feat(ui): 下拉刷新完成后才回弹

lib/core/widgets/app_pull_to_refresh.dart

@@ -9,10 +9,11 @@ import '../theme/app_colors.dart';
 
 const double _maxPullDistance = 96;
 const double _refreshThreshold = 56;
-const double _indicatorHeight = 64;
+const double _holdDistance = 56;
+const double _indicatorHeight = 56;
 const double _indicatorMaxOffset = 10;
 const Duration _arrowTurnDuration = Duration(milliseconds: 160);
-const Duration _retractDuration = Duration(milliseconds: 200);
+const Duration _settleDuration = Duration(milliseconds: 200);
 
 enum _PullState { idle, pull, armed, refreshing }
 
@@ -26,7 +27,7 @@ class AppPullToRefresh extends StatefulWidget {
   });
 
   static const AlwaysScrollableScrollPhysics physics =
-      AlwaysScrollableScrollPhysics(parent: BouncingScrollPhysics());
+      AlwaysScrollableScrollPhysics(parent: ClampingScrollPhysics());
 
   final Widget child;
   final Future<void> Function() onRefresh;
@@ -36,11 +37,28 @@ class AppPullToRefresh extends StatefulWidget {
   State<AppPullToRefresh> createState() => _AppPullToRefreshState();
 }
 
-class _AppPullToRefreshState extends State<AppPullToRefresh> {
+class _AppPullToRefreshState extends State<AppPullToRefresh>
+    with SingleTickerProviderStateMixin {
+  late final AnimationController _offsetController;
   _PullState _state = _PullState.idle;
-  double _pullDistance = 0;
   bool _refreshing = false;
 
+  @override
+  void initState() {
+    super.initState();
+    _offsetController = AnimationController(
+      vsync: this,
+      duration: _settleDuration,
+      upperBound: _maxPullDistance,
+    );
+  }
+
+  @override
+  void dispose() {
+    _offsetController.dispose();
+    super.dispose();
+  }
+
   bool _onScroll(ScrollNotification notification) {
     if (notification.depth != 0 || _refreshing) return false;
     if (notification is ScrollStartNotification) {
@@ -53,7 +71,7 @@ class _AppPullToRefreshState extends State<AppPullToRefresh> {
       }
     } else if (notification is OverscrollNotification) {
       if (notification.dragDetails != null) {
-        _setPullDistance(_pullDistance - notification.overscroll);
+        _setPullDistance(_offsetController.value - notification.overscroll);
       }
     } else if (notification is ScrollEndNotification) {
       _release();
@@ -68,19 +86,17 @@ class _AppPullToRefreshState extends State<AppPullToRefresh> {
         : distance > 0
         ? _PullState.pull
         : _PullState.idle;
-    if (distance == _pullDistance && state == _state) return;
-    setState(() {
-      _pullDistance = distance;
-      _state = state;
-    });
+    _offsetController.value = distance;
+    if (state != _state) setState(() => _state = state);
   }
 
   void _release() {
+    if (_refreshing) return;
     if (_state == _PullState.armed) {
       unawaited(_refresh());
     } else if (_state == _PullState.pull) {
+      _offsetController.value = 0;
       setState(() {
-        _pullDistance = 0;
         _state = _PullState.idle;
       });
     }
@@ -90,53 +106,74 @@ class _AppPullToRefreshState extends State<AppPullToRefresh> {
     if (_refreshing) return;
     _refreshing = true;
     setState(() => _state = _PullState.refreshing);
+    final refreshFuture = Future<void>.sync(widget.onRefresh);
     try {
-      await widget.onRefresh();
+      await _animateOffsetTo(_holdDistance);
+      await refreshFuture;
     } finally {
-      await Future<void>.delayed(_retractDuration);
       if (mounted) {
-        setState(() {
-          _pullDistance = 0;
-          _state = _PullState.idle;
-          _refreshing = false;
-        });
+        await _animateOffsetTo(0);
+        if (mounted) {
+          setState(() {
+            _state = _PullState.idle;
+            _refreshing = false;
+          });
+        }
       }
     }
   }
 
+  Future<void> _animateOffsetTo(double target) async {
+    try {
+      await _offsetController
+          .animateTo(target, duration: _settleDuration, curve: Curves.easeOut)
+          .orCancel;
+    } on TickerCanceled {
+      // The overlay can be removed while the refresh future is still pending.
+    }
+  }
+
   @override
   Widget build(BuildContext context) {
     return NotificationListener<ScrollNotification>(
       onNotification: _onScroll,
-      child: Stack(
-        fit: StackFit.expand,
-        children: [
-          Listener(
-            onPointerUp: (_) => _release(),
-            onPointerCancel: (_) => _release(),
-            child: widget.child,
-          ),
-          if (_state != _PullState.idle)
-            Positioned(
-              top: widget.edgeOffset,
-              left: 0,
-              right: 0,
-              child: IgnorePointer(child: _indicatorLayer(context)),
-            ),
-        ],
+      child: AnimatedBuilder(
+        animation: _offsetController,
+        child: Listener(
+          onPointerUp: (_) => _release(),
+          onPointerCancel: (_) => _release(),
+          child: widget.child,
+        ),
+        builder: (context, child) {
+          final offset = _offsetController.value;
+          return Stack(
+            fit: StackFit.expand,
+            children: [
+              Transform.translate(
+                key: const Key('pull-refresh-content'),
+                offset: Offset(0, offset),
+                child: IgnorePointer(ignoring: _refreshing, child: child),
+              ),
+              if (_state != _PullState.idle && offset > 0)
+                Positioned(
+                  top: widget.edgeOffset,
+                  left: 0,
+                  right: 0,
+                  child: IgnorePointer(child: _indicatorLayer(context, offset)),
+                ),
+            ],
+          );
+        },
       ),
     );
   }
 
-  Widget _indicatorLayer(BuildContext context) {
-    final progress = (_pullDistance / _refreshThreshold).clamp(0.0, 1.0);
-    final opacity = _state == _PullState.refreshing
-        ? 1.0
-        : progress.clamp(0.0, 1.0);
+  Widget _indicatorLayer(BuildContext context, double offset) {
+    final progress = (offset / _refreshThreshold).clamp(0.0, 1.0);
     return SizedBox(
       height: _indicatorHeight,
       child: Opacity(
-        opacity: opacity,
+        opacity: progress,
         child: Transform.translate(
           offset: Offset(0, _indicatorMaxOffset * progress),
           child: Align(