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| Title | Make a browser that prevents the user from viewing the URL in Visual Basic .NET |
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| Description | This example shows how to make a browser that prevents the user from viewing the URL in Visual Basic .NET |
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| Keywords | browser, URL, restricted browser, hide URL, VB.NET |
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| Categories | Internet, VB.NET |
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I had a customer that wanted to allow the user to visit a Web site but not to easily see what URL it was. The program must stop the user from right-clicking on the form to view the page's properties, which include the URL.
This program uses a form that contains a WebBrowser control. The form's ShowBrowser command displays the form. It adds the form as a message filter (the form must implement IMessageFilter to be a filter), navigates the the desired URL, and displays itself.
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' Install ourself as a message filter.
Public Sub ShowBrowser(ByVal url As String, ByVal _
show_modal As Boolean)
' Add a message filter.
Application.AddMessageFilter(Me)
' Navigate to the URL.
webRestricted.Navigate(url)
If show_modal Then
Me.ShowDialog()
Else
Me.Show()
End If
End Sub
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When the form receives a message, the PreFilterMessage function executes. The version here (adapted from http://www.freevbcode.com/ShowCode.asp?ID=5635) returns True for various special keys such as BrowserBack and the right-click to indicate that the message has been handled and should not be passed on to the WebBrowser control.
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' WebBrowser adapted code from:
' http://www.freevbcode.com/ShowCode.asp?ID=5635
Private Bstop As Boolean
Public Function PreFilterMessage(ByRef m As _
System.Windows.Forms.Message) As Boolean Implements _
IMessageFilter.PreFilterMessage
' WM_KEYDOWN As Int32 = &H100 Private Const WM_KEYUP As
' Int32 = &H101 WM_SYSKEYDOWN As Integer = &H104
Dim keyCode As Keys = CType(m.WParam.ToInt32(), Keys) _
And Keys.KeyCode
Static ControlP As Boolean
Select Case keyCode
Case Keys.BrowserBack : Return True
Case Keys.BrowserFavorites : Return True
Case Keys.BrowserForward : Return True
Case Keys.BrowserHome : Return True
Case Keys.BrowserRefresh : Return True
Case Keys.BrowserSearch : Return True
Case Keys.BrowserStop : Return True
Case Keys.RButton : Return True 'right mousebutton
Case Keys.Back ' backspace key to handle history -1
If m.Msg = &H100 Then
Bstop = True 'stop this bb event !
Else
Bstop = False
End If
Case Keys.F5 : Return True ' no refresh
Case Keys.ControlKey ' control down ? then bypass P
' key
If m.Msg = &H100 Then
ControlP = True
Else
ControlP = False
End If
Case Keys.P
If ControlP Then Return True
Case Else
If m.Msg = &H104 Then ' no more ALT shortcuts (
' alt F4 etc etc )
Return True
End If
End Select
End Function
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