GDI画图问题
在一个有背景的FORM中画两条跟随鼠标的十字线要不断的刷新才可以。这样很大的占用了CPU。能不能象在没有背景的FORM中画十字线（即画之前不用刷新）。

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看下你的代码
建议用双缓冲技术
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使用异或绘图或双缓冲~~
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用graphicpath，只需重画十字架的path，不用全部重绘
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用两个PIC,然后一个宽度设置为1，一个高度设置为1，跟着你鼠标移动不就OK啦
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Public Class Form2

Dim OldPoint As Point

Private Sub Form2_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
Me.SetStyle(ControlStyles.AllPaintingInWmPaint Or ControlStyles.OptimizedDoubleBuffer Or ControlStyles.UserPaint, True)
End Sub

Private Sub Form1_MouseMove(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles Me.MouseMove
Dim p1, p2, p3, p4 As Point

If OldPoint <> Nothing Then
p1 = PointToScreen(New Point(OldPoint.X, 0))
p2 = PointToScreen(New Point(OldPoint.X, Me.ClientSize.Height))
p3 = PointToScreen(New Point(0, OldPoint.Y))
p4 = PointToScreen(New Point(Me.ClientSize.Width, OldPoint.Y))

ControlPaint.DrawReversibleLine(p1, p2, Color.Cyan)
ControlPaint.DrawReversibleLine(p3, p4, Color.Cyan)
End If

p1 = PointToScreen(New Point(e.X, 0))
p2 = PointToScreen(New Point(e.X, Me.ClientSize.Height))
p3 = PointToScreen(New Point(0, e.Y))
p4 = PointToScreen(New Point(Me.ClientSize.Width, e.Y))

ControlPaint.DrawReversibleLine(p1, p2, Color.Cyan)
ControlPaint.DrawReversibleLine(p3, p4, Color.Cyan)

OldPoint = New Point(e.X, e.Y)
End Sub

End Class
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直接把鼠标的光标设为十字架行不行？你的十字架有多大啊。