53 lines
1.6 KiB
Dart
53 lines
1.6 KiB
Dart
// Author: fruit.com.cn
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// 职责：协调首页三页的点击动画、最终选中目标和手势中断。
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import 'package:flutter/widgets.dart';
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const _transitionDuration = Duration(milliseconds: 220);
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/// 页面移动时保留用户最终目标，防止跨页动画途中的页面抢占高亮。
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class HomeTabMotionController extends PageController {
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/// [onSettled] 在动画结束或被手势中断时同步实际停留页面。
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HomeTabMotionController({required this.onSettled});
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final ValueChanged<int> onSettled;
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int? _target;
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int _revision = 0;
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bool _disposed = false;
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/// 供导航绘制连续位置；布局尚未建立时使用初始页。
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double get pagePosition => hasClients && position.hasContentDimensions
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? page ?? initialPage.toDouble()
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: initialPage.toDouble();
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/// 点击跨页过程中只接受最终目标；拖动和稳定状态接受实际页。
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bool acceptsSelection(int index) => _target == null || _target == index;
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/// 点击导航时平滑移动；系统减少动画时直接到位。
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Future<void> selectPage(int index, {required bool reduceMotion}) async {
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final revision = ++_revision;
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_target = index;
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if (!hasClients) {
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_target = null;
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return;
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}
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if (reduceMotion) {
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jumpToPage(index);
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} else {
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await animateToPage(
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index,
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duration: _transitionDuration,
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curve: Curves.easeOut,
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);
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}
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if (_disposed || revision != _revision) return;
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_target = null;
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if (hasClients) onSettled(pagePosition.round());
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}
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@override
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void dispose() {
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_disposed = true;
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super.dispose();
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}
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}
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