Added leadingBuilder for improved customization.

lib/flutter_quill.dart

@@ -11,6 +11,7 @@ export 'src/models/themes/quill_icon_theme.dart';
 export 'src/widgets/controller.dart';
 export 'src/widgets/default_styles.dart';
 export 'src/widgets/editor.dart';
+export 'src/widgets/leading/default_leading_builder.dart';
 export 'src/widgets/link.dart' show LinkActionPickerDelegate, LinkMenuAction;
 export 'src/widgets/style_widgets/style_widgets.dart';
 export 'src/widgets/toolbar.dart';

lib/src/widgets/delegate.dart

@@ -3,11 +3,23 @@ import 'package:flutter/gestures.dart';
 import 'package:flutter/material.dart';
 
 import '../../flutter_quill.dart';
+import '../models/documents/nodes/line.dart';
 import 'text_selection.dart';
 
 typedef EmbedBuilder = Widget Function(BuildContext context,
     QuillController controller, Embed node, bool readOnly);
 
+typedef LeadingBuilder = Widget? Function(
+    BuildContext context,
+    Line line,
+    int index,
+    Map<int, int> indentLevelCounts,
+    int count,
+    CheckboxTapCallback onCheckboxTap,
+    bool readOnly);
+
+typedef CheckboxTapCallback = void Function(int index, bool checked);
+
 typedef CustomStyleBuilder = TextStyle Function(Attribute attribute);
 
 /// Delegate interface for the [EditorTextSelectionGestureDetectorBuilder].

lib/src/widgets/editor.dart

@@ -20,6 +20,7 @@ import 'default_styles.dart';
 import 'delegate.dart';
 import 'embeds/default_embed_builder.dart';
 import 'float_cursor.dart';
+import 'leading/default_leading_builder.dart';
 import 'link.dart';
 import 'raw_editor.dart';
 import 'text_selection.dart';
@@ -168,6 +169,7 @@ class QuillEditor extends StatefulWidget {
       this.onSingleLongTapMoveUpdate,
       this.onSingleLongTapEnd,
       this.embedBuilder = defaultEmbedBuilder,
+      this.leadingBuilder = defaultLeadingBuilder,
       this.linkActionPickerDelegate = defaultLinkActionPickerDelegate,
       this.customStyleBuilder,
       this.locale,
@@ -339,6 +341,7 @@ class QuillEditor extends StatefulWidget {
       onSingleLongTapEnd;
 
   final EmbedBuilder embedBuilder;
+  final LeadingBuilder leadingBuilder;
   final CustomStyleBuilder? customStyleBuilder;
 
   /// The locale to use for the editor toolbar, defaults to system locale
@@ -453,6 +456,7 @@ class QuillEditorState extends State<QuillEditor>
       enableInteractiveSelection: widget.enableInteractiveSelection,
       scrollPhysics: widget.scrollPhysics,
       embedBuilder: widget.embedBuilder,
+      leadingBuilder: widget.leadingBuilder,
       linkActionPickerDelegate: widget.linkActionPickerDelegate,
       customStyleBuilder: widget.customStyleBuilder,
       floatingCursorDisabled: widget.floatingCursorDisabled,

lib/src/widgets/leading/default_leading_builder.dart

@@ -0,0 +1,72 @@
+import 'package:flutter/widgets.dart';
+import '../../models/documents/attribute.dart';
+import '../../models/documents/nodes/line.dart' as line;
+import '../default_styles.dart';
+import '../delegate.dart';
+import '../style_widgets/style_widgets.dart';
+
+Widget? defaultLeadingBuilder(
+    BuildContext context,
+    line.Line line,
+    int index,
+    Map<int, int> indentLevelCounts,
+    int count,
+    CheckboxTapCallback onCheckboxTap,
+    bool readOnly) {
+  final defaultStyles = QuillStyles.getStyles(context, false);
+  final attrs = line.style.attributes;
+  if (attrs[Attribute.list.key] == Attribute.ol) {
+    return QuillNumberPoint(
+      index: index,
+      indentLevelCounts: indentLevelCounts,
+      count: count,
+      style: defaultStyles!.leading!.style,
+      attrs: attrs,
+      width: 32,
+      padding: 8,
+    );
+  }
+
+  if (attrs[Attribute.list.key] == Attribute.ul) {
+    return QuillBulletPoint(
+      style:
+          defaultStyles!.leading!.style.copyWith(fontWeight: FontWeight.bold),
+      width: 32,
+    );
+  }
+
+  if (attrs[Attribute.list.key] == Attribute.checked) {
+    return CheckboxPoint(
+      size: 14,
+      value: true,
+      enabled: !readOnly,
+      onChanged: (checked) => onCheckboxTap(line.documentOffset, checked),
+      uiBuilder: defaultStyles?.lists?.checkboxUIBuilder,
+    );
+  }
+
+  if (attrs[Attribute.list.key] == Attribute.unchecked) {
+    return CheckboxPoint(
+      size: 14,
+      value: false,
+      enabled: !readOnly,
+      onChanged: (checked) => onCheckboxTap(line.documentOffset, checked),
+      uiBuilder: defaultStyles?.lists?.checkboxUIBuilder,
+    );
+  }
+
+  if (attrs.containsKey(Attribute.codeBlock.key)) {
+    return QuillNumberPoint(
+      index: index,
+      indentLevelCounts: indentLevelCounts,
+      count: count,
+      style: defaultStyles!.code!.style
+          .copyWith(color: defaultStyles.code!.style.color!.withOpacity(0.4)),
+      width: 32,
+      attrs: attrs,
+      padding: 16,
+      withDot: false,
+    );
+  }
+  return null;
+}

lib/src/widgets/raw_editor.dart

@@ -29,6 +29,7 @@ import 'editor.dart';
 import 'embeds/default_embed_builder.dart';
 import 'embeds/image.dart';
 import 'keyboard_listener.dart';
+import 'leading/default_leading_builder.dart';
 import 'link.dart';
 import 'proxy.dart';
 import 'quill_single_child_scroll_view.dart';
@@ -72,6 +73,7 @@ class RawEditor extends StatefulWidget {
       this.enableInteractiveSelection = true,
       this.scrollPhysics,
       this.embedBuilder = defaultEmbedBuilder,
+      this.leadingBuilder = defaultLeadingBuilder,
       this.linkActionPickerDelegate = defaultLinkActionPickerDelegate,
       this.customStyleBuilder,
       this.floatingCursorDisabled = false})
@@ -223,6 +225,9 @@ class RawEditor extends StatefulWidget {
 
   /// Builder function for embeddable objects.
   final EmbedBuilder embedBuilder;
+
+  /// Builder function for leading objects.
+  final LeadingBuilder leadingBuilder;
   final LinkActionPickerDelegate linkActionPickerDelegate;
   final CustomStyleBuilder? customStyleBuilder;
   final bool floatingCursorDisabled;
@@ -456,6 +461,7 @@ class RawEditorState extends EditorState
                 ? const EdgeInsets.all(16)
                 : null,
             embedBuilder: widget.embedBuilder,
+            leadingBuilder: widget.leadingBuilder,
             linkActionPicker: _linkActionPicker,
             onLaunchUrl: widget.onLaunchUrl,
             cursorCont: _cursorCont,

lib/src/widgets/text_block.dart

@@ -59,6 +59,7 @@ class EditableTextBlock extends StatelessWidget {
       required this.hasFocus,
       required this.contentPadding,
       required this.embedBuilder,
+      required this.leadingBuilder,
       required this.linkActionPicker,
       required this.cursorCont,
       required this.indentLevelCounts,
@@ -80,12 +81,13 @@ class EditableTextBlock extends StatelessWidget {
   final bool hasFocus;
   final EdgeInsets? contentPadding;
   final EmbedBuilder embedBuilder;
+  final LeadingBuilder leadingBuilder;
   final LinkActionPicker linkActionPicker;
   final ValueChanged<String>? onLaunchUrl;
   final CustomStyleBuilder? customStyleBuilder;
   final CursorCont cursorCont;
   final Map<int, int> indentLevelCounts;
-  final Function(int, bool) onCheckboxTap;
+  final CheckboxTapCallback onCheckboxTap;
   final bool readOnly;
 
   @override
@@ -126,7 +128,15 @@ class EditableTextBlock extends StatelessWidget {
       index++;
       final editableTextLine = EditableTextLine(
           line,
-          _buildLeading(context, line, index, indentLevelCounts, count),
+          leadingBuilder(
+            context,
+            line,
+            index,
+            indentLevelCounts,
+            count,
+            onCheckboxTap,
+            readOnly,
+          ),
           TextLine(
             line: line,
             textDirection: textDirection,
@@ -154,66 +164,6 @@ class EditableTextBlock extends StatelessWidget {
     return children.toList(growable: false);
   }
 
-  Widget? _buildLeading(BuildContext context, Line line, int index,
-      Map<int, int> indentLevelCounts, int count) {
-    final defaultStyles = QuillStyles.getStyles(context, false);
-    final attrs = line.style.attributes;
-    if (attrs[Attribute.list.key] == Attribute.ol) {
-      return QuillNumberPoint(
-        index: index,
-        indentLevelCounts: indentLevelCounts,
-        count: count,
-        style: defaultStyles!.leading!.style,
-        attrs: attrs,
-        width: 32,
-        padding: 8,
-      );
-    }
-
-    if (attrs[Attribute.list.key] == Attribute.ul) {
-      return QuillBulletPoint(
-        style:
-            defaultStyles!.leading!.style.copyWith(fontWeight: FontWeight.bold),
-        width: 32,
-      );
-    }
-
-    if (attrs[Attribute.list.key] == Attribute.checked) {
-      return CheckboxPoint(
-        size: 14,
-        value: true,
-        enabled: !readOnly,
-        onChanged: (checked) => onCheckboxTap(line.documentOffset, checked),
-        uiBuilder: defaultStyles?.lists?.checkboxUIBuilder,
-      );
-    }
-
-    if (attrs[Attribute.list.key] == Attribute.unchecked) {
-      return CheckboxPoint(
-        size: 14,
-        value: false,
-        enabled: !readOnly,
-        onChanged: (checked) => onCheckboxTap(line.documentOffset, checked),
-        uiBuilder: defaultStyles?.lists?.checkboxUIBuilder,
-      );
-    }
-
-    if (attrs.containsKey(Attribute.codeBlock.key)) {
-      return QuillNumberPoint(
-        index: index,
-        indentLevelCounts: indentLevelCounts,
-        count: count,
-        style: defaultStyles!.code!.style
-            .copyWith(color: defaultStyles.code!.style.color!.withOpacity(0.4)),
-        width: 32,
-        attrs: attrs,
-        padding: 16,
-        withDot: false,
-      );
-    }
-    return null;
-  }
-
   double _getIndentWidth() {
     final attrs = block.style.attributes;