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WebBrowser.CreateSink Method

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Definition

Namespace:
System.Windows.Forms
Assembly:
System.Windows.Forms.dll
Source:
WebBrowser.cs
Source:
WebBrowser.cs
Source:
WebBrowser.cs

Associates the underlying ActiveX control with a client that can handle control events.

protected:
 override void CreateSink();
protected override void CreateSink ();
override this.CreateSink : unit -> unit
Protected Overrides Sub CreateSink ()

Examples

The following code example illustrates the use of this method in a class derived from WebBrowser that supplements the normal WebBrowser events with the NavigateError event from the OLE DWebBrowserEvents2 interface.

using System;
using System.Windows.Forms;
using System.Runtime.InteropServices;
using System.Security.Permissions;

namespace WebBrowserExtensibility
{
    public class Form1 : Form
    {
        [STAThread]
        public static void Main()
        {
            Application.Run(new Form1());
        }

        private WebBrowser2 wb = new WebBrowser2();
        public Form1()
        {
            wb.Dock = DockStyle.Fill;
            wb.NavigateError += new 
                WebBrowserNavigateErrorEventHandler(wb_NavigateError);
            Controls.Add(wb);

            // Attempt to navigate to an invalid address.
            wb.Navigate("www.widgets.microsoft.com");
        }

        private void wb_NavigateError(
            object sender, WebBrowserNavigateErrorEventArgs e)
        {
            // Display an error message to the user.
            MessageBox.Show("Cannot navigate to " + e.Url);
        }
    }

    public class WebBrowser2 : WebBrowser
    {
        AxHost.ConnectionPointCookie cookie;
        WebBrowser2EventHelper helper;

        protected override void CreateSink()
        {
            base.CreateSink();

            // Create an instance of the client that will handle the event
            // and associate it with the underlying ActiveX control.
            helper = new WebBrowser2EventHelper(this);
            cookie = new AxHost.ConnectionPointCookie(
                this.ActiveXInstance, helper, typeof(DWebBrowserEvents2));
        }

        protected override void DetachSink()
        {
            // Disconnect the client that handles the event
            // from the underlying ActiveX control.
            if (cookie != null)
            {
                cookie.Disconnect();
                cookie = null;
            }
            base.DetachSink();
        }

        public event WebBrowserNavigateErrorEventHandler NavigateError;

        // Raises the NavigateError event.
        protected virtual void OnNavigateError(
            WebBrowserNavigateErrorEventArgs e)
        {
            if (this.NavigateError != null)
            {
                this.NavigateError(this, e);
            }
        }

        // Handles the NavigateError event from the underlying ActiveX 
        // control by raising the NavigateError event defined in this class.
        private class WebBrowser2EventHelper : 
            StandardOleMarshalObject, DWebBrowserEvents2
        {
            private WebBrowser2 parent;

            public WebBrowser2EventHelper(WebBrowser2 parent)
            {
                this.parent = parent;
            }

            public void NavigateError(object pDisp, ref object url, 
                ref object frame, ref object statusCode, ref bool cancel)
            {
                // Raise the NavigateError event.
                this.parent.OnNavigateError(
                    new WebBrowserNavigateErrorEventArgs(
                    (String)url, (String)frame, (Int32)statusCode, cancel));
            }
        }
    }

    // Represents the method that will handle the WebBrowser2.NavigateError event.
    public delegate void WebBrowserNavigateErrorEventHandler(object sender, 
        WebBrowserNavigateErrorEventArgs e);

    // Provides data for the WebBrowser2.NavigateError event.
    public class WebBrowserNavigateErrorEventArgs : EventArgs
    {
        private String urlValue;
        private String frameValue;
        private Int32 statusCodeValue;
        private Boolean cancelValue;

        public WebBrowserNavigateErrorEventArgs(
            String url, String frame, Int32 statusCode, Boolean cancel)
        {
            urlValue = url;
            frameValue = frame;
            statusCodeValue = statusCode;
            cancelValue = cancel;
        }

        public String Url
        {
            get { return urlValue; }
            set { urlValue = value; }
        }

        public String Frame
        {
            get { return frameValue; }
            set { frameValue = value; }
        }

        public Int32 StatusCode
        {
            get { return statusCodeValue; }
            set { statusCodeValue = value; }
        }

        public Boolean Cancel
        {
            get { return cancelValue; }
            set { cancelValue = value; }
        }
    }

    // Imports the NavigateError method from the OLE DWebBrowserEvents2 
    // interface. 
    [ComImport, Guid("34A715A0-6587-11D0-924A-0020AFC7AC4D"),
    InterfaceType(ComInterfaceType.InterfaceIsIDispatch),
    TypeLibType(TypeLibTypeFlags.FHidden)]
    public interface DWebBrowserEvents2
    {
        [DispId(271)]
        void NavigateError(
            [In, MarshalAs(UnmanagedType.IDispatch)] object pDisp,
            [In] ref object URL, [In] ref object frame, 
            [In] ref object statusCode, [In, Out] ref bool cancel);
    }
}

Imports System.Windows.Forms
Imports System.Runtime.InteropServices
Imports System.Security.Permissions

Namespace WebBrowserExtensibility

    <PermissionSetAttribute(SecurityAction.Demand, Name:="FullTrust")> _
    Public Class Form1
        Inherits Form

        <STAThreadAttribute()> Public Shared Sub Main()
            Application.Run(New Form1())
        End Sub

        Private WithEvents wb As New WebBrowser2()

        Public Sub New()

            wb.Dock = DockStyle.Fill
            Controls.Add(wb)

            ' Attempt to navigate to an invalid address.
            wb.Navigate("www.widgets.microsoft.com")

        End Sub

        Private Sub wb_NavigateError( _
            ByVal sender As Object, _
            ByVal e As WebBrowserNavigateErrorEventArgs) _
            Handles wb.NavigateError

            ' Display an error message to the user.
            MessageBox.Show("Cannot navigate to " + e.Url)

        End Sub

    End Class

    Public Class WebBrowser2
        Inherits WebBrowser

        Private cookie As AxHost.ConnectionPointCookie
        Private helper As WebBrowser2EventHelper

        <PermissionSetAttribute(SecurityAction.LinkDemand, _
        Name := "FullTrust")> Protected Overrides Sub CreateSink()

            MyBase.CreateSink()

            ' Create an instance of the client that will handle the event
            ' and associate it with the underlying ActiveX control.
            helper = New WebBrowser2EventHelper(Me)
            cookie = New AxHost.ConnectionPointCookie( _
                Me.ActiveXInstance, helper, GetType(DWebBrowserEvents2))
        End Sub

        <PermissionSetAttribute(SecurityAction.LinkDemand, _
        Name := "FullTrust")> Protected Overrides Sub DetachSink()

            ' Disconnect the client that handles the event
            ' from the underlying ActiveX control.
            If cookie IsNot Nothing Then
                cookie.Disconnect()
                cookie = Nothing
            End If
            MyBase.DetachSink()

        End Sub

        Public Event NavigateError As WebBrowserNavigateErrorEventHandler

        ' Raises the NavigateError event.
        Protected Overridable Sub OnNavigateError( _
            ByVal e As WebBrowserNavigateErrorEventArgs)

            RaiseEvent NavigateError(Me, e)

        End Sub

        ' Handles the NavigateError event from the underlying ActiveX 
        ' control by raising the NavigateError event defined in this class.
        Private Class WebBrowser2EventHelper
            Inherits StandardOleMarshalObject
            Implements DWebBrowserEvents2

            Private parent As WebBrowser2

            Public Sub New(ByVal parent As WebBrowser2)
                Me.parent = parent
            End Sub

            Public Sub NavigateError(ByVal pDisp As Object, _
                ByRef URL As Object, ByRef frame As Object, _
                ByRef statusCode As Object, ByRef cancel As Boolean) _
                Implements DWebBrowserEvents2.NavigateError

                ' Raise the NavigateError event.
                Me.parent.OnNavigateError( _
                    New WebBrowserNavigateErrorEventArgs( _
                    CStr(URL), CStr(frame), CInt(statusCode), cancel))

            End Sub

        End Class

    End Class

    ' Represents the method that will handle the WebBrowser2.NavigateError event.
    Public Delegate Sub WebBrowserNavigateErrorEventHandler(ByVal sender As Object, _
        ByVal e As WebBrowserNavigateErrorEventArgs)

    ' Provides data for the WebBrowser2.NavigateError event.
    Public Class WebBrowserNavigateErrorEventArgs
        Inherits EventArgs

        Private urlValue As String
        Private frameValue As String
        Private statusCodeValue As Int32
        Private cancelValue As Boolean

        Public Sub New( _
            ByVal url As String, ByVal frame As String, _
            ByVal statusCode As Int32, ByVal cancel As Boolean)

            Me.urlValue = url
            Me.frameValue = frame
            Me.statusCodeValue = statusCode
            Me.cancelValue = cancel

        End Sub

        Public Property Url() As String
            Get
                Return urlValue
            End Get
            Set(ByVal value As String)
                urlValue = value
            End Set
        End Property

        Public Property Frame() As String
            Get
                Return frameValue
            End Get
            Set(ByVal value As String)
                frameValue = value
            End Set
        End Property

        Public Property StatusCode() As Int32
            Get
                Return statusCodeValue
            End Get
            Set(ByVal value As Int32)
                statusCodeValue = value
            End Set
        End Property

        Public Property Cancel() As Boolean
            Get
                Return cancelValue
            End Get
            Set(ByVal value As Boolean)
                cancelValue = value
            End Set
        End Property

    End Class

    ' Imports the NavigateError method from the OLE DWebBrowserEvents2 
    ' interface. 
    <ComImport(), Guid("34A715A0-6587-11D0-924A-0020AFC7AC4D"), _
    InterfaceType(ComInterfaceType.InterfaceIsIDispatch), _
    TypeLibType(TypeLibTypeFlags.FHidden)> _
    Public Interface DWebBrowserEvents2

        <DispId(271)> Sub NavigateError( _
            <InAttribute(), MarshalAs(UnmanagedType.IDispatch)> _
            ByVal pDisp As Object, _
            <InAttribute()> ByRef URL As Object, _
            <InAttribute()> ByRef frame As Object, _
            <InAttribute()> ByRef statusCode As Object, _
            <InAttribute(), OutAttribute()> ByRef cancel As Boolean)

    End Interface

End Namespace

Remarks

This method is useful if you are familiar with OLE development using the unmanaged WebBrowser ActiveX control and you want to extend the functionality of the Windows Forms WebBrowser control, which is a managed wrapper for the ActiveX control. You can use this extensibility to implement events from the ActiveX control that are not provided by the wrapper control.

Applies to

See also