Add Plugin platform interface

lib/src/gal.dart

@@ -1,6 +1,6 @@
 import 'package:flutter/foundation.dart';
 import 'package:gal/src/gal_exception.dart';
-import 'package:gal/src/gal_platform.dart';
+import 'package:gal/src/gal_platform_interface.dart';
 
 /// Main class of gal.
 ///
@@ -20,7 +20,7 @@ final class Gal {
   /// if an error occurs during saving.
   /// See: [Formats](https://github.com/natsuk4ze/gal/wiki/Formats)
   static Future<void> putVideo(String path, {String? album}) async =>
-      GalPlatform.putVideo(path, album: album);
+      GalPlatform.instance.putVideo(path, album: album);
 
   /// Save a image to the gallery from file [path].
   ///
@@ -33,7 +33,7 @@ final class Gal {
   /// if an error occurs during saving.
   /// See: [Formats](https://github.com/natsuk4ze/gal/wiki/Formats)
   static Future<void> putImage(String path, {String? album}) async =>
-      GalPlatform.putImage(path, album: album);
+      GalPlatform.instance.putImage(path, album: album);
 
   /// Save a image to the gallery from [Uint8List].
   ///
@@ -42,20 +42,20 @@ final class Gal {
   /// if an error occurs during saving.
   /// See: [Formats](https://github.com/natsuk4ze/gal/wiki/Formats)
   static Future<void> putImageBytes(Uint8List bytes, {String? album}) async =>
-      GalPlatform.putImageBytes(bytes, album: album);
+      GalPlatform.instance.putImageBytes(bytes, album: album);
 
   /// Open gallery app.
   ///
   /// If there are multiple gallery apps, App selection sheet may be displayed.
-  static Future<void> open() async => GalPlatform.open();
+  static Future<void> open() async => GalPlatform.instance.open();
 
   /// Check if the app has access permissions.
   ///
   /// Use the [toAlbum] for additional permissions to save to an album.
   /// If you want to save to an album other than the one created by your app
   /// See: [Permissions](https://github.com/natsuk4ze/gal/wiki/Permissions)
   static Future<bool> hasAccess({bool toAlbum = false}) async =>
-      GalPlatform.hasAccess(toAlbum: toAlbum);
+      GalPlatform.instance.hasAccess(toAlbum: toAlbum);
 
   /// Request access permissions.
   ///
@@ -65,5 +65,5 @@ final class Gal {
   /// If you want to save to an album other than the one created by your app
   /// See: [Permissions](https://github.com/natsuk4ze/gal/wiki/Permissions)
   static Future<bool> requestAccess({bool toAlbum = false}) async =>
-      GalPlatform.requestAccess(toAlbum: toAlbum);
+      GalPlatform.instance.requestAccess(toAlbum: toAlbum);
 }

lib/src/gal_platform.dart → lib/src/gal_method_channel.dart

@@ -1,49 +1,57 @@
 import 'package:flutter/foundation.dart';
 import 'package:flutter/services.dart';
-import 'package:gal/gal.dart';
+import 'package:gal/src/gal_exception.dart';
 
-const _channel = MethodChannel('gal');
+import 'gal_platform_interface.dart';
 
 /// Plugin Communication
 @immutable
-final class GalPlatform {
-  const GalPlatform._();
+final class MethodChannelGal extends GalPlatform {
+  final _methodChannel = const MethodChannel('gal');
 
-  static Future<T?> _invokeMethod<T>(
-      String method, Map<String, dynamic> args) async {
+  Future<T?> _invokeMethod<T>(String method, Map<String, dynamic> args) async {
     try {
-      return await _channel.invokeMethod<T>(method, args);
+      return await _methodChannel.invokeMethod<T>(method, args);
     } on PlatformException catch (error, stackTrace) {
       throw GalException.fromCode(
-          code: error.code, platformException: error, stackTrace: stackTrace);
+        code: error.code,
+        platformException: error,
+        stackTrace: stackTrace,
+      );
     }
   }
 
-  static Future<void> putVideo(String path, {String? album}) async {
+  @override
+  Future<void> putVideo(String path, {String? album}) async {
     await requestAccess(toAlbum: album != null);
     await _invokeMethod<void>('putVideo', {'path': path, 'album': album});
   }
 
-  static Future<void> putImage(String path, {String? album}) async {
+  @override
+  Future<void> putImage(String path, {String? album}) async {
     await requestAccess(toAlbum: album != null);
     await _invokeMethod<void>('putImage', {'path': path, 'album': album});
   }
 
-  static Future<void> putImageBytes(Uint8List bytes, {String? album}) async {
+  @override
+  Future<void> putImageBytes(Uint8List bytes, {String? album}) async {
     await requestAccess(toAlbum: album != null);
     await _invokeMethod<void>(
         'putImageBytes', {'bytes': bytes, 'album': album});
   }
 
-  static Future<void> open() async => _invokeMethod<void>('open', {});
+  @override
+  Future<void> open() async => _invokeMethod<void>('open', {});
 
-  static Future<bool> hasAccess({bool toAlbum = false}) async {
+  @override
+  Future<bool> hasAccess({bool toAlbum = false}) async {
     final hasAccess =
         await _invokeMethod<bool>('hasAccess', {'toAlbum': toAlbum});
     return hasAccess ?? false;
   }
 
-  static Future<bool> requestAccess({bool toAlbum = false}) async {
+  @override
+  Future<bool> requestAccess({bool toAlbum = false}) async {
     final granted =
         await _invokeMethod<bool>('requestAccess', {'toAlbum': toAlbum});
     return granted ?? false;

lib/src/gal_platform_interface.dart

@@ -0,0 +1,39 @@
+import 'dart:typed_data';
+
+import 'gal_method_channel.dart';
+
+/// Plugin Platform Interface
+base class GalPlatform {
+  const GalPlatform();
+  static GalPlatform instance = MethodChannelGal();
+
+  /// throw [UnimplementedError] when Plugin [MethodChannelGal] did not
+  /// define [putVideo].
+  Future<void> putVideo(String path, {String? album}) =>
+      throw UnimplementedError('putVideo() has not been implemented.');
+
+  /// throw [UnimplementedError] when Plugin [MethodChannelGal] did not
+  /// define [putImage].
+  Future<void> putImage(String path, {String? album}) =>
+      throw UnimplementedError('putImage() has not been implemented.');
+
+  /// throw [UnimplementedError] when Plugin [MethodChannelGal] did not
+  /// define [putImageBytes].
+  Future<void> putImageBytes(Uint8List bytes, {String? album}) =>
+      throw UnimplementedError('putImageBytes() has not been implemented.');
+
+  /// throw [UnimplementedError] when Plugin [MethodChannelGal] did not
+  /// define [open].
+  Future<void> open() =>
+      throw UnimplementedError('open() has not been implemented.');
+
+  /// throw [UnimplementedError] when Plugin [MethodChannelGal] did not
+  /// define [hasAccess].
+  Future<bool> hasAccess({bool toAlbum = false}) =>
+      throw UnimplementedError('hasAccess() has not been implemented.');
+
+  /// throw [UnimplementedError] when Plugin [MethodChannelGal] did not
+  /// define [requestAccess].
+  Future<bool> requestAccess({bool toAlbum = false}) =>
+      throw UnimplementedError('requestAccess() has not been implemented.');
+}