FEAT: Highlight any widget with small configuration

example/lib/main.dart

@@ -34,6 +34,8 @@ class _MyHomePageState extends State<MyHomePage> {
       appBar: AppBar(),
       body: Center(
         child: FlutterHighlight(
+          duration: Duration(milliseconds: 500),
+          color: Theme.of(context).colorScheme.primary,
           child: Column(
             crossAxisAlignment: CrossAxisAlignment.start,
             children: <Widget>[

lib/flutter_highlight.dart

@@ -1,11 +1,157 @@
 import 'package:flutter/material.dart';
+import 'package:flutter/rendering.dart';
 
-class FlutterHighlight extends StatelessWidget {
+@immutable
+class FlutterHighlight extends StatefulWidget {
+  final Duration duration;
+  final int blinkNumber;
+  final Color? color;
   final Widget child;
-  const FlutterHighlight({super.key, required this.child});
+
+  const FlutterHighlight({
+    super.key,
+    required this.duration,
+    this.blinkNumber = 3,
+    this.color,
+    required this.child,
+  });
+
+  @override
+  State<FlutterHighlight> createState() => _FlutterHighlightState();
+}
+
+class _FlutterHighlightState extends State<FlutterHighlight>
+    with SingleTickerProviderStateMixin {
+  late AnimationController _animationController;
+
+  Future<void> _runAnimation() async {
+    int count = 0;
+    while (count < widget.blinkNumber) {
+      await _animationController.forward();
+      await _animationController.reverse();
+      count++;
+    }
+  }
+
+  @override
+  void initState() {
+    super.initState();
+    _animationController = AnimationController(
+      vsync: this,
+      duration: widget.duration,
+      upperBound: 0.6,
+    );
+    _runAnimation();
+  }
+
+  @override
+  void dispose() {
+    _animationController.dispose();
+    super.dispose();
+  }
 
   @override
   Widget build(BuildContext context) {
-    return child;
+    return AnimatedBuilder(
+      animation: _animationController,
+      builder: (context, child) {
+        return _FlutterHighlightRender(
+          percent: _animationController.value,
+          color: widget.color ?? Theme.of(context).colorScheme.surface,
+          child: child,
+        );
+      },
+      child: widget.child,
+    );
+  }
+}
+
+/// ----------------------------------------------------------------------------
+
+@immutable
+class _FlutterHighlightRender extends SingleChildRenderObjectWidget {
+  final double percent;
+  final Color color;
+
+  const _FlutterHighlightRender({
+    required this.percent,
+    required this.color,
+    required super.child,
+  });
+
+  @override
+  _FlutterHighlightFilter createRenderObject(BuildContext context) {
+    return _FlutterHighlightFilter(percent, color);
+  }
+
+  @override
+  void updateRenderObject(
+    BuildContext context,
+    _FlutterHighlightFilter filter,
+  ) {
+    filter.percent = percent;
+    filter.color = color;
+  }
+}
+
+/// ----------------------------------------------------------------------------
+
+class _FlutterHighlightFilter extends RenderProxyBox {
+  double _percent;
+  Color _color;
+
+  _FlutterHighlightFilter(this._percent, this._color);
+
+  @override
+  ShaderMaskLayer? get layer => super.layer as ShaderMaskLayer?;
+
+  @override
+  bool get alwaysNeedsCompositing => child != null;
+
+  set percent(double newValue) {
+    if (newValue == _percent) return;
+    _percent = newValue;
+    markNeedsPaint();
+  }
+
+  set color(Color newValue) {
+    if (newValue == _color) return;
+    _color = newValue;
+    markNeedsPaint();
+  }
+
+  double _offset(double start, double end, double percent) {
+    return start + (end - start) * percent;
+  }
+
+  @override
+  void paint(PaintingContext context, Offset offset) {
+    if (child != null) {
+      final double width = child!.size.width;
+      final double height = child!.size.height;
+
+      Rect rect;
+      double dx, dy;
+
+      dx = _offset(-width, width, 1);
+      dy = 0.0;
+      rect = Rect.fromLTWH(dx - width, dy, 3 * width, height);
+
+      layer ??= ShaderMaskLayer();
+      layer!
+        ..shader = LinearGradient(
+          begin: Alignment.centerLeft,
+          end: Alignment.centerRight,
+          colors: [
+            _color.withValues(alpha: _percent),
+            _color.withValues(alpha: _percent),
+          ],
+        ).createShader(rect)
+        ..maskRect = offset & size
+        ..blendMode = BlendMode.srcATop;
+      context.pushLayer(layer!, super.paint, offset);
+    } else {
+      layer = null;
+    }
   }
 }