Bug 1837030: Treat fuzzily-matched text leaves as valid in OffsetAtPo…

…int r=Jamie,nlapre, a=dmeehan

Differential Revision: https://phabricator.services.mozilla.com/D180515

accessible/basetypes/HyperTextAccessibleBase.cpp

@@ -292,6 +292,17 @@ int32_t HyperTextAccessibleBase::OffsetAtPoint(int32_t aX, int32_t aY,
       nsAccUtils::ConvertToScreenCoords(aX, aY, aCoordType, thisAcc);
   if (!thisAcc->Bounds().Contains(coords.x, coords.y)) {
     // The requested point does not exist in this accessible.
+    // Check if we used fuzzy hittesting to get here and, if
+    // so, return 0 to indicate this text leaf is a valid match.
+    LayoutDeviceIntPoint p(aX, aY);
+    if (aCoordType != nsIAccessibleCoordinateType::COORDTYPE_SCREEN_RELATIVE) {
+      p = nsAccUtils::ConvertToScreenCoords(aX, aY, aCoordType, thisAcc);
+    }
+    Accessible* hittestMatch = nsAccUtils::DocumentFor(thisAcc)->ChildAtPoint(
+        p.x, p.y, Accessible::EWhichChildAtPoint::DeepestChild);
+    if (thisAcc == hittestMatch->Parent()) {
+      return 0;
+    }
     return -1;
   }
 

accessible/tests/browser/hittest/browser_test_general.js

@@ -302,6 +302,14 @@ addAccessibleTask(
       generic, // Direct Child
       invisible.firstChild // Deepest Child
     );
+
+    await testOffsetAtPoint(
+      findAccessibleChildByID(docAcc, "invisible", [Ci.nsIAccessibleText]),
+      1,
+      1,
+      COORDTYPE_PARENT_RELATIVE,
+      0
+    );
   },
   { chrome: false, iframe: true, remoteIframe: true }
 );