拖动控件时出现闪烁的问题

[power_hust]

在一个窗体上放上一个按纽，在鼠标的移动事件中添加以下代码：
private sub Form1_MouseMove(.....) '记不清了，哈哈
btn1.left=x-btn1.width/2
btn1.top=y-btn1.height/2
end sub
然后运行程序。结果发现按纽边缘剧烈闪烁，而且还有一长串的黑影伴随。
请问各位高手，如何处理才可以让它不再闪烁，而且去掉那令控件魂断梦牵的黑影？
为求明白起见，奢望方家给出个中缘由。

[zyl910]

btn1.Move x-btn1.width/2, y-btn1.height/2

[Sean918]

zyl910(910：分儿，我来了！) ,哈哈。。。难得看见你马虎写的东西阿

[power_hust]

好，试试看先。

[Sean918]

顺便问一句，移动的时候如何能让它连贯？

就算用SendMessage去移动也会有停顿，怎么解决比较好？

[carefulman]

这是我写的一个移动的例子，点击鼠标开始移动，放开停止，希望对你有帮助
'在窗体上放置一个COMMAND作为拖动对象

Option Explicit
Dim Flag As Boolean '拖动标志
Dim oldx, oldx1, oldy1, oldy As Double '记录原来的坐标

Private Sub Command1_MouseDown(Button As Integer, Shift As Integer, X As Single, Y As Single)
'开始拖动
Flag = True
'记录下应该绘图的左上角坐标
oldx = Command1.Left
oldy = Command1.Top
'在控件内部的位置
oldx1 = X
oldy1 = Y
Form1.DrawMode = 6
Form1.DrawStyle = 2
'绘制一个拖动的虚线框
Form1.Line (oldx, oldy)-(oldx + Command1.Width, oldy + Command1.Height), , B
End Sub

Private Sub Command1_MouseMove(Button As Integer, Shift As Integer, X As Single, Y As Single)
If Flag = False Then
Exit Sub
End If
'首先消除原先的边框
Form1.DrawMode = 6
Form1.DrawStyle = 2
Form1.Line (oldx, oldy)-(oldx + Command1.Width, oldy + Command1.Height), , B
'计算新的虚线框位置
oldx = Command1.Left - oldx1 + X
oldy = Command1.Top + Y - oldy1
'重新绘制拖动位置
Form1.Line (oldx, oldy)-(oldx + Command1.Width, oldy + Command1.Height), , B
End Sub

Private Sub Command1_MouseUp(Button As Integer, Shift As Integer, X As Single, Y As Single)
If Flag = False Then Exit Sub
'消除最后的边框
Form1.Line (oldx, oldy)-(oldx + Command1.Width, oldy + Command1.Height), , B
Command1.Move oldx, oldy
'不让控件被别的东西遮住
Command1.ZOrder 0
'不能跑出窗体
If oldx < 0 Then
Command1.Move 0, oldy
oldx = 0
End If
If oldx > (Form1.ScaleWidth - Command1.Width) Then
Command1.Move Me.ScaleWidth - Command1.Width, oldy
oldx = Me.ScaleWidth - Command1.Width
End If
If oldy < 0 Then
Command1.Move oldx, 0
oldy = 0
End If
If oldy > (Form1.ScaleHeight - Command1.Height) Then
Command1.Move oldx, Me.ScaleHeight - Command1.Height
oldy = Me.ScaleHeight - Command1.Height
End If

'结束拖动
Flag = False
End Sub