feat(fleather): add iPad Scribble support

packages/fleather/example/integration_test/editing_performance_test.dart

@@ -22,12 +22,12 @@ void main() {
         await tester.tap(find.byType(RawEditor));
         controller.updateSelection(const TextSelection.collapsed(offset: 0));
         await tester.pump();
-        await tester.ime.typeText(iputText, finder: find.byType(RawEditor));
+        await tester.ime.typeText(iputText);
         await tester.pump();
         controller.updateSelection(
             TextSelection.collapsed(offset: document.length - 1));
         await tester.pump();
-        await tester.ime.typeText(iputText, finder: find.byType(RawEditor));
+        await tester.ime.typeText(iputText);
       },
       reportKey: 'timeline',
     );

packages/fleather/lib/src/rendering/editable_text_block.dart

@@ -334,7 +334,26 @@ class RenderEditableTextBlock extends RenderEditableContainerBox
 
   @override
   List<TextBox> getBoxesForSelection(TextSelection selection) {
-    throw UnimplementedError();
+    final boxes = <TextBox>[];
+    var child = firstChild;
+    while (child != null) {
+      if (intersectsWithSelection(child.node, selection, fromParent: true)) {
+        final childSelection =
+            localSelection(child.node, selection, fromParent: true);
+        final childOffset = (child.parentData as BoxParentData).offset;
+        boxes.addAll(child.getBoxesForSelection(childSelection).map((box) {
+          return TextBox.fromLTRBD(
+            box.left + childOffset.dx,
+            box.top + childOffset.dy,
+            box.right + childOffset.dx,
+            box.bottom + childOffset.dy,
+            box.direction,
+          );
+        }));
+      }
+      child = childAfter(child);
+    }
+    return boxes;
   }
 
   @override

packages/fleather/lib/src/rendering/editor.dart

@@ -670,6 +670,9 @@ class RenderEditor extends RenderEditableContainerBox
     return defaultHitTestChildren(result, position: effectivePosition);
   }
 
+  @override
+  bool hitTestSelf(Offset position) => true;
+
   void _paintHandleLayers(
       PaintingContext context, List<TextSelectionPoint> endpoints) {
     var startPoint = endpoints[0].point + paintOffset;
@@ -757,8 +760,32 @@ class RenderEditor extends RenderEditableContainerBox
     final childLocalRect = targetChild.getLocalRectForCaret(localPosition);
 
     final boxParentData = targetChild.parentData as BoxParentData;
-    return childLocalRect.shift(Offset(
-        resolvedPadding!.left, boxParentData.offset.dy + paintOffset.dy));
+    return childLocalRect.shift(boxParentData.offset + paintOffset);
+  }
+
+  /// Returns text boxes for a document selection in this editor's coordinates.
+  List<TextBox> getBoxesForSelection(TextSelection selection) {
+    final boxes = <TextBox>[];
+    var child = firstChild;
+    while (child != null) {
+      if (intersectsWithSelection(child.node, selection, fromParent: true)) {
+        final childSelection =
+            localSelection(child.node, selection, fromParent: true);
+        final childOffset =
+            (child.parentData as BoxParentData).offset + paintOffset;
+        boxes.addAll(child.getBoxesForSelection(childSelection).map((box) {
+          return TextBox.fromLTRBD(
+            box.left + childOffset.dx,
+            box.top + childOffset.dy,
+            box.right + childOffset.dx,
+            box.bottom + childOffset.dy,
+            box.direction,
+          );
+        }));
+      }
+      child = childAfter(child);
+    }
+    return boxes;
   }
 
   // Start floating cursor

packages/fleather/lib/src/widgets/editable_text_block.dart

@@ -28,6 +28,7 @@ class EditableTextBlock extends StatelessWidget {
   final LinkActionPicker linkActionPicker;
   final ValueChanged<String?>? onLaunchUrl;
   final EdgeInsets? contentPadding;
+  final FleatherScribblePlaceholder? scribblePlaceholder;
 
   const EditableTextBlock({
     super.key,
@@ -45,6 +46,7 @@ class EditableTextBlock extends StatelessWidget {
     required this.linkActionPicker,
     this.onLaunchUrl,
     this.contentPadding,
+    this.scribblePlaceholder,
   });
 
   @override
@@ -87,6 +89,7 @@ class EditableTextBlock extends StatelessWidget {
             linkActionPicker: linkActionPicker,
             onLaunchUrl: onLaunchUrl,
             textWidthBasis: textWidthBasis,
+            scribblePlaceholder: scribblePlaceholder,
           ),
           cursorController: cursorController,
           selection: selection,