ExploreByTouchHelper

const val HOST_ID = -1: Int

Virtual node identifier value for the host view's node.

const val INVALID_ID = -2147483648: Int

Virtual node identifier value for invalid nodes.

ExploreByTouchHelper(host: View)

Constructs a new helper that can expose a virtual view hierarchy for the specified host view.

fun clearKeyboardFocusForVirtualView(virtualViewId: Int): Boolean

Attempts to clear keyboard focus from a virtual view.

fun dispatchHoverEvent(event: MotionEvent): Boolean

Delegates hover events from the host view.

Dispatches hover MotionEvents to the virtual view hierarchy when the Explore by Touch feature is enabled.

This method should be called by overriding the host view's dispatchHoverEvent method:

@Override
public boolean dispatchHoverEvent(MotionEvent event) {
  return mHelper.dispatchHoverEvent(this, event)
      || super.dispatchHoverEvent(event);
}

fun dispatchKeyEvent(event: KeyEvent): Boolean

Delegates key events from the host view.

This method should be called by overriding the host view's dispatchKeyEvent method:

@Override
public boolean dispatchKeyEvent(KeyEvent event) {
  return mHelper.dispatchKeyEvent(event)
      || super.dispatchKeyEvent(event);
}

fun getAccessibilityNodeProvider(host: View!): AccessibilityNodeProviderCompat!

Gets the provider for managing a virtual view hierarchy rooted at this View and reported to AccessibilityServices that explore the window content.

The default implementation behaves as ViewCompat#getAccessibilityNodeProvider(View) for the case of no accessibility delegate been set.

fun getFocusedVirtualView(): Int

Returns the virtual view ID for the currently accessibility focused item.

fun invalidateRoot(): Unit

Notifies the accessibility framework that the properties of the parent view have changed.

You must call this method after adding or removing items from the parent view.

fun invalidateVirtualView(virtualViewId: Int): Unit

Notifies the accessibility framework that the properties of a particular item have changed.

You must call this method after changing any of the properties set in onPopulateNodeForVirtualView.

fun invalidateVirtualView(virtualViewId: Int, changeTypes: Int): Unit

Notifies the accessibility framework that the properties of a particular item have changed.

You must call this method after changing any of the properties set in onPopulateNodeForVirtualView.

fun onFocusChanged(
    gainFocus: Boolean,
    direction: Int,
    previouslyFocusedRect: Rect?
): Unit

Delegates focus changes from the host view.

This method should be called by overriding the host view's onFocusChanged method:

@Override
public boolean onFocusChanged(boolean gainFocus, int direction,
    Rect previouslyFocusedRect) {
  super.onFocusChanged(gainFocus, direction, previouslyFocusedRect);
  mHelper.onFocusChanged(gainFocus, direction, previouslyFocusedRect);
}

fun onInitializeAccessibilityEvent(host: View!, event: AccessibilityEvent!): Unit

Initializes an AccessibilityEvent with information about the the host View which is the event source.

The default implementation behaves as ViewCompat#onInitalizeAccessibilityEvent(View v, AccessibilityEvent event) for the case of no accessibility delegate been set.

fun onInitializeAccessibilityNodeInfo(
    host: View!,
    info: AccessibilityNodeInfoCompat!
): Unit

Initializes an AccessibilityNodeInfoCompat with information about the host view.

The default implementation behaves as ViewCompat#onInitializeAccessibilityNodeInfo(View, AccessibilityNodeInfoCompat) for the case of no accessibility delegate been set.

fun requestKeyboardFocusForVirtualView(virtualViewId: Int): Boolean

Attempts to give keyboard focus to a virtual view.

fun sendEventForVirtualView(virtualViewId: Int, eventType: Int): Boolean

Populates an event of the specified type with information about an item and attempts to send it up through the view hierarchy.

You should call this method after performing a user action that normally fires an accessibility event, such as clicking on an item.

public void performItemClick(T item) {
  ...
  sendEventForVirtualViewId(item.id, AccessibilityEvent.TYPE_VIEW_CLICKED);
}

fun setBoundsInScreenFromBoundsInParent(
    node: AccessibilityNodeInfoCompat,
    boundsInParent: Rect
): Unit

Calculates and assigns screen-relative bounds based on bounds in parent. Instead of calling the deprecated setBoundsInParent, it provides a convenient method to calculate and assign setBoundsInScreen based on boundsInParent.

protected abstract fun getVirtualViewAt(x: Float, y: Float): Int

Provides a mapping between view-relative coordinates and logical items.

protected abstract fun getVisibleVirtualViews(virtualViewIds: (Mutable)List<Int!>!): Unit

Populates a list with the view's visible items. The ordering of items within virtualViewIds specifies order of accessibility focus traversal.

protected abstract fun onPerformActionForVirtualView(
    virtualViewId: Int,
    action: Int,
    arguments: Bundle?
): Boolean

Performs the specified accessibility action on the item associated with the virtual view identifier. See performAction for more information.

Implementations must handle any actions added manually in onPopulateNodeForVirtualView.

The helper class automatically handles focus management resulting from ACTION_ACCESSIBILITY_FOCUS and ACTION_CLEAR_ACCESSIBILITY_FOCUS actions.

protected fun onPopulateEventForHost(event: AccessibilityEvent): Unit

Populates an AccessibilityEvent with information about the host view.

The default implementation is a no-op.

protected fun onPopulateEventForVirtualView(
    virtualViewId: Int,
    event: AccessibilityEvent
): Unit

Populates an AccessibilityEvent with information about the specified item.

The helper class automatically populates the following fields based on the values set by onPopulateNodeForVirtualView, but implementations may optionally override them:

• event text, see getText
• content description, see setContentDescription
• scrollability, see setScrollable
• password state, see setPassword
• enabled state, see setEnabled
• checked state, see setChecked

The following required fields are automatically populated by the helper class and may not be overridden:

• item class name, set to the value used in onPopulateNodeForVirtualView
• package name, set to the package of the host view's Context, see setPackageName
• event source, set to the host view and virtual view identifier, see setSource

protected fun onPopulateNodeForHost(node: AccessibilityNodeInfoCompat): Unit

Populates an AccessibilityNodeInfoCompat with information about the host view.

The default implementation is a no-op.

protected abstract fun onPopulateNodeForVirtualView(
    virtualViewId: Int,
    node: AccessibilityNodeInfoCompat
): Unit

Populates an AccessibilityNodeInfoCompat with information about the specified item.

Implementations must populate the following required fields:

• event text, see setText or setContentDescription
• bounds in screen coordinates, see setBoundsInScreen and (AccessibilityNodeInfoCompat, Rect)

The helper class automatically populates the following fields with default values, but implementations may optionally override them:

• enabled state, set to true, see setEnabled
• keyboard focusability, set to true, see setFocusable
• item class name, set to android.view.View, see setClassName

The following required fields are automatically populated by the helper class and may not be overridden:

• package name, identical to the package name set by onPopulateEventForVirtualView, see setPackageName
• node source, identical to the event source set in onPopulateEventForVirtualView, see setSource
• parent view, set to the host view, see setParent
• visibility, computed based on parent-relative bounds, see setVisibleToUser
• accessibility focus, computed based on internal helper state, see setAccessibilityFocused
• keyboard focus, computed based on internal helper state, see setFocused

Additionally, the helper class automatically handles keyboard focus and accessibility focus management by adding the appropriate ACTION_FOCUS, ACTION_CLEAR_FOCUS, ACTION_ACCESSIBILITY_FOCUS, or ACTION_CLEAR_ACCESSIBILITY_FOCUS actions. Implementations must never manually add these actions.

The helper class also automatically modifies parent- and screen-relative bounds to reflect the portion of the item visible within its parent.

protected fun onVirtualViewKeyboardFocusChanged(virtualViewId: Int, hasFocus: Boolean): Unit

Called when the focus state of a virtual view changes.