diff --git a/.gitignore b/.gitignore
index 1947834..ea93a4f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -9,3 +9,5 @@ ios/.generated/
 ios/Flutter/Generated.xcconfig
 ios/Runner/GeneratedPluginRegistrant.*
 *.log
+.idea
+*.iml
diff --git a/.idea/codeStyles/Project.xml b/.idea/codeStyles/Project.xml
deleted file mode 100644
index 30aa626..0000000
--- a/.idea/codeStyles/Project.xml
+++ /dev/null
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diff --git a/.idea/libraries/Dart_Packages.xml b/.idea/libraries/Dart_Packages.xml
deleted file mode 100644
index 6cd3499..0000000
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\ No newline at end of file
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7c70a41..e81f901 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,6 @@
+## [1.0.0]
+    * Migrate to null-safety
+
 ## [0.0.3]
     * Fix bugs
     * Support loop mode for layout: PageIndicatorLayout.COLOR & PageIndicatorLayout.COLOR.
diff --git a/example/android/app/src/debug/AndroidManifest.xml b/example/android/app/src/debug/AndroidManifest.xml
new file mode 100644
index 0000000..c208884
--- /dev/null
+++ b/example/android/app/src/debug/AndroidManifest.xml
@@ -0,0 +1,7 @@
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="com.example.example">
+    <!-- Flutter needs it to communicate with the running application
+         to allow setting breakpoints, to provide hot reload, etc.
+    -->
+    <uses-permission android:name="android.permission.INTERNET"/>
+</manifest>
diff --git a/example/android/app/src/main/kotlin/com/example/example/MainActivity.kt b/example/android/app/src/main/kotlin/com/example/example/MainActivity.kt
new file mode 100644
index 0000000..e793a00
--- /dev/null
+++ b/example/android/app/src/main/kotlin/com/example/example/MainActivity.kt
@@ -0,0 +1,6 @@
+package com.example.example
+
+import io.flutter.embedding.android.FlutterActivity
+
+class MainActivity: FlutterActivity() {
+}
diff --git a/example/android/app/src/main/res/drawable-v21/launch_background.xml b/example/android/app/src/main/res/drawable-v21/launch_background.xml
new file mode 100644
index 0000000..f74085f
--- /dev/null
+++ b/example/android/app/src/main/res/drawable-v21/launch_background.xml
@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Modify this file to customize your launch splash screen -->
+<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
+    <item android:drawable="?android:colorBackground" />
+
+    <!-- You can insert your own image assets here -->
+    <!-- <item>
+        <bitmap
+            android:gravity="center"
+            android:src="@mipmap/launch_image" />
+    </item> -->
+</layer-list>
diff --git a/example/android/app/src/main/res/values-night/styles.xml b/example/android/app/src/main/res/values-night/styles.xml
new file mode 100644
index 0000000..449a9f9
--- /dev/null
+++ b/example/android/app/src/main/res/values-night/styles.xml
@@ -0,0 +1,18 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <!-- Theme applied to the Android Window while the process is starting when the OS's Dark Mode setting is on -->
+    <style name="LaunchTheme" parent="@android:style/Theme.Black.NoTitleBar">
+        <!-- Show a splash screen on the activity. Automatically removed when
+             Flutter draws its first frame -->
+        <item name="android:windowBackground">@drawable/launch_background</item>
+    </style>
+    <!-- Theme applied to the Android Window as soon as the process has started.
+         This theme determines the color of the Android Window while your
+         Flutter UI initializes, as well as behind your Flutter UI while its
+         running.
+         
+         This Theme is only used starting with V2 of Flutter's Android embedding. -->
+    <style name="NormalTheme" parent="@android:style/Theme.Black.NoTitleBar">
+        <item name="android:windowBackground">?android:colorBackground</item>
+    </style>
+</resources>
diff --git a/example/android/app/src/profile/AndroidManifest.xml b/example/android/app/src/profile/AndroidManifest.xml
new file mode 100644
index 0000000..c208884
--- /dev/null
+++ b/example/android/app/src/profile/AndroidManifest.xml
@@ -0,0 +1,7 @@
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="com.example.example">
+    <!-- Flutter needs it to communicate with the running application
+         to allow setting breakpoints, to provide hot reload, etc.
+    -->
+    <uses-permission android:name="android.permission.INTERNET"/>
+</manifest>
diff --git a/example/ios/Flutter/flutter_export_environment.sh b/example/ios/Flutter/flutter_export_environment.sh
new file mode 100755
index 0000000..c640307
--- /dev/null
+++ b/example/ios/Flutter/flutter_export_environment.sh
@@ -0,0 +1,14 @@
+#!/bin/sh
+# This is a generated file; do not edit or check into version control.
+export "FLUTTER_ROOT=/Users/p0z00vu/Programs/flutter"
+export "FLUTTER_APPLICATION_PATH=/Users/p0z00vu/Projects/flutter/flutter_page_indicator/example"
+export "FLUTTER_TARGET=/Users/p0z00vu/Projects/flutter/flutter_page_indicator/example/lib/main.dart"
+export "FLUTTER_BUILD_DIR=build"
+export "SYMROOT=${SOURCE_ROOT}/../build/ios"
+export "FLUTTER_BUILD_NAME=1.0.0"
+export "FLUTTER_BUILD_NUMBER=1"
+export "DART_DEFINES=flutter.inspector.structuredErrors%3Dtrue"
+export "DART_OBFUSCATION=false"
+export "TRACK_WIDGET_CREATION=true"
+export "TREE_SHAKE_ICONS=false"
+export "PACKAGE_CONFIG=/Users/p0z00vu/Projects/flutter/flutter_page_indicator/example/.dart_tool/package_config.json"
diff --git a/example/ios/Runner.xcodeproj/project.pbxproj b/example/ios/Runner.xcodeproj/project.pbxproj
index bdbe25e..629f42e 100644
--- a/example/ios/Runner.xcodeproj/project.pbxproj
+++ b/example/ios/Runner.xcodeproj/project.pbxproj
@@ -8,12 +8,7 @@
 
 /* Begin PBXBuildFile section */
 		1498D2341E8E89220040F4C2 /* GeneratedPluginRegistrant.m in Sources */ = {isa = PBXBuildFile; fileRef = 1498D2331E8E89220040F4C2 /* GeneratedPluginRegistrant.m */; };
-		2D5378261FAA1A9400D5DBA9 /* flutter_assets in Resources */ = {isa = PBXBuildFile; fileRef = 2D5378251FAA1A9400D5DBA9 /* flutter_assets */; };
 		3B3967161E833CAA004F5970 /* AppFrameworkInfo.plist in Resources */ = {isa = PBXBuildFile; fileRef = 3B3967151E833CAA004F5970 /* AppFrameworkInfo.plist */; };
-		3B80C3941E831B6300D905FE /* App.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 3B80C3931E831B6300D905FE /* App.framework */; };
-		3B80C3951E831B6300D905FE /* App.framework in Embed Frameworks */ = {isa = PBXBuildFile; fileRef = 3B80C3931E831B6300D905FE /* App.framework */; settings = {ATTRIBUTES = (CodeSignOnCopy, RemoveHeadersOnCopy, ); }; };
-		9705A1C61CF904A100538489 /* Flutter.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 9740EEBA1CF902C7004384FC /* Flutter.framework */; };
-		9705A1C71CF904A300538489 /* Flutter.framework in Embed Frameworks */ = {isa = PBXBuildFile; fileRef = 9740EEBA1CF902C7004384FC /* Flutter.framework */; settings = {ATTRIBUTES = (CodeSignOnCopy, RemoveHeadersOnCopy, ); }; };
 		9740EEB41CF90195004384FC /* Debug.xcconfig in Resources */ = {isa = PBXBuildFile; fileRef = 9740EEB21CF90195004384FC /* Debug.xcconfig */; };
 		978B8F6F1D3862AE00F588F7 /* AppDelegate.m in Sources */ = {isa = PBXBuildFile; fileRef = 7AFFD8EE1D35381100E5BB4D /* AppDelegate.m */; };
 		97C146F31CF9000F007C117D /* main.m in Sources */ = {isa = PBXBuildFile; fileRef = 97C146F21CF9000F007C117D /* main.m */; };
@@ -29,8 +24,6 @@
 			dstPath = "";
 			dstSubfolderSpec = 10;
 			files = (
-				3B80C3951E831B6300D905FE /* App.framework in Embed Frameworks */,
-				9705A1C71CF904A300538489 /* Flutter.framework in Embed Frameworks */,
 			);
 			name = "Embed Frameworks";
 			runOnlyForDeploymentPostprocessing = 0;
@@ -40,15 +33,12 @@
 /* Begin PBXFileReference section */
 		1498D2321E8E86230040F4C2 /* GeneratedPluginRegistrant.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = GeneratedPluginRegistrant.h; sourceTree = "<group>"; };
 		1498D2331E8E89220040F4C2 /* GeneratedPluginRegistrant.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = GeneratedPluginRegistrant.m; sourceTree = "<group>"; };
-		2D5378251FAA1A9400D5DBA9 /* flutter_assets */ = {isa = PBXFileReference; lastKnownFileType = folder; name = flutter_assets; path = Flutter/flutter_assets; sourceTree = SOURCE_ROOT; };
 		3B3967151E833CAA004F5970 /* AppFrameworkInfo.plist */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.plist.xml; name = AppFrameworkInfo.plist; path = Flutter/AppFrameworkInfo.plist; sourceTree = "<group>"; };
-		3B80C3931E831B6300D905FE /* App.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = App.framework; path = Flutter/App.framework; sourceTree = "<group>"; };
 		7AFA3C8E1D35360C0083082E /* Release.xcconfig */ = {isa = PBXFileReference; lastKnownFileType = text.xcconfig; name = Release.xcconfig; path = Flutter/Release.xcconfig; sourceTree = "<group>"; };
 		7AFFD8ED1D35381100E5BB4D /* AppDelegate.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = AppDelegate.h; sourceTree = "<group>"; };
 		7AFFD8EE1D35381100E5BB4D /* AppDelegate.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = AppDelegate.m; sourceTree = "<group>"; };
 		9740EEB21CF90195004384FC /* Debug.xcconfig */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.xcconfig; name = Debug.xcconfig; path = Flutter/Debug.xcconfig; sourceTree = "<group>"; };
 		9740EEB31CF90195004384FC /* Generated.xcconfig */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.xcconfig; name = Generated.xcconfig; path = Flutter/Generated.xcconfig; sourceTree = "<group>"; };
-		9740EEBA1CF902C7004384FC /* Flutter.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = Flutter.framework; path = Flutter/Flutter.framework; sourceTree = "<group>"; };
 		97C146EE1CF9000F007C117D /* Runner.app */ = {isa = PBXFileReference; explicitFileType = wrapper.application; includeInIndex = 0; path = Runner.app; sourceTree = BUILT_PRODUCTS_DIR; };
 		97C146F21CF9000F007C117D /* main.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = main.m; sourceTree = "<group>"; };
 		97C146FB1CF9000F007C117D /* Base */ = {isa = PBXFileReference; lastKnownFileType = file.storyboard; name = Base; path = Base.lproj/Main.storyboard; sourceTree = "<group>"; };
@@ -62,8 +52,6 @@
 			isa = PBXFrameworksBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
-				9705A1C61CF904A100538489 /* Flutter.framework in Frameworks */,
-				3B80C3941E831B6300D905FE /* App.framework in Frameworks */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
@@ -73,10 +61,7 @@
 		9740EEB11CF90186004384FC /* Flutter */ = {
 			isa = PBXGroup;
 			children = (
-				2D5378251FAA1A9400D5DBA9 /* flutter_assets */,
-				3B80C3931E831B6300D905FE /* App.framework */,
 				3B3967151E833CAA004F5970 /* AppFrameworkInfo.plist */,
-				9740EEBA1CF902C7004384FC /* Flutter.framework */,
 				9740EEB21CF90195004384FC /* Debug.xcconfig */,
 				7AFA3C8E1D35360C0083082E /* Release.xcconfig */,
 				9740EEB31CF90195004384FC /* Generated.xcconfig */,
@@ -190,7 +175,6 @@
 				3B3967161E833CAA004F5970 /* AppFrameworkInfo.plist in Resources */,
 				9740EEB41CF90195004384FC /* Debug.xcconfig in Resources */,
 				97C146FE1CF9000F007C117D /* Assets.xcassets in Resources */,
-				2D5378261FAA1A9400D5DBA9 /* flutter_assets in Resources */,
 				97C146FC1CF9000F007C117D /* Main.storyboard in Resources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
@@ -210,7 +194,7 @@
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 			shellPath = /bin/sh;
-			shellScript = "/bin/sh \"$FLUTTER_ROOT/packages/flutter_tools/bin/xcode_backend.sh\" thin";
+			shellScript = "/bin/sh \"$FLUTTER_ROOT/packages/flutter_tools/bin/xcode_backend.sh\" embed_and_thin";
 		};
 		9740EEB61CF901F6004384FC /* Run Script */ = {
 			isa = PBXShellScriptBuildPhase;
@@ -263,7 +247,6 @@
 /* Begin XCBuildConfiguration section */
 		97C147031CF9000F007C117D /* Debug */ = {
 			isa = XCBuildConfiguration;
-			baseConfigurationReference = 9740EEB21CF90195004384FC /* Debug.xcconfig */;
 			buildSettings = {
 				ALWAYS_SEARCH_USER_PATHS = NO;
 				CLANG_ANALYZER_NONNULL = YES;
@@ -317,7 +300,6 @@
 		};
 		97C147041CF9000F007C117D /* Release */ = {
 			isa = XCBuildConfiguration;
-			baseConfigurationReference = 7AFA3C8E1D35360C0083082E /* Release.xcconfig */;
 			buildSettings = {
 				ALWAYS_SEARCH_USER_PATHS = NO;
 				CLANG_ANALYZER_NONNULL = YES;
diff --git a/example/ios/Runner.xcodeproj/project.xcworkspace/contents.xcworkspacedata b/example/ios/Runner.xcodeproj/project.xcworkspace/contents.xcworkspacedata
index 1d526a1..919434a 100644
--- a/example/ios/Runner.xcodeproj/project.xcworkspace/contents.xcworkspacedata
+++ b/example/ios/Runner.xcodeproj/project.xcworkspace/contents.xcworkspacedata
@@ -2,6 +2,6 @@
 <Workspace
    version = "1.0">
    <FileRef
-      location = "group:Runner.xcodeproj">
+      location = "self:">
    </FileRef>
 </Workspace>
diff --git a/example/ios/Runner.xcodeproj/project.xcworkspace/xcshareddata/IDEWorkspaceChecks.plist b/example/ios/Runner.xcodeproj/project.xcworkspace/xcshareddata/IDEWorkspaceChecks.plist
new file mode 100644
index 0000000..18d9810
--- /dev/null
+++ b/example/ios/Runner.xcodeproj/project.xcworkspace/xcshareddata/IDEWorkspaceChecks.plist
@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>IDEDidComputeMac32BitWarning</key>
+	<true/>
+</dict>
+</plist>
diff --git a/example/ios/Runner.xcodeproj/project.xcworkspace/xcshareddata/WorkspaceSettings.xcsettings b/example/ios/Runner.xcodeproj/project.xcworkspace/xcshareddata/WorkspaceSettings.xcsettings
new file mode 100644
index 0000000..f9b0d7c
--- /dev/null
+++ b/example/ios/Runner.xcodeproj/project.xcworkspace/xcshareddata/WorkspaceSettings.xcsettings
@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>PreviewsEnabled</key>
+	<false/>
+</dict>
+</plist>
diff --git a/example/ios/Runner.xcworkspace/xcshareddata/IDEWorkspaceChecks.plist b/example/ios/Runner.xcworkspace/xcshareddata/IDEWorkspaceChecks.plist
new file mode 100644
index 0000000..18d9810
--- /dev/null
+++ b/example/ios/Runner.xcworkspace/xcshareddata/IDEWorkspaceChecks.plist
@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>IDEDidComputeMac32BitWarning</key>
+	<true/>
+</dict>
+</plist>
diff --git a/example/ios/Runner.xcworkspace/xcshareddata/WorkspaceSettings.xcsettings b/example/ios/Runner.xcworkspace/xcshareddata/WorkspaceSettings.xcsettings
new file mode 100644
index 0000000..f9b0d7c
--- /dev/null
+++ b/example/ios/Runner.xcworkspace/xcshareddata/WorkspaceSettings.xcsettings
@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>PreviewsEnabled</key>
+	<false/>
+</dict>
+</plist>
diff --git a/example/ios/Runner/AppDelegate.swift b/example/ios/Runner/AppDelegate.swift
new file mode 100644
index 0000000..70693e4
--- /dev/null
+++ b/example/ios/Runner/AppDelegate.swift
@@ -0,0 +1,13 @@
+import UIKit
+import Flutter
+
+@UIApplicationMain
+@objc class AppDelegate: FlutterAppDelegate {
+  override func application(
+    _ application: UIApplication,
+    didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
+  ) -> Bool {
+    GeneratedPluginRegistrant.register(with: self)
+    return super.application(application, didFinishLaunchingWithOptions: launchOptions)
+  }
+}
diff --git a/example/ios/Runner/Runner-Bridging-Header.h b/example/ios/Runner/Runner-Bridging-Header.h
new file mode 100644
index 0000000..308a2a5
--- /dev/null
+++ b/example/ios/Runner/Runner-Bridging-Header.h
@@ -0,0 +1 @@
+#import "GeneratedPluginRegistrant.h"
diff --git a/example/lib/main.dart b/example/lib/main.dart
index 9e47897..0678d83 100644
--- a/example/lib/main.dart
+++ b/example/lib/main.dart
@@ -1,8 +1,6 @@
 import 'package:flutter/material.dart';
-
 import 'package:flutter_page_indicator/flutter_page_indicator.dart';
-
-import "package:transformer_page_view/transformer_page_view.dart";
+import 'package:another_transformer_page_view/another_transformer_page_view.dart';
 
 void main() => runApp(new MyApp());
 
@@ -13,14 +11,6 @@ class MyApp extends StatelessWidget {
     return new MaterialApp(
       title: 'Flutter Demo',
       theme: new ThemeData(
-        // This is the theme of your application.
-        //
-        // Try running your application with "flutter run". You'll see the
-        // application has a blue toolbar. Then, without quitting the app, try
-        // changing the primarySwatch below to Colors.green and then invoke
-        // "hot reload" (press "r" in the console where you ran "flutter run",
-        // or press Run > Flutter Hot Reload in IntelliJ). Notice that the
-        // counter didn't reset back to zero; the application is not restarted.
         primarySwatch: Colors.blue,
       ),
       home: new MyHomePage(title: 'Flutter Demo Home Page'),
@@ -29,30 +19,24 @@ class MyApp extends StatelessWidget {
 }
 
 class MyHomePage extends StatefulWidget {
-  MyHomePage({Key key, this.title}) : super(key: key);
-
-  // This widget is the home page of your application. It is stateful, meaning
-  // that it has a State object (defined below) that contains fields that affect
-  // how it looks.
-
-  // This class is the configuration for the state. It holds the values (in this
-  // case the title) provided by the parent (in this case the App widget) and
-  // used by the build method of the State. Fields in a Widget subclass are
-  // always marked "final".
+  MyHomePage({Key? key, this.title}) : super(key: key);
 
-  final String title;
+  final String? title;
 
   @override
   _MyHomePageState createState() => new _MyHomePageState();
 }
 
 class RadioGroup extends StatefulWidget {
-  final List<String> titles;
+  final List<String>? titles;
 
   final ValueChanged<int> onIndexChanged;
 
-  const RadioGroup({Key key, this.titles, this.onIndexChanged})
-      : super(key: key);
+  const RadioGroup({
+    Key? key,
+    this.titles,
+    required this.onIndexChanged,
+  }) : super(key: key);
 
   @override
   State<StatefulWidget> createState() {
@@ -66,7 +50,7 @@ class _RadioGroupState extends State<RadioGroup> {
   @override
   Widget build(BuildContext context) {
     List<Widget> list = [];
-    for (int i = 0; i < widget.titles.length; ++i) {
+    for (int i = 0; i < widget.titles!.length; ++i) {
       list.add(((String title, int index) {
         return new Row(
           mainAxisSize: MainAxisSize.min,
@@ -74,16 +58,16 @@ class _RadioGroupState extends State<RadioGroup> {
             new Radio<int>(
                 value: index,
                 groupValue: _index,
-                onChanged: (int index) {
+                onChanged: (int? index) {
                   setState(() {
-                    _index = index;
+                    _index = index!;
                     widget.onIndexChanged(_index);
                   });
                 }),
             new Text(title)
           ],
         );
-      })(widget.titles[i], i));
+      })(widget.titles![i], i));
     }
 
     return new Wrap(
@@ -98,13 +82,13 @@ class _MyHomePageState extends State<MyHomePage> {
   double size = 20.0;
   double activeSize = 30.0;
 
-  PageController controller;
+  PageController? controller;
 
   PageIndicatorLayout layout = PageIndicatorLayout.SLIDE;
 
   List<PageIndicatorLayout> layouts = PageIndicatorLayout.values;
 
-  bool loop = false;
+  bool? loop = false;
 
   @override
   void initState() {
@@ -135,30 +119,10 @@ class _MyHomePageState extends State<MyHomePage> {
     ];
     return new Scaffold(
         appBar: new AppBar(
-          title: new Text(widget.title),
+          title: new Text(widget.title!),
         ),
         body: new Column(
           children: <Widget>[
-            new Row(
-              children: <Widget>[
-                new Checkbox(
-                    value: loop,
-                    onChanged: (bool value) {
-                      setState(() {
-                        if (value) {
-                          controller = new TransformerPageController(
-                              itemCount: 4, loop: true);
-                        } else {
-                          controller = new PageController(
-                            initialPage: 0,
-                          );
-                        }
-                        loop = value;
-                      });
-                    }),
-                new Text("loop"),
-              ],
-            ),
             new RadioGroup(
               titles: layouts.map((s) {
                 var str = s.toString();
@@ -174,10 +138,11 @@ class _MyHomePageState extends State<MyHomePage> {
             new Expanded(
                 child: new Stack(
               children: <Widget>[
-                loop
+                loop!
                     ? new TransformerPageView.children(
                         children: children,
-                        pageController: controller,
+                        pageController:
+                            controller as TransformerPageController?,
                       )
                     : new PageView(
                         controller: controller,
@@ -191,7 +156,7 @@ class _MyHomePageState extends State<MyHomePage> {
                       layout: layout,
                       size: size,
                       activeSize: activeSize,
-                      controller: controller,
+                      controller: controller!,
                       space: 5.0,
                       count: 4,
                     ),
diff --git a/example/pubspec.lock b/example/pubspec.lock
index 92859fa..ec8db36 100644
--- a/example/pubspec.lock
+++ b/example/pubspec.lock
@@ -1,76 +1,69 @@
 # Generated by pub
-# See https://www.dartlang.org/tools/pub/glossary#lockfile
+# See https://dart.dev/tools/pub/glossary#lockfile
 packages:
-  analyzer:
-    dependency: transitive
-    description:
-      name: analyzer
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "0.32.4"
-  args:
-    dependency: transitive
+  another_transformer_page_view:
+    dependency: "direct main"
     description:
-      name: args
-      url: "https://pub.flutter-io.cn"
+      name: another_transformer_page_view
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.5.0"
+    version: "1.0.0"
   async:
     dependency: transitive
     description:
       name: async
-      url: "https://pub.flutter-io.cn"
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.0.8"
+    version: "2.5.0"
   boolean_selector:
     dependency: transitive
     description:
       name: boolean_selector
-      url: "https://pub.flutter-io.cn"
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.0.4"
-  charcode:
+    version: "2.1.0"
+  characters:
     dependency: transitive
     description:
-      name: charcode
-      url: "https://pub.flutter-io.cn"
+      name: characters
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.2"
-  collection:
-    dependency: transitive
-    description:
-      name: collection
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "1.14.11"
-  convert:
+    version: "1.1.0"
+  charcode:
     dependency: transitive
     description:
-      name: convert
-      url: "https://pub.flutter-io.cn"
+      name: charcode
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.0.2"
-  crypto:
+    version: "1.2.0"
+  clock:
     dependency: transitive
     description:
-      name: crypto
-      url: "https://pub.flutter-io.cn"
+      name: clock
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.0.6"
-  csslib:
+    version: "1.1.0"
+  collection:
     dependency: transitive
     description:
-      name: csslib
-      url: "https://pub.flutter-io.cn"
+      name: collection
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.14.5"
+    version: "1.15.0"
   cupertino_icons:
     dependency: "direct main"
     description:
       name: cupertino_icons
-      url: "https://pub.flutter-io.cn"
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "0.1.3"
+  fake_async:
+    dependency: transitive
+    description:
+      name: fake_async
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.1.2"
+    version: "1.2.0"
   flutter:
     dependency: "direct main"
     description: flutter
@@ -82,318 +75,100 @@ packages:
       path: ".."
       relative: true
     source: path
-    version: "0.0.3"
+    version: "1.0.0"
   flutter_test:
     dependency: "direct dev"
     description: flutter
     source: sdk
     version: "0.0.0"
-  front_end:
-    dependency: transitive
-    description:
-      name: front_end
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "0.1.4"
-  glob:
-    dependency: transitive
-    description:
-      name: glob
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "1.1.7"
-  html:
-    dependency: transitive
-    description:
-      name: html
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "0.13.3+3"
-  http:
-    dependency: transitive
-    description:
-      name: http
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "0.11.3+17"
-  http_multi_server:
-    dependency: transitive
-    description:
-      name: http_multi_server
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "2.0.5"
-  http_parser:
-    dependency: transitive
-    description:
-      name: http_parser
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "3.1.3"
-  io:
-    dependency: transitive
-    description:
-      name: io
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "0.3.3"
-  js:
-    dependency: transitive
-    description:
-      name: js
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "0.6.1+1"
-  json_rpc_2:
-    dependency: transitive
-    description:
-      name: json_rpc_2
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "2.0.9"
-  kernel:
-    dependency: transitive
-    description:
-      name: kernel
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "0.3.4"
-  logging:
-    dependency: transitive
-    description:
-      name: logging
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "0.11.3+2"
   matcher:
     dependency: transitive
     description:
       name: matcher
-      url: "https://pub.flutter-io.cn"
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.12.3+1"
+    version: "0.12.10"
   meta:
     dependency: transitive
     description:
       name: meta
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "1.1.6"
-  mime:
-    dependency: transitive
-    description:
-      name: mime
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "0.9.6+2"
-  multi_server_socket:
-    dependency: transitive
-    description:
-      name: multi_server_socket
-      url: "https://pub.flutter-io.cn"
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.0.2"
-  node_preamble:
-    dependency: transitive
-    description:
-      name: node_preamble
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "1.4.4"
-  package_config:
-    dependency: transitive
-    description:
-      name: package_config
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "1.0.5"
-  package_resolver:
-    dependency: transitive
-    description:
-      name: package_resolver
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "1.0.4"
+    version: "1.3.0"
   path:
     dependency: transitive
     description:
       name: path
-      url: "https://pub.flutter-io.cn"
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.6.2"
-  plugin:
+    version: "1.8.0"
+  pedantic:
     dependency: transitive
     description:
-      name: plugin
-      url: "https://pub.flutter-io.cn"
+      name: pedantic
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.2.0+3"
-  pool:
-    dependency: transitive
-    description:
-      name: pool
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "1.3.6"
-  pub_semver:
-    dependency: transitive
-    description:
-      name: pub_semver
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "1.4.2"
-  quiver:
-    dependency: transitive
-    description:
-      name: quiver
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "2.0.0+1"
-  shelf:
-    dependency: transitive
-    description:
-      name: shelf
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "0.7.3+3"
-  shelf_packages_handler:
-    dependency: transitive
-    description:
-      name: shelf_packages_handler
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "1.0.4"
-  shelf_static:
-    dependency: transitive
-    description:
-      name: shelf_static
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "0.2.8"
-  shelf_web_socket:
-    dependency: transitive
-    description:
-      name: shelf_web_socket
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "0.2.2+4"
+    version: "1.11.0"
   sky_engine:
     dependency: transitive
     description: flutter
     source: sdk
     version: "0.0.99"
-  source_map_stack_trace:
-    dependency: transitive
-    description:
-      name: source_map_stack_trace
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "1.1.5"
-  source_maps:
-    dependency: transitive
-    description:
-      name: source_maps
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "0.10.7"
   source_span:
     dependency: transitive
     description:
       name: source_span
-      url: "https://pub.flutter-io.cn"
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.4.1"
+    version: "1.8.0"
   stack_trace:
     dependency: transitive
     description:
       name: stack_trace
-      url: "https://pub.flutter-io.cn"
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.9.3"
+    version: "1.10.0"
   stream_channel:
     dependency: transitive
     description:
       name: stream_channel
-      url: "https://pub.flutter-io.cn"
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.6.8"
+    version: "2.1.0"
   string_scanner:
     dependency: transitive
     description:
       name: string_scanner
-      url: "https://pub.flutter-io.cn"
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.0.4"
+    version: "1.1.0"
   term_glyph:
     dependency: transitive
     description:
       name: term_glyph
-      url: "https://pub.flutter-io.cn"
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.0.1"
-  test:
+    version: "1.2.0"
+  test_api:
     dependency: transitive
     description:
-      name: test
-      url: "https://pub.flutter-io.cn"
+      name: test_api
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.3.0"
-  transformer_page_view:
-    dependency: "direct main"
-    description:
-      path: "/Users/jzoom/SourceCode/transformer_page_view"
-      relative: false
-    source: path
-    version: "0.1.0"
+    version: "0.2.19"
   typed_data:
     dependency: transitive
     description:
       name: typed_data
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "1.1.6"
-  utf:
-    dependency: transitive
-    description:
-      name: utf
-      url: "https://pub.flutter-io.cn"
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.9.0+5"
+    version: "1.3.0"
   vector_math:
     dependency: transitive
     description:
       name: vector_math
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "2.0.8"
-  vm_service_client:
-    dependency: transitive
-    description:
-      name: vm_service_client
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "0.2.6"
-  watcher:
-    dependency: transitive
-    description:
-      name: watcher
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "0.9.7+10"
-  web_socket_channel:
-    dependency: transitive
-    description:
-      name: web_socket_channel
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "1.0.9"
-  yaml:
-    dependency: transitive
-    description:
-      name: yaml
-      url: "https://pub.flutter-io.cn"
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.1.15"
+    version: "2.1.0"
 sdks:
-  dart: ">=2.0.0-dev.68.0 <3.0.0"
-  flutter: ">=0.1.4 <3.0.0"
+  dart: ">=2.12.0 <3.0.0"
diff --git a/example/pubspec.yaml b/example/pubspec.yaml
index 59144dc..98a65cc 100644
--- a/example/pubspec.yaml
+++ b/example/pubspec.yaml
@@ -10,7 +10,7 @@ description: A new Flutter project.
 version: 1.0.0+1
 
 environment:
-  sdk: ">=2.0.0-dev.68.0 <3.0.0"
+  sdk: '>=2.12.0 <3.0.0'
 
 dependencies:
   flutter:
@@ -23,8 +23,7 @@ dependencies:
   flutter_page_indicator:
     path: ../
 
-  transformer_page_view:
-    path: /Users/jzoom/SourceCode/transformer_page_view
+  another_transformer_page_view: ^1.0.0
 
 dev_dependencies:
   flutter_test:
diff --git a/example/web/favicon.png b/example/web/favicon.png
new file mode 100644
index 0000000..8aaa46a
Binary files /dev/null and b/example/web/favicon.png differ
diff --git a/example/web/icons/Icon-192.png b/example/web/icons/Icon-192.png
new file mode 100644
index 0000000..b749bfe
Binary files /dev/null and b/example/web/icons/Icon-192.png differ
diff --git a/example/web/icons/Icon-512.png b/example/web/icons/Icon-512.png
new file mode 100644
index 0000000..88cfd48
Binary files /dev/null and b/example/web/icons/Icon-512.png differ
diff --git a/example/web/index.html b/example/web/index.html
new file mode 100644
index 0000000..1460b5e
--- /dev/null
+++ b/example/web/index.html
@@ -0,0 +1,45 @@
+<!DOCTYPE html>
+<html>
+<head>
+  <!--
+    If you are serving your web app in a path other than the root, change the
+    href value below to reflect the base path you are serving from.
+
+    The path provided below has to start and end with a slash "/" in order for
+    it to work correctly.
+
+    Fore more details:
+    * https://developer.mozilla.org/en-US/docs/Web/HTML/Element/base
+  -->
+  <base href="/">
+
+  <meta charset="UTF-8">
+  <meta content="IE=Edge" http-equiv="X-UA-Compatible">
+  <meta name="description" content="A new Flutter project.">
+
+  <!-- iOS meta tags & icons -->
+  <meta name="apple-mobile-web-app-capable" content="yes">
+  <meta name="apple-mobile-web-app-status-bar-style" content="black">
+  <meta name="apple-mobile-web-app-title" content="example">
+  <link rel="apple-touch-icon" href="icons/Icon-192.png">
+
+  <!-- Favicon -->
+  <link rel="icon" type="image/png" href="favicon.png"/>
+
+  <title>example</title>
+  <link rel="manifest" href="manifest.json">
+</head>
+<body>
+  <!-- This script installs service_worker.js to provide PWA functionality to
+       application. For more information, see:
+       https://developers.google.com/web/fundamentals/primers/service-workers -->
+  <script>
+    if ('serviceWorker' in navigator) {
+      window.addEventListener('flutter-first-frame', function () {
+        navigator.serviceWorker.register('flutter_service_worker.js');
+      });
+    }
+  </script>
+  <script src="main.dart.js" type="application/javascript"></script>
+</body>
+</html>
diff --git a/example/web/manifest.json b/example/web/manifest.json
new file mode 100644
index 0000000..8c01291
--- /dev/null
+++ b/example/web/manifest.json
@@ -0,0 +1,23 @@
+{
+    "name": "example",
+    "short_name": "example",
+    "start_url": ".",
+    "display": "standalone",
+    "background_color": "#0175C2",
+    "theme_color": "#0175C2",
+    "description": "A new Flutter project.",
+    "orientation": "portrait-primary",
+    "prefer_related_applications": false,
+    "icons": [
+        {
+            "src": "icons/Icon-192.png",
+            "sizes": "192x192",
+            "type": "image/png"
+        },
+        {
+            "src": "icons/Icon-512.png",
+            "sizes": "512x512",
+            "type": "image/png"
+        }
+    ]
+}
diff --git a/flutter_page_indicator.iml b/flutter_page_indicator.iml
deleted file mode 100644
index 75456de..0000000
--- a/flutter_page_indicator.iml
+++ /dev/null
@@ -1,23 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<module type="JAVA_MODULE" version="4">
-  <component name="NewModuleRootManager" inherit-compiler-output="true">
-    <exclude-output />
-    <content url="file://$MODULE_DIR$">
-      <sourceFolder url="file://$MODULE_DIR$/lib" isTestSource="false" />
-      <sourceFolder url="file://$MODULE_DIR$/test" isTestSource="true" />
-      <excludeFolder url="file://$MODULE_DIR$/.dart_tool" />
-      <excludeFolder url="file://$MODULE_DIR$/.idea" />
-      <excludeFolder url="file://$MODULE_DIR$/.pub" />
-      <excludeFolder url="file://$MODULE_DIR$/build" />
-      <excludeFolder url="file://$MODULE_DIR$/example/.dart_tool" />
-      <excludeFolder url="file://$MODULE_DIR$/example/.pub" />
-      <excludeFolder url="file://$MODULE_DIR$/example/build" />
-      <excludeFolder url="file://$MODULE_DIR$/example/ios/Flutter/flutter_assets/packages" />
-    </content>
-    <orderEntry type="jdk" jdkName="Android API 25 Platform" jdkType="Android SDK" />
-    <orderEntry type="sourceFolder" forTests="false" />
-    <orderEntry type="library" name="Dart Packages" level="project" />
-    <orderEntry type="library" name="Dart SDK" level="project" />
-    <orderEntry type="library" name="Flutter Plugins" level="project" />
-  </component>
-</module>
\ No newline at end of file
diff --git a/lib/flutter_page_indicator.dart b/lib/flutter_page_indicator.dart
index 1ab652c..78550dd 100644
--- a/lib/flutter_page_indicator.dart
+++ b/lib/flutter_page_indicator.dart
@@ -123,12 +123,12 @@ class ScalePainter extends BasePainter {
         : radius + ((index + 1) * (size + space));
 
     double progress = page - index;
-    _paint.color = Color.lerp(widget.activeColor, widget.color, progress);
+    _paint.color = Color.lerp(widget.activeColor, widget.color, progress)!;
     //last
     canvas.drawCircle(new Offset(radius + (index * (size + space)), radius),
         lerp(radius, radius * widget.scale, progress), _paint);
     //first
-    _paint.color = Color.lerp(widget.color, widget.activeColor, progress);
+    _paint.color = Color.lerp(widget.color, widget.activeColor, progress)!;
     canvas.drawCircle(new Offset(secondOffset, radius),
         lerp(radius * widget.scale, radius, progress), _paint);
   }
@@ -154,12 +154,12 @@ class ColorPainter extends BasePainter {
         ? radius
         : radius + ((index + 1) * (size + space));
 
-    _paint.color = Color.lerp(widget.activeColor, widget.color, progress);
+    _paint.color = Color.lerp(widget.activeColor, widget.color, progress)!;
     //left
     canvas.drawCircle(
         new Offset(radius + (index * (size + space)), radius), radius, _paint);
     //right
-    _paint.color = Color.lerp(widget.color, widget.activeColor, progress);
+    _paint.color = Color.lerp(widget.color, widget.activeColor, progress)!;
     canvas.drawCircle(new Offset(secondOffset, radius), radius, _paint);
   }
 }
@@ -181,6 +181,7 @@ abstract class BasePainter extends CustomPainter {
   bool _shouldSkip(int index) {
     return false;
   }
+
   //double secondOffset = index == widget.count-1 ? radius : radius + ((index + 1) * (size + space));
 
   @override
@@ -330,12 +331,12 @@ class PageIndicator extends StatefulWidget {
   final double activeSize;
 
   PageIndicator(
-      {Key key,
+      {Key? key,
       this.size: 20.0,
       this.space: 5.0,
-      this.count,
+      required this.count,
       this.activeSize: 20.0,
-      this.controller,
+      required this.controller,
       this.color: Colors.white30,
       this.layout: PageIndicatorLayout.SLIDE,
       this.activeColor: Colors.white,
diff --git a/pubspec.lock b/pubspec.lock
index 8c0490c..49a0ce6 100644
--- a/pubspec.lock
+++ b/pubspec.lock
@@ -1,69 +1,55 @@
 # Generated by pub
-# See https://www.dartlang.org/tools/pub/glossary#lockfile
+# See https://dart.dev/tools/pub/glossary#lockfile
 packages:
-  analyzer:
-    dependency: transitive
-    description:
-      name: analyzer
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "0.32.4"
-  args:
-    dependency: transitive
-    description:
-      name: args
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "1.5.0"
   async:
     dependency: transitive
     description:
       name: async
-      url: "https://pub.flutter-io.cn"
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.0.8"
+    version: "2.5.0"
   boolean_selector:
     dependency: transitive
     description:
       name: boolean_selector
-      url: "https://pub.flutter-io.cn"
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.0.4"
-  charcode:
+    version: "2.1.0"
+  characters:
     dependency: transitive
     description:
-      name: charcode
-      url: "https://pub.flutter-io.cn"
+      name: characters
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.2"
-  collection:
+    version: "1.1.0"
+  charcode:
     dependency: transitive
     description:
-      name: collection
-      url: "https://pub.flutter-io.cn"
+      name: charcode
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.14.11"
-  convert:
+    version: "1.2.0"
+  clock:
     dependency: transitive
     description:
-      name: convert
-      url: "https://pub.flutter-io.cn"
+      name: clock
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.0.2"
-  crypto:
+    version: "1.1.0"
+  collection:
     dependency: transitive
     description:
-      name: crypto
-      url: "https://pub.flutter-io.cn"
+      name: collection
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.0.6"
-  csslib:
+    version: "1.15.0"
+  fake_async:
     dependency: transitive
     description:
-      name: csslib
-      url: "https://pub.flutter-io.cn"
+      name: fake_async
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.14.5"
+    version: "1.2.0"
   flutter:
     dependency: "direct main"
     description: flutter
@@ -74,305 +60,87 @@ packages:
     description: flutter
     source: sdk
     version: "0.0.0"
-  front_end:
-    dependency: transitive
-    description:
-      name: front_end
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "0.1.4"
-  glob:
-    dependency: transitive
-    description:
-      name: glob
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "1.1.7"
-  html:
-    dependency: transitive
-    description:
-      name: html
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "0.13.3+3"
-  http:
-    dependency: transitive
-    description:
-      name: http
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "0.11.3+17"
-  http_multi_server:
-    dependency: transitive
-    description:
-      name: http_multi_server
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "2.0.5"
-  http_parser:
-    dependency: transitive
-    description:
-      name: http_parser
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "3.1.3"
-  io:
-    dependency: transitive
-    description:
-      name: io
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "0.3.3"
-  js:
-    dependency: transitive
-    description:
-      name: js
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "0.6.1+1"
-  json_rpc_2:
-    dependency: transitive
-    description:
-      name: json_rpc_2
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "2.0.9"
-  kernel:
-    dependency: transitive
-    description:
-      name: kernel
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "0.3.4"
-  logging:
-    dependency: transitive
-    description:
-      name: logging
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "0.11.3+2"
   matcher:
     dependency: transitive
     description:
       name: matcher
-      url: "https://pub.flutter-io.cn"
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.12.3+1"
+    version: "0.12.10"
   meta:
     dependency: transitive
     description:
       name: meta
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "1.1.6"
-  mime:
-    dependency: transitive
-    description:
-      name: mime
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "0.9.6+2"
-  multi_server_socket:
-    dependency: transitive
-    description:
-      name: multi_server_socket
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "1.0.2"
-  node_preamble:
-    dependency: transitive
-    description:
-      name: node_preamble
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "1.4.4"
-  package_config:
-    dependency: transitive
-    description:
-      name: package_config
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "1.0.5"
-  package_resolver:
-    dependency: transitive
-    description:
-      name: package_resolver
-      url: "https://pub.flutter-io.cn"
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.0.4"
+    version: "1.3.0"
   path:
     dependency: transitive
     description:
       name: path
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "1.6.2"
-  plugin:
-    dependency: transitive
-    description:
-      name: plugin
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "0.2.0+3"
-  pool:
-    dependency: transitive
-    description:
-      name: pool
-      url: "https://pub.flutter-io.cn"
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.3.6"
-  pub_semver:
-    dependency: transitive
-    description:
-      name: pub_semver
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "1.4.2"
-  quiver:
-    dependency: transitive
-    description:
-      name: quiver
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "2.0.0+1"
-  shelf:
-    dependency: transitive
-    description:
-      name: shelf
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "0.7.3+3"
-  shelf_packages_handler:
-    dependency: transitive
-    description:
-      name: shelf_packages_handler
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "1.0.4"
-  shelf_static:
-    dependency: transitive
-    description:
-      name: shelf_static
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "0.2.8"
-  shelf_web_socket:
-    dependency: transitive
-    description:
-      name: shelf_web_socket
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "0.2.2+4"
+    version: "1.8.0"
   sky_engine:
     dependency: transitive
     description: flutter
     source: sdk
     version: "0.0.99"
-  source_map_stack_trace:
-    dependency: transitive
-    description:
-      name: source_map_stack_trace
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "1.1.5"
-  source_maps:
-    dependency: transitive
-    description:
-      name: source_maps
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "0.10.7"
   source_span:
     dependency: transitive
     description:
       name: source_span
-      url: "https://pub.flutter-io.cn"
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.4.1"
+    version: "1.8.0"
   stack_trace:
     dependency: transitive
     description:
       name: stack_trace
-      url: "https://pub.flutter-io.cn"
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.9.3"
+    version: "1.10.0"
   stream_channel:
     dependency: transitive
     description:
       name: stream_channel
-      url: "https://pub.flutter-io.cn"
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.6.8"
+    version: "2.1.0"
   string_scanner:
     dependency: transitive
     description:
       name: string_scanner
-      url: "https://pub.flutter-io.cn"
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.0.4"
+    version: "1.1.0"
   term_glyph:
     dependency: transitive
     description:
       name: term_glyph
-      url: "https://pub.flutter-io.cn"
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.0.1"
-  test:
+    version: "1.2.0"
+  test_api:
     dependency: transitive
     description:
-      name: test
-      url: "https://pub.flutter-io.cn"
+      name: test_api
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.3.0"
+    version: "0.2.19"
   typed_data:
     dependency: transitive
     description:
       name: typed_data
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "1.1.6"
-  utf:
-    dependency: transitive
-    description:
-      name: utf
-      url: "https://pub.flutter-io.cn"
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.9.0+5"
+    version: "1.3.0"
   vector_math:
     dependency: transitive
     description:
       name: vector_math
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "2.0.8"
-  vm_service_client:
-    dependency: transitive
-    description:
-      name: vm_service_client
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "0.2.6"
-  watcher:
-    dependency: transitive
-    description:
-      name: watcher
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "0.9.7+10"
-  web_socket_channel:
-    dependency: transitive
-    description:
-      name: web_socket_channel
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "1.0.9"
-  yaml:
-    dependency: transitive
-    description:
-      name: yaml
-      url: "https://pub.flutter-io.cn"
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.1.15"
+    version: "2.1.0"
 sdks:
-  dart: ">=2.0.0-dev.68.0 <3.0.0"
-  flutter: ">=0.1.4 <3.0.0"
+  dart: ">=2.12.0 <3.0.0"
diff --git a/pubspec.yaml b/pubspec.yaml
index d4dfab8..d09e9b8 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,7 +1,6 @@
 name: flutter_page_indicator
 description: Page indicator for flutter, with multiple build-in layouts.
-version: 0.0.3
-author: JZoom <jzoom8112@gmail.com>
+version: 1.0.0
 homepage: https://github.com/jzoom/flutter_page_indicator
 
 dependencies:
@@ -9,9 +8,7 @@ dependencies:
     sdk: flutter
 
 environment:
-  sdk: ">=2.0.0-dev.48.0 <3.0.0"
-  flutter: ">=0.1.4 <3.0.0"
-
+  sdk: '>=2.12.0 <3.0.0'
 
 dev_dependencies:
   flutter_test:
diff --git a/test/flutter_page_indicator_test.dart b/test/flutter_page_indicator_test.dart
index dd83cf8..0da434d 100644
--- a/test/flutter_page_indicator_test.dart
+++ b/test/flutter_page_indicator_test.dart
@@ -1,6 +1,4 @@
-import 'package:test/test.dart';
-
-import 'package:flutter_page_indicator/flutter_page_indicator.dart';
+import 'package:flutter_test/flutter_test.dart';
 
 void main() {
   test('adds one to input values', () {});