update dependencies, refactor code for newer dart version

example/android/app/src/main/AndroidManifest.xml

@@ -13,7 +13,7 @@
          additional functionality it is fine to subclass or reimplement
          FlutterApplication and put your custom class here. -->
     <application
-        android:name="io.flutter.app.FlutterApplication"
+        android:name="${applicationName}"
         android:label="photofilters_example"
         android:icon="@mipmap/ic_launcher">
         <activity
@@ -23,13 +23,9 @@
             android:configChanges="orientation|keyboardHidden|keyboard|screenSize|locale|layoutDirection|fontScale|screenLayout|density"
             android:hardwareAccelerated="true"
             android:windowSoftInputMode="adjustResize">
-            <!-- This keeps the window background of the activity showing
-                 until Flutter renders its first frame. It can be removed if
-                 there is no splash screen (such as the default splash screen
-                 defined in @style/LaunchTheme). -->
             <meta-data
-                android:name="io.flutter.app.android.SplashScreenUntilFirstFrame"
-                android:value="true" />
+                android:name="flutterEmbedding"
+                android:value="2" />
             <intent-filter>
                 <action android:name="android.intent.action.MAIN"/>
                 <category android:name="android.intent.category.LAUNCHER"/>

example/android/app/src/main/java/com/skkallayath/photofiltersexample/MainActivity.java

@@ -1,13 +1,6 @@
 package com.skkallayath.photofiltersexample;
 
-import android.os.Bundle;
-import io.flutter.app.FlutterActivity;
-import io.flutter.plugins.GeneratedPluginRegistrant;
+import io.flutter.embedding.android.FlutterActivity;
 
 public class MainActivity extends FlutterActivity {
-  @Override
-  protected void onCreate(Bundle savedInstanceState) {
-    super.onCreate(savedInstanceState);
-    GeneratedPluginRegistrant.registerWith(this);
-  }
 }

example/lib/main.dart

@@ -7,68 +7,69 @@ import 'package:photofilters/photofilters.dart';
 import 'package:image/image.dart' as imageLib;
 import 'package:image_picker/image_picker.dart';
 
-void main() => runApp(new MaterialApp(home: MyApp()));
+void main() => runApp(const MaterialApp(home: MyApp()));
 
 class MyApp extends StatefulWidget {
+  const MyApp({super.key});
+
   @override
-  _MyAppState createState() => new _MyAppState();
+  _MyAppState createState() => _MyAppState();
 }
 
 class _MyAppState extends State<MyApp> {
-  String fileName;
   List<Filter> filters = presetFiltersList;
   final picker = ImagePicker();
-  File imageFile;
+  File? imageFile;
 
   Future getImage(context) async {
-    final pickedFile = await picker.getImage(source: ImageSource.gallery);
+    final pickedFile = await picker.pickImage(source: ImageSource.gallery);
     if(pickedFile!=null){
-    imageFile = new File(pickedFile.path);
-    fileName = basename(imageFile.path);
-    var image = imageLib.decodeImage(await imageFile.readAsBytes());
-    image = imageLib.copyResize(image, width: 600);
-    Map imagefile = await Navigator.push(
-      context,
-      new MaterialPageRoute(
-        builder: (context) => new PhotoFilterSelector(
-          title: Text("Photo Filter Example"),
-          image: image,
-          filters: presetFiltersList,
-          filename: fileName,
-          loader: Center(child: CircularProgressIndicator()),
-          fit: BoxFit.contain,
+      final File imageFile = File(pickedFile.path);
+      final String fileName = basename(imageFile.path);
+      var image = imageLib.decodeImage(await imageFile.readAsBytes())!;
+      image = imageLib.copyResize(image, width: 600);
+      Map imagefile = await Navigator.push(
+        context,
+        MaterialPageRoute(
+          builder: (context) => PhotoFilterSelector(
+            title: Text("Photo Filter Example"),
+            image: image,
+            filters: presetFiltersList,
+            filename: fileName,
+            loader: Center(child: CircularProgressIndicator()),
+            fit: BoxFit.contain,
+          ),
         ),
-      ),
-    );
-
-    if (imagefile != null && imagefile.containsKey('image_filtered')) {
-      setState(() {
-        imageFile = imagefile['image_filtered'];
-      });
-      print(imageFile.path);
-    }
+      );
+
+      if (imagefile.containsKey('image_filtered')) {
+        setState(() {
+          this.imageFile = imagefile['image_filtered'];
+        });
+        print(imageFile.path);
+      }
     }
   }
 
   @override
   Widget build(BuildContext context) {
-    return new Scaffold(
-      appBar: new AppBar(
-        title: new Text('Photo Filter Example'),
+    return Scaffold(
+      appBar: AppBar(
+        title: Text('Photo Filter Example'),
       ),
       body: Center(
-        child: new Container(
+        child: Container(
           child: imageFile == null
               ? Center(
-                  child: new Text('No image selected.'),
+                  child: Text('No image selected.'),
                 )
-              : Image.file(new File(imageFile.path)),
+              : Image.file(File(imageFile!.path)),
         ),
       ),
-      floatingActionButton: new FloatingActionButton(
+      floatingActionButton: FloatingActionButton(
         onPressed: () => getImage(context),
         tooltip: 'Pick Image',
-        child: new Icon(Icons.add_a_photo),
+        child: Icon(Icons.add_a_photo),
       ),
     );
   }

example/pubspec.yaml

@@ -10,7 +10,7 @@ description: Demonstrates how to use the photofilters plugin.
 version: 1.0.0+1
 
 environment:
-  sdk: ">=2.0.0-dev.68.0 <3.0.0"
+  sdk: ">=2.18.0 <3.0.0"
 
 dependencies:
   flutter:

example/test/widget_test.dart

@@ -13,13 +13,13 @@ import '../lib/main.dart';
 void main() {
   testWidgets('Verify Platform version', (WidgetTester tester) async {
     // Build our app and trigger a frame.
-    await tester.pumpWidget(new MyApp());
+    await tester.pumpWidget(MyApp());
 
     // Verify that platform version is retrieved.
     expect(
         find.byWidgetPredicate(
           (Widget widget) =>
-              widget is Text && widget.data.startsWith('Running on:'),
+              widget is Text && (widget.data?.startsWith('Running on:') ?? false),
         ),
         findsOneWidget);
   });

lib/filters/convolution_filters.dart

@@ -2,37 +2,37 @@ import 'package:photofilters/filters/image_filters.dart';
 import 'package:photofilters/filters/subfilters.dart';
 import 'package:photofilters/utils/convolution_kernels.dart';
 
-var presetConvolutionFiltersList = [
-  new ImageFilter(name: "Identity")
+final presetConvolutionFiltersList = [
+  ImageFilter(name: "Identity")
     ..addSubFilter(ConvolutionSubFilter.fromKernel(identityKernel)),
-  new ImageFilter(name: "Sharpen")
+  ImageFilter(name: "Sharpen")
     ..addSubFilter(ConvolutionSubFilter.fromKernel(sharpenKernel)),
-  new ImageFilter(name: "Emboss")
+  ImageFilter(name: "Emboss")
     ..addSubFilter(ConvolutionSubFilter.fromKernel(embossKernel)),
-  new ImageFilter(name: "Colored Edge Detection")
+  ImageFilter(name: "Colored Edge Detection")
     ..subFilters
         .add(ConvolutionSubFilter.fromKernel(coloredEdgeDetectionKernel)),
-  new ImageFilter(name: "Edge Detection Medium")
+  ImageFilter(name: "Edge Detection Medium")
     ..subFilters
         .add(ConvolutionSubFilter.fromKernel(edgeDetectionMediumKernel)),
-  new ImageFilter(name: "Edge Detection Hard")
+  ImageFilter(name: "Edge Detection Hard")
     ..addSubFilter(ConvolutionSubFilter.fromKernel(edgeDetectionHardKernel)),
-  new ImageFilter(name: "Blur")
+  ImageFilter(name: "Blur")
     ..addSubFilter(ConvolutionSubFilter.fromKernel(blurKernel)),
-  new ImageFilter(name: "Guassian 3x3")
+  ImageFilter(name: "Guassian 3x3")
     ..addSubFilter(ConvolutionSubFilter.fromKernel(guassian3x3Kernel)),
-  new ImageFilter(name: "Guassian 5x5")
+  ImageFilter(name: "Guassian 5x5")
     ..addSubFilter(ConvolutionSubFilter.fromKernel(guassian5x5Kernel)),
-  new ImageFilter(name: "Guassian 7x7")
+  ImageFilter(name: "Guassian 7x7")
     ..addSubFilter(ConvolutionSubFilter.fromKernel(guassian7x7Kernel)),
-  new ImageFilter(name: "Mean 3x3")
+  ImageFilter(name: "Mean 3x3")
     ..addSubFilter(ConvolutionSubFilter.fromKernel(mean3x3Kernel)),
-  new ImageFilter(name: "Mean 5x5")
+  ImageFilter(name: "Mean 5x5")
     ..addSubFilter(ConvolutionSubFilter.fromKernel(mean5x5Kernel)),
-  new ImageFilter(name: "Low Pass 3x3")
+  ImageFilter(name: "Low Pass 3x3")
     ..addSubFilter(ConvolutionSubFilter.fromKernel(lowPass3x3Kernel)),
-  new ImageFilter(name: "Low Pass 5x5")
+  ImageFilter(name: "Low Pass 5x5")
     ..addSubFilter(ConvolutionSubFilter.fromKernel(lowPass5x5Kernel)),
-  new ImageFilter(name: "High Pass 3x3")
+  ImageFilter(name: "High Pass 3x3")
     ..addSubFilter(ConvolutionSubFilter.fromKernel(highPass3x3Kernel)),
 ];

lib/filters/filters.dart

@@ -3,7 +3,7 @@ import 'dart:typed_data';
 ///The [Filter] class to define a Filter consists of multiple [SubFilter]s
 abstract class Filter extends Object {
   final String name;
-  Filter({required this.name});
+  const Filter({required this.name});
 
   ///Apply the [SubFilter] to an Image.
   void apply(Uint8List pixels, int width, int height);

lib/filters/image_filters.dart

@@ -9,7 +9,7 @@ mixin ImageSubFilter on SubFilter {
 }
 
 class ImageFilter extends Filter {
-  List<ImageSubFilter> subFilters;
+  final List<ImageSubFilter> subFilters;
 
   ImageFilter({required String name})
       : subFilters = [],