paper.paperToLocalPoint(p)

Transform the point p defined in the paper coordinate system to the local coordinate system.

var paperCenter = g.Point(paper.options.width / 2, paper.options.height / 2);
var localPoint1 = paper.paperToLocalPoint(paperCenter);
 // alternative method signature
var localPoint2 = paper.paperToLocalPoint(paper.options.width / 2, paper.options.height / 2);
// Move the element to the center of the paper viewport.
var elSize = element.size();
element.position(localPoint1.x - elSize.width, localPoint1.y - elSize.height);