Fix getPlainText

lib/src/models/documents/nodes/line.dart

@@ -449,27 +449,52 @@ class Line extends Container<Leaf?> {
 
   /// Returns plain text within the specified text range.
   String getPlainText(int offset, int len) {
+    final res = _getPlainText(offset, len);
+    if (res.length == 1) {
+      final data = queryChild(offset, true);
+      final text = res.single.item2;
+      return text.substring(data.offset, data.offset + len);
+    }
+
+    final total = <String>[];
+    // Adjust first node
+    final firstNodeLen = res[1].item1;
+    var text = res[0].item2;
+    total.add(text.substring(text.length - firstNodeLen));
+
+    for (var i = 1; i < res.length - 1; i++) {
+      total.add(res[i].item2);
+    }
+
+    // Adjust last node
+    final lastNodeLen = len - res[res.length - 1].item1;
+    text = res[res.length - 1].item2;
+    total.add(text.substring(0, lastNodeLen));
+    return total.join();
+  }
+
+  List<Tuple2<int, String>> _getPlainText(int offset, int len, {int beg = 0}) {
     final local = math.min(length - offset, len);
-    final result = <String>[];
+    final result = <Tuple2<int, String>>[];
 
     final data = queryChild(offset, true);
     var node = data.node as Leaf?;
     if (node != null) {
-      result.add(node.toPlainText());
       var pos = node.length - data.offset;
+      result.add(Tuple2(beg, node.toPlainText()));
       while (!node!.isLast && pos < local) {
         node = node.next as Leaf;
-        result.add(node.toPlainText());
+        result.add(Tuple2(pos + beg, node.toPlainText()));
         pos += node.length;
       }
     }
 
     final remaining = len - local;
     if (remaining > 0) {
-      final rest = nextLine!.getPlainText(0, remaining);
-      result.add(rest);
+      final rest = nextLine!._getPlainText(0, remaining, beg: local);
+      result.addAll(rest);
     }
 
-    return result.join();
+    return result;
   }
 }

lib/src/widgets/toolbar/link_style_button.dart

@@ -102,7 +102,7 @@ class _LinkStyleButtonState extends State<LinkStyleButton> {
       context: context,
       builder: (ctx) {
         final link = _getLinkAttributeValue();
-        final index = widget.controller.selection.baseOffset;
+        final index = widget.controller.selection.start;
 
         var text;
         if (link != null) {
@@ -115,8 +115,7 @@ class _LinkStyleButtonState extends State<LinkStyleButton> {
         }
 
         text ??= widget.controller.document
-            .toPlainText()
-            .substring(index, widget.controller.selection.extentOffset);
+            .getPlainText(index, widget.controller.selection.end - index);
         return _LinkDialog(
             dialogTheme: widget.dialogTheme, link: link, text: text);
       },
@@ -135,8 +134,8 @@ class _LinkStyleButtonState extends State<LinkStyleButton> {
     final String text = (value as Tuple2).item1;
     final String link = value.item2.trim();
 
-    var index = widget.controller.selection.baseOffset;
-    var length = widget.controller.selection.extentOffset - index;
+    var index = widget.controller.selection.start;
+    var length = widget.controller.selection.end - index;
     if (_getLinkAttributeValue() != null) {
       // text should be the link's corresponding text, not selection
       final leaf = widget.controller.document.querySegmentLeafNode(index).item2;