Make pane logic consistent with documentation

APPEARED and DISAPPEARED events should be sent when a title is first
given and nulled respectively, following the Javadoc.

Test: Manual, atest AccessibilityPaneTest
Bug: 133131221
Change-Id: I41cd2548aa949c7ce320e228c2b07ef04ea0298b

2 files changed, 28 insertions, 4 deletions

diff --git a/core/java/android/view/View.java b/core/java/android/view/View.java
index 34a13868f4d7..553c537d9b95 100644
--- a/core/java/android/view/View.java
+++ b/core/java/android/view/View.java
@@ -8226,9 +8226,25 @@ public class View implements Drawable.Callback, KeyEvent.Callback,
      */
     public void setAccessibilityPaneTitle(@Nullable CharSequence accessibilityPaneTitle) {
         if (!TextUtils.equals(accessibilityPaneTitle, mAccessibilityPaneTitle)) {
+            boolean currentPaneTitleEmpty = mAccessibilityPaneTitle == null;
+            boolean newPaneTitleEmpty =  accessibilityPaneTitle == null;
             mAccessibilityPaneTitle = accessibilityPaneTitle;
-            notifyViewAccessibilityStateChangedIfNeeded(
-                    AccessibilityEvent.CONTENT_CHANGE_TYPE_PANE_TITLE);
+            // Make explicitly important as nulled titles need to be important for DISAPPEARED
+            // events.
+            if (mAccessibilityPaneTitle != null
+                    && getImportantForAccessibility() == IMPORTANT_FOR_ACCESSIBILITY_AUTO) {
+                setImportantForAccessibility(IMPORTANT_FOR_ACCESSIBILITY_YES);
+            }
+            if (currentPaneTitleEmpty) {
+                notifyViewAccessibilityStateChangedIfNeeded(
+                        AccessibilityEvent.CONTENT_CHANGE_TYPE_PANE_APPEARED);
+            } else if (newPaneTitleEmpty) {
+                notifyViewAccessibilityStateChangedIfNeeded(
+                        AccessibilityEvent.CONTENT_CHANGE_TYPE_PANE_DISAPPEARED);
+            } else {
+                notifyViewAccessibilityStateChangedIfNeeded(
+                        AccessibilityEvent.CONTENT_CHANGE_TYPE_PANE_TITLE);
+            }
         }
     }
 
@@ -14168,9 +14184,12 @@ public class View implements Drawable.Callback, KeyEvent.Callback,
         }
 
         // Changes to views with a pane title count as window state changes, as the pane title
-        // marks them as significant parts of the UI.
+        // marks them as significant parts of the UI. A visible view with a nulled title may send
+        // a disappeared event.
         if ((changeType != AccessibilityEvent.CONTENT_CHANGE_TYPE_SUBTREE)
-                && isAccessibilityPane()) {
+                && (isAccessibilityPane()
+                || (changeType == AccessibilityEvent.CONTENT_CHANGE_TYPE_PANE_DISAPPEARED)
+                && isAggregatedVisible())) {
             // If the pane isn't visible, content changed events are sufficient unless we're
             // reporting that the view just disappeared
             if ((isAggregatedVisible())
diff --git a/core/java/android/view/accessibility/AccessibilityEvent.java b/core/java/android/view/accessibility/AccessibilityEvent.java
index cd8dd86b8e02..7e16531663d5 100644
--- a/core/java/android/view/accessibility/AccessibilityEvent.java
+++ b/core/java/android/view/accessibility/AccessibilityEvent.java
@@ -592,6 +592,11 @@ public final class AccessibilityEvent extends AccessibilityRecord implements Par
     /**
      * Change type for {@link #TYPE_WINDOW_STATE_CHANGED} event:
      * The node's pane title changed.
+     * <p>
+     * If this makes the pane appear, {@link #CONTENT_CHANGE_TYPE_PANE_APPEARED} is sent
+     * instead. If this makes the pane disappear, {@link #CONTENT_CHANGE_TYPE_PANE_DISAPPEARED}
+     * is sent.
+     *
      */
     public static final int CONTENT_CHANGE_TYPE_PANE_TITLE = 0x00000008;