WPF

Dim hlper As New System.Windows.Interop.WindowInteropHelper(Me)
Dim gr As System.Drawing.Graphics = System.Drawing.Graphics.FromHwnd(hlper.Handle)
Dim ms As New MemoryStream

Dim bmp As System.Drawing.Bitmap = New System.Drawing.Bitmap(gr.VisibleClipBounds.Width, gr.VisibleClipBounds.Height, gr)
bmp.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg)

Dim bImg As System.Windows.Media.Imaging.BitmapImage = New System.Windows.Media.Imaging.BitmapImage()
bImg.BeginInit()
bImg.StreamSource = New MemoryStream(ms.ToArray())
bImg.EndInit()
Return bImg

GraGra_33 wrote:

Dim gr As System.Drawing.Graphics = System.Drawing.Graphics.FromHwnd(hlper.Handle)

GraGra_33 wrote:

Dim bmp As System.Drawing.Bitmap = New System.Drawing.Bitmap(gr.VisibleClipBounds.Width, gr.VisibleClipBounds.Height, gr)

Eslam Afifi wrote:

I tried sending WM_PAINT to the window but I only got the border without the content.

Private Const WM_PRINT As Integer = &H317
Private Const PRF_NON_CLIENT As Integer = &H2
Private Const PRF_CLIENT As Integer = &H4

Private Declare Function SendMessage Lib "user32.dll" Alias "SendMessageW" (ByVal hWnd As IntPtr, _
                                                                            ByVal Msg As Integer, _
                                                                            ByVal wParam As Integer, _
                                                                            ByVal lParam As Integer) As Integer

Public Sub DrawToBitmap(ByVal hWnd As IntPtr, ByVal bitmap As System.Drawing.Bitmap, _
                        ByVal targetBounds As System.Drawing.Rectangle)
    If (bitmap Is Nothing) Then Throw New ArgumentNullException("bitmap")
    If (((targetBounds.Width <= 0) OrElse (targetBounds.Height <= 0)) _
        OrElse ((targetBounds.X < 0) OrElse (targetBounds.Y < 0))) Then _
        Throw New ArgumentException("targetBounds")

    Using graphics = System.Drawing.Graphics.FromImage(bitmap)
        Dim hDC = graphics.GetHdc()
        SendMessage(hWnd, WM_PRINT, hDC.ToInt32(), PRF_CLIENT + PRF_NON_CLIENT)
        graphics.ReleaseHdc(hDC)
    End Using
End Sub