opt persist header

Signed-off-by: dom <githubaccount56556@proton.me>

lib/common/widgets/custom_sliver_persistent_header_delegate.dart

@@ -1,18 +1,15 @@
-import 'dart:io' show Platform;
-
 import 'package:flutter/material.dart';
+import 'package:flutter/rendering.dart' show RenderProxyBox;
 
 class CustomSliverPersistentHeaderDelegate
     extends SliverPersistentHeaderDelegate {
   const CustomSliverPersistentHeaderDelegate({
     required this.child,
-    required this.bgColor,
-    double extent = 45,
+    this.bgColor,
+    this.extent = 45,
     this.needRebuild = false,
-  }) : _minExtent = extent,
-       _maxExtent = extent;
-  final double _minExtent;
-  final double _maxExtent;
+  });
+  final double extent;
   final Widget child;
   final Color? bgColor;
   final bool needRebuild;
@@ -26,31 +23,16 @@ class CustomSliverPersistentHeaderDelegate
     //创建child子组件
     //shrinkOffset：child偏移值minExtent~maxExtent
     //overlapsContent：SliverPersistentHeader覆盖其他子组件返回true，否则返回false
-    return bgColor != null
-        ? DecoratedBox(
-            decoration: BoxDecoration(
-              color: bgColor,
-              boxShadow: Platform.isIOS
-                  ? null
-                  : [
-                      BoxShadow(
-                        color: bgColor!,
-                        offset: const Offset(0, -1),
-                      ),
-                    ],
-            ),
-            child: child,
-          )
-        : child;
+    return _DecoratedBox(color: bgColor, child: child);
   }
 
   //SliverPersistentHeader最大高度
   @override
-  double get maxExtent => _maxExtent;
+  double get maxExtent => extent;
 
   //SliverPersistentHeader最小高度
   @override
-  double get minExtent => _minExtent;
+  double get minExtent => extent;
 
   @override
   bool shouldRebuild(CustomSliverPersistentHeaderDelegate oldDelegate) {
@@ -58,3 +40,62 @@ class CustomSliverPersistentHeaderDelegate
         (needRebuild && oldDelegate.child != child);
   }
 }
+
+class _DecoratedBox extends SingleChildRenderObjectWidget {
+  const _DecoratedBox({
+    this.color,
+    super.child,
+  });
+
+  final Color? color;
+
+  @override
+  RenderObject createRenderObject(BuildContext context) {
+    return _RenderDecoratedBox(color: color);
+  }
+
+  @override
+  void updateRenderObject(
+    BuildContext context,
+    _RenderDecoratedBox renderObject,
+  ) {
+    renderObject.color = color;
+  }
+}
+
+class _RenderDecoratedBox extends RenderProxyBox {
+  _RenderDecoratedBox({
+    Color? color,
+  }) : _color = color;
+
+  Color? _color;
+  Color? get color => _color;
+  set color(Color? value) {
+    if (_color == value) return;
+    _color = value;
+    markNeedsPaint();
+  }
+
+  @override
+  void paint(PaintingContext context, Offset offset) {
+    if (_color case final color?) {
+      final size = this.size;
+      context.canvas.drawRect(
+        Rect.fromLTWH(
+          offset.dx,
+          offset.dy - 2,
+          size.width,
+          size.height + 2,
+        ),
+        Paint()..color = color,
+      );
+    }
+    super.paint(context, offset);
+  }
+
+  @override
+  bool hitTestSelf(Offset position) => true;
+
+  @override
+  bool get isRepaintBoundary => true;
+}