code: function PageViewport_convertToViewportRectangle(rect) {
        var tl = Util.applyTransform([rect[0], rect[1]], this.transform);
        var br = Util.applyTransform([rect[2], rect[3]], this.transform);
        return [tl[0], tl[1], br[0], br[1]];
      }
docs: Converts PDF rectangle to the viewport coordinates.
  @param rect {Array} xMin, yMin, xMax and yMax coordinates.
  @returns {Array} Contains corresponding coordinates of the rectangle
  in the viewport coordinate space.
  @see {@link convertToViewportPoint}