link graphics

procedure main()
    s := "Hello World! "
    WOpen("size=640,400", "label=Animation")
    Font("typewriter,60,bold")
    direction := 1
    w := TextWidth(s)
    h := WAttrib("fheight")
    x := (WAttrib("width") - w) / 2
    y := (WAttrib("height") - 20 + h) / 2

    repeat
    {   if *Pending() > 0 then if (Event() = &lrelease) & (x < &x < x + w) & (y > &y > y-h) then direction := ixor(direction, 1)
        s := s[2 - 3 * direction:0] || s[1:2 - 3 * direction]
        EraseArea(x, y, w, -h)
        DrawString(x,y - WAttrib("descent")-1,s)
        WFlush()
        delay(250)
    }
end