refactor(mobile): widgets (#9291)

* refactor(mobile): widgets

* update

mobile/lib/widgets/asset_viewer/animated_play_pause.dart

@@ -0,0 +1,57 @@
+import 'package:flutter/material.dart';
+
+/// A widget that animates implicitly between a play and a pause icon.
+class AnimatedPlayPause extends StatefulWidget {
+  const AnimatedPlayPause({
+    super.key,
+    required this.playing,
+    this.size,
+    this.color,
+  });
+
+  final double? size;
+  final bool playing;
+  final Color? color;
+
+  @override
+  State<StatefulWidget> createState() => AnimatedPlayPauseState();
+}
+
+class AnimatedPlayPauseState extends State<AnimatedPlayPause>
+    with SingleTickerProviderStateMixin {
+  late final animationController = AnimationController(
+    vsync: this,
+    value: widget.playing ? 1 : 0,
+    duration: const Duration(milliseconds: 300),
+  );
+
+  @override
+  void didUpdateWidget(AnimatedPlayPause oldWidget) {
+    super.didUpdateWidget(oldWidget);
+    if (widget.playing != oldWidget.playing) {
+      if (widget.playing) {
+        animationController.forward();
+      } else {
+        animationController.reverse();
+      }
+    }
+  }
+
+  @override
+  void dispose() {
+    animationController.dispose();
+    super.dispose();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Center(
+      child: AnimatedIcon(
+        color: widget.color,
+        size: widget.size,
+        icon: AnimatedIcons.play_pause,
+        progress: animationController,
+      ),
+    );
+  }
+}