51 lines
1.3 KiB
Dart
51 lines
1.3 KiB
Dart
/// 自定义粘性委托类
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library;
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import 'package:flutter/material.dart';
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import 'package:get/get.dart';
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typedef OnPinnedChanged = void Function(bool pinned);
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class CustomStickyHeader extends SliverPersistentHeaderDelegate {
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final PreferredSize child;
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RxBool? isPinned;
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RxDouble? positions;
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CustomStickyHeader({
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required this.child,
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this.isPinned,
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this.positions,
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});
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@override
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double get minExtent => child.preferredSize.height;
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@override
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double get maxExtent => child.preferredSize.height;
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@override
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bool shouldRebuild(SliverPersistentHeaderDelegate oldDelegate) {
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return true;
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}
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@override
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Widget build(BuildContext context, double shrinkOffset, bool overlapsContent) {
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// overlapsContent 或 shrinkOffset >= maxExtent - minExtent 都可以判断是否吸顶
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bool pinned = overlapsContent; // true 表示已经吸顶
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if (isPinned != null && isPinned!.value != pinned) {
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WidgetsBinding.instance.addPostFrameCallback((_) {
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isPinned!.value = pinned;
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});
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}
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if (positions != null) {
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if ((maxExtent - minExtent) >= shrinkOffset) {
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WidgetsBinding.instance.addPostFrameCallback((_) {
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positions!.value = shrinkOffset;
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});
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}
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}
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return child;
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}
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}
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