Initial commit

lib/widgets/pulsating_widget.dart

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+// SPDX-FileCopyrightText: 2019-Present Christian Kußowski
+// SPDX-FileCopyrightText: 2019-Present Contributors to FluffyChat
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+import 'package:flutter/material.dart';
+
+class PulsatingWidget extends StatefulWidget {
+  final Color color;
+  final Widget child;
+  final double spreadRadius;
+  const PulsatingWidget({
+    required this.child,
+    this.color = Colors.red,
+    this.spreadRadius = 1.0,
+    super.key,
+  });
+
+  @override
+  State<PulsatingWidget> createState() => _PulsatingWidgetState();
+}
+
+/// [AnimationController]s can be created with `vsync: this` because of
+/// [TickerProviderStateMixin].
+class _PulsatingWidgetState extends State<PulsatingWidget>
+    with TickerProviderStateMixin {
+  late final DecorationTween decorationTween = DecorationTween(
+    begin: BoxDecoration(
+      borderRadius: BorderRadius.circular(128),
+      boxShadow: <BoxShadow>[
+        BoxShadow(
+          color: widget.color.withAlpha(16),
+          blurRadius: 0.0,
+          spreadRadius: 0.0,
+        ),
+      ],
+    ),
+    end: BoxDecoration(
+      borderRadius: BorderRadius.circular(128),
+      boxShadow: <BoxShadow>[
+        BoxShadow(
+          color: widget.color.withAlpha(128),
+          blurRadius: 0.0,
+          spreadRadius: widget.spreadRadius,
+        ),
+      ],
+    ),
+  );
+
+  late final AnimationController _controller = AnimationController(
+    vsync: this,
+    duration: const Duration(seconds: 2),
+  )..repeat(reverse: true);
+
+  @override
+  void dispose() {
+    _controller.dispose();
+    super.dispose();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    if (MediaQuery.disableAnimationsOf(context)) return widget.child;
+    return DecoratedBoxTransition(
+      decoration: decorationTween.animate(_controller),
+      child: widget.child,
+    );
+  }
+}