Ignore text selection boxes when assembling semantics for placeholder runs (#70487)

packages/flutter/lib/src/rendering/paragraph.dart

@@ -902,38 +902,11 @@ class RenderParagraph extends RenderBox
     RenderBox? child = firstChild;
     final Queue<SemanticsNode> newChildCache = Queue<SemanticsNode>();
     for (final InlineSpanSemanticsInformation info in _combineSemanticsInfo()) {
-      final TextDirection initialDirection = currentDirection;
       final TextSelection selection = TextSelection(
         baseOffset: start,
         extentOffset: start + info.text.length,
       );
-      final List<ui.TextBox> rects = getBoxesForSelection(selection);
       start += info.text.length;
-      if (rects.isEmpty) {
-        continue;
-      }
-      Rect rect = rects.first.toRect();
-      currentDirection = rects.first.direction;
-      for (final ui.TextBox textBox in rects.skip(1)) {
-        rect = rect.expandToInclude(textBox.toRect());
-        currentDirection = textBox.direction;
-      }
-      // Any of the text boxes may have had infinite dimensions.
-      // We shouldn't pass infinite dimensions up to the bridges.
-      rect = Rect.fromLTWH(
-        math.max(0.0, rect.left),
-        math.max(0.0, rect.top),
-        math.min(rect.width, constraints.maxWidth),
-        math.min(rect.height, constraints.maxHeight),
-      );
-      // round the current rectangle to make this API testable and add some
-      // padding so that the accessibility rects do not overlap with the text.
-      currentRect = Rect.fromLTRB(
-        rect.left.floorToDouble() - 4.0,
-        rect.top.floorToDouble() - 4.0,
-        rect.right.ceilToDouble() + 4.0,
-        rect.bottom.ceilToDouble() + 4.0,
-      );
 
       if (info.isPlaceholder) {
         // A placeholder span may have 0 to multple semantics nodes, we need
@@ -954,6 +927,33 @@ class RenderParagraph extends RenderBox
         child = childAfter(child!);
         placeholderIndex += 1;
       } else {
+        final TextDirection initialDirection = currentDirection;
+        final List<ui.TextBox> rects = getBoxesForSelection(selection);
+        if (rects.isEmpty) {
+          continue;
+        }
+        Rect rect = rects.first.toRect();
+        currentDirection = rects.first.direction;
+        for (final ui.TextBox textBox in rects.skip(1)) {
+          rect = rect.expandToInclude(textBox.toRect());
+          currentDirection = textBox.direction;
+        }
+        // Any of the text boxes may have had infinite dimensions.
+        // We shouldn't pass infinite dimensions up to the bridges.
+        rect = Rect.fromLTWH(
+          math.max(0.0, rect.left),
+          math.max(0.0, rect.top),
+          math.min(rect.width, constraints.maxWidth),
+          math.min(rect.height, constraints.maxHeight),
+        );
+        // round the current rectangle to make this API testable and add some
+        // padding so that the accessibility rects do not overlap with the text.
+        currentRect = Rect.fromLTRB(
+          rect.left.floorToDouble() - 4.0,
+          rect.top.floorToDouble() - 4.0,
+          rect.right.ceilToDouble() + 4.0,
+          rect.bottom.ceilToDouble() + 4.0,
+        );
         final SemanticsConfiguration configuration = SemanticsConfiguration()
           ..sortKey = OrdinalSortKey(ordinal++)
           ..textDirection = initialDirection

packages/flutter/test/rendering/paragraph_test.dart

@@ -37,6 +37,26 @@ class RenderParagraphWithEmptySelectionBoxList extends RenderParagraph {
   }
 }
 
+// A subclass of RenderParagraph that returns an empty list in getBoxesForSelection
+// for a selection representing a WidgetSpan.
+// This is intended to simulate how SkParagraph's implementation of Paragraph.getBoxesForRange
+// can return an empty list for a WidgetSpan with empty dimensions.
+class RenderParagraphWithEmptyBoxListForWidgetSpan extends RenderParagraph {
+  RenderParagraphWithEmptyBoxListForWidgetSpan(
+    InlineSpan text, {
+    required List<RenderBox> children,
+    required TextDirection textDirection,
+  }) : super(text, children: children, textDirection: textDirection);
+
+  @override
+  List<ui.TextBox> getBoxesForSelection(TextSelection selection) {
+    if (text.getSpanForPosition(selection.base) is WidgetSpan) {
+      return <ui.TextBox>[];
+    }
+    return super.getBoxesForSelection(selection);
+  }
+}
+
 void main() {
   test('getOffsetForCaret control test', () {
     final RenderParagraph paragraph = RenderParagraph(
@@ -588,4 +608,25 @@ void main() {
     paragraph.assembleSemanticsNode(node, SemanticsConfiguration(), <SemanticsNode>[]);
     expect(node.childrenCount, 2);
   }, skip: isBrowser); // https://github.com/flutter/flutter/issues/61020
+
+  test('assembleSemanticsNode handles empty WidgetSpans that do not yield selection boxes', () {
+    final TextSpan text = TextSpan(text: '', children: <InlineSpan>[
+      TextSpan(text: 'A', recognizer: TapGestureRecognizer()..onTap = () {}),
+      const WidgetSpan(child: SizedBox(width: 0, height: 0)),
+      TextSpan(text: 'C', recognizer: TapGestureRecognizer()..onTap = () {}),
+    ]);
+    final List<RenderBox> renderBoxes = <RenderBox>[
+      RenderParagraph(const TextSpan(text: 'b'), textDirection: TextDirection.ltr),
+    ];
+    final RenderParagraph paragraph = RenderParagraphWithEmptyBoxListForWidgetSpan(
+      text,
+      children: renderBoxes,
+      textDirection: TextDirection.ltr,
+    );
+    layout(paragraph);
+
+    final SemanticsNode node = SemanticsNode();
+    paragraph.assembleSemanticsNode(node, SemanticsConfiguration(), <SemanticsNode>[]);
+    expect(node.childrenCount, 2);
+  }, skip: isBrowser); // https://github.com/flutter/flutter/issues/61020
 }