我想实现在运行后，用鼠标点击a点或b点拖动，能使对应的直线可以上下左右移动。

我是个初学者，还不懂，又着急用，请求高人给编写代码。请专家伸出援助之手，感激不尽，万分感谢！！

Option Explicit

Private Type 坐标类型
   X As Integer
   Y As Integer
End Type

Dim A As 坐标类型
Dim B As 坐标类型

Dim MD As Integer
'MD ,鼠标状态
'=0 ,无操作，1=拖动A，2=拖动B

Private Sub Form_Load()

MD = 0

A.X = 500
A.Y = 500
B.X = 2000
B.Y = 2000


End Sub

Private Sub Form_MouseDown(Button As Integer, Shift As Integer, X As Single, Y As Single)

If Button = 1 Then
    If Abs(X - A.X) < 75 And Abs(Y - A.Y) < 75 Then
        MD = 1
        Me.MousePointer = vbSizeAll
    ElseIf Abs(X - B.X) < 75 And Abs(Y - B.Y) < 75 Then
        MD = 2
        Me.MousePointer = vbSizeAll
     Else
        Me.MousePointer = vbDefault
    End If
Else
    Me.MousePointer = vbDefault
End If

End Sub

Private Sub Form_MouseMove(Button As Integer, Shift As Integer, X As Single, Y As Single)
    If MD = 1 Then
        A.X = X
        A.Y = Y
        Call Form_Paint
    ElseIf MD = 2 Then
        B.X = X
        B.Y = Y
        Call Form_Paint
   
    End If
End Sub

Private Sub Form_MouseUp(Button As Integer, Shift As Integer, X As Single, Y As Single)
    MD = 0
    Me.MousePointer = vbDefault
   
End Sub

Private Sub Form_Paint()

With Me
    .Cls
    Me.Line (A.X, 0)-(A.X, A.Y)
    Me.Line (0, A.Y)-(A.X, A.Y)
   
    Me.Line (B.X, Me.ScaleHeight)-(B.X, B.Y)
    Me.Line (Me.ScaleWidth, B.Y)-(B.X, B.Y)

End With

End Sub

看看是不是要这个效果：
Private Sub Form_MouseMove(Button As Integer, Shift As Integer, X As Single, Y As Single)
    If MD = 1 Then
        B.X = B.X + (X - A.X)
        B.Y = B.Y + (Y - A.Y)
        A.X = X
        A.Y = Y
        Call Form_Paint
    ElseIf MD = 2 Then
        A.X = A.X + (X - B.X)
        A.Y = A.Y + (Y - B.Y)
        B.X = X
        B.Y = Y
        Call Form_Paint
    End If
End Sub
Private Sub Form_Paint()
With Me
    .Cls
    Me.Line (A.X, A.Y)-(B.X, B.Y)
End With
End Sub

首先谢谢高手，程序可以运行，但是为啥运行的图上又多出两条线，还请高手给看看，太谢谢了啊！


[ 本帖最后由 zixiacherry 于 2011-8-2 21:29 编辑 ]

运行时出现错误  Me.Line (A.X, A.Y)-(B.X, B.Y)有问题，请高手再给看看，万分感谢！

是不是原来的代码没删除？
全：
Option Explicit
Private Type 坐标类型
   X As Integer
   Y As Integer
End Type
Dim A As 坐标类型
Dim B As 坐标类型
Dim MD As Integer
'MD ,鼠标状态
'=0 ,无操作，1=拖动A，2=拖动B
Private Sub Form_Load()
MD = 0
A.X = 500
A.Y = 500
B.X = 2000
B.Y = 2000
End Sub
Private Sub Form_MouseDown(Button As Integer, Shift As Integer, X As Single, Y As Single)
If Button = 1 Then
    If Abs(X - A.X) < 75 And Abs(Y - A.Y) < 75 Then
        MD = 1
        Me.MousePointer = vbSizeAll
    ElseIf Abs(X - B.X) < 75 And Abs(Y - B.Y) < 75 Then
        MD = 2
        Me.MousePointer = vbSizeAll
     Else
        Me.MousePointer = vbDefault
    End If
Else
    Me.MousePointer = vbDefault
End If
End Sub
Private Sub Form_MouseMove(Button As Integer, Shift As Integer, X As Single, Y As Single)
    If MD = 1 Then
        B.X = B.X + (X - A.X)
        B.Y = B.Y + (Y - A.Y)
        A.X = X
        A.Y = Y
        Call Form_Paint
     ElseIf MD = 2 Then
        A.X = A.X + (X - B.X)
        A.Y = A.Y + (Y - B.Y)
        B.X = X
        B.Y = Y
        Call Form_Paint
    End If
End Sub
Private Sub Form_MouseUp(Button As Integer, Shift As Integer, X As Single, Y As Single)
    MD = 0
    Me.MousePointer = vbDefault
End Sub
Private Sub Form_Paint()
With Me
    .Cls
    Me.Line (A.X, A.Y)-(B.X, B.Y)
End With
End Sub

我把代码都删了  才粘进去的，你给的这个代码和之前的那个不一样了，运行起来不能拖动了，而且还多了条斜线出来，而且斜线可以自由移动，好奇怪。

又出现二条直线是你原来那二根直线。

我程序里是使用画线的方式显示直线的，不影响你原来的直线。

  嗯，明白啦！ 高手 你太厉害了！！！ 太感谢了！！！！！
 
就是我还有个小问题，能不能实现在直线拖动的时候，不允许交叉？？？
还请高手帮助一下，万分感谢！！！

怎么交叉？？

在
这个函数中 判断 坐标关系 。
Private Sub Form_MouseMove(Button As Integer, Shift As Integer, X As Single, Y As Single)
    If MD = 1 Then
        B.X = B.X + (X - A.X)
        B.Y = B.Y + (Y - A.Y)
        A.X = X
        A.Y = Y
        Call Form_Paint
     ElseIf MD = 2 Then
        A.X = A.X + (X - B.X)
        A.Y = A.Y + (Y - B.Y)
        B.X = X
        B.Y = Y
        Call Form_Paint
    End If
'坐标关系
   
End Sub

然后，不能再拖动时，置 MD =0 ，置鼠标状态 Me.MousePointer = vbDefault