When dragging make the content of the drag layer not accessible but keep the drag View accessible

Continuation of change I842415f689c992f64d863743f019455701da22e9

Fix: 392872410
Bug: 374642145
Bug: 374656225
Bug: 374658319
Test: manual
Flag: EXEMPT bugfix
Change-Id: I282f1f6ca30e10c5aef6947feee9b10514e286a6

src/com/android/launcher3/dragndrop/LauncherDragController.java

@@ -151,9 +151,7 @@ public class LauncherDragController extends DragController<Launcher> {
                         initialDragViewScale,
                         dragViewScaleOnDrop,
                         scalePx);
-        // During a drag, we don't want to expose the descendendants of drag view to a11y users,
-        // since those decendents are not a valid position in the workspace.
-        dragView.setImportantForAccessibility(View.IMPORTANT_FOR_ACCESSIBILITY_NO_HIDE_DESCENDANTS);
+
         dragView.setItemInfo(dragInfo);
         mDragObject.dragComplete = false;
 
@@ -161,6 +159,7 @@ public class LauncherDragController extends DragController<Launcher> {
         mDragObject.yOffset = mMotionDown.y - (dragLayerY + dragRegionTop);
 
         mDragDriver = DragDriver.create(this, mOptions, mFlingToDeleteHelper::recordMotionEvent);
+        prepareViewForAccessibility(dragView);
         if (!mOptions.isAccessibleDrag) {
             mDragObject.stateAnnouncer = DragViewStateAnnouncer.createFor(dragView);
         }
@@ -198,6 +197,21 @@ public class LauncherDragController extends DragController<Launcher> {
         return dragView;
     }
 
+    /**
+     * During a drag, we don't want to expose the descendants of drag view to a11y users,
+     * since those descendants are not a valid position in the workspace.
+     * We need to go through the children because the view itself is important for
+     * accessibility, basically we are implementing:
+     * IMPORTANT_FOR_ACCESSIBILITY_YES_HIDE_DESCENDANTS
+     */
+    void prepareViewForAccessibility(DragView dragView) {
+        for (int i = 0; i < dragView.getChildCount(); i++) {
+            dragView.getChildAt(i).setImportantForAccessibility(
+                    View.IMPORTANT_FOR_ACCESSIBILITY_NO_HIDE_DESCENDANTS
+            );
+        }
+    }
+
 
     /**
      * Returns the scale in terms of pixels (to be applied on width) to scale the preview