points=[] point = QgsPoint() point.setX(10) point.setY(10) points.append(point) point = QgsPoint() point.setX(30) point.setY(20) points.append(point) line = QgsLineString() line.setPoints(points) point = QgsPoint() point.setX(15) point.setY(10) p = QgsGeometryUtils.closestPoint(line, point) p <QgsPoint: Point (14 12)>