refactor: add RSizedBox widget

+import 'package:flutter/material.dart';
+import 'package:flutter/rendering.dart';
+
+import 'size_extension.dart';
+
+class RSizedBox extends SizedBox {
+  const RSizedBox({
+    Key? key,
+    double? height,
+    double? width,
+    Widget? child,
+  })  : _square = false,
+        super(key: key, child: child, width: width, height: height);
+
+  const RSizedBox.square({
+    Key? key,
+    double? height,
+    double? dimension,
+    Widget? child,
+  })  : _square = true,
+        super.square(key: key, child: child, dimension: dimension);
+
+  RSizedBox.fromSize({
+    Key? key,
+    Size? size,
+    Widget? child,
+  })  : _square = false,
+        super.fromSize(key: key, child: child, size: size);
+
+  @override
+  RenderConstrainedBox createRenderObject(BuildContext context) {
+    return RenderConstrainedBox(
+      additionalConstraints: _additionalConstraints,
+    );
+  }
+
+  final bool _square;
+
+  BoxConstraints get _additionalConstraints {
+    final boxConstraints =
+        BoxConstraints.tightFor(width: width, height: height);
+    return _square ? boxConstraints.r : boxConstraints.hw;
+  }
+
+  @override
+  void updateRenderObject(
+      BuildContext context, RenderConstrainedBox renderObject) {
+    renderObject.additionalConstraints = _additionalConstraints;
+  }
+}

@@ -2,7 +2,7 @@ import 'dart:math';
 
 import 'package:flutter/material.dart';
 
-import '../flutter_screenutil.dart';
+import 'screen_util.dart';
 
 extension SizeExtension on num {
   ///[ScreenUtil.setWidth]
@@ -75,3 +75,21 @@ extension RaduisExtension on Radius {
     ..x.r
     ..y.r;
 }
+
+extension BoxConstraintsExtension on BoxConstraints {
+  /// Creates adapt BoxConstraints using r [SizeExtension].
+  BoxConstraints get r => this.copyWith(
+        maxHeight: maxHeight.r,
+        maxWidth: maxWidth.r,
+        minHeight: minHeight.r,
+        minWidth: minWidth.r,
+      );
+
+  /// Creates adapt BoxConstraints using h-w [SizeExtension].
+  BoxConstraints get hw => this.copyWith(
+        maxHeight: maxHeight.h,
+        maxWidth: maxWidth.w,
+        minHeight: minHeight.h,
+        minWidth: minWidth.w,
+      );
+}