opt: 视频详情页appbar下滑动画

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

@@ -0,0 +1,64 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_meedu_media_kit/meedu_player.dart';
+
+class ScrollAppBar extends StatelessWidget {
+  final double scrollVal;
+  Function callback;
+  final PlayerStatus playerStatus;
+
+  ScrollAppBar(
+    this.scrollVal,
+    this.callback,
+    this.playerStatus,
+  );
+
+  @override
+  Widget build(BuildContext context) {
+    final double statusBarHeight = MediaQuery.of(context).padding.top;
+    final videoHeight = MediaQuery.of(context).size.width * 9 / 16;
+    return Positioned(
+      top: -videoHeight + scrollVal + kToolbarHeight + 0.5,
+      left: 0,
+      right: 0,
+      child: Opacity(
+        opacity: scrollVal / (videoHeight - kToolbarHeight),
+        child: Container(
+          height: statusBarHeight + kToolbarHeight,
+          color: Theme.of(context).colorScheme.background,
+          padding: EdgeInsets.only(top: statusBarHeight),
+          child: AppBar(
+            primary: false,
+            elevation: 0,
+            scrolledUnderElevation: 0,
+            centerTitle: true,
+            title: TextButton(
+              onPressed: () => callback(),
+              child: Row(
+                mainAxisSize: MainAxisSize.min,
+                children: [
+                  const Icon(Icons.play_arrow_rounded),
+                  Text(
+                    playerStatus == PlayerStatus.paused
+                        ? '继续播放'
+                        : playerStatus == PlayerStatus.completed
+                            ? '重新播放'
+                            : '播放中',
+                  )
+                ],
+              ),
+            ),
+            actions: [
+              IconButton(
+                  onPressed: () {},
+                  icon: const Icon(
+                    Icons.share,
+                    size: 20,
+                  )),
+              const SizedBox(width: 12)
+            ],
+          ),
+        ),
+      ),
+    );
+  }
+}