[flutter_markdown] Ensure customize nested bullet list style.

packages/flutter_markdown/example/lib/demos/custom_bullet_list_demo.dart

@@ -0,0 +1,84 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// TODO(goderbauer): Restructure the examples to avoid this ignore, https://github.com/flutter/flutter/issues/110208.
+// ignore_for_file: avoid_implementing_value_types
+
+import 'package:flutter/material.dart';
+import 'package:flutter_markdown/flutter_markdown.dart';
+import '../shared/markdown_demo_widget.dart';
+
+// ignore_for_file: public_member_api_docs
+
+const String _markdownData = '''
+# Custom Ordered List Demo
+
+## Unordered List
+
+- first
+- second
+   - first
+      - first
+      - second
+   - first
+      - second
+
+## Ordered List
+
+1. first
+2. second
+   1. first
+      1. first
+      2. second
+   1. first
+      1. second
+''';
+
+const String _notes = '''
+# Custom Bullet List Demo
+---
+
+## Overview
+
+This is the custom bullet list demo. This demo shows how to customize the bullet list style.
+This demo example is being preserved for reference purposes.
+''';
+
+class CustomBulletListDemo extends StatelessWidget
+    implements MarkdownDemoWidget {
+  const CustomBulletListDemo({super.key});
+
+  static const String _title = 'Custom Bullet List Demo';
+
+  @override
+  String get title => CustomBulletListDemo._title;
+
+  @override
+  String get description => 'Shows how to customize the bullet list style.';
+
+  @override
+  Future<String> get data => Future<String>.value(_markdownData);
+
+  @override
+  Future<String> get notes => Future<String>.value(_notes);
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      body: SafeArea(
+        child: Markdown(
+          data: _markdownData,
+          bulletBuilder: (int index, BulletStyle style, int nestLevel) =>
+              FittedBox(
+            fit: BoxFit.scaleDown,
+            child: switch (style) {
+              BulletStyle.unorderedList => const Text('・'),
+              BulletStyle.orderedList => Text('$nestLevel-${index + 1}.'),
+            },
+          ),
+        ),
+      ),
+    );
+  }
+}

packages/flutter_markdown/example/lib/screens/home_screen.dart

@@ -5,6 +5,7 @@
 import 'package:flutter/material.dart';
 import '../demos/basic_markdown_demo.dart';
 import '../demos/centered_header_demo.dart';
+import '../demos/custom_bullet_list_demo.dart';
 import '../demos/extended_emoji_demo.dart';
 import '../demos/markdown_body_shrink_wrap_demo.dart';
 import '../demos/minimal_markdown_demo.dart';
@@ -30,6 +31,7 @@ class HomeScreen extends StatelessWidget {
     OriginalMarkdownDemo(),
     const CenteredHeaderDemo(),
     const MarkdownBodyShrinkWrapDemo(),
+    const CustomBulletListDemo(),
   ];
 
   @override

packages/flutter_markdown/lib/src/builder.dart

@@ -611,8 +611,11 @@ class MarkdownBuilder implements md.NodeVisitor {
     if (bulletBuilder != null) {
       return Padding(
         padding: styleSheet.listBulletPadding!,
-        child: bulletBuilder!(index,
-            isUnordered ? BulletStyle.unorderedList : BulletStyle.orderedList),
+        child: bulletBuilder!(
+          index,
+          isUnordered ? BulletStyle.unorderedList : BulletStyle.orderedList,
+          _listIndents.length - 1,
+        ),
       );
     }
 

packages/flutter_markdown/lib/src/widget.dart

@@ -46,7 +46,11 @@ typedef MarkdownCheckboxBuilder = Widget Function(bool value);
 /// Signature for custom bullet widget.
 ///
 /// Used by [MarkdownWidget.bulletBuilder]
-typedef MarkdownBulletBuilder = Widget Function(int index, BulletStyle style);
+typedef MarkdownBulletBuilder = Widget Function(
+  int index,
+  BulletStyle style,
+  int nestLevel,
+);
 
 /// Enumeration sent to the user when calling [MarkdownBulletBuilder]
 ///

packages/flutter_markdown/test/list_test.dart

@@ -94,6 +94,35 @@ void defineTests() {
         ]);
       },
     );
+
+    testWidgets('custom bullet builder', (WidgetTester tester) async {
+      const String data =
+          '* Item 1\n   * Item 2\n      * Item 3\n   * Item 4\n* Item 5';
+      Widget builder(int index, BulletStyle style, int nestLevel) => Text(
+            '$index ${style == BulletStyle.orderedList ? 'ordered' : 'unordered'} $nestLevel',
+          );
+
+      await tester.pumpWidget(
+        boilerplate(
+          Markdown(data: data, bulletBuilder: builder),
+        ),
+      );
+
+      final Iterable<Widget> widgets = tester.allWidgets;
+
+      expectTextStrings(widgets, <String>[
+        '0 unordered 0',
+        'Item 1',
+        '0 unordered 1',
+        'Item 2',
+        '0 unordered 2',
+        'Item 3',
+        '1 unordered 1',
+        'Item 4',
+        '1 unordered 0',
+        'Item 5',
+      ]);
+    });
   });
 
   group('Ordered List', () {
@@ -135,6 +164,35 @@ void defineTests() {
       final Iterable<Widget> widgets = tester.allWidgets;
       expectTextStrings(widgets, <String>['1.', 'one', 'two']);
     });
+
+    testWidgets('custom bullet builder', (WidgetTester tester) async {
+      const String data =
+          '1. Item 1\n   1. Item 2\n      1. Item 3\n   1. Item 4\n1. Item 5';
+      Widget builder(int index, BulletStyle style, int nestLevel) => Text(
+            '$index ${style == BulletStyle.orderedList ? 'ordered' : 'unordered'} $nestLevel',
+          );
+
+      await tester.pumpWidget(
+        boilerplate(
+          Markdown(data: data, bulletBuilder: builder),
+        ),
+      );
+
+      final Iterable<Widget> widgets = tester.allWidgets;
+
+      expectTextStrings(widgets, <String>[
+        '0 ordered 0',
+        'Item 1',
+        '0 ordered 1',
+        'Item 2',
+        '0 ordered 2',
+        'Item 3',
+        '1 ordered 1',
+        'Item 4',
+        '1 ordered 0',
+        'Item 5',
+      ]);
+    });
   });
 
   group('Task List', () {
@@ -161,7 +219,7 @@ void defineTests() {
 
     testWidgets('custom bullet builder', (WidgetTester tester) async {
       const String data = '* Item 1\n* Item 2\n1) Item 3\n2) Item 4';
-      Widget builder(int index, BulletStyle style) => Text(
+      Widget builder(int index, BulletStyle style, _) => Text(
           '$index ${style == BulletStyle.orderedList ? 'ordered' : 'unordered'}');
 
       await tester.pumpWidget(