VB.NET中的BitBlt 问题

Public Class Form1
Const NOTSRCCOPY = &H33008
Const NOTSRCERASE = &H1100A6
Private Const SRCAND = &H8800C6
Private Const SRCCOPY = &HCC0020
Private Const SRCERASE = &H440328
Private Const SRECINVERT = &HEE0086
Private Declare Sub Sleep Lib "Kernel32" (ByVal dwMilliseconds As Long)
Private Declare Function BitBlt Lib "gdi32" (ByVal hDestDC As Long, ByVal x As Long, ByVal y As Long, ByVal nWidth As Long, ByVal nHeight As Long, ByVal hSrcDC As Long, ByVal xSrc As Long, ByVal ySrc As Long, ByVal dwRop As Long) As Long

Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
Dim ret As Long
Dim hdc2 As IntPtr
Dim hdc1 As IntPtr
Dim i, j As Integer
hdc2 = Me.PictureBox2.CreateGraphics.GetHdc
hdc1 = Me.PictureBox1.CreateGraphics.GetHdc
Dim w As Integer
Dim h As Integer
w = Me.PictureBox1.Size.Width
h = Me.PictureBox1.Size.Height
i = w / 2
j = h / 2
While (i > 0)
ret = BitBlt(hdc2, i, j, w - 2 * i, h - 2 * j, hdc1, i, j, SRCCOPY)
i = i - 2
j = j - 2 * h / w
End While
Me.Text = ret
End Sub

函数执行成功 可是PIctureBox2就是不显示图形 求助高手啊。。。。急

我暂时保留我的看法！

bitblt picture2.hdc, 0, 0, picture1.scalewidth, picture1.scaleheight, picture1.hdc, 0, 0, vbsrccopy