VB中窗口不显示画线

tairuibao

上周五刚接触VB，连菜鸟都不算，现在做一个最小的系统，就是下位传上来6个字节，VB用line画出来。我知道一般用pic，但是现在涉及到项目的一些问题，得现在窗口上显示。代码如下：
Dim flagup
Private Sub Command1_Click()
MSComm1.PortOpen = Faule
Unload Me
End Sub
Private Sub Form_Load()
MSComm1.InBufferSize = 1024
MSComm1.OutBufferSize = 512
MSComm1.InputMode = comInputModeBinary
MSComm1.Settings = "9600,n,8,1"
MSComm1.RThreshold = 1
MSComm1.PortOpen = True
End Sub
Private Sub Form_Click()  '画坐标轴
    Dim X1 As Byte
     Dim X2 As Byte
      Dim Y1 As Byte
       Dim Y2 As Byte

End Sub
Private Sub shang_MouseDown(Button As Integer, Shift As Integer, X As Single, Y As Single)
    Dim receivelen As Integer
    ReDim numup(0) As Byte   '发送一个字节

    numup(0) = &H12
    MSComm1.Output = numup
Select Case MSComm1.CommEvent   '接收一个字节
    Case comEvReceive
    ReDim receivenum(40) As Byte
     receivelen = MSComm1.InBufferCount  '定义字符串长度
    receivenum = MSComm1.Input
'For i = 0 To i = 5 Step 1
'   Text1.Text = receivenum(4)
End Select

       Dim X1 As Byte
     Dim X2 As Byte
      Dim Y1 As Byte
       Dim Y2 As Byte
   Cls                                    '画坐标轴
Form1.Scale (-120, 120)-(120, -120)
Line (-100, -100)-(100, -100): Line (-100, -100)-(-100, 100)
CurrentX = 100: CurrentY = -95: Print "Time"
CurrentX = -95: CurrentY = 100: Print "Val"
CurrentX = -90: CurrentY = -90: Print "Start"
For i = -100 To 100 Step 5
   CurrentX = i: CurrentY = -95: Line -(i, -100)
   CurrentX = i - 5: CurrentY = -105: Print (i + 100) / 5
Next i
For i = -95 To 100 Step 5
   CurrentX = -95: CurrentY = i: Line -(-100, i)
   CurrentX = -108: CurrentY = i: Print (i + 100) / 5
Next i


   Line (-20, -20)-(60, 50) '测试，只显示一根直线

    ' For i = 0 To i = 4 Step 1         '绘图
     ' X1 = 5 * i - 95
     '  Y1 = 5 * receivenum(i) - 95
      'X2 = 5 * (i + 1) - 95
      '  Y2 = 5 * receivenum(i + 1) - 95

       'Line (X1, Y1)-(X2, Y2)
       'Next i
End Sub
能检测到VB的却接收了正确的数据，但是就是不能绘制。单单 Line (-20, -20)-(60, 50) 是可以有条线的，但是一进了for循环就不行了，还提示 X1 = 5 * i - 95这行溢出。请各位大侠帮我看看神马问题吧，现在只能在窗口显示，不能调用pic。谢谢~

lcw_swust

X1为BYTE型，不能为负数
窗体的autoredraw属性要设为true

marshallemon

上个图看看

cqfeiyu

自古二楼出真相

tairuibao

已经解决了，嘎嘎~