mod: home: show anonymous icon

Closes #81

opt: SliverPersistentHeaderDelegate

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

lib/common/widgets/custom_sliver_persistent_header_delegate.dart

@@ -0,0 +1,36 @@
+import 'package:flutter/material.dart';
+
+class CustomSliverPersistentHeaderDelegate
+    extends SliverPersistentHeaderDelegate {
+  CustomSliverPersistentHeaderDelegate({
+    required this.child,
+    double extent = 45,
+  })  : _minExtent = extent,
+        _maxExtent = extent;
+  final double _minExtent;
+  final double _maxExtent;
+  final Widget child;
+
+  @override
+  Widget build(
+      BuildContext context, double shrinkOffset, bool overlapsContent) {
+    //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 child;
+  }
+
+  //SliverPersistentHeader最大高度
+  @override
+  double get maxExtent => _maxExtent;
+
+  //SliverPersistentHeader最小高度
+  @override
+  double get minExtent => _minExtent;
+
+  @override
+  bool shouldRebuild(
+      covariant CustomSliverPersistentHeaderDelegate oldDelegate) {
+    return false;
+  }
+}