = nil,
253 });
254 break;
255 }
256 case ui::AXEventGenerator::Event::MENU_ITEM_SELECTED:
257 events.push_back({
258 .name = kAccessibilityMenuItemSelectedNotification,
259 .target = native_node,
260 .user_info = nil,
261 });
262 break;
263 case ui::AXEventGenerator::Event::CHILDREN_CHANGED: {
264 // NSAccessibilityCreatedNotification seems to be the only way to let
265 // Voiceover pick up layout changes.
266 events.push_back({
267 .name = NSAccessibilityCreatedNotification,
268 .target = view_controller_.view.window,
269 .user_info = nil,
270 });
271 break;
272 }
273 case ui::AXEventGenerator::Event::SUBTREE_CREATED:
274 case ui::AXEventGenerator::Event::ACCESS_KEY_CHANGED:
275 case ui::AXEventGenerator::Event::ATK_TEXT_OBJECT_ATTRIBUTE_CHANGED:
276 case ui::AXEventGenerator::Event::ATOMIC_CHANGED:
277 case ui::AXEventGenerator::Event::AUTO_COMPLETE_CHANGED:
278 case ui::AXEventGenerator::Event::BUSY_CHANGED:
279 case ui::AXEventGenerator::Event::CONTROLS_CHANGED:
280 case ui::AXEventGenerator::Event::CLASS_NAME_CHANGED:
281 case ui::AXEventGenerator::Event::DESCRIBED_BY_CHANGED:
282 case ui::AXEventGenerator::Event::DESCRIPTION_CHANGED:
283 case ui::AXEventGenerator::Event::DOCUMENT_TITLE_CHANGED:
284 case ui::AXEventGenerator::Event::DROPEFFECT_CHANGED:
285 case ui::AXEventGenerator::Event::ENABLED_CHANGED:
286 case ui::AXEventGenerator::Event::FOCUS_CHANGED:
287 case ui::AXEventGenerator::Event::FLOW_FROM_CHANGED:
288 case ui::AXEventGenerator::Event::FLOW_TO_CHANGED:
289 case ui::AXEventGenerator::Event::GRABBED_CHANGED:
290 case ui::AXEventGenerator::Event::HASPOPUP_CHANGED:
291 case ui::AXEventGenerator::Event::HIERARCHICAL_LEVEL_CHANGED:
292 case ui::AXEventGenerator::Event::IGNORED_CHANGED:
293 case ui::AXEventGenerator::Event::IMAGE_ANNOTATION_CHANGED:
294 case ui::AXEventGenerator::Event::KEY_SHORTCUTS_CHANGED:
295 case ui::AXEventGenerator::Event::LABELED_BY_CHANGED:
296 case ui::AXEventGenerator::Event::LANGUAGE_CHANGED:
297 case ui::AXEventGenerator::Event::LAYOUT_INVALIDATED:
298 case ui::AXEventGenerator::Event::LIVE_REGION_NODE_CHANGED:
299 case ui::AXEventGenerator::Event::LIVE_RELEVANT_CHANGED:
300 case ui::AXEventGenerator::Event::LIVE_STATUS_CHANGED:
301 case ui::AXEventGenerator::Event::LOAD_START:
302 case ui::AXEventGenerator::Event::MULTILINE_STATE_CHANGED:
303 case ui::AXEventGenerator::Event::MULTISELECTABLE_STATE_CHANGED:
304 case ui::AXEventGenerator::Event::NAME_CHANGED:
305 case ui::AXEventGenerator::Event::OBJECT_ATTRIBUTE_CHANGED:
306 case ui::AXEventGenerator::Event::OTHER_ATTRIBUTE_CHANGED:
307 case ui::AXEventGenerator::Event::PLACEHOLDER_CHANGED:
308 case ui::AXEventGenerator::Event::PORTAL_ACTIVATED:
309 case ui::AXEventGenerator::Event::POSITION_IN_SET_CHANGED:
310 case ui::AXEventGenerator::Event::READONLY_CHANGED:
311 case ui::AXEventGenerator::Event::RELATED_NODE_CHANGED:
312 case ui::AXEventGenerator::Event::REQUIRED_STATE_CHANGED:
313 case ui::AXEventGenerator::Event::ROLE_CHANGED:
314 case ui::AXEventGenerator::Event::SCROLL_HORIZONTAL_POSITION_CHANGED:
315 case ui::AXEventGenerator::Event::SCROLL_VERTICAL_POSITION_CHANGED:
316 case ui::AXEventGenerator::Event::SELECTED_CHANGED:
317 case ui::AXEventGenerator::Event::SET_SIZE_CHANGED:
318 case ui::AXEventGenerator::Event::SORT_CHANGED:
319 case ui::AXEventGenerator::Event::STATE_CHANGED:
320 case ui::AXEventGenerator::Event::TEXT_ATTRIBUTE_CHANGED:
321 case ui::AXEventGenerator::Event::VALUE_MAX_CHANGED:
322 case ui::AXEventGenerator::Event::VALUE_MIN_CHANGED:
323 case ui::AXEventGenerator::Event::VALUE_STEP_CHANGED:
324 case ui::AXEventGenerator::Event::WIN_IACCESSIBLE_STATE_CHANGED:
325 // There are some notifications that aren't meaningful on Mac.
326 // It's okay to skip them.
327 break;
328 }
329 return events;
330 }
331
332 void AccessibilityBridgeMac::DispatchAccessibilityAction(ui::AXNode::AXID target,
333 FlutterSemanticsAction action,
334 fml::MallocMapping data) {
335 // TODO(mattkae): Remove implicit view assumption.
336 // https://github.com/flutter/flutter/issues/142845
337 NSCAssert(flutter_engine_, @"Flutter engine should not be deallocated");
338 NSCAssert(view_controller_.viewLoaded && view_controller_.view.window,
339 @"The accessibility bridge should not receive accessibility actions if the flutter view"
340 @"is not loaded or attached to a NSWindow.");
341 [flutter_engine_ dispatchSemanticsAction:action toTarget:target withData:std::move(data)];
342 }
343
344 std::shared_ptr<FlutterPlatformNodeDelegate>
345 AccessibilityBridgeMac::CreateFlutterPlatformNodeDelegate() {
346 return std::make_shared<FlutterPlatformNodeDelegateMac>(weak_from_this(), view_controller_);
347 }
348
349 // Private method
350 void AccessibilityBridgeMac::DispatchMacOSNotification(
351 gfx::NativeViewAccessible native_node,
352 NSAccessibilityNotificationName mac_notification) {
353 NSCAssert(mac_notification, @"The notification must not be null.");
354 NSCAssert(native_node, @"The notification target must not be null.");
355 NSAccessibilityPostNotification(native_node, mac_notification);
356 }
357
358 void AccessibilityBridgeMac::DispatchMacOSNotificationWithUserInfo(
359 gfx::NativeViewAccessible native_node,
360 NSAccessibilityNotificationName mac_notification,
361 NSDictionary* user_info) {
362 NSCAssert(mac_notification, @"The notification must not be null.");
363 NSCAssert(native_node, @"The notification target must not be null.");
364 NSCAssert(user_info, @"The notification data must not be null.");
365 NSAccessibilityPostNotificationWithUserInfo(native_node, mac_notification, user_info);
366 }
367
368 bool AccessibilityBridgeMac::HasPendingEvent(ui::AXEventGenerator::Event event) const {
369 NSCAssert(flutter_engine_, @"Flutter engine should not be deallocated");
370 std::vector<ui::AXEventGenerator::TargetedEvent> pending_events = GetPendingEvents();
371 for (const auto& pending_event : GetPendingEvents()) {
372 if (pending_event.event_params.event == event) {
373 return true;
374 }
375 }
376 return false;
377 }
378
379 } // namespace flutter
AccessibilityBridgeMac.h
FlutterEngine_Internal.h
FlutterPlatformNodeDelegateMac.h
FlutterTextInputSemanticsObject.h
FlutterViewController_Internal.h
flutter::AccessibilityBridge::RootDelegate
ui::AXPlatformNodeDelegate * RootDelegate() const override
Definition: accessibility_bridge.cc:732
flutter::AccessibilityBridge::GetFlutterPlatformNodeDelegateFromID
std::weak_ptr< FlutterPlatformNodeDelegate > GetFlutterPlatformNodeDelegateFromID(AccessibilityNodeId id) const
Get the flutter platform node delegate with the given id from this accessibility bridge....
Definition: accessibility_bridge.cc:131
flutter::AccessibilityBridge::GetAXTreeData
const ui::AXTreeData & GetAXTreeData() const
Get the ax tree data from this accessibility bridge. The tree data contains information such as the i...
Definition: accessibility_bridge.cc:141
flutter::AccessibilityBridge::GetPendingEvents
const std::vector< ui::AXEventGenerator::TargetedEvent > GetPendingEvents() const
Gets all pending accessibility events generated during semantics updates. This is useful when decidin...
Definition: accessibility_bridge.cc:146
flutter::AccessibilityBridgeMac::AccessibilityBridgeMac
AccessibilityBridgeMac(__weak FlutterEngine *flutter_engine, __weak FlutterViewController *view_controller)
Creates an AccessibilityBridgeMacDelegate.
Definition: AccessibilityBridgeMac.mm:23
flutter::AccessibilityBridgeMac::OnAccessibilityEvent
void OnAccessibilityEvent(ui::AXEventGenerator::TargetedEvent targeted_event) override
Handle accessibility events generated due to accessibility tree changes. These events are needed to b...
Definition: AccessibilityBridgeMac.mm:27
flutter::AccessibilityBridgeMac::CreateFlutterPlatformNodeDelegate
std::shared_ptr< FlutterPlatformNodeDelegate > CreateFlutterPlatformNodeDelegate() override
Creates a platform specific FlutterPlatformNodeDelegate. Ownership passes to the caller....
Definition: AccessibilityBridgeMac.mm:345
flutter::AccessibilityBridgeMac::DispatchAccessibilityAction
void DispatchAccessibilityAction(AccessibilityNodeId target, FlutterSemanticsAction action, fml::MallocMapping data) override
Dispatch accessibility action back to the Flutter framework. These actions are generated in the nativ...
Definition: AccessibilityBridgeMac.mm:332
FlutterEngine
Definition: FlutterEngine.h:32
FlutterTextField
Definition: FlutterTextInputSemanticsObject.h:82
FlutterViewController
Definition: FlutterViewController.h:73
flutter
Definition: AccessibilityBridgeMac.h:16
flutter::kAccessibilityLoadCompleteNotification
static NSString *const kAccessibilityLoadCompleteNotification
Definition: AccessibilityBridgeMac.mm:16
flutter::kAccessibilityExpandedChanged
static NSString *const kAccessibilityExpandedChanged
Definition: AccessibilityBridgeMac.mm:20
flutter::kAccessibilityMenuItemSelectedNotification
static NSString *const kAccessibilityMenuItemSelectedNotification
Definition: AccessibilityBridgeMac.mm:21
flutter::kAccessibilityLiveRegionChangedNotification
static NSString *const kAccessibilityLiveRegionChangedNotification
Definition: AccessibilityBridgeMac.mm:19
flutter::kAccessibilityInvalidStatusChangedNotification
static NSString *const kAccessibilityInvalidStatusChangedNotification
Definition: AccessibilityBridgeMac.mm:17
flutter::kAccessibilityLiveRegionCreatedNotification
static NSString *const kAccessibilityLiveRegionCreatedNotification
Definition: AccessibilityBridgeMac.mm:18