WPF

Private Sub Button1_Click(ByVal sender As System.Object, _
                          ByVal e As System.Windows.RoutedEventArgs) _
                             Handles Button1.Click

    Dim CaptureForm As New TestForm
    CaptureForm.Left = -999
    CaptureForm.Show()

    Image1.Source = CaptureFrameworkElement(CaptureForm)

    CaptureForm.Close()
    CaptureForm = Nothing

End Sub

Function CaptureFrameworkElement(ByVal fe As FrameworkElement) As BitmapSource

    Dim renderBitmap As New RenderTargetBitmap(CInt(Math.Ceiling(fe.ActualWidth)), _
                                               CInt(Math.Ceiling(fe.ActualHeight)), _
                                               96, 96, PixelFormats.Pbgra32)
    Dim dv As New DrawingVisual()

    Using dc As DrawingContext = CType(dv.RenderOpen(), DrawingContext)

        Dim visualBrush As New VisualBrush(fe)
        Dim rect1 As New Rect(New System.Windows.Point(0, 0),_
                              VisualTreeHelper.GetDescendantBounds(fe).Size)
        dc.DrawRectangle(visualBrush, Nothing, rect1)

    End Using

    renderBitmap.Render(dv)

    Return CType(renderBitmap, BitmapSource)

End Function

GraGra_33 wrote:

The only issue I have now is that only the contents of the form are captured and not the non-client area.

' the code is not tested
Dim hlper As New System.Windows.Interop.WindowInteropHelper(Me)
Dim windowAsForm = System.Windows.Forms.Form.FromHandle(hlper.Handle) ' returns null, don't know why

Dim w = windowAsForm.Size.Width
Dim h = windowAsForm.Size.Height
Dim bitmap As New System.Drawing.Bitmap(w, h)
windowAsForm.DrawToBitmap(bitmap, New System.Drawing.Rectangle(0, 0, w, h))

' code from <a href="http://dedjo.blogspot.com/2007/05/how-to-use-systemdrawingbitmap-hbitmap.html">here</a>[<a href="http://dedjo.blogspot.com/2007/05/how-to-use-systemdrawingbitmap-hbitmap.html" target="_blank" title="New Window">^</a>], i didn't test it
Return System.Windows.Interop.Imaging.CreateBitmapSourceFromHBitmap(bitmap.GetHbitmap(), _
                                                                    IntPtr.Zero, _
                                                                    Int32Rect.Empty, _
                                                                    System.Windows.Media.Imaging.BitmapSizeOptions.FromEmptyOptions())

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