I have an array of coordinates [x1,y1, x2, y2 ....] which represents a polygon on a html canvas. I am drawing the polygon using KonvaJS. I am trying to retrieve the scaled coordinates for the polygon where [x1, y1, x2, y2 ...] is the scaled coordinates.

I have tried the following:

1. Using JSTS https://github.com/bjornharrtell/jsts to add buffer to the coordinates. Followed this snippet http://jsfiddle.net/qdv1n4yL/7/ and tried in integrate into my react/typescript app and created the snippet as shown below function vectorCoordinates2JTS (polygon) { var coordinates: any = [];

   for (var i = 0; i < polygon.length; i++) {
       coordinates.push(new Coordinate(polygon[i].x, polygon[i].y));
   }
   return coordinates;
   }
   
   function inflatePolygon(poly, spacing) {
       var geoInput = vectorCoordinates2JTS(poly);
       geoInput.push(geoInput[0]);
   
       var geometryFactory = new GeometryFactory();
   
       var shell = geometryFactory.createPolygon(geoInput);
       var polygon = new BufferOp(poly);
       console.log(polygon.getResultGeometry())
   
       var inflatedCoordinates: any = [];
       var oCoordinates;
       oCoordinates = polygon.shell.points.coordinates;
       console.log(oCoordinates.length)
       for (let i = 0; i < oCoordinates.length; i++) {
           var oItem;
           oItem = oCoordinates[i];
           inflatedCoordinates.push(Math.ceil(oItem.x), Math.ceil(oItem.y));
       }
       return inflatedCoordinates;
   }
   

Here I am passing poly as [{x: 1, y:1}, {x:2, y:2}] and spacing as 1.5. It breaks on this line here polygon.getResultGeometry() with an error.

2. Also tried using this library to get the transformed coordinates http://turfjs.org/docs/#transformScale but it returns me a bunch of coordinates which i cant seem to use and get my end result as just a simple list of scaled coordinates.

My overall requirements for solving this problem is the polygon should have a cushioning like buffer around the original polygon which can be used to detect collision. I was able to get the collision detection between the polygon and a point working but been stuck on adding the scale/buffer for the past few days. Any help or follow up questions to this problem is highly appreciated. Thanks!