[resolved] bitblt copy problem..

I have a small form. Simply, it has a textbox, a button, and a picturebox.

On click of the button, I take the window title typed into the text box, find the handle of the window, and do a bitblt of the window's contents into the picture box.

Everything works except the last part, and I think the sample code I got (the GetShot() func) was written for legacy vb.

bitblt returns a non-zero return code, which as far as I can find is success, I get no errors, and the picturebox just doesn't contain anything.

Any help would be appreciated on figuring out where I'm goofing up...

Thanks.

(note: this is on xp pro using vs.net 2003)

VB Code:

Imports System.Drawing.Graphics
Public Class frm_WC
    Inherits System.Windows.Forms.Form
    Declare Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As Long
    Declare Function SetForegroundWindow Lib "user32" Alias "SetForegroundWindow" (ByVal hWnd As Long) As Long
 
    Private Declare Function GetWindowRect Lib "user32" (ByRef hwnd As Long, ByRef lpRect As S_RECT) As Long
    Private Declare Function GetDesktopWindow Lib "user32" () As Long
 
    Private Declare Function GetActiveWindow Lib "user32" () As Long
    Private Declare Function GetTopWindow Lib "user32" (ByVal hwnd As Long) As Long
    Private Declare Function GetClientRect Lib "user32" (ByVal hwnd As Long, ByVal lpRect As S_RECT) As Long
    Private Declare Function GetWindowDC Lib "user32" (ByVal hwnd As Long) As Long
    Private Declare Function BitBlt Lib "gdi32" (ByVal hDestDC As IntPtr, 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 Declare Function ReleaseDC Lib "user32" (ByVal hwnd As Long, ByVal hDC As Long) As Long
    Private Const SRCCOPY = &HCC0020
 
    Private Structure S_RECT
        Dim Left As Long
        Dim Top As Long
        Dim Right As Long
        Dim Bottom As Long
    End Structure
    Private Structure S_BITMAP
        Dim bmType As Long
        Dim bmWidth As Long
        Dim bmHeight As Long
        Dim bmWidthBytes As Long
        Dim bmPlanes As Integer
        Dim bmBitsPixel As Integer
        Dim bmBits As Long
    End Structure
 
 
#Region " Windows Form Designer generated code "
'... omitted auto-generated code
#End Region
 
    Private Sub cmd_Capture_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmd_Capture.Click
        Dim lpWindowHandle As Long
        Dim lpWindowHandle2 As Long
        Dim lpWindowHandle3 As Long
        'name of window to capture
        Dim lpWindowName As String = txt_Window.Text.Trim
 
        lpWindowHandle = FindWindow(vbNullString, lpWindowName)
 
        'display window handle
        MsgBox("hwnd returns " & Hex(lpWindowHandle), MsgBoxStyle.OKOnly, "Results")
 
        'bring it to the foreground
        'SetForegroundWindow(lpWindowHandle)
        GetShot(lpWindowHandle, PictureBox1)
 
    End Sub
 
    Private Sub GetShot(ByRef lWindowhWnd As Long, ByRef picScreen As PictureBox)
        Dim nLeft As Long
        Dim nTop As Long
        Dim nWidth As Long
        Dim nHeight As Long
        Dim rRect As New S_RECT
        Dim bm As New S_BITMAP
        Dim lWindowhDC As Long
        Dim vbSrcCopy As Long
        Dim errCode As Integer
 
        'picScreen.Image = Nothing
        GetWindowRect(lWindowhWnd, rRect)
        lWindowhDC = GetWindowDC(lWindowhWnd)
        '// Get coordinates
        nLeft = 0
        nTop = 0
        nWidth = rRect.Right - rRect.Left
        nHeight = rRect.Bottom - rRect.Top
        '// Blt to frm.picScreen
        BitBlt(picScreen.Handle, 0, 0, nWidth, nHeight, lWindowhDC, nLeft, nTop, SRCCOPY)
        '// Del DC
        ReleaseDC(lWindowhWnd, lWindowhDC)
        '// set picture
        picScreen.Refresh()
 
    End Sub
End Class

you need to use " Integer or Int32 " inplace of your " Long's " when using Apis in .NET

I'm not quite sure how that would cause my problem, but I changed everything to integer's, still a no go...

After some searching and tweaking I think I got it figured out... atleast, it works.

VB Code:

Imports System.Drawing.Graphics
Public Class frm_WC
    Inherits System.Windows.Forms.Form
 
    Private Declare Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As Integer
    Private Declare Function SetForegroundWindow Lib "user32" Alias "SetForegroundWindow" (ByVal hWnd As Integer) As Integer
    Private Declare Function BitBlt Lib "gdi32" Alias "BitBlt" _
         (ByVal hDestDC As IntPtr, ByVal x As Integer, _
         ByVal y As Integer, ByVal nWidth As Integer, _
         ByVal nHeight As Integer, ByVal hSrcDC As IntPtr, _
         ByVal xSrc As Integer, ByVal ySrc As Integer, _
         ByVal dwRop As Integer) As Integer
    Private Declare Function GetDC Lib "user32" Alias "GetDC" _
         (ByVal hwnd As IntPtr) As IntPtr
    Private Declare Function ReleaseDC Lib "user32" Alias "ReleaseDC" _
       (ByVal hwnd As IntPtr, ByVal hdc As IntPtr) As Integer
    Private Const SRCCOPY As Integer = &HCC0020
 
#Region " Windows Form Designer generated code "
'removed system generated code
#End Region
 
    Private Sub cmd_Capture_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmd_Capture.Click
        Dim lpWindowHandle As Integer
        'name of window to capture
        Dim lpWindowName As String = txtTitle.Text.Trim
 
        lpWindowHandle = FindWindow(vbNullString, lpWindowName)
 
        'display window handle
        MsgBox("hwnd returns " & Hex(lpWindowHandle), MsgBoxStyle.OKOnly, "Results")
 
        'bring it to the foreground
        SetForegroundWindow(lpWindowHandle)
        Dim bmp As Bitmap = CreateScreenshot(lpWindowHandle)
        PictureBox1.Image = bmp
 
 
    End Sub
 
    Function CreateScreenshot(ByVal winHandle As Integer) As Bitmap
 
        Dim Rect As Rectangle = Screen.PrimaryScreen.Bounds
        Dim gDest As Graphics
        Dim hdcDest, hdcSrc As IntPtr
 
        CreateScreenshot = New Bitmap(Rect.Right, Rect.Bottom)
        gDest = gDest.FromImage(CreateScreenshot)
 
        'hdcSrc = GetDC(IntPtr.Zero)
        hdcSrc = GetDC(IntPtr.op_Explicit(winHandle))
 
        hdcDest = gDest.GetHdc
        BitBlt(hdcDest, 0, 0, _
           Rect.Right, Rect.Bottom, hdcSrc, 0, 0, SRCCOPY)
        gDest.ReleaseHdc(hdcDest)
        ReleaseDC(IntPtr.Zero, hdcSrc)
 
    End Function
End Class