add scripts

lib/base/ui/lazy_load_state.dart

@@ -0,0 +1,29 @@
+import 'package:flutter/material.dart';
+
+/// @author NewTab
+
+mixin LazyLoadState<T extends StatefulWidget> on State<T> {
+  @override
+  void initState() {
+    super.initState();
+    WidgetsBinding.instance?.addPostFrameCallback((timeStamp) {
+      var route = ModalRoute.of(context);
+      void handler(status) {
+        if (status == AnimationStatus.completed) {
+          route?.animation?.removeStatusListener(handler);
+          onLazyLoad();
+        }
+      }
+
+      if (route == null ||
+          route.animation == null ||
+          route.animation!.status == AnimationStatus.completed) {
+        onLazyLoad();
+      } else {
+        route.animation!.addStatusListener(handler);
+      }
+    });
+  }
+
+  void onLazyLoad();
+}