Function _getCenterValue

docs/app/js/sanddance-app.js:31771–31774

* Returns the middle value of an edge. Only returns 1 value rather than xy coordinates as * the itself already contains the other coordinate. * For instance, a bottom edge's current value is it's y coordinate, so the number returned is the x.

(rect, edge)

 * the itself already contains the other coordinate.
 * For instance, a bottom edge's current value is it's y coordinate, so the number returned is the x.
 */ function _getCenterValue(rect, edge) {
    var edges = _getFlankingEdges(edge);
    return (_getEdgeValue(rect, edges.positiveEdge) + _getEdgeValue(rect, edges.negativeEdge)) / 2;
}
/**
 * Flips the value depending on the edge.
 * If the edge is a "positive" edge, Top or Left, then the value should stay as it is.