code: function(scale, canvasSize, sketchCanvasSize) {
          // The translation vector must have positive values, otherwise the image goes a bit off
          // the sketch canvas to the top and left and we must use negative coordinates to repaint it
          // to the main canvas. In that case, some browsers throw:
          // INDEX_SIZE_ERR: DOM Exception 1: Index or size was negative, or greater than the allowed value.
          var x = Math.max(1, Math.ceil((sketchCanvasSize.x - canvasSize.x) / 2));
          var y = Math.max(1, Math.ceil((sketchCanvasSize.y - canvasSize.y) / 2));
          return new $.Point(x, y).minus(
              this.position
                  .times($.pixelDensityRatio)
                  .times(scale || 1)
                  .apply(function(x) {
                      return x % 1;
                  })
          );
      }
docs: Get a translation vector that when applied to the tile position produces integer coordinates.
  Needed to avoid swimming and twitching.
  @function
  @param {Number} [scale=1] - Scale to be applied to position.
  @return {OpenSeadragon.Point}