How To: Close the Form hosting the WebBrowser control when scripting calls window.close in the .Net Framework version 2.0


By design the WebBrowser Control does not close the parent Form when WebBrowser Control is closed.  Here is one way you can accomplish this.

The WebBrowser will send a WM_NOTIFYPARENT notification that can be captured and an event raised that a host can respond to.

Here is the documentation on the WM_NOTIFYPARENT notification:  http://msdn2.microsoft.com/en-us/library/ms632638.aspx

In this case we care about when the WebBrowser is closed, so we will respond to the wParam WM_DESTROY only.  Since I am going to override the WebBrowser control for other purposes, I will simply add an event to this control that any Form can act on.

First define a new VB Windows Project.  Drag and drop the WebBrowser Control onto your form from the Common Controls section of the Toolbox.

Next we want to extend the WebBrowser control so we can process the WndProc function.  Create a new Class(Add, Class) and call it MyExtendedBrowserControl.

Public

Class MyExtendedBrowserControl
‘ Based on WebBrowser
Inherits System.Windows.Forms.WebBrowser

‘ Define constants from winuser.h
Private Const WM_PARENTNOTIFY As Integer = &H210
Private Const WM_DESTROY As Integer = 2

‘Define New event to fire
Public Event WBWantsToClose()

Protected Overrides Sub WndProc(ByRef m As Message)
    Select Case m.Msg
        Case WM_PARENTNOTIFY
            If (Not DesignMode) Then
                If (m.WParam = WM_DESTROY) Then
                    ‘ Tell whoever cares we are closing
                    RaiseEvent WBWantsToClose()
                End If
            End If
            DefWndProc(m)
        Case Else
            MyBase.WndProc(m)
    End Select
End Sub

End

Class

Now we have to get into the guts of the Form.  Although we dropped a WebBrowserControl on the form (and VB wired that up nicely for us) we REALLY want to create our new Control that extends the WebBrowser Control.

Choose File, Open from the Visual Studio menu and open the designer vb code (in this case Form1.Designer.vb).

Replace System.Windows.Forms.WebBrowser with the extended control MyExtendedBrowserControl.  There should be Two Places:

Me.WebBrowser1 = New VBCloseBrowser.ExtendedWebBrowser.ExtendWebBrowser

Friend WithEvents WebBrowser1 As VBCloseBrowser.ExtendedWebBrowser.ExtendWebBrowser

Save all the files and Build the project (you will see errors in the designers until you do build).

Now go to the design view of your Form.  Right Click on the Browser control and choose Properties‚Ķ  Click on the Events Icon (the lightning bolt) and you will see at the bottom your new event WBWantsToClose.  Double click on that name and you will automatically add the handler for that event.  In my case, I simply want to close this form so I added Me.Close() in the handler.

Enjoy!

Comments (3)

  1. NeilS says:

    Jeff – following on from your NewWindow2 event capture in a managed web browser article – again this was really helpful.

  2. disccomp says:

    I am using an extendedwebbrowser, Your code almost ties up the last loose end. The only trouble is the closing event fires after windows asks whether to close the window after window.close is called from a script.

    ———————————

    Imports System.Runtime

    Imports System.ComponentModel

    ‘Extend the WebBrowser control

    Public Class ExtendedWebBrowser

       Inherits WebBrowser

       Private cookie As AxHost.ConnectionPointCookie

       Private events As WebBrowserExtendedEvents

       Private Const WM_PARENTNOTIFY As Integer = &H210

       Private Const WM_DESTROY As Integer = 2

       ‘Define New event to fire

       Public Event WindowClosing()

       Protected Overrides Sub WndProc(ByRef m As Message)

           Select Case m.Msg

               Case WM_PARENTNOTIFY

                   If (Not DesignMode) Then

                       If (m.WParam = WM_DESTROY) Then

                           ‘ Tell whoever cares we are closing

                           RaiseEvent WindowClosing()

                       End If

                   End If

                   DefWndProc(m)

               Case Else

                   MyBase.WndProc(m)

           End Select

       End Sub

       ‘This method will be called to give you a chance to create your own event sink

       Protected Overloads Overrides Sub CreateSink()

           ‘MAKE SURE TO CALL THE BASE or the normal events won’t fire

           MyBase.CreateSink()

           events = New WebBrowserExtendedEvents(Me)

           cookie = New AxHost.ConnectionPointCookie(Me.ActiveXInstance, events, GetType(DWebBrowserEvents2))

       End Sub

       Protected Overloads Overrides Sub DetachSink()

           If cookie IsNot Nothing Then

               cookie.Disconnect()

               cookie = Nothing

           End If

           MyBase.DetachSink()

       End Sub

       ‘This new event will fire when the page is navigating

       Public Event NewWindowWithTaget As EventHandler(Of WebBrowserExtendedNavigatingEventArgs)

       Protected Sub OnNewWindow3(ByVal url As String, ByVal e As WebBrowserExtendedNavigatingEventArgs)

           RaiseEvent NewWindowWithTaget(Me, e)

       End Sub

       ‘This class will capture events from the WebBrowser

       Private Class WebBrowserExtendedEvents

           Inherits System.Runtime.InteropServices.StandardOleMarshalObject

           Implements DWebBrowserEvents2

           Private _Browser As ExtendedWebBrowser

           Public Sub New(ByVal browser As ExtendedWebBrowser)

               _Browser = browser

           End Sub

           Public Sub NewWindow3(ByVal pDisp As Object, ByRef cancel As Boolean, ByRef flags As Object, ByRef hostURL As Object, ByRef URL As Object) Implements DWebBrowserEvents2.NewWindow3

               Dim args As New WebBrowserExtendedNavigatingEventArgs(URL)

               args.Cancel = cancel

               _Browser.OnNewWindow3(URL, args)

               cancel = args.Cancel

           End Sub

       End Class

       <InteropServices.ComImport(), InteropServices.Guid("34A715A0-6587-11D0-924A-0020AFC7AC4D"), InteropServices.InterfaceTypeAttribute(InteropServices.ComInterfaceType.InterfaceIsIDispatch), InteropServices.TypeLibType(InteropServices.TypeLibTypeFlags.FHidden)> _

       Public Interface DWebBrowserEvents2

           <InteropServices.DispId(273)> _

           Sub NewWindow3(ByVal pDisp As Object, ByRef cancel As Boolean, ByRef flags As Object, ByRef hostURL As Object, ByRef URL As Object)

       End Interface

    End Class

    Public Class WebBrowserExtendedNavigatingEventArgs

       Inherits CancelEventArgs

       Private _Url As String

       Public Sub New(ByVal url As String)

           _Url = url

       End Sub

       Public ReadOnly Property Url() As String

           Get

               Return _Url

           End Get

       End Property

    End Class

  3. Evahn says:

    Worked perfectly for Windows form in Vis Studio 2010 and .net 4 too. Thanks for this