Add getPlainText method

lib/src/models/documents/document.dart

@@ -169,6 +169,12 @@ class Document {
     return (res.node as Line).collectAllStyles(res.offset, len);
   }
 
+  /// Returns plain text within the specified text range.
+  String getPlainText(int index, int len) {
+    final res = queryChild(index);
+    return (res.node as Line).getPlainText(res.offset, len);
+  }
+
   /// Returns [Line] located at specified character [offset].
   ChildQuery queryChild(int offset) {
     // TODO: prevent user from moving caret after last line-break.

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

@@ -384,7 +384,7 @@ class Line extends Container<Leaf?> {
   }
 
   /// Returns each node segment's length in selection
-  /// with its corresponding styles as a list
+  /// with its corresponding style as a list
   List<Tuple2<int, Style>> collectAllIndividualStyles(int offset, int len) {
     final local = math.min(length - offset, len);
     final result = <Tuple2<int, Style>>[];
@@ -401,7 +401,7 @@ class Line extends Container<Leaf?> {
       }
     }
 
-    // TODO: add current line's style and parent block style as well
+    // Need to add current line's style or parent block's style?
 
     final remaining = len - local;
     if (remaining > 0) {
@@ -444,4 +444,30 @@ class Line extends Container<Leaf?> {
 
     return result;
   }
+
+  /// Returns plain text within the specified text range.
+  String getPlainText(int offset, int len) {
+    final local = math.min(length - offset, len);
+    final result = <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;
+      while (!node!.isLast && pos < local) {
+        node = node.next as Leaf;
+        result.add(node.toPlainText());
+        pos += node.length;
+      }
+    }
+
+    final remaining = len - local;
+    if (remaining > 0) {
+      final rest = nextLine!.getPlainText(0, remaining);
+      result.add(rest);
+    }
+
+    return result.join();
+  }
 }

lib/src/widgets/controller.dart

@@ -91,6 +91,13 @@ class QuillController extends ChangeNotifier {
     return styles;
   }
 
+  /// Returns plain text for each node within selection
+  String getPlainText() {
+    final text =
+        document.getPlainText(selection.start, selection.end - selection.start);
+    return text;
+  }
+
   /// Returns all styles for any character within the specified text range.
   List<Style> getAllSelectionStyles() {
     final styles = document.collectAllStyles(