How to make rounded-perpendicular lines with react-konva?

Question

I need to make rounded-perpendicular lines with react-konva, is it achievable using existing APIs? If yes, how?

I used bezier API for Line class, it works great. Somehow now I need to revamp the bezier curve to be rounded-perpendicular lines.

Sth like this:

Answer 1

There are many ways you can implement it. You can use tension to create curved lines or use lineCap property.

But to have more control it is better to create a custom shape.

const RADIUS = 20;

const Line = ({ points }) => {
  return (
    <Shape
      points={points}
      sceneFunc={(context, shape) => {
        const width = points[1].x - points[0].x;
        const height = points[1].y - points[0].y;
        const dir = Math.sign(height);
        const radius = Math.min(RADIUS, Math.abs(height / 2), Math.abs(width / 2));

        context.beginPath();
        context.moveTo(points[0].x, points[0].y);
        context.lineTo(points[0].x + width / 2 - RADIUS, points[0].y);
        context.quadraticCurveTo(
          points[0].x + width / 2,
          points[0].y,
          points[0].x + width / 2,
          points[0].y + dir * radius
        );
        context.lineTo(points[0].x + width / 2, points[1].y - dir * radius);
        context.quadraticCurveTo(
          points[0].x + width / 2,
          points[1].y,
          points[0].x + width / 2 + radius,
          points[1].y
        );
        context.lineTo(points[1].x, points[1].y);
        context.fillStrokeShape(shape);
      }}
      stroke="black"
      strokeWidth={2}
    />
  );
};

Demo: https://codesandbox.io/s/757nw05p6