title: How to add a neon glow effect to an widget border / shadow?
body: <p>Is there any way to create effects like these using flutter (a CustomPaint with a special shadder or something like this)?</p>
  
  <p><img src="https://i.stack.imgur.com/gBsnj.jpg" alt="enter image description here"></p>
  
  <p><img src="https://i.stack.imgur.com/9HKS4.jpg" alt="enter image description here"></p>
  
  <p>For example. I have this container and I drew some lines on it using a CustomPainter. Could I draw these lines using a neon effect just like the pictures? The Paint class has a shader property that I thought I could set up to achieve this goal, but I don't realize how. </p>
  
  <pre><code>Container(
            color: Colors.white,
            width: 300,
            height: 300,
            child: CustomPaint(
              painter: NeonPainter(),
  
            ),
  
  
          ),
  
  
  
  class NeonPainter extends CustomPainter {
    Paint neonPaint = Paint();
  
  
    NeonPainter() {
      neonPaint.color = const Color(0xFF3F5BFA);
      neonPaint.strokeWidth = 2.5;
      neonPaint.shader = /// how to create a shader or something for that?
      neonPaint.someOtherProperty///
  
    }
  
    @override
    void paint(Canvas canvas, Size size) {
      drawLine(canvas, size.width / 2 - 50, size.height / 2, size.width / 2 + 50,
          size.height / 2);
      drawLine(canvas, size.width / 2 + 50, size.height / 2, size.width / 2 + 100,
          size.height / 2 + 50);
      drawLine(canvas, size.width / 2 + 100, size.height / 2 + 50,
          size.width / 2 - 100, size.height / 2 + 50);
      drawLine(
          canvas, size.width / 2 - 100, size.height / 2 + 50, size.width / 2 - 50,
          size.height / 2);
    }
  
    void drawLine(canvas, double x1, double y1, double x2, double y2) {
      canvas.drawLine(Offset(x1, y1), Offset(x2, y2), neonPaint);
    }
  
    @override
    bool shouldRepaint(CustomPainter oldDelegate) {
      return true;
    }
  }
  </code></pre>