mod: 视频详情、跳转Hero效果

lib/pages/video/detail/widgets/expandable_section.dart

@@ -0,0 +1,83 @@
+import 'package:flutter/material.dart';
+
+class ExpandedSection extends StatefulWidget {
+  final Widget child;
+  final bool expand;
+  double begin = 0.0;
+  double end = 1.0;
+
+  ExpandedSection(
+      {this.expand = false,
+      required this.child,
+      required this.begin,
+      required this.end});
+
+  @override
+  _ExpandedSectionState createState() => _ExpandedSectionState();
+}
+
+class _ExpandedSectionState extends State<ExpandedSection>
+    with SingleTickerProviderStateMixin {
+  late AnimationController expandController;
+  late Animation<double> animation;
+
+  @override
+  void initState() {
+    super.initState();
+    prepareAnimations();
+    _runExpandCheck();
+  }
+
+  ///Setting up the animation
+  // void prepareAnimations() {
+  //   expandController = AnimationController(
+  //       vsync: this, duration: const Duration(milliseconds: 500));
+  //   animation = CurvedAnimation(
+  //     parent: expandController,
+  //     curve: Curves.fastOutSlowIn,
+  //   );
+  // }
+
+  void prepareAnimations() {
+    expandController = AnimationController(
+        vsync: this, duration: const Duration(milliseconds: 400));
+    Animation<double> curve = CurvedAnimation(
+      parent: expandController,
+      curve: Curves.fastOutSlowIn,
+    );
+    animation = Tween(begin: widget.begin, end: widget.end).animate(curve);
+    //   animation = CurvedAnimation(
+    //     parent: expandController,
+    //     curve: Curves.fastOutSlowIn,
+    //   );
+  }
+
+  void _runExpandCheck() {
+    if (widget.expand) {
+      expandController.forward();
+    } else {
+      expandController.reverse();
+    }
+  }
+
+  @override
+  void didUpdateWidget(ExpandedSection oldWidget) {
+    super.didUpdateWidget(oldWidget);
+    _runExpandCheck();
+  }
+
+  @override
+  void dispose() {
+    expandController.dispose();
+    super.dispose();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return SizeTransition(
+      axisAlignment: -1.0,
+      sizeFactor: animation,
+      child: widget.child,
+    );
+  }
+}