migrate to null safety

lib/screenshot.dart

@@ -16,16 +16,16 @@ import 'dart:ui' as ui;
 ///
 ///
 class ScreenshotController {
-  GlobalKey _containerKey;
+  GlobalKey? _containerKey;
   ScreenshotController() {
     _containerKey = GlobalKey();
   }
 
 /// Captures image and saves to given path
   Future<String> captureAndSave(
     String directory, {
-    String fileName,
-    double pixelRatio,
+    String? fileName,
+    double? pixelRatio,
     Duration delay: const Duration(milliseconds: 20),
   }) async {
     Uint8List content = await capture(
@@ -39,7 +39,7 @@ class ScreenshotController {
   }
 
   Future<Uint8List> capture({
-    double pixelRatio,
+    double? pixelRatio,
     Duration delay: const Duration(milliseconds: 20),
   }) {
     //Delay is required. See Issue https://github.com/flutter/flutter/issues/22308
@@ -50,7 +50,7 @@ class ScreenshotController {
           pixelRatio: pixelRatio,
         );
         ByteData byteData =
-            await image.toByteData(format: ui.ImageByteFormat.png);
+            await (image.toByteData(format: ui.ImageByteFormat.png) as FutureOr<ByteData>);
         Uint8List pngBytes = byteData.buffer.asUint8List();
 
         return pngBytes;
@@ -61,18 +61,18 @@ class ScreenshotController {
   }
 
   Future<ui.Image> captureAsUiImage(
-      {double pixelRatio: 1,
+      {double? pixelRatio: 1,
       Duration delay: const Duration(milliseconds: 20)}) {
     //Delay is required. See Issue https://github.com/flutter/flutter/issues/22308
     return new Future.delayed(delay, () async {
       try {
         RenderRepaintBoundary boundary = this
-            ._containerKey
-            .currentContext
+            ._containerKey!
+            .currentContext!
             .findRenderObject() as RenderRepaintBoundary;
         pixelRatio = pixelRatio ??
-            MediaQuery.of(_containerKey.currentContext).devicePixelRatio;
-        ui.Image image = await boundary.toImage(pixelRatio: pixelRatio);
+            MediaQuery.of(_containerKey!.currentContext!).devicePixelRatio;
+        ui.Image image = await boundary.toImage(pixelRatio: pixelRatio!);
         return image;
       } catch (Exception) {
         throw (Exception);
@@ -82,10 +82,10 @@ class ScreenshotController {
 }
 
 class Screenshot<T> extends StatefulWidget {
-  final Widget child;
-  final ScreenshotController controller;
+  final Widget? child;
+  final ScreenshotController? controller;
   const Screenshot({
-    Key key,
+    Key? key,
     this.child,
     this.controller,
   }) : super(key: key);
@@ -97,7 +97,7 @@ class Screenshot<T> extends StatefulWidget {
 }
 
 class ScreenshotState extends State<Screenshot> with TickerProviderStateMixin {
-  ScreenshotController _controller;
+  ScreenshotController? _controller;
 
   @override
   void initState() {
@@ -127,7 +127,7 @@ class ScreenshotState extends State<Screenshot> with TickerProviderStateMixin {
   @override
   Widget build(BuildContext context) {
     return RepaintBoundary(
-      key: _controller._containerKey,
+      key: _controller!._containerKey,
       child: widget.child,
     );
   }

lib/src/platform_specific/file_manager/file_manager.dart

@@ -7,5 +7,5 @@ import 'file_manager_stub.dart'
 
 abstract class PlatformFileManager {
   factory PlatformFileManager() => getFileManager();
-  Future<String> saveFile(Uint8List fileContent, String path, {String name});
+  Future<String> saveFile(Uint8List fileContent, String path, {String? name});
 }

lib/src/platform_specific/file_manager/file_manager_io.dart

@@ -8,7 +8,7 @@ PlatformFileManager getFileManager() => PlatformFilePickerWindows();
 class PlatformFilePickerWindows implements PlatformFileManager {
   @override
   Future<String> saveFile(Uint8List fileContent, String path,
-      {String name}) async {
+      {String? name}) async {
     name = name ?? "${DateTime.now().microsecondsSinceEpoch}.png";
     File file = await File("$path/$name").create(recursive: true);
     file.writeAsBytesSync(fileContent);

lib/src/platform_specific/file_manager/non_io.dart

@@ -8,7 +8,7 @@ PlatformFileManager getFileManager() => PlatformFileManagerWeb();
 class PlatformFileManagerWeb implements PlatformFileManager {
   @override
   Future<String> saveFile(Uint8List fileContent, String path,
-      {String name}) async {
+      {String? name}) async {
   throw UnsupportedError("File cannot be saved in current platform");
     // name = name ?? "${DateTime.now().microsecondsSinceEpoch}.png";
     // File file = await File("$path/$name").create(recursive: true);

pubspec.lock

@@ -7,49 +7,49 @@ packages:
       name: async
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.5.0-nullsafety.3"
+    version: "2.6.1"
   boolean_selector:
     dependency: transitive
     description:
       name: boolean_selector
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.1.0-nullsafety.3"
+    version: "2.1.0"
   characters:
     dependency: transitive
     description:
       name: characters
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.0-nullsafety.5"
+    version: "1.1.0"
   charcode:
     dependency: transitive
     description:
       name: charcode
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.2.0-nullsafety.3"
+    version: "1.2.0"
   clock:
     dependency: transitive
     description:
       name: clock
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.0-nullsafety.3"
+    version: "1.1.0"
   collection:
     dependency: transitive
     description:
       name: collection
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.15.0-nullsafety.5"
+    version: "1.15.0"
   fake_async:
     dependency: transitive
     description:
       name: fake_async
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.2.0-nullsafety.3"
+    version: "1.2.0"
   flutter:
     dependency: "direct main"
     description: flutter
@@ -66,21 +66,21 @@ packages:
       name: matcher
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.12.10-nullsafety.3"
+    version: "0.12.10"
   meta:
     dependency: transitive
     description:
       name: meta
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.3.0-nullsafety.6"
+    version: "1.3.0"
   path:
     dependency: transitive
     description:
       name: path
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.8.0-nullsafety.3"
+    version: "1.8.0"
   sky_engine:
     dependency: transitive
     description: flutter
@@ -92,55 +92,55 @@ packages:
       name: source_span
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.8.0-nullsafety.4"
+    version: "1.8.1"
   stack_trace:
     dependency: transitive
     description:
       name: stack_trace
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.10.0-nullsafety.6"
+    version: "1.10.0"
   stream_channel:
     dependency: transitive
     description:
       name: stream_channel
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.1.0-nullsafety.3"
+    version: "2.1.0"
   string_scanner:
     dependency: transitive
     description:
       name: string_scanner
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.0-nullsafety.3"
+    version: "1.1.0"
   term_glyph:
     dependency: transitive
     description:
       name: term_glyph
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.2.0-nullsafety.3"
+    version: "1.2.0"
   test_api:
     dependency: transitive
     description:
       name: test_api
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.2.19-nullsafety.6"
+    version: "0.3.0"
   typed_data:
     dependency: transitive
     description:
       name: typed_data
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.3.0-nullsafety.5"
+    version: "1.3.0"
   vector_math:
     dependency: transitive
     description:
       name: vector_math
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.1.0-nullsafety.5"
+    version: "2.1.0"
 sdks:
-  dart: ">=2.12.0-0.0 <3.0.0"
+  dart: ">=2.12.0 <3.0.0"

pubspec.yaml

@@ -4,7 +4,7 @@ version: 0.3.0
 homepage: https://github.com/SachinGanesh/screenshot
 
 environment:
-  sdk: '>=2.8.0 <3.0.0'
+  sdk: '>=2.12.0 <3.0.0'
   # sdk: '>=2.12.0-259.8.beta <3.0.0'
 
 # analyzer: