SemanticsObjectContainer Class Reference

#include <SemanticsObject.h>

Inheritance diagram for SemanticsObjectContainer:

Instance Methods
(instancetype)	- NS_UNAVAILABLE
(instancetype)	- initWithAccessibilityContainer:
(instancetype)	- initWithSemanticsObject:bridge:
(instancetype)	- init [implementation]
(NSInteger)	- accessibilityElementCount [implementation]
(nullable id)	- accessibilityElementAtIndex: [implementation]
(NSInteger)	- indexOfAccessibilityElement: [implementation]
(BOOL)	- isAccessibilityElement [implementation]
(CGRect)	- accessibilityFrame [implementation]
(id)	- accessibilityContainer [implementation]
(BOOL)	- accessibilityScroll: [implementation]

Class Methods
(instancetype)	+ NS_UNAVAILABLE

Properties
SemanticsObject *	semanticsObject

Detailed Description

Represents a semantics object that has children and hence has to be presented to the OS as a UIAccessibilityContainer.

The SemanticsObject class cannot implement the UIAccessibilityContainer protocol because an object that returns YES for isAccessibilityElement cannot also implement UIAccessibilityContainer.

With the help of SemanticsObjectContainer, the hierarchy of semantic objects received from the framework, such as:

SemanticsObject1 SemanticsObject2 SemanticsObject3 SemanticsObject4

is translated into the following hierarchy, which is understood by iOS:

SemanticsObjectContainer1 SemanticsObject1 SemanticsObjectContainer2 SemanticsObject2 SemanticsObject3 SemanticsObject4

From Flutter's view of the world (the first tree seen above), we construct iOS's view of the world (second tree) as follows: We replace each SemanticsObjects that has children with a SemanticsObjectContainer, which has the original SemanticsObject and its children as children.

SemanticsObjects have semantic information attached to them which is interpreted by VoiceOver (they return YES for isAccessibilityElement). The SemanticsObjectContainers are just there for structure and they don't provide any semantic information to VoiceOver (they return NO for isAccessibilityElement).

Definition at line 226 of file SemanticsObject.h.

Method Documentation

accessibilityContainer

- (id) accessibilityContainer

implementation

Definition at line 899 of file SemanticsObject.mm.

                             {
  if (!_bridge) {
    return nil;
  }
  return ([_semanticsObject uid] == kRootNodeId)
             ? _bridge->view()
             : [[_semanticsObject parent] accessibilityContainer];
}

accessibilityElementAtIndex:

- (nullable id) accessibilityElementAtIndex: (NSInteger)  index

implementation

Definition at line 899 of file SemanticsObject.mm.

                                          :(NSInteger)index {
  if (index < 0 || index >= [self accessibilityElementCount]) {
    return nil;
  }
  if (index == 0) {
    return _semanticsObject.nativeAccessibility;
  }
 
  SemanticsObject* child = [_semanticsObject children][index - 1];
 
  if ([child hasChildren]) {
    return [child accessibilityContainer];
  }
  return child.nativeAccessibility;
}

accessibilityElementCount

- (NSInteger) accessibilityElementCount

implementation

Definition at line 899 of file SemanticsObject.mm.

                                       {
  NSInteger count = [[_semanticsObject children] count] + 1;
  return count;
}

accessibilityFrame

- (CGRect) accessibilityFrame

implementation

Definition at line 899 of file SemanticsObject.mm.

                             {
  return [_semanticsObject accessibilityFrame];
}

accessibilityScroll:

- (BOOL) accessibilityScroll: (UIAccessibilityScrollDirection)  direction

implementation

Definition at line 899 of file SemanticsObject.mm.

                           :(UIAccessibilityScrollDirection)direction {
  return [_semanticsObject accessibilityScroll:direction];
}

indexOfAccessibilityElement:

- (NSInteger) indexOfAccessibilityElement: (id)  element

implementation

Definition at line 899 of file SemanticsObject.mm.

                                        :(id)element {
  if (element == _semanticsObject.nativeAccessibility) {
    return 0;
  }
 
  NSArray<SemanticsObject*>* children = [_semanticsObject children];
  for (size_t i = 0; i < [children count]; i++) {
    SemanticsObject* child = children[i];
    if ((![child hasChildren] && child.nativeAccessibility == element) ||
        ([child hasChildren] && [child.nativeAccessibility accessibilityContainer] == element)) {
      return i + 1;
    }
  }
  return NSNotFound;
}

init

- (instancetype) init

implementation

Definition at line 899 of file SemanticsObject.mm.

                     {
  [self release];
  [super doesNotRecognizeSelector:_cmd];
  return nil;
}

initWithAccessibilityContainer:

- (instancetype) initWithAccessibilityContainer:

(id)

NS_UNAVAILABLE

initWithSemanticsObject:bridge:

- (instancetype) initWithSemanticsObject:		(SemanticsObject*)	semanticsObject
bridge:		(fml::WeakPtr<flutter::AccessibilityBridgeIos>)	NS_DESIGNATED_INITIALIZER

Definition at line 899 of file SemanticsObject.mm.

                                       :(SemanticsObject*)semanticsObject
                                 bridge:(fml::WeakPtr<flutter::AccessibilityBridgeIos>)bridge {
  FML_DCHECK(semanticsObject) << "semanticsObject must be set";
  // Initialize with the UIView as the container.
  // The UIView will not necessarily be accessibility parent for this object.
  // The bridge informs the OS of the actual structure via
  // `accessibilityContainer` and `accessibilityElementAtIndex`.
  self = [super initWithAccessibilityContainer:bridge->view()];
 
  if (self) {
    _semanticsObject = semanticsObject;
    _bridge = bridge;
  }
 
  return self;
}

isAccessibilityElement

- (BOOL) isAccessibilityElement

implementation

Definition at line 899 of file SemanticsObject.mm.

                               {
  return NO;
}

NS_UNAVAILABLE [1/2]

- (instancetype) NS_UNAVAILABLE

NS_UNAVAILABLE [2/2]

+ (instancetype) NS_UNAVAILABLE

Property Documentation

semanticsObject

- (SemanticsObject*) semanticsObject

readwritenonatomicweak

Definition at line 234 of file SemanticsObject.h.

---

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