bitblt 函数问题

Posted 2023-03-17

Declare Function BitBlt Lib "gdi32" Alias "BitBlt" (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 Pic2_Paint(ByVal sender As Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles Pic2.Paint
Pic2.BackColor = Color.Black
e.Graphics.DrawLine(Pens.Red, 0, 0, 100, 100)
End Sub

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
BitBlt(Pic1.CreateGraphics.GetHdc, 0, 0, 100, 100, Pic2.CreateGraphics.GetHdc, 0, 0, &HCC0020)
End Sub

请大家帮我看下这段代码，我想利用 bitblt 函数将 pic2 中的图像放到 pic1 中，但运行后，没有反应
此问题根据 CSDN 的网友 bw555 提供的代码已解决。

原因是对 bitblt 函数的声明不正确，修改如下：

Public Class Form1

Private Declare Function BitBlt Lib "GDI32" (ByVal srchDC As Integer, ByVal srcX As Integer, ByVal srcY As Integer, _
ByVal srcW As Integer, ByVal srcH As Integer, ByVal desthDC As Integer, _
ByVal destX As Integer, ByVal destY As Integer, ByVal op As Integer) As Integer

Const SRCCOPY As Integer = &HCC0020

Private Sub Pic2_Paint(ByVal sender As Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles Pic2.Paint
Pic2.BackColor = Color.Black
e.Graphics.DrawLine(Pens.Red, 0, 0, 100, 100)
End Sub

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
BitBlt(Pic1.CreateGraphics.GetHdc, 0, 0, 100, 100, Pic2.CreateGraphics.GetHdc, 0, 0, SRCCOPY)
End Sub

End Class

参考技术A 属性栏autoredraw勾上, 然后把BitBlt写到FormActivate中, 并且加上循环试试~