Fix selection in readOnly mode, Add magnifier via RawMagnifier widget (singerdmx#2529)

* enable selection handles in read only mode, added magnifier

* hide the context menu when dragging selection handles

* added entry to change log file

* after a long press (from double tap or drag) make sure magnifier is removed

* added dragOffsetNotifier explanation

* created [QuillMagnifer] and added a [QuillEditorConfig] parameter quillMangifierBuilder, also added a defaultQuillMagnifierBuilder function, when not specified the magnifier will not be used.

---------

Co-authored-by: Ellet <[email protected]>

Author: mtallenca

CHANGELOG.md

@@ -10,6 +10,14 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Fixed
+
+- Can't select text when `readOnly` is true [#2529](https://github.com/singerdmx/flutter-quill/pull/2529).
+
+### Added
+
+- Display magnifier using `RawMagnifier` widget when dragging on iOS/Android [#2529](https://github.com/singerdmx/flutter-quill/pull/2529).
+
 ## [11.2.0] - 2025-03-26
 
 ### Added 

lib/flutter_quill.dart

@@ -27,6 +27,7 @@ export 'src/editor/style_widgets/style_widgets.dart';
 export 'src/editor/widgets/cursor.dart';
 export 'src/editor/widgets/default_styles.dart';
 export 'src/editor/widgets/link.dart';
+export 'src/editor/widgets/text/magnifier.dart';
 export 'src/editor/widgets/text/utils/text_block_utils.dart';
 export 'src/editor_toolbar_controller_shared/copy_cut_service/copy_cut_service.dart';
 export 'src/editor_toolbar_controller_shared/copy_cut_service/copy_cut_service_provider.dart';

lib/src/editor/config/editor_config.dart

@@ -14,6 +14,7 @@ import '../raw_editor/raw_editor.dart';
 import '../widgets/default_styles.dart';
 import '../widgets/delegate.dart';
 import '../widgets/link.dart';
+import '../widgets/text/magnifier.dart';
 import '../widgets/text/utils/text_block_utils.dart';
 import 'search_config.dart';
 
@@ -56,6 +57,7 @@ class QuillEditorConfig {
     this.enableAlwaysIndentOnTab = false,
     this.embedBuilders,
     this.textSpanBuilder = defaultSpanBuilder,
+    this.quillMagnifierBuilder,
     this.unknownEmbedBuilder,
     @experimental this.searchConfig = const QuillSearchConfig(),
     this.linkActionPickerDelegate = defaultLinkActionPickerDelegate,
@@ -367,6 +369,14 @@ class QuillEditorConfig {
 
   final TextSpanBuilder textSpanBuilder;
 
+  /// To add a magnifier when selecting, specify a builder that returns the magnfier widget
+  ///
+  /// The default is no magnifier
+  ///
+  /// There is a provided magnifier [QuillMagnifier] that is available via the function
+  /// defaultQuillMagnifierBuilder
+  final QuillMagnifierBuilder? quillMagnifierBuilder;
+
   /// See [search](https://github.com/singerdmx/flutter-quill/blob/master/doc/configurations/search.md)
   /// page for docs.
   @experimental

lib/src/editor/editor.dart

@@ -196,6 +196,9 @@ class QuillEditorState extends State<QuillEditor>
   QuillEditorConfig get configurations => widget.config;
   QuillEditorConfig get config => widget.config;
 
+  /// {@macro drag_offset_notifier}
+  final dragOffsetNotifier = isMobileApp ? ValueNotifier<Offset?>(null) : null;
+
   @override
   void initState() {
     super.initState();
@@ -260,6 +263,7 @@ class QuillEditorState extends State<QuillEditor>
     final child = QuillRawEditor(
       key: _editorKey,
       controller: controller,
+      dragOffsetNotifier: dragOffsetNotifier,
       config: QuillRawEditorConfig(
         characterShortcutEvents: widget.config.characterShortcutEvents,
         spaceShortcutEvents: widget.config.spaceShortcutEvents,
@@ -305,6 +309,7 @@ class QuillEditorState extends State<QuillEditor>
         scrollPhysics: config.scrollPhysics,
         embedBuilder: _getEmbedBuilder,
         textSpanBuilder: config.textSpanBuilder,
+        quillMagnifierBuilder: config.quillMagnifierBuilder,
         linkActionPickerDelegate: config.linkActionPickerDelegate,
         customStyleBuilder: config.customStyleBuilder,
         customRecognizerBuilder: config.customRecognizerBuilder,
@@ -330,6 +335,8 @@ class QuillEditorState extends State<QuillEditor>
             behavior: HitTestBehavior.translucent,
             detectWordBoundary: config.detectWordBoundary,
             child: child,
+            dragOffsetNotifier: dragOffsetNotifier,
+            quillMagnifierBuilder: config.quillMagnifierBuilder,
           )
         : child;
 

lib/src/editor/raw_editor/config/raw_editor_config.dart

@@ -12,6 +12,7 @@ import '../../../editor/widgets/default_styles.dart';
 import '../../../editor/widgets/delegate.dart';
 import '../../../editor/widgets/link.dart';
 import '../../../toolbar/theme/quill_dialog_theme.dart';
+import '../../widgets/text/magnifier.dart';
 import '../../widgets/text/utils/text_block_utils.dart';
 import '../builders/leading_block_builder.dart';
 import 'events/events.dart';
@@ -70,6 +71,7 @@ class QuillRawEditorConfig {
     this.readOnlyMouseCursor = SystemMouseCursors.text,
     this.onPerformAction,
     @experimental this.customLeadingBuilder,
+    this.quillMagnifierBuilder,
   });
 
   /// Controls whether this editor has keyboard focus.
@@ -408,4 +410,7 @@ class QuillRawEditorConfig {
 
   /// Called when a text input action is performed.
   final void Function(TextInputAction action)? onPerformAction;
+
+  /// Used to build the [QuillMagnifier] when long-pressing/dragging selection
+  final QuillMagnifierBuilder? quillMagnifierBuilder;
 }

lib/src/editor/raw_editor/raw_editor.dart

@@ -11,6 +11,7 @@ class QuillRawEditor extends StatefulWidget {
   QuillRawEditor({
     required this.config,
     required this.controller,
+    this.dragOffsetNotifier,
     super.key,
   })  : assert(config.maxHeight == null || config.maxHeight! > 0,
             'maxHeight cannot be null'),
@@ -25,6 +26,28 @@ class QuillRawEditor extends StatefulWidget {
   final QuillController controller;
   final QuillRawEditorConfig config;
 
+  /// {@template drag_offset_notifier}
+  /// dragOffsetNotifier - Only used on iOS and Android
+  ///
+  /// [QuillRawEditor] contains a gesture detector [EditorTextSelectionGestureDetector]
+  /// within it's widget tree that includes a [RawMagnifier]. The RawMagnifier needs
+  /// the current position of selection drag events in order to display the magnifier
+  /// in the correct location. Setting the position to null will hide the magnifier.
+  ///
+  /// Initial selection events are posted by [EditorTextSelectionGestureDetector]. Once
+  /// a selection has been created, dragging the selection handles happens in
+  /// [EditorTextSelectionOverlay].
+  ///
+  /// Both [EditorTextSelectionGestureDetector] and [EditorTextSelectionOverlay] will update
+  /// the value of the dragOffsetNotifier.
+  ///
+  /// The [EditorTextSelectionGestureDetector] will use the value to display the magnifier in
+  /// the correct location (or hide the magnifier if null). [EditorTextSelectionOverlay] will
+  /// use the value of the dragOffsetNotifier to hide the context menu when the magnifier is
+  /// displayed and show the context menu when dragging is complete.
+  /// {@endtemplate}
+  final ValueNotifier<Offset?>? dragOffsetNotifier;
+
   @override
   State<StatefulWidget> createState() => QuillRawEditorState();
 }

lib/src/editor/raw_editor/raw_editor_state.dart

@@ -853,8 +853,9 @@ class QuillRawEditorState extends EditorState
       });
     }
 
+    controller.addListener(_didChangeTextEditingValueListener);
+
     if (!widget.config.readOnly) {
-      controller.addListener(_didChangeTextEditingValueListener);
       // listen to composing range changes
       composingRange.addListener(_onComposingRangeChanged);
       // Focus
@@ -965,8 +966,8 @@ class QuillRawEditorState extends EditorState
     assert(!hasConnection);
     _selectionOverlay?.dispose();
     _selectionOverlay = null;
+    controller.removeListener(_didChangeTextEditingValueListener);
     if (!widget.config.readOnly) {
-      controller.removeListener(_didChangeTextEditingValueListener);
       widget.config.focusNode.removeListener(_handleFocusChanged);
       composingRange.removeListener(_onComposingRangeChanged);
     }
@@ -1081,6 +1082,7 @@ class QuillRawEditorState extends EditorState
         contextMenuBuilder: widget.config.contextMenuBuilder == null
             ? null
             : (context) => widget.config.contextMenuBuilder!(context, this),
+        dragOffsetNotifier: widget.dragOffsetNotifier,
       );
       _selectionOverlay!.handlesVisible = _shouldShowSelectionHandles();
       _selectionOverlay!.showHandles();

lib/src/editor/widgets/delegate.dart

@@ -8,6 +8,7 @@ import '../../document/attribute.dart';
 import '../../document/nodes/leaf.dart';
 import '../editor.dart';
 import '../raw_editor/raw_editor.dart';
+import 'text/magnifier.dart';
 import 'text/text_selection.dart';
 
 typedef CustomStyleBuilder = TextStyle Function(Attribute attribute);
@@ -361,6 +362,8 @@ class EditorTextSelectionGestureDetectorBuilder {
     required Widget child,
     Key? key,
     bool detectWordBoundary = true,
+    ValueNotifier<Offset?>? dragOffsetNotifier,
+    QuillMagnifierBuilder? quillMagnifierBuilder,
   }) {
     return EditorTextSelectionGestureDetector(
       key: key,
@@ -379,6 +382,8 @@ class EditorTextSelectionGestureDetectorBuilder {
       onDragSelectionEnd: onDragSelectionEnd,
       behavior: behavior,
       detectWordBoundary: detectWordBoundary,
+      dragOffsetNotifier: dragOffsetNotifier,
+      quillMagnifierBuilder: quillMagnifierBuilder,
       child: child,
     );
   }

lib/src/editor/widgets/text/magnifier.dart

@@ -0,0 +1,43 @@
+import 'package:flutter/material.dart';
+
+typedef QuillMagnifierBuilder = Widget Function(Offset dragPosition);
+
+Widget defaultQuillMagnifierBuilder(Offset dragPosition) =>
+    QuillMagnifier(dragPosition: dragPosition);
+
+class QuillMagnifier extends StatelessWidget {
+  const QuillMagnifier({required this.dragPosition,  super.key});
+
+  final Offset dragPosition;
+
+  @override
+  Widget build(BuildContext context) {
+    final position = dragPosition.translate(-60, -80);
+    return Positioned(
+      top: position.dy,
+      left: position.dx,
+      child: Container(
+        decoration: BoxDecoration(
+            borderRadius: BorderRadius.circular(20),
+        ),
+        child: RawMagnifier(
+          clipBehavior: Clip.hardEdge,
+          decoration: MagnifierDecoration(
+            shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(20)),
+            shadows: const [
+              BoxShadow(
+                color: Colors.black26,
+                spreadRadius: 2,
+                blurRadius: 5,
+                offset: Offset(3, 3), // changes position of shadow
+              ),
+            ],
+          ),
+          size: const Size(100, 45),
+          focalPointOffset: const Offset(5, 55),
+          magnificationScale: 1.3,
+        ),
+      ),
+    );
+  }
+}