[SuperEditor][SuperTextField][iOS] Fix focal point for native toolbar (…

…Resolves #2345) (#2428)

super_editor/example/lib/demos/in_the_lab/feature_ios_native_context_menu.dart

@@ -123,6 +123,10 @@ class _NativeIosContextMenuFeatureDemoState extends State<NativeIosContextMenuFe
     Key mobileToolbarKey,
     LeaderLink focalPoint,
   ) {
+    if (_editor.composer.selection == null) {
+      return const SizedBox();
+    }
+
     return iOSSystemPopoverEditorToolbarWithFallbackBuilder(
       context,
       mobileToolbarKey,

super_editor/lib/src/default_editor/super_editor.dart

@@ -923,16 +923,9 @@ Widget iOSSystemPopoverEditorToolbarWithFallbackBuilder(
     return const SizedBox();
   }
 
-  if (focalPoint.offset == null || focalPoint.leaderSize == null) {
-    // It's unclear when/why this might happen. But there seem to be some
-    // cases, such as placing a caret in an empty document and tapping again
-    // to show the toolbar.
-    return const SizedBox();
-  }
-
   if (IOSSystemContextMenu.isSupported(context)) {
     return IOSSystemContextMenu(
-      anchor: focalPoint.offset! & focalPoint.leaderSize!,
+      leaderLink: focalPoint,
     );
   }
 

super_editor/lib/src/infrastructure/platforms/ios/ios_system_context_menu.dart

@@ -1,5 +1,7 @@
 import 'package:flutter/services.dart';
 import 'package:flutter/widgets.dart';
+import 'package:follow_the_leader/follow_the_leader.dart';
+import 'package:super_editor/src/infrastructure/flutter/flutter_scheduler.dart';
 
 /// Displays the iOS system context menu on top of the Flutter view.
 ///
@@ -33,12 +35,13 @@ class IOSSystemContextMenu extends StatefulWidget {
 
   const IOSSystemContextMenu({
     super.key,
-    required this.anchor,
+    required this.leaderLink,
     this.onSystemHide,
   });
 
-  /// The [Rect] that the context menu should point to.
-  final Rect anchor;
+  /// A [LeaderLink] attached to the widget that determines the position
+  /// of the system context menu.
+  final LeaderLink leaderLink;
 
   /// Called when the system hides this context menu.
   ///
@@ -62,23 +65,41 @@ class _IOSSystemContextMenuState extends State<IOSSystemContextMenu> {
     _systemContextMenuController = SystemContextMenuController(
       onSystemHide: widget.onSystemHide,
     );
-    _systemContextMenuController.show(widget.anchor);
+    widget.leaderLink.addListener(_onLeaderChanged);
+    onNextFrame((_) => _positionSystemMenu());
   }
 
   @override
   void didUpdateWidget(IOSSystemContextMenu oldWidget) {
     super.didUpdateWidget(oldWidget);
-    if (widget.anchor != oldWidget.anchor) {
-      _systemContextMenuController.show(widget.anchor);
+    if (widget.leaderLink != oldWidget.leaderLink) {
+      oldWidget.leaderLink.removeListener(_onLeaderChanged);
+      widget.leaderLink.addListener(_onLeaderChanged);
+      onNextFrame((_) => _positionSystemMenu());
     }
   }
 
   @override
   void dispose() {
+    widget.leaderLink.removeListener(_onLeaderChanged);
     _systemContextMenuController.dispose();
     super.dispose();
   }
 
+  void _onLeaderChanged() {
+    if (widget.leaderLink.offset == null || widget.leaderLink.leaderSize == null) {
+      return;
+    }
+
+    onNextFrame((_) {
+      _positionSystemMenu();
+    });
+  }
+
+  void _positionSystemMenu() {
+    _systemContextMenuController.show(widget.leaderLink.offset! & widget.leaderLink.leaderSize!);
+  }
+
   @override
   Widget build(BuildContext context) {
     assert(IOSSystemContextMenu.isSupported(context));

super_editor/lib/src/super_textfield/ios/ios_textfield.dart

@@ -704,8 +704,8 @@ typedef IOSPopoverToolbarBuilder = Widget Function(BuildContext, IOSEditingOverl
 /// iOS is recent enough, otherwise builds [defaultIosPopoverToolbarBuilder].
 Widget iOSSystemPopoverTextFieldToolbarWithFallback(BuildContext context, IOSEditingOverlayController controller) {
   if (IOSSystemContextMenu.isSupported(context)) {
-    return IOSSystemContextMenu(
-      anchor: controller.toolbarFocalPoint.offset! & controller.toolbarFocalPoint.leaderSize!,
+    return IOSSuperTextFieldSystemContextMenu(
+      controller: controller,
     );
   }
 
@@ -752,3 +752,75 @@ Widget defaultIosPopoverToolbarBuilder(BuildContext context, IOSEditingOverlayCo
     },
   );
 }
+
+class IOSSuperTextFieldSystemContextMenu extends StatefulWidget {
+  const IOSSuperTextFieldSystemContextMenu({
+    super.key,
+    required this.controller,
+  });
+
+  final IOSEditingOverlayController controller;
+
+  @override
+  State<IOSSuperTextFieldSystemContextMenu> createState() => _IOSSuperTextFieldSystemContextMenuState();
+}
+
+class _IOSSuperTextFieldSystemContextMenuState extends State<IOSSuperTextFieldSystemContextMenu> {
+  late final SystemContextMenuController _systemContextMenuController;
+
+  @override
+  void initState() {
+    super.initState();
+    _systemContextMenuController = SystemContextMenuController();
+    widget.controller.addListener(_onControllerChanged);
+    onNextFrame((_) {
+      _positionSystemMenu();
+    });
+  }
+
+  @override
+  void didUpdateWidget(covariant IOSSuperTextFieldSystemContextMenu oldWidget) {
+    super.didUpdateWidget(oldWidget);
+    if (widget.controller != oldWidget.controller) {
+      oldWidget.controller.removeListener(_onControllerChanged);
+      widget.controller.addListener(_onControllerChanged);
+    }
+    onNextFrame((_) {
+      _positionSystemMenu();
+    });
+  }
+
+  @override
+  void dispose() {
+    widget.controller.removeListener(_onControllerChanged);
+    _systemContextMenuController.dispose();
+    super.dispose();
+  }
+
+  void _onControllerChanged() {
+    onNextFrame((_) {
+      _positionSystemMenu();
+    });
+  }
+
+  void _positionSystemMenu() {
+    // The size reported by the controller's toolbarFocalPoint is one frame behind. Query the information
+    // overlayController instead.
+    final topAnchor = widget.controller.overlayController.toolbarTopAnchor;
+    final bottomAnchor = widget.controller.overlayController.toolbarTopAnchor;
+
+    if (topAnchor == null || bottomAnchor == null) {
+      // We don't expect the toolbar builder to be called without having the anchors
+      // defined. But, since these properties are nullable, we account for that.
+      return;
+    }
+
+    _systemContextMenuController.show(Rect.fromLTRB(topAnchor.dx, topAnchor.dy, bottomAnchor.dx, bottomAnchor.dy));
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    assert(IOSSystemContextMenu.isSupported(context));
+    return const SizedBox.shrink();
+  }
+}