Bug 1786963 - Make cached TextBounds return rect of whole input if it is empty. r=morgan

Differential Revision: https://phabricator.services.mozilla.com/D155513

accessible/basetypes/HyperTextAccessibleBase.cpp

@@ -183,8 +183,14 @@ LayoutDeviceIntRect HyperTextAccessibleBase::CharBounds(int32_t aOffset,
 LayoutDeviceIntRect HyperTextAccessibleBase::TextBounds(int32_t aStartOffset,
                                                         int32_t aEndOffset,
                                                         uint32_t aCoordType) {
-  if (CharacterCount() == 0 ||
-      (aEndOffset > -1 && aStartOffset >= aEndOffset)) {
+  LayoutDeviceIntRect result;
+  if (CharacterCount() == 0) {
+    result = Acc()->Bounds();
+    nsAccUtils::ConvertScreenCoordsTo(&result.x, &result.y, aCoordType, Acc());
+    return result;
+  }
+
+  if (aEndOffset > -1 && aStartOffset >= aEndOffset) {
     return LayoutDeviceIntRect();
   }
 
@@ -204,7 +210,6 @@ LayoutDeviceIntRect HyperTextAccessibleBase::TextBounds(int32_t aStartOffset,
   endPoint = endPoint.FindBoundary(nsIAccessibleText::BOUNDARY_CHAR,
                                    eDirPrevious, false);
 
-  LayoutDeviceIntRect result;
   if (endPoint == currPoint) {
     result = currPoint.CharBounds();
     nsAccUtils::ConvertScreenCoordsTo(&result.x, &result.y, aCoordType, Acc());

accessible/tests/browser/bounds/browser_test_zoom_text.js

@@ -20,6 +20,14 @@ async function runTests(browser, accDoc) {
       [x, y, width, height],
       COORDTYPE_SCREEN_RELATIVE
     );
+    // A 0 range should return an empty rect.
+    testTextBounds(
+      hyperTextNode,
+      0,
+      0,
+      [0, 0, 0, 0],
+      COORDTYPE_SCREEN_RELATIVE
+    );
   }
 
   async function testEmptyInputNode(id) {
@@ -33,6 +41,8 @@ async function runTests(browser, accDoc) {
       [x, y, width, height],
       COORDTYPE_SCREEN_RELATIVE
     );
+    // A 0 range in an empty input should still return
+    // rect of input node.
     testTextBounds(
       inputNode,
       0,