Accessibility focus traversal in virtual nodes.

1. Finished the implementation of support for maintaining
   accessibility focus in view with virtual descendants.

2. Finished the NumberPicker implementation of virtual
   subtree such that all requred attributes are reported
   and ensuring that it support accessibility focus in
   its virtual descentants.

3. Fixed a bug where if a predecessor of the view that is
   accessiiblity focused is removed the accessibliity focus
   host in ViewRootImpl is not cleared leading to a crash
   when trying to draw the accessibility focus highlight.:

bug:6472646
bug:6433864

Change-Id: I3645642b87b4a26025c0b2ba9dfaad92d11a48f1

Author: sganov

core/java/android/view/AccessibilityInteractionController.java

@@ -491,20 +491,28 @@ private void focusSearchUiThread(Message message) {
                 if ((direction & View.FOCUS_ACCESSIBILITY) ==  View.FOCUS_ACCESSIBILITY) {
                     AccessibilityNodeProvider provider = root.getAccessibilityNodeProvider();
                     if (provider != null) {
-                        next = provider.accessibilityFocusSearch(direction,
-                                virtualDescendantId);
-                    } else if (virtualDescendantId == View.NO_ID) {
-                        View nextView = root.focusSearch(direction);
-                        if (nextView != null) {
-                            // If the focus search reached a node with a provider
-                            // we delegate to the provider to find the next one.
-                            provider = nextView.getAccessibilityNodeProvider();
-                            if (provider != null) {
-                                next = provider.accessibilityFocusSearch(direction,
-                                        virtualDescendantId);
-                            } else {
-                                next = nextView.createAccessibilityNodeInfo();
-                             }
+                        next = provider.accessibilityFocusSearch(direction, virtualDescendantId);
+                        if (next != null) {
+                            return;
+                        }
+                    }
+                    View nextView = root.focusSearch(direction);
+                    while (nextView != null) {
+                        // If the focus search reached a node with a provider
+                        // we delegate to the provider to find the next one.
+                        // If the provider does not return a virtual view to
+                        // take accessibility focus we try the next view found
+                        // by the focus search algorithm.
+                        provider = nextView.getAccessibilityNodeProvider();
+                        if (provider != null) {
+                            next = provider.accessibilityFocusSearch(direction, View.NO_ID);
+                            if (next != null) {
+                                break;
+                            }
+                            nextView = nextView.focusSearch(direction);
+                        } else {
+                            next = nextView.createAccessibilityNodeInfo();
+                            break;
                         }
                     }
                 } else {

core/java/android/view/View.java

@@ -6027,7 +6027,7 @@ public void addFocusables(ArrayList<View> views, int direction, int focusableMod
             return;
         }
         if ((focusableMode & FOCUSABLES_ACCESSIBILITY) == FOCUSABLES_ACCESSIBILITY) {
-            if (canTakeAccessibilityFocusFromHover()) {
+            if (canTakeAccessibilityFocusFromHover() || getAccessibilityNodeProvider() != null) {
                 views.add(this);
                 return;
             }
@@ -6156,12 +6156,15 @@ public boolean requestAccessibilityFocus() {
      * @hide
      */
     public void clearAccessibilityFocus() {
-        if ((mPrivateFlags2 & ACCESSIBILITY_FOCUSED) != 0) {
-            mPrivateFlags2 &= ~ACCESSIBILITY_FOCUSED;
-            ViewRootImpl viewRootImpl = getViewRootImpl();
-            if (viewRootImpl != null) {
+        ViewRootImpl viewRootImpl = getViewRootImpl();
+        if (viewRootImpl != null) {
+            View focusHost = viewRootImpl.getAccessibilityFocusedHost();
+            if (focusHost != null && ViewRootImpl.isViewDescendantOf(focusHost, this)) {
                 viewRootImpl.setAccessibilityFocusedHost(null);
             }
+        }
+        if ((mPrivateFlags2 & ACCESSIBILITY_FOCUSED) != 0) {
+            mPrivateFlags2 &= ~ACCESSIBILITY_FOCUSED;
             invalidate();
             sendAccessibilityEvent(AccessibilityEvent.TYPE_VIEW_ACCESSIBILITY_FOCUS_CLEARED);
             notifyAccessibilityStateChanged();

core/java/android/view/ViewRootImpl.java

@@ -488,7 +488,9 @@ public void setView(View view, WindowManager.LayoutParams attrs, View panelParen
                 mFallbackEventHandler.setView(view);
                 mWindowAttributes.copyFrom(attrs);
                 attrs = mWindowAttributes;
-                
+
+                setAccessibilityFocusedHost(null);
+
                 if (view instanceof RootViewSurfaceTaker) {
                     mSurfaceHolderCallback =
                             ((RootViewSurfaceTaker)view).willYouTakeTheSurface();
@@ -556,6 +558,7 @@ public void setView(View view, WindowManager.LayoutParams attrs, View panelParen
                     mInputChannel = null;
                     mFallbackEventHandler.setView(null);
                     unscheduleTraversals();
+                    setAccessibilityFocusedHost(null);
                     throw new RuntimeException("Adding window failed", e);
                 } finally {
                     if (restore) {
@@ -575,6 +578,7 @@ public void setView(View view, WindowManager.LayoutParams attrs, View panelParen
                     mAdded = false;
                     mFallbackEventHandler.setView(null);
                     unscheduleTraversals();
+                    setAccessibilityFocusedHost(null);
                     switch (res) {
                         case WindowManagerImpl.ADD_BAD_APP_TOKEN:
                         case WindowManagerImpl.ADD_BAD_SUBWINDOW_TOKEN:
@@ -635,8 +639,6 @@ public void setView(View view, WindowManager.LayoutParams attrs, View panelParen
                 if (view.getImportantForAccessibility() == View.IMPORTANT_FOR_ACCESSIBILITY_AUTO) {
                     view.setImportantForAccessibility(View.IMPORTANT_FOR_ACCESSIBILITY_YES);
                 }
-
-                setAccessibilityFocusedHost(null);
             }
         }
     }
@@ -2543,11 +2545,51 @@ public AccessibilityNodeInfo getAccessibilityFocusedVirtualView() {
     }
 
     void setAccessibilityFocusedHost(View host) {
-        if (mAccessibilityFocusedHost != null && mAccessibilityFocusedVirtualView == null) {
+        // If we have a virtual view with accessibility focus we need
+        // to clear the focus and invalidate the virtual view bounds.
+        if (mAccessibilityFocusedVirtualView != null) {
+
+            AccessibilityNodeInfo focusNode = mAccessibilityFocusedVirtualView;
+            View focusHost = mAccessibilityFocusedHost;
+            focusHost.clearAccessibilityFocusNoCallbacks();
+
+            // Wipe the state of the current accessibility focus since
+            // the call into the provider to clear accessibility focus
+            // will fire an accessibility event which will end up calling
+            // this method and we want to have clean state when this
+            // invocation happens.
+            mAccessibilityFocusedHost = null;
+            mAccessibilityFocusedVirtualView = null;
+
+            AccessibilityNodeProvider provider = focusHost.getAccessibilityNodeProvider();
+            if (provider != null) {
+                // Invalidate the area of the cleared accessibility focus.
+                focusNode.getBoundsInParent(mTempRect);
+                focusHost.invalidate(mTempRect);
+                // Clear accessibility focus in the virtual node.
+                final int virtualNodeId = AccessibilityNodeInfo.getVirtualDescendantId(
+                        focusNode.getSourceNodeId());
+                provider.performAction(virtualNodeId,
+                        AccessibilityNodeInfo.ACTION_CLEAR_ACCESSIBILITY_FOCUS, null);
+            }
+        }
+        if (mAccessibilityFocusedHost != null) {
+            // Clear accessibility focus in the view.
             mAccessibilityFocusedHost.clearAccessibilityFocusNoCallbacks();
         }
+
+        // Set the new focus host.
         mAccessibilityFocusedHost = host;
-        mAccessibilityFocusedVirtualView = null;
+
+        // If the host has a provide find the virtual descendant that has focus.
+        if (mAccessibilityFocusedHost != null) {
+            AccessibilityNodeProvider provider =
+                mAccessibilityFocusedHost.getAccessibilityNodeProvider();
+            if (provider != null) {
+                mAccessibilityFocusedVirtualView = provider.findAccessibilityFocus(View.NO_ID);
+                return;
+            }
+        }
     }
 
     public void requestChildFocus(View child, View focused) {
@@ -2633,6 +2675,8 @@ void dispatchDetachedFromWindow() {
 
         destroyHardwareRenderer();
 
+        setAccessibilityFocusedHost(null);
+
         mView = null;
         mAttachInfo.mRootView = null;
         mAttachInfo.mSurface = null;
@@ -4608,6 +4652,31 @@ public boolean requestSendAccessibilityEvent(View child, AccessibilityEvent even
         if (mView == null) {
             return false;
         }
+        // Watch for accessibility focus change events from virtual nodes
+        // to keep track of accessibility focus being on a virtual node.
+        final int eventType = event.getEventType();
+        switch (eventType) {
+            case AccessibilityEvent.TYPE_VIEW_ACCESSIBILITY_FOCUSED: {
+                final long sourceId = event.getSourceNodeId();
+                // If the event is not from a virtual node we are not interested.
+                final int virtualViewId = AccessibilityNodeInfo.getVirtualDescendantId(sourceId);
+                if (virtualViewId == AccessibilityNodeInfo.UNDEFINED) {
+                    break;
+                }
+                final int realViewId = AccessibilityNodeInfo.getAccessibilityViewId(sourceId);
+                View focusHost = mView.findViewByAccessibilityId(realViewId);
+                setAccessibilityFocusedHost(focusHost);
+            } break;
+            case AccessibilityEvent.TYPE_VIEW_ACCESSIBILITY_FOCUS_CLEARED: {
+                final long sourceId = event.getSourceNodeId();
+                // If the event is not from a virtual node we are not interested.
+                final int virtualViewId = AccessibilityNodeInfo.getVirtualDescendantId(sourceId);
+                if (virtualViewId == AccessibilityNodeInfo.UNDEFINED) {
+                    break;
+                }
+                setAccessibilityFocusedHost(null);
+            } break;
+        }
         mAccessibilityManager.sendAccessibilityEvent(event);
         return true;
     }