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Instance Methods | Properties | List of all members
SemanticsObject Class Reference

`#import <SemanticsObject.h>`

Inheritance diagram for SemanticsObject:

## Instance Methods
(BOOL) | - isAccessibilityBridgeAlive
(void) | - setSemanticsNode:
(void) | - replaceChildAtIndex:withChild:
(BOOL) | - nodeWillCauseLayoutChange:
(BOOL) | - nodeWillCauseScroll:
(BOOL) | - nodeShouldTriggerAnnouncement:
(void) | - collectRoutes:
(NSString *) | - routeName
(BOOL) | - onCustomAccessibilityAction:
(void) | - accessibilityBridgeDidFinishUpdate
((unavailable("Use initWithBridge instead") | - __attribute__
(instancetype) | - initWithBridge:uid:
(BOOL) | - accessibilityScrollToVisible
(BOOL) | - accessibilityScrollToVisibleWithChild:
(id) | - _accessibilityHitTest:withEvent:

## Properties
int32_t | uid
SemanticsObject * | parent
fml::WeakPtr< flutter::AccessibilityBridgeIos > | bridge
flutter::SemanticsNode | node
BOOL | hasChildren
NSArray< SemanticsObject * > * | children
NSArray< SemanticsObject * > * | childrenInHitTestOrder
id | nativeAccessibility

## Detailed Description

A node in the iOS semantics tree. This object is a wrapper over a native accessibiliy object, which is stored in the property `nativeAccessibility`. In the most case, the `nativeAccessibility` directly returns this object. Some subclasses such as the `FlutterScrollableSemanticsObject` creates a native `UIScrollView` as its `nativeAccessibility` so that it can interact with iOS.

Definition at line 31 of file SemanticsObject.h.

## Method Documentation

## ◆ __attribute__

- ((unavailable("Use initWithBridge instead") __attribute__ |  |  |

## ◆ _accessibilityHitTest:withEvent:

- (id) _accessibilityHitTest: |  | (CGPoint) | point
withEvent: |  | (UIEvent *) | event

Provided by category SemanticsObject(Tests).

## ◆ accessibilityBridgeDidFinishUpdate

- (void) accessibilityBridgeDidFinishUpdate |  |  |

Called after accessibility bridge finishes a semantics update.

Subclasses can override this method if they contain states that can only be updated once every node in the accessibility tree has finished updating.

Definition at line 259 of file SemanticsObject.mm.

336 { /* Do nothing by default */
337 }

## ◆ accessibilityScrollToVisible

- (BOOL) accessibilityScrollToVisible |  |  |

Provided by category SemanticsObject(Tests).

## ◆ accessibilityScrollToVisibleWithChild:

- (BOOL) accessibilityScrollToVisibleWithChild: |  | (id) | child |

Provided by category SemanticsObject(Tests).

## ◆ collectRoutes:

- (void) collectRoutes: |  | (NSMutableArray<SemanticsObject*>*) | edges |

Definition at line 259 of file SemanticsObject.mm.

471 :(NSMutableArray<SemanticsObject*>*)edges {
472 if (self.node.flags.scopesRoute) {
473 [edges addObject:self];
474 }
475 if ([self hasChildren]) {
476 for (SemanticsObject* child in self.children) {
477 [child collectRoutes:edges];
478 }
479 }
480 }
SemanticsObject
Definition: SemanticsObject.h:32
SemanticsObject::hasChildren
BOOL hasChildren
Definition: SemanticsObject.h:62
SemanticsObject::node
flutter::SemanticsNode node
Definition: SemanticsObject.h:57
SemanticsObject::children
NSArray< SemanticsObject * > * children
Definition: SemanticsObject.h:68

## ◆ initWithBridge:uid:

- (instancetype) initWithBridge: |  | (fml::WeakPtr<flutter::AccessibilityBridgeIos>) | bridge
uid: |  | (int32_t) | NS_DESIGNATED_INITIALIZER

Reimplemented in FlutterPlatformViewSemanticsContainer.

Definition at line 259 of file SemanticsObject.mm.

264 :(fml::WeakPtr<flutter::AccessibilityBridgeIos>)bridge
265 uid:(int32_t)uid {
266 FML_DCHECK(bridge) << "bridge must be set";
267 FML_DCHECK(uid >= kRootNodeId);
268 // Initialize with the UIView as the container.
269 // The UIView will not necessarily be accessibility parent for this object.
270 // The bridge informs the OS of the actual structure via
271 // `accessibilityContainer` and `accessibilityElementAtIndex`.
272 self = [super initWithAccessibilityContainer:bridge->view()];
273
274 if (self) {
275 _bridge = bridge;
276 _uid = uid;
277 _children = [[NSMutableArray alloc] init];
278 _childrenInHitTestOrder = [[NSArray alloc] init];
279 }
280
281 return self;
282 }
kRootNodeId
constexpr int32_t kRootNodeId
Definition: SemanticsObject.h:16
SemanticsObject::uid
int32_t uid
Definition: SemanticsObject.h:36
SemanticsObject::bridge
fml::WeakPtr< flutter::AccessibilityBridgeIos > bridge
Definition: SemanticsObject.h:52

## ◆ isAccessibilityBridgeAlive

- (BOOL) isAccessibilityBridgeAlive |  |  |

Due to the fact that VoiceOver may hold onto SemanticObjects even after it shuts down, there can be situations where the AccessibilityBridge is shutdown, but the SemanticObject will still be alive. If VoiceOver is turned on again, it may try to access this orphaned SemanticObject. Methods that are called from the accessiblity framework should use this to guard against this case by just returning early if its bridge has been shutdown.

See https://github.com/flutter/flutter/issues/43795 for more information.

Definition at line 259 of file SemanticsObject.mm.

328 {
329 return self.bridge.get() != nil;
330 }

## ◆ nodeShouldTriggerAnnouncement:

- (BOOL) nodeShouldTriggerAnnouncement: |  | (const flutter::SemanticsNode*) | node |

Whether calling `setSemanticsNode:` with `node` should trigger an announcement.

Definition at line 259 of file SemanticsObject.mm.

358 :(const flutter::SemanticsNode*)node {
359 // The node dropped the live region flag, if it ever had one.
360 if (!node || !node->flags.isLiveRegion) {
361 return NO;
362 }
363
364 // The node has gained a new live region flag, always announce.
365 if (!self.node.flags.isLiveRegion) {
366 return YES;
367 }
368
369 // The label has updated, and the new node has a live region flag.
370 return self.node.label != node->label;
371 }

## ◆ nodeWillCauseLayoutChange:

- (BOOL) nodeWillCauseLayoutChange: |  | (const flutter::SemanticsNode*) | node |

Whether calling `setSemanticsNode:` with `node` would cause a layout change.

Definition at line 259 of file SemanticsObject.mm.

342 :(const flutter::SemanticsNode*)node {
343 return self.node.rect != node->rect || self.node.transform != node->transform;
344 }

## ◆ nodeWillCauseScroll:

- (BOOL) nodeWillCauseScroll: |  | (const flutter::SemanticsNode*) | node |

Whether calling `setSemanticsNode:` with `node` would cause a scroll event.

Definition at line 259 of file SemanticsObject.mm.

349 :(const flutter::SemanticsNode*)node {
350 return !isnan(self.node.scrollPosition) && !isnan(node->scrollPosition) &&
351 self.node.scrollPosition != node->scrollPosition;
352 }

## ◆ onCustomAccessibilityAction:

- (BOOL) onCustomAccessibilityAction: |  | (FlutterCustomAccessibilityAction*) | action |

Definition at line 259 of file SemanticsObject.mm.

482 :(FlutterCustomAccessibilityAction*)action {
483 if (!self.node.HasAction(flutter::SemanticsAction::kCustomAction)) {
484 return NO;
485 }
486 int32_t action_id = action.uid;
487 std::vector<uint8_t> args;
488 args.push_back(3); // type=int32.
489 args.push_back(action_id);
490 args.push_back(action_id >> 8);
491 args.push_back(action_id >> 16);
492 args.push_back(action_id >> 24);
493 self.bridge->DispatchSemanticsAction(
494 self.uid, flutter::SemanticsAction::kCustomAction,
495 fml::MallocMapping::Copy(args.data(), args.size() * sizeof(uint8_t)));
496 return YES;
497 }
FlutterCustomAccessibilityAction
Definition: SemanticsObject.h:136
FlutterCustomAccessibilityAction::uid
int32_t uid
Definition: SemanticsObject.h:140

## ◆ replaceChildAtIndex:withChild:

- (void) replaceChildAtIndex: |  | (NSInteger) | index
withChild: |  | (SemanticsObject*) | child

Definition at line 259 of file SemanticsObject.mm.

373 :(NSInteger)index withChild:(SemanticsObject*)child {
374 SemanticsObject* oldChild = _children[index];
375 oldChild.parent = nil;
376 child.parent = self;
377 [_children replaceObjectAtIndex:index withObject:child];
378 }
SemanticsObject::parent
SemanticsObject * parent
Definition: SemanticsObject.h:42

## ◆ routeName

- (NSString *) routeName |  |  |

Definition at line 259 of file SemanticsObject.mm.

380 {
381 // Returns the first non-null and non-empty semantic label of a child
382 // with an NamesRoute flag. Otherwise returns nil.
383 if (self.node.flags.namesRoute) {
384 NSString* newName = self.accessibilityLabel;
385 if (newName != nil && [newName length] > 0) {
386 return newName;
387 }
388 }
389 if ([self hasChildren]) {
390 for (SemanticsObject* child in self.children) {
391 NSString* newName = [child routeName];
392 if (newName != nil && [newName length] > 0) {
393 return newName;
394 }
395 }
396 }
397 return nil;
398 }

## ◆ setSemanticsNode:

- (void) setSemanticsNode: |  | (const flutter::SemanticsNode*) | NS_REQUIRES_SUPER |

Updates this semantics object using data from the `node` argument.

Definition at line 259 of file SemanticsObject.mm.

332 :(const flutter::SemanticsNode*)node {
333 _node = *node;
334 }

## Property Documentation

## ◆ bridge

- (WeakPtr<)flutter:
| read nonatomic assign

The accessibility bridge that this semantics object is attached to. This object may use the bridge to access contextual application information. A weak pointer is used because the platform view owns the accessibility bridge. If you are referencing this property from an iOS callback, be sure to use `isAccessibilityBridgeActive` to protect against the case where this node may be orphaned.

Definition at line 52 of file SemanticsObject.h.

Referenced by FLUTTER_ASSERT_ARC::ConvertPointToGlobal(), FLUTTER_ASSERT_ARC::ConvertRectToGlobal(), and SemanticsObjectContainer::initWithSemanticsObject:bridge:.

## ◆ children

- (NSArray<SemanticsObject*>*) children
| read write nonatomic copy

Direct children of this semantics object. Each child's `parent` property must be equal to this object.

Definition at line 68 of file SemanticsObject.h.

## ◆ childrenInHitTestOrder

- (NSArray<SemanticsObject*>*) childrenInHitTestOrder
| read write nonatomic copy

Direct children of this semantics object in hit test order. Each child's `parent` property must be equal to this object.

Definition at line 74 of file SemanticsObject.h.

## ◆ hasChildren

- (BOOL) hasChildren
| read nonatomic assign

Whether this semantics object has child semantics objects.

Definition at line 62 of file SemanticsObject.h.

## ◆ nativeAccessibility

- (id) nativeAccessibility
| read nonatomic assign

The UIAccessibility that represents this object.

By default, this return self. Subclasses can override to return different objects to represent them. For example, FlutterScrollableSemanticsObject[s] maintain UIScrollView[s] to represent their UIAccessibility[s].

Definition at line 83 of file SemanticsObject.h.

## ◆ node

- (SemanticsNode) SemanticsObject:
| read nonatomic assign

The semantics node used to produce this semantics object.

Definition at line 57 of file SemanticsObject.h.

## ◆ parent

- (SemanticsObject*) parent
| read nonatomic weak

The parent of this node in the node tree. Will be nil for the root node and during transient state changes.

Definition at line 42 of file SemanticsObject.h.

Referenced by FLUTTER_ASSERT_ARC::GetGlobalTransform().

## ◆ uid

- (int32_t) uid
| read nonatomic assign

The globally unique identifier for this node.

Definition at line 36 of file SemanticsObject.h.

Referenced by FlutterPlatformViewSemanticsContainer::initWithBridge:uid:, and SemanticsObjectContainer::initWithSemanticsObject:bridge:.

The documentation for this class was generated from the following files:

- shell/platform/darwin/ios/framework/Source/SemanticsObject.h
- shell/platform/darwin/ios/framework/Source/SemanticsObject.mm