fix(player): 完善进度预览清屏与下拉刷新

lib/pages/player/widgets/feed_pull_refresh.dart

@@ -0,0 +1,180 @@
+// Author: fruit.com.cn
+
+import 'package:flutter/material.dart';
+
+import '../../../core/theme/app_colors.dart';
+import '../../../core/theme/app_dimens.dart';
+
+const double _maxPull = 96;
+const double _refreshThreshold = 56;
+const double _firstPageEpsilon = 0.01;
+
+/// 第一条已经到顶时，向下的拖动不再翻页。
+class FeedRefreshPhysics extends PageScrollPhysics {
+  const FeedRefreshPhysics({super.parent});
+
+  @override
+  FeedRefreshPhysics applyTo(ScrollPhysics? ancestor) {
+    return FeedRefreshPhysics(parent: buildParent(ancestor));
+  }
+
+  @override
+  double applyPhysicsToUserOffset(ScrollMetrics position, double offset) {
+    if (position.pixels <= position.minScrollExtent && offset > 0) {
+      return 0;
+    }
+    return super.applyPhysicsToUserOffset(position, offset);
+  }
+
+  @override
+  Simulation? createBallisticSimulation(
+    ScrollMetrics position,
+    double velocity,
+  ) {
+    if (position.pixels <= position.minScrollExtent && velocity < 0) {
+      return super.createBallisticSimulation(position, 0);
+    }
+    return super.createBallisticSimulation(position, velocity);
+  }
+}
+
+/// 竖滑到第一条后继续下拉时刷新，其它页仍交给翻页。
+class FeedPullRefresh extends StatefulWidget {
+  const FeedPullRefresh({
+    super.key,
+    required this.pageController,
+    required this.onRefresh,
+    required this.child,
+    this.topInset = 0,
+  });
+
+  final PageController pageController;
+  final Future<void> Function() onRefresh;
+  final Widget child;
+  final double topInset;
+
+  @override
+  State<FeedPullRefresh> createState() => _FeedPullRefreshState();
+}
+
+class _FeedPullRefreshState extends State<FeedPullRefresh> {
+  Offset? _origin;
+  double _pull = 0;
+  bool _tracking = false;
+  bool _refreshing = false;
+
+  bool _atFirstPage() {
+    final controller = widget.pageController;
+    if (!controller.hasClients) return false;
+    return (controller.page ?? 0) <= _firstPageEpsilon;
+  }
+
+  void _setPull(double value) {
+    final next = value.clamp(0.0, _maxPull);
+    if (next == _pull) return;
+    setState(() => _pull = next);
+  }
+
+  void _onPointerDown(PointerDownEvent event) {
+    if (_refreshing || !_atFirstPage()) {
+      _tracking = false;
+      return;
+    }
+    _origin = event.position;
+    _tracking = true;
+  }
+
+  void _onPointerMove(PointerMoveEvent event) {
+    final origin = _origin;
+    if (!_tracking || origin == null || _refreshing) return;
+    final delta = event.position - origin;
+    if (delta.dx.abs() > delta.dy.abs() && delta.dy < _refreshThreshold) {
+      _tracking = false;
+      _setPull(0);
+      return;
+    }
+    if (delta.dy > 0) _holdFirstPage();
+    _setPull(delta.dy);
+  }
+
+  void _holdFirstPage() {
+    final controller = widget.pageController;
+    if (!controller.hasClients) return;
+    final position = controller.position;
+    if (position.pixels <= position.minScrollExtent) return;
+    controller.jumpTo(position.minScrollExtent);
+  }
+
+  void _onPointerEnd() {
+    final shouldRefresh = _tracking && _pull >= _refreshThreshold;
+    _origin = null;
+    _tracking = false;
+    if (shouldRefresh) {
+      _refresh();
+      return;
+    }
+    _setPull(0);
+  }
+
+  Future<void> _refresh() async {
+    if (_refreshing) return;
+    _refreshing = true;
+    _setPull(_refreshThreshold);
+    try {
+      await widget.onRefresh();
+    } finally {
+      _refreshing = false;
+      if (mounted) _setPull(0);
+    }
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Listener(
+      onPointerDown: _onPointerDown,
+      onPointerMove: _onPointerMove,
+      onPointerUp: (_) => _onPointerEnd(),
+      onPointerCancel: (_) => _onPointerEnd(),
+      child: Stack(
+        fit: StackFit.expand,
+        children: [
+          widget.child,
+          if (_pull > 0)
+            Positioned(
+              top: widget.topInset,
+              left: 0,
+              right: 0,
+              child: IgnorePointer(
+                child: Align(
+                  alignment: Alignment.topCenter,
+                  child: Container(
+                    key: const Key('pull-refresh-indicator'),
+                    width: AppDimens.refreshIndicatorSize,
+                    height: AppDimens.refreshIndicatorSize,
+                    padding: const EdgeInsets.all(
+                      (AppDimens.refreshIndicatorSize -
+                              AppDimens.refreshSpinnerSize) /
+                          2,
+                    ),
+                    decoration: BoxDecoration(
+                      color: AppColors.refreshIndicatorSurface,
+                      borderRadius: BorderRadius.circular(
+                        AppDimens.refreshIndicatorRadius,
+                      ),
+                    ),
+                    child: const SizedBox.square(
+                      dimension: AppDimens.refreshSpinnerSize,
+                      child: CircularProgressIndicator(
+                        strokeWidth: AppDimens.refreshSpinnerStroke,
+                        color: AppColors.textPrimary,
+                      ),
+                    ),
+                  ),
+                ),
+              ),
+            ),
+        ],
+      ),
+    );
+  }
+}