feat(capitalization): add header capitalization

example/lib/main.dart

@@ -29,10 +29,11 @@ class MyApp extends StatelessWidget {
             },
             defaultStyle:
                 theme.textTheme.titleLarge!.copyWith(color: Colors.green),
+            capitalization: CategoryHeaderCapitalization.uppercase,
           ),
           content: [
             Category(
-              name: "Category 1",
+              name: "category 1",
               content: [
                 const Text("Content 1"),
                 Image.network(

lib/flutter_nested_categories.dart

@@ -5,5 +5,6 @@
 library flutter_nested_categories;
 
 export "src/category.dart";
+export "src/category_header_capitalization.dart";
 export "src/category_header_styling.dart";
 export "src/category_list.dart";

lib/src/category_header_capitalization.dart

@@ -0,0 +1,16 @@
+/// An enum that represents the capitalization of the category header.
+/// This is used to determine how the header should be displayed.
+/// The header is the name of the category.
+enum CategoryHeaderCapitalization {
+  /// The first letter of the header will be capitalized.
+  capitalizeFirstLetter,
+
+  /// The header will be displayed in all lowercase.
+  lowercase,
+
+  /// The header will be displayed in all uppercase.
+  uppercase,
+
+  /// The header will be displayed as is.
+  none,
+}

lib/src/category_header_styling.dart

@@ -1,4 +1,5 @@
 import "package:flutter/widgets.dart";
+import "package:flutter_nested_categories/src/category_header_capitalization.dart";
 
 /// This class is used to style the headers of the categories in the list.
 /// The headers are the names of the categories.
@@ -8,11 +9,16 @@ class CategoryHeaderStyling {
     /// is not found in the [headerStyles].
     required this.defaultStyle,
 
+    /// The capitalization of the headers. This is used to determine how the
+    /// headers should be displayed.
+    this.capitalization = CategoryHeaderCapitalization.none,
+
     /// The styles for the headers. The key is the depth of the category.
     /// The value is the text style for the header.
     this.headerStyles = const {},
   });
 
   final Map<int, TextStyle?> headerStyles;
+  final CategoryHeaderCapitalization capitalization;
   final TextStyle defaultStyle;
 }

lib/src/category_list.dart

@@ -193,6 +193,23 @@ class _CategoryColumnState extends State<_CategoryColumn> {
     );
   }
 
+  String? formatCategoryName() {
+    var name = widget.category.name;
+    if (name == null) return null;
+
+    switch (widget.headerStyling?.capitalization) {
+      case CategoryHeaderCapitalization.capitalizeFirstLetter:
+        return name[0].toUpperCase() + name.substring(1);
+      case CategoryHeaderCapitalization.lowercase:
+        return name.toLowerCase();
+      case CategoryHeaderCapitalization.uppercase:
+        return name.toUpperCase();
+      case CategoryHeaderCapitalization.none:
+      default:
+        return name;
+    }
+  }
+
   Widget _buildCollapsibleHeader(TextStyle styleOfCategory) => InkWell(
         onTap: () {
           setState(() {
@@ -216,7 +233,7 @@ class _CategoryColumnState extends State<_CategoryColumn> {
               widget.category.customTitle!
             else
               Text(
-                widget.category.name!,
+                formatCategoryName()!,
                 style: styleOfCategory,
               ),
           ],
@@ -229,14 +246,14 @@ class _CategoryColumnState extends State<_CategoryColumn> {
               child: widget.category.customTitle != null
                   ? widget.category.customTitle!
                   : Text(
-                      widget.category.name!,
+                      formatCategoryName()!,
                       style: styleOfCategory,
                     ),
             )
           : widget.category.customTitle != null
               ? widget.category.customTitle!
               : Text(
-                  widget.category.name!,
+                  formatCategoryName()!,
                   style: styleOfCategory,
                 );