Find the rendered image memory address of a Webbrowser Control

  • 12 years ago

    I have been using IHTML2Element for quite some time to thumbnail a WebBrowser screen’s image and it
    works fine…except now xsl/xml rendered HTML is not available in IHTML2Element.  I have developed code
    to go after the memory address of the Desktop Window and have successfully thumb nailed the desktop
    screen from memory with a form on it hosting a WebBrowser control on it.  This is not a screen scrap
    or copy from screen operation I have the desktop windows memory address and I am using StretchBlt from
    that address in memory to a thumbnail.

    Being able to use IHTMLElement to thumbnail WebBrowser controls allows me to create thumbnails of hosted
    webBrowser without displaying them.  This is what I am looking to do only now from finding the address
    where webBrowser controls are fully rendered in memory.  

    I thought I could just use Me.WebBrowser1.handle and that would point to where the rendered HTML lives…
    but that did not work.

    The following code below works fine for the Desktop window:


                'Handle for the desktop window
                Dim AddrDesktopWindow As IntPtr
                If AddrDesktopWindow = 0 Then AddrDesktopWindow = GetDesktopWindow

                'getWindow Size
                Dim rcWindow As RECT
                GetWindowRect(AddrDesktopWindow, rcWindow)
                Dim WinHeight As Integer = rcWindow.Right - rcWindow.Left
                Dim WinWidth As Integer = rcWindow.Bottom - rcWindow.Top

                Dim PB1 As Graphics = Me.PictureBox1.CreateGraphics
                Dim AddrOfPB1 As IntPtr = PB1.GetHdc

                Dim AddrOfPictureBox1 As IntPtr = Me.PictureBox1.Handle

                'create a compatible DC
                Dim AddrCreateCompatibleDC As IntPtr = CreateCompatibleDC(IntPtr.Zero)

                'create a memory bitmap in the DC just created, the size of the window we're capturing
                Dim AddrCreateCompatibleBitmap As IntPtr = CreateCompatibleBitmap(AddrOfPB1, WinWidth, WinHeight)

                'Prepare DC as a Bitmap using selectObject to configure the DC
                SelectObject(AddrCreateCompatibleDC, AddrCreateCompatibleBitmap)

                'copy the screen image into the DC
                BitBlt(AddrCreateCompatibleDC, 0, 0, WinWidth, WinHeight, GetWindowDC(AddrDesktopWindow), 0, 0, SRCCOPY)

                'Clone image of PictureBox1 to Picturebox2 when the IMAGE is in the Device Context
                '#### BitBlt(AddrOfPB1, 0, 0, WinWidth, WinHeight, AddrCreateCompatibleDC, 0, 0, SRCCOPY)
                StretchBlt(AddrOfPB1, 0, 0, 100, 100, AddrCreateCompatibleDC, 0, 0, WinWidth, WinHeight, TernaryRasterOperations.SRCCOPY)

                CType(PB1, IDisposable).Dispose()

            Catch ex As System.NullReferenceException
                MsgBox("--- NullReferenceException ---" & "  " & _
                vbCrLf & "Message --- " & ex.Message & "  " & _
                vbCrLf & "Source --- " & ex.Source & "  " & _
                vbCrLf & "StackTrace --- " & ex.StackTrace & "  " & _
                vbCrLf & "TargetSite --- " & ex.TargetSite.ToString)
                ' Code reacting to NullReferenceException
            Catch ex As Exception
                ' Code reacting to any exception
                MsgBox(vbCrLf & "Message --- " & ex.Message & "  " & _
                vbCrLf & "Source --- " & ex.Source & "  " & _
                vbCrLf & "StackTrace --- " & ex.StackTrace & "  " & _
                vbCrLf & "TargetSite --- " & ex.TargetSite.ToString)
            End Try
        End Sub


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