Added TargetPlatform.supportsAccentColor helper (#26)

Author: bdlukaa

README.md

@@ -99,6 +99,22 @@ SystemThemeBuilder(builder: (context, accent) {
 });
 ```
 
+### Checking if accent color is supported
+
+The `flutter/foundation` package provides a `defaultTargetPlatform` getter, which can be used to check what platform the current app is running on.
+
+You can check if the current platform supports accent colors using this extension method:
+
+```dart
+import 'package:flutter/foundation.dart' show defaultTargetPlatform;
+
+void main() {
+  final supported = defaultTargetPlatform.supportsAccentColor;
+
+  print('Accent color is: ${supported ? 'supported' : 'not supported'} on the current platform');
+}
+```
+
 ## Contribution
 
 Feel free to [open an issue](https://github.com/bdlukaa/system_theme/issues/new) if you find an error or [make pull requests](https://github.com/bdlukaa/system_theme/pulls).

example/lib/main.dart

@@ -1,5 +1,6 @@
 import 'package:flutter/material.dart';
 import 'package:system_theme/system_theme.dart';
+import 'package:flutter/foundation.dart' show defaultTargetPlatform;
 
 void main() async {
   WidgetsFlutterBinding.ensureInitialized();
@@ -32,8 +33,10 @@ class _MyAppState extends State<MyApp> {
         accent.darkest,
       ];
       return Scaffold(
-        body: Column(
-          children: colors.map((color) {
+        body: Column(children: [
+          Text(
+              'Accent color: ${defaultTargetPlatform.supportsAccentColor ? 'supported' : 'not supported'}'),
+          ...colors.map((color) {
             return Expanded(
               child: Container(
                 color: color,
@@ -58,7 +61,7 @@ class _MyAppState extends State<MyApp> {
               ),
             );
           }).toList(),
-        ),
+        ]),
       );
     });
   }

lib/system_theme.dart

@@ -1,7 +1,8 @@
 import 'dart:async';
 import 'dart:io';
 
-import 'package:flutter/foundation.dart' show debugPrint, kIsWeb;
+import 'package:flutter/foundation.dart'
+    show TargetPlatform, debugPrint, kIsWeb;
 import 'package:flutter/services.dart'
     show Color, EventChannel, MethodChannel, MissingPluginException;
 import 'package:flutter/widgets.dart' show WidgetsFlutterBinding;
@@ -19,6 +20,19 @@ const _eventChannel = EventChannel('system_theme_events/switch_callback');
 /// Platform channel handler for invoking native methods.
 const MethodChannel _channel = MethodChannel('system_theme');
 
+extension PlatformHelpers on TargetPlatform {
+  /// A helper that can be used to check if the current platform supports
+  /// accent colors.
+  bool get supportsAccentColor =>
+      kIsWeb ||
+      [
+        TargetPlatform.windows,
+        TargetPlatform.macOS,
+        TargetPlatform.android,
+        TargetPlatform.linux,
+      ].contains(this);
+}
+
 /// Class to return current system theme state on Windows.
 ///
 /// [accentColor] returns the current accent color as a [SystemAccentColor].