Improve link button

lib/src/models/documents/document.dart

@@ -9,6 +9,7 @@ import 'history.dart';
 import 'nodes/block.dart';
 import 'nodes/container.dart';
 import 'nodes/embeddable.dart';
+import 'nodes/leaf.dart';
 import 'nodes/line.dart';
 import 'nodes/node.dart';
 import 'style.dart';
@@ -136,6 +137,22 @@ class Document {
     return block.queryChild(res.offset, true);
   }
 
+  /// Given offset, find its leaf node in document
+  Tuple2<Line?, Leaf?> querySegmentLeafNode(int offset) {
+    final result = queryChild(offset);
+    if (result.node == null) {
+      return const Tuple2(null, null);
+    }
+
+    final line = result.node as Line;
+    final segmentResult = line.queryChild(result.offset, false);
+    if (segmentResult.node == null) {
+      return Tuple2(line, null);
+    }
+    final segment = segmentResult.node as Leaf;
+    return Tuple2(line, segment);
+  }
+
   void compose(Delta delta, ChangeSource changeSource) {
     assert(!_observer.isClosed);
     delta.trim();

lib/src/widgets/editor.dart

@@ -9,7 +9,6 @@ import 'package:flutter/services.dart';
 
 import '../models/documents/document.dart';
 import '../models/documents/nodes/container.dart' as container_node;
-import '../models/documents/nodes/line.dart';
 import '../utils/platform.dart';
 import 'box.dart';
 import 'controller.dart';
@@ -535,13 +534,14 @@ class _QuillEditorSelectionGestureDetectorBuilder
       return false;
     }
     final pos = renderEditor!.getPositionForOffset(details.globalPosition);
-    final result = editor!.widget.controller.document.queryChild(pos.offset);
-    if (result.node == null) {
+    final result =
+        editor!.widget.controller.document.querySegmentLeafNode(pos.offset);
+    final line = result.item1;
+    if (line == null) {
       return false;
     }
-    final line = result.node as Line;
-    final segmentResult = line.queryChild(result.offset, false);
-    if (segmentResult.node == null && line.length == 1) {
+    final segmentLeaf = result.item2;
+    if (segmentLeaf == null && line.length == 1) {
       editor!.widget.controller.updateSelection(
           TextSelection.collapsed(offset: pos.offset), ChangeSource.LOCAL);
       return true;

lib/src/widgets/toolbar/link_style_button.dart

@@ -103,10 +103,17 @@ class _LinkStyleButtonState extends State<LinkStyleButton> {
         final link = _getLinkAttributeValue();
         final index = widget.controller.selection.baseOffset;
 
+        var text;
         if (link != null) {
-          // TODO: text should be the link's corresponding text, not selection
+          // text should be the link's corresponding text, not selection
+          final leaf =
+              widget.controller.document.querySegmentLeafNode(index).item2;
+          if (leaf != null) {
+            text = leaf.toPlainText();
+          }
         }
-        final text = widget.controller.document
+
+        text ??= widget.controller.document
             .toPlainText()
             .substring(index, widget.controller.selection.extentOffset);
         return _LinkDialog(