151 lines
3.3 KiB
Dart
151 lines
3.3 KiB
Dart
import 'package:flutter/material.dart';
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/// 磁吸进度状态
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class MagneticSnapState {
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/// 吸附进度 0.0 ~ 1.0
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final double progress;
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/// 媒体库透明度
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double get mediaOpacity {
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// 0% ~ 70%: 1.0 → 0.45
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// 70% ~ 100%: 0.45 → 0
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if (progress <= 0.7) {
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return 1.0 - (progress / 0.7) * 0.55;
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} else {
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final t = (progress - 0.7) / 0.3;
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return 0.45 * (1 - t);
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}
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}
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/// 收藏标题位移（从 +12px → 0）
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double get favoriteTranslateY {
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return (1 - progress) * 12;
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}
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/// 收藏列表展开程度 0.0 ~ 1.0
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double get listReveal {
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if (progress <= 0.7) return 0.0;
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return (progress - 0.7) / 0.3;
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}
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/// 是否完全吸附
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bool get isSnapped => progress >= 1.0;
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/// 是否在磁吸区（进度 > 70%）
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bool get isInMagneticZone => progress > 0.7;
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const MagneticSnapState(this.progress);
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factory MagneticSnapState.initial() => const MagneticSnapState(0.0);
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MagneticSnapState copyWith({double? progress}) {
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return MagneticSnapState(progress ?? this.progress);
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}
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}
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/// 磁吸控制器
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class MagneticScrollController extends ChangeNotifier {
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/// 吸附进度
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double _progress = 0.0;
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double get progress => _progress;
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/// 是否已吸附
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bool _isSnapped = false;
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bool get isSnapped => _isSnapped;
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/// 动画控制器（用于吸附动画）
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AnimationController? _animationController;
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TickerProvider? _tickerProvider;
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/// 状态
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MagneticSnapState get state => MagneticSnapState(_progress);
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void init(TickerProvider vsync) {
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_animationController = AnimationController(
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vsync: vsync,
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duration: const Duration(milliseconds: 300),
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);
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}
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@override
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void dispose() {
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_animationController?.dispose();
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super.dispose();
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}
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/// 更新滚动进度（在滚动时调用）
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void updateProgress(double newProgress) {
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if (_isSnapped) return;
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_progress = newProgress.clamp(0.0, 1.0);
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notifyListeners();
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}
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/// 处理松手事件
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void onDragEnd(double velocity) {
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if (_isSnapped) return;
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final threshold = 0.45; // 45% 触发吸附
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final shouldSnap = _progress > threshold || velocity > 800;
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if (shouldSnap) {
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snapOpen();
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} else {
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snapBack();
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}
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}
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/// 吸附展开
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void snapOpen() {
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if (_isSnapped) return;
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_isSnapped = true;
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_animationController?.reset();
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_animationController
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?.animateTo(
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1.0,
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duration: const Duration(milliseconds: 300),
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curve: Curves.easeOutBack,
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)
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.then((_) {
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_progress = 1.0;
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notifyListeners();
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});
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// 实时更新进度
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_animationController?.addListener(() {
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_progress = _animationController!.value;
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notifyListeners();
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});
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}
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/// 回弹
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void snapBack() {
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if (_isSnapped) return;
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_animationController?.reset();
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_animationController
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?.animateTo(
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0.0,
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duration: const Duration(milliseconds: 250),
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curve: Curves.easeOut,
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)
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.then((_) {
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_progress = 0.0;
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notifyListeners();
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});
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_animationController?.addListener(() {
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_progress = _animationController!.value;
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notifyListeners();
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});
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}
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/// 重置状态（退出页面时）
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void reset() {
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_isSnapped = false;
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_progress = 0.0;
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_animationController?.reset();
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notifyListeners();
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}
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}
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