(.NET/GDI/BitBlt) Bitmaps will not display correctly.   

This code works fine, and displays an image on the PictureBox

Private bmpConv As Bitmap = Nothing
Private bmpBtl As Bitmap = Nothing
Private bmpBtlMask As Bitmap = Nothing

bmpConv = Image.FromFile("..\Images\Conveyor.bmp")
pbConv.BackgroundImage = bmpConv

bmpBtl = Image.FromFile("..\Images\Mist50White.bmp")
pbBtl.BackgroundImage = bmpBtl

bmpBtlMask = Image.FromFile("..Images\Mist50Mask.bmp")
pbBtlMask.BackgroundImage = bmpBtlMask

MyBitBlt(pbConv, pbBtl, pbBtlMask, 0, 0)

-----------------------------------------

    Public Sub MyBitBlt(ByVal Dst As PictureBox, ByVal Src As PictureBox, 
ByVal Mask As PictureBox, ByVal X As Long, ByRef Y As Long)
        ' Get device context of source and destination picture boxes
        Dim srcHDC As IntPtr = Src.CreateGraphics.GetHdc
        Dim dstHDC As IntPtr = Dst.CreateGraphics.GetHdc
        Dim maskHDC As IntPtr = Mask.CreateGraphics.GetHdc

        BitBlt(dstHDC.ToInt32, X, Y, 50, 50, maskHDC.ToInt32, 0, 0, 
TernaryRasterOperations.SRCPAINT)
        'put the picture onto the main screen
        BitBlt(dstHDC.ToInt32, X, Y, 50, 50, srcHDC.ToInt32, 0, 0, 
TernaryRasterOperations.SRCAND)

    End Sub

however, the following code doesn't and its using the same images

Private bmpConv As Bitmap = Nothing
Private bmpBtl As Bitmap = Nothing
Private bmpBtlMask As Bitmap = Nothing

bmpConv = Image.FromFile("..\Images\Conveyor.bmp")
pbConv.BackgroundImage = bmpConv

bmpBtl = Image.FromFile("..\Images\Mist50White.bmp")
pbBtl.BackgroundImage = bmpBtl

bmpBtlMask = Image.FromFile("..Images\Mist50Mask.bmp")
pbBtlMask.BackgroundImage = bmpBtlMask

MyBitBlt(pbConv, bmpBtl, bmpBtlMask, 0, 0)

--------------------------------

    Public Sub MyBitBlt(ByVal Dst As PictureBox, ByVal Src As Bitmap, ByVal 
Mask As Bitmap, ByVal X As Long, ByRef Y As Long)

        Try

            Dim srcMem As Graphics = Graphics.FromImage(Src)
            Dim srcHDC As IntPtr = srcMem.GetHdc

            Dim maskMem As Graphics = Graphics.FromImage(Mask)
            Dim maskHDC As IntPtr = maskMem.GetHdc

            Dim dstHDC As IntPtr = Dst.CreateGraphics.GetHdc

            BitBlt(dstHDC, X, Y, 50, 50, maskHDC, 0, 0, 
TernaryRasterOperations.SRCPAINT)
            'put the picture onto the main screen
            BitBlt(dstHDC, X, Y, 50, 50, srcHDC, 0, 0, 
TernaryRasterOperations.SRCAND)

            srcMem.ReleaseHdc(srcHDC)
            maskMem.ReleaseHdc(maskHDC)
            srcMem.Dispose()
            maskMem.Dispose()

        Catch ex As Exception
            Dim err As String = ex.Message
        End Try

    End Sub

It draws nothing on the first bitblt, and a black rectangle on the second 
bitblt.
Wondered if anyone had any ideas or insights.

Thanks.

date: Thu, 15 May 2008 15:09:00 -0700   author:   Tony (Goody Goody Liquor,Dallas)

And a solution seems to be....   

Public Sub MyBitBlt(ByVal Dst As PictureBox, ByVal Back As Bitmap, ByVal Src 
As Bitmap, ByVal Mask As Bitmap, ByVal X As Long, ByRef Y As Long)

        Try

            Dim dstHDC As IntPtr = Dst.CreateGraphics.GetHdc

            Dim gdiHandleBack As IntPtr = CreateCompatibleDC(dstHDC.ToInt32)
            Dim bmHandleBack As IntPtr = Back.GetHbitmap()
            SelectObject(gdiHandleBack, bmHandleBack)
            Dim backMem As Graphics = Graphics.FromHdc(gdiHandleBack)
            Dim backHDC As IntPtr = backMem.GetHdc

            Dim gdiHandleMask As IntPtr = CreateCompatibleDC(dstHDC.ToInt32)
            Dim bmHandleMask As IntPtr = Mask.GetHbitmap()
            SelectObject(gdiHandleMask, bmHandleMask)
            Dim maskMem As Graphics = Graphics.FromHdc(gdiHandleMask)
            Dim maskHDC As IntPtr = maskMem.GetHdc
            BitBlt(backHDC, X, Y, 50, 50, maskHDC, 0, 0, 
TernaryRasterOperations.SRCPAINT)

            Dim gdiHandleSrc As IntPtr = CreateCompatibleDC(dstHDC.ToInt32)
            Dim bmHandleSrc As IntPtr = Src.GetHbitmap()
            SelectObject(gdiHandleSrc, bmHandleSrc)
            Dim srcMem As Graphics = Graphics.FromHdc(gdiHandleSrc)
            Dim srcHDC As IntPtr = srcMem.GetHdc
            BitBlt(backHDC, X, Y, 50, 50, srcHDC, 0, 0, 
TernaryRasterOperations.SRCAND)

            BitBlt(dstHDC, 0, 0, Back.Width, Back.Height, backHDC, 0, 0, 
TernaryRasterOperations.SRCCOPY)

            srcMem.ReleaseHdc(srcHDC)
            maskMem.ReleaseHdc(maskHDC)
            backMem.ReleaseHdc(backHDC)
            srcMem.Dispose()
            maskMem.Dispose()
            backMem.Dispose()

        Catch ex As Exception
            Dim err As String = ex.Message
        End Try

    End Sub

...didn't take the time to check for memory leaks.

There may be other more efficient solutions.

date: Fri, 16 May 2008 08:33:00 -0700   author:   Tony (Goody Goody Liquor,Dallas)