Adding a shadow effect to a folder-shaped container with Flutter

Question

I'm making a folder-shaped container component in Flutter.

I am using the code below to create a folder-shaped container and give it a shadow effect. (I got some help from Stack Overflow.)

I want to give a natural shadow effect like the image above. The shadow effect I made is so ugly.

Below I'll show you the shadow effect I made. I want it to be as natural as the shadow effect of the text field below it.

I tried various methods, but I can't make natural shadows like the image above. I am so lacking.

help me.

Column(
                children: [
                  SizedBox(
                    height: 50,
                  ),
                  ClipPath(
                    clipper: FolderShapeClipper(),
                    child: Card(
                      elevation: 0,
                      shape: RoundedRectangleBorder(
                          borderRadius: BorderRadius.circular(2)),
                      child: Container(
                        width: 274,
                        height: 188,
                        decoration: FolderShapeDecoration(
                          shadowColor: Color.fromRGBO(0, 0, 0, 0.2),
                          shadowBlurRadius: 5,
                          shadowOffset: Offset(-2, -2),
                        ),
                        child: Column(
                          mainAxisAlignment:
                              MainAxisAlignment.spaceAround,
                          children: [
                            const SizedBox(
                              height: 12,
                            ),
                            Padding(
                              padding: const EdgeInsets.symmetric(
                                  horizontal: 24),
                              child: Row(
                                mainAxisAlignment:
                                    MainAxisAlignment.spaceBetween,
                                children: const [
                                  Text('test'),
                                  Icon(Icons.star),
                                ],
                              ),
                            ),
                            Padding(
                              padding: const EdgeInsets.symmetric(
                                  horizontal: 24),
                              child: Row(
                                mainAxisAlignment:
                                    MainAxisAlignment.spaceBetween,
                                children: const [
                                  Text('count'),
                                  Text('10'),
                                ],
                              ),
                            ),
                          ],
                        ),
                      ),
                    ),
                  ),
                ],
              ),

class FolderShapeClipper extends CustomClipper<Path> {
final a = 0.10;
final b = 0.25;
final c = 0.5;
@override
Path getClip(Size size) {
return Path()
..moveTo(size.width * a, 0)
..lineTo(0, size.height * b)
..lineTo(0, size.height)
..lineTo(size.width, size.height)
..lineTo(size.width, size.height * b)
..lineTo(size.width * c, size.height * b)
..lineTo(size.width * c, 0)
..lineTo(size.width * a, 0)
..close();
} 

@override
bool shouldReclip(covariant CustomClipper<Path> oldClipper) {
return true;
 }
}

class FolderShapeDecoration extends BoxDecoration {
final Color shadowColor;
final double shadowBlurRadius;
final Offset shadowOffset;

 FolderShapeDecoration({
required this.shadowColor,
required this.shadowBlurRadius,
required this.shadowOffset,
});

 @override
BoxPainter createBoxPainter([VoidCallback? onChanged]) {
return _FolderShapeBoxPainter(
shadowColor: shadowColor,
shadowBlurRadius: shadowBlurRadius,
shadowOffset: shadowOffset);
 }
}

 class _FolderShapeBoxPainter extends BoxPainter {
 final Color shadowColor;
 final double shadowBlurRadius;
 final Offset shadowOffset;
 final FolderShapeClipper clipper = FolderShapeClipper();

 _FolderShapeBoxPainter({
 required this.shadowColor,
 required this.shadowBlurRadius,
 required this.shadowOffset,
 });

 @override
 void paint(Canvas canvas, Offset offset, ImageConfiguration configuration) {
 final size = configuration.size!;
 final borderPath = clipper.getClip(size);

 final shadowPaint = Paint()
 ..color = shadowColor
 ..maskFilter = MaskFilter.blur(BlurStyle.outer, shadowBlurRadius);

 canvas.drawPath(borderPath.shift(offset + shadowOffset), shadowPaint);
 }
}