code: function render(context, xyPoints, map, canvasFeature) {
      ctx = context;
      
      if( canvasFeature.type === 'Point' ) {
          renderPoint(xyPoints, this.size);
      } else if( canvasFeature.type === 'LineString' ) {
          renderLine(xyPoints);
      } else if( canvasFeature.type === 'Polygon' ) {
          renderPolygon(xyPoints);
      } else if( canvasFeature.type === 'MultiPolygon' ) {
          xyPoints.forEach(renderPolygon);
      }
  }
docs: Fuction called in scope of CanvasFeature