io.flutter.view.AccessibilityViewEmbedder Class Reference

Public Member Functions
AccessibilityNodeInfo	getRootNode ( @NonNull View embeddedView, int flutterId, @NonNull Rect displayBounds)
AccessibilityNodeInfo	createAccessibilityNodeInfo (int flutterId)
boolean	requestSendAccessibilityEvent ( @NonNull View embeddedView, @NonNull View eventOrigin, @NonNull AccessibilityEvent event)
boolean	performAction (int flutterId, int accessibilityAction, @Nullable Bundle arguments)
Integer	getRecordFlutterId ( @NonNull View embeddedView, @NonNull AccessibilityRecord record)
boolean	onAccessibilityHoverEvent (int rootFlutterId, @NonNull MotionEvent event)
View	platformViewOfNode (int flutterId)

Package Functions
	AccessibilityViewEmbedder (@NonNull View rootAccessibiiltyView, int firstVirtualNodeId)

Detailed Description

Facilitates embedding of platform views in the accessibility tree generated by the accessibility bridge.

Embedding is done by mirroring the accessibility tree of the platform view as a subtree of the flutter accessibility tree.

This class relies on hidden system APIs to extract the accessibility information and does not work starting Android P; If the reflection accessors are not available we fail silently by embedding a null node, the app continues working but the accessibility information for the platform view will not be embedded.

We use the term flutterId for virtual accessibility node IDs in the FlutterView tree, and the term originId for the virtual accessibility node IDs in the platform view's tree. Internally this class maintains a bidirectional mapping between flutterIds and the corresponding platform view and originId.

Definition at line 49 of file AccessibilityViewEmbedder.java.

Constructor & Destructor Documentation

AccessibilityViewEmbedder()

io.flutter.view.AccessibilityViewEmbedder.AccessibilityViewEmbedder ( @NonNull View  rootAccessibiiltyView, int  firstVirtualNodeId  )

inlinepackage

Definition at line 71 of file AccessibilityViewEmbedder.java.

                                                                                         {
    reflectionAccessors = new ReflectionAccessors();
    flutterIdToOrigin = new SparseArray<>();
    this.rootAccessibilityView = rootAccessibiiltyView;
    nextFlutterId = firstVirtualNodeId;
    originToFlutterId = new HashMap<>();
    embeddedViewToDisplayBounds = new HashMap<>();
  }

Member Function Documentation

createAccessibilityNodeInfo()

AccessibilityNodeInfo io.flutter.view.AccessibilityViewEmbedder.createAccessibilityNodeInfo ( int  flutterId )

inline

Creates the accessibility node info for the node identified with flutterId.

Definition at line 101 of file AccessibilityViewEmbedder.java.

                                                                          {
    ViewAndId origin = flutterIdToOrigin.get(flutterId);
    if (origin == null) {
      return null;
    }
    if (!embeddedViewToDisplayBounds.containsKey(origin.view)) {
      // This might happen if the embedded view is sending accessibility event before the first
      // Flutter semantics
      // tree was sent to the accessibility bridge. In this case we don't return a node as we do not
      // know the
      // bounds yet.
      // https://github.com/flutter/flutter/issues/30068
      return null;
    }
    AccessibilityNodeProvider provider = origin.view.getAccessibilityNodeProvider();
    if (provider == null) {
      // The provider is null for views that don't have a virtual accessibility tree.
      // We currently only support embedding virtual hierarchies in the Flutter tree.
      // TODO(amirh): support embedding non virtual hierarchies.
      // https://github.com/flutter/flutter/issues/29717
      return null;
    }
    AccessibilityNodeInfo originNode =
        origin.view.getAccessibilityNodeProvider().createAccessibilityNodeInfo(origin.id);
    if (originNode == null) {
      return null;
    }
    return convertToFlutterNode(originNode, flutterId, origin.view);
  }

getRecordFlutterId()

Integer io.flutter.view.AccessibilityViewEmbedder.getRecordFlutterId ( @NonNull View  embeddedView, @NonNull AccessibilityRecord  record  )

inline

Returns a flutterID for an accessibility record, or null if no mapping exists.

Parameters

embeddedView

the embedded view that the record is associated with.

Definition at line 331 of file AccessibilityViewEmbedder.java.

                                                                       {
    Long originPackedId = reflectionAccessors.getRecordSourceNodeId(record);
    if (originPackedId == null) {
      return null;
    }
    int originVirtualId = ReflectionAccessors.getVirtualNodeId(originPackedId);
    return originToFlutterId.get(new ViewAndId(embeddedView, originVirtualId));
  }

getRootNode()

AccessibilityNodeInfo io.flutter.view.AccessibilityViewEmbedder.getRootNode ( @NonNull View  embeddedView, int  flutterId, @NonNull Rect  displayBounds  )

inline

Returns the root accessibility node for an embedded platform view.

Parameters

flutterId	the virtual accessibility ID for the node in flutter accessibility tree
displayBounds	the display bounds for the node in screen coordinates

Definition at line 86 of file AccessibilityViewEmbedder.java.

                                                                              {
    AccessibilityNodeInfo originNode = embeddedView.createAccessibilityNodeInfo();
    Long originPackedId = reflectionAccessors.getSourceNodeId(originNode);
    if (originPackedId == null) {
      return null;
    }
    embeddedViewToDisplayBounds.put(embeddedView, displayBounds);
    int originId = ReflectionAccessors.getVirtualNodeId(originPackedId);
    cacheVirtualIdMappings(embeddedView, originId, flutterId);
    return convertToFlutterNode(originNode, flutterId, embeddedView);
  }

onAccessibilityHoverEvent()

boolean io.flutter.view.AccessibilityViewEmbedder.onAccessibilityHoverEvent ( int  rootFlutterId, @NonNull MotionEvent  event  )

inline

Delegates a View::onHoverEvent event from the AccessibilityBridge to an embedded view.

The pointer coordinates are translated to the embedded view's coordinate system.

Definition at line 346 of file AccessibilityViewEmbedder.java.

                                                                                          {
    ViewAndId origin = flutterIdToOrigin.get(rootFlutterId);
    if (origin == null) {
      return false;
    }
    Rect displayBounds = embeddedViewToDisplayBounds.get(origin.view);
    int pointerCount = event.getPointerCount();
    MotionEvent.PointerProperties[] pointerProperties =
        new MotionEvent.PointerProperties[pointerCount];
    MotionEvent.PointerCoords[] pointerCoords = new MotionEvent.PointerCoords[pointerCount];
    for (int i = 0; i < event.getPointerCount(); i++) {
      pointerProperties[i] = new MotionEvent.PointerProperties();
      event.getPointerProperties(i, pointerProperties[i]);
 
      MotionEvent.PointerCoords originCoords = new MotionEvent.PointerCoords();
      event.getPointerCoords(i, originCoords);
 
      pointerCoords[i] = new MotionEvent.PointerCoords(originCoords);
      pointerCoords[i].x -= displayBounds.left;
      pointerCoords[i].y -= displayBounds.top;
    }
    MotionEvent translatedEvent =
        MotionEvent.obtain(
            event.getDownTime(),
            event.getEventTime(),
            event.getAction(),
            event.getPointerCount(),
            pointerProperties,
            pointerCoords,
            event.getMetaState(),
            event.getButtonState(),
            event.getXPrecision(),
            event.getYPrecision(),
            event.getDeviceId(),
            event.getEdgeFlags(),
            event.getSource(),
            event.getFlags());
    return origin.view.dispatchGenericMotionEvent(translatedEvent);
  }

performAction()

boolean io.flutter.view.AccessibilityViewEmbedder.performAction ( int  flutterId, int  accessibilityAction, @Nullable Bundle  arguments  )

inline

Delegates anlink AccessibilityNodeProvider::performAction} from the AccessibilityBridge to the embedded view's accessibility node provider.

Returns

True if the action was performed.

Definition at line 312 of file AccessibilityViewEmbedder.java.

                                                                                                   {
    ViewAndId origin = flutterIdToOrigin.get(flutterId);
    if (origin == null) {
      return false;
    }
    View embeddedView = origin.view;
    AccessibilityNodeProvider provider = embeddedView.getAccessibilityNodeProvider();
    if (provider == null) {
      return false;
    }
    return provider.performAction(origin.id, accessibilityAction, arguments);
  }

platformViewOfNode()

View io.flutter.view.AccessibilityViewEmbedder.platformViewOfNode ( int  flutterId )

inline

Returns the View that contains the accessibility node identified by the provided flutterId or null if it doesn't belong to a view.

Definition at line 390 of file AccessibilityViewEmbedder.java.

                                                {
    ViewAndId viewAndId = flutterIdToOrigin.get(flutterId);
    if (viewAndId == null) {
      return null;
    }
    return viewAndId.view;
  }

requestSendAccessibilityEvent()

boolean io.flutter.view.AccessibilityViewEmbedder.requestSendAccessibilityEvent ( @NonNull View  embeddedView, @NonNull View  eventOrigin, @NonNull AccessibilityEvent  event  )

inline

Delegates an AccessibilityNodeProvider::requestSendAccessibilityEvent from the AccessibilityBridge to the embedded view.

Returns

True if the event was sent.

Definition at line 269 of file AccessibilityViewEmbedder.java.

                                                                                                {
    AccessibilityEvent translatedEvent = AccessibilityEvent.obtain(event);
    Long originPackedId = reflectionAccessors.getRecordSourceNodeId(event);
    if (originPackedId == null) {
      return false;
    }
    int originVirtualId = ReflectionAccessors.getVirtualNodeId(originPackedId);
    Integer flutterId = originToFlutterId.get(new ViewAndId(embeddedView, originVirtualId));
    if (flutterId == null) {
      flutterId = nextFlutterId++;
      cacheVirtualIdMappings(embeddedView, originVirtualId, flutterId);
    }
    translatedEvent.setSource(rootAccessibilityView, flutterId);
    translatedEvent.setClassName(event.getClassName());
    translatedEvent.setPackageName(event.getPackageName());
 
    for (int i = 0; i < translatedEvent.getRecordCount(); i++) {
      AccessibilityRecord record = translatedEvent.getRecord(i);
      Long recordOriginPackedId = reflectionAccessors.getRecordSourceNodeId(record);
      if (recordOriginPackedId == null) {
        return false;
      }
      int recordOriginVirtualID = ReflectionAccessors.getVirtualNodeId(recordOriginPackedId);
      ViewAndId originViewAndId = new ViewAndId(embeddedView, recordOriginVirtualID);
      if (!originToFlutterId.containsKey(originViewAndId)) {
        return false;
      }
      int recordFlutterId = originToFlutterId.get(originViewAndId);
      record.setSource(rootAccessibilityView, recordFlutterId);
    }
 
    return rootAccessibilityView
        .getParent()
        .requestSendAccessibilityEvent(eventOrigin, translatedEvent);
  }

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

• shell/platform/android/io/flutter/view/AccessibilityViewEmbedder.java