             openChevron()
             postNotification(streamCellDidOpenNotification, self)
         } else {
-            var angle: CGFloat = CGFloat(M_PI) * scrollView.contentOffset.x / revealWidth
+            var angle: CGFloat = -CGFloat(M_PI) + CGFloat(M_PI) * scrollView.contentOffset.x / revealWidth
             rotateChevron(angle)
             isOpen = false
         }

    }

    private func rotateChevron(var angle: CGFloat) {
        if angle < 0 {
            angle = 0
        }
        else if angle > CGFloat(M_PI) {
            angle = CGFloat(M_PI)


    private func openChevron(isOpen: Bool = true) {
        if isOpen {
            rotateChevron(0)
        }
        else {
            rotateChevron(CGFloat(M_PI))
        }
    }

