title: VNC demo have some black Lines
body: <p>I wanna to build a VNC client project in iPad,but when i'm using NPDeskTop demo ,i found that when the picture changes, the screen on iPad maybe show some black lines. I want to know how to fix it.
  Here is the demo adress: <a href="https://github.com/leonliu/NPDesktop" rel="nofollow noreferrer">enter link description here</a></p>