WebBrowser Control: How to Print Preview

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Introduction

The WebBrowser control is widely used to display web pages either in MFC or in Windows Forms applications. The control has more functionality than you may think - print preview, for instance. If you have been using IE 5.5 or higher, you probably have already seen the print preview window. It is a part of the WebBrowser control. If you have worked with CHtmlView, you also should know this functionality. And you perhaps have recognized that this preview window has nothing to do with the traditional print preview with MFC. This article shows you how simple it is to use print preview and page setup in the WebBrowser control. The requirement is IE 5.5 or higher installed.

Add print preview functionality

In the print preview method, I start by verifying the WebBrowser control is valid. Then, I retrieve a pointer to the IDispatch interface pointer to the HTMLDocument, from which I query the IOleCommandTarget interface, and store the pointer in lpTarget. You can find information on the IOleCommandTarget interface in MSDN. I won't repeat the instructions here. Finally, I execute the print preview command by calling IOleCommandTarget::Exec with the appropriate parameters. The command ID OLECMDID_PRINTPREVIEW is defined in "docobj.h". The GUI of print preview is handled by the WebBrowser control.

Following is the source code of the method:

void CWBPDlg::OnDemoPrintpreview() 
{
    // Verify the WebBrowser control is valid.
    LPDISPATCH lpDispApp = m_wndBrowser.GetApplication();
    if(lpDispApp)
    {
        // Get the HTMLDocument interface.
        LPDISPATCH lpDispDoc = m_wndBrowser.GetDocument();
        if (lpDispDoc != NULL)
        {
            // Get the IOleCommandTarget interface so that 
            // we can dispatch the command.
            LPOLECOMMANDTARGET lpTarget = NULL;
            if (SUCCEEDED(lpDispDoc->
                  QueryInterface(IID_IOleCommandTarget,
                                     (LPVOID*) &lpTarget)))
            {
                // Execute the print preview command. The 
                // control will handle the print preview
                // GUI.
                // OLECMDID_PRINTPREVIEW is defined in
                // "docobj.h".
                lpTarget->Exec(NULL,
                    OLECMDID_PRINTPREVIEW, 0, NULL, NULL);
                lpTarget->Release();
            }
            lpDispDoc->Release();
        }
        lpDispApp->Release();
    }
}

Now you can compile and run the application. The GUI of print preview is the same as that you have seen in IE.

Use WebBrowser::ExecWB method - Alexander Tsarfin's contribution

The WebBrowser class implements a wrapper that allows you to execute a command on an OLE object using the IOleCommandTarget::Exec method.

void CWBPDlg::OnDemoPrintpreview()
{
    m_wndBrowser.ExecWB(OLECMDID_PRINTPREVIEW,
                    OLECMDEXECOPT_PROMPTUSER, NULL, NULL);
}

Add page setup

With the same pattern, the following function opens the page setup dialog box:

void CWBPDlg::OnPagesetup()
{
    m_wndBrowser.ExecWB(OLECMDID_PAGESETUP, OLECMDEXECOPT_PROMPTUSER, NULL, NULL);
}

Conclusion

The above two approaches do the same work – one works with COM interfaces, and the other uses a nicely wrapped method. If you go a further step, you will find other OLE command IDs defined in docobj.h. Once you get the IOleCommandTarget interface, you can easily use them. That is beyond the scope of this article.

Revision History

• 26 Jun 2002 - Reformatted code to prevent scrolling.
• 20 March 2005 - Added page setup dialog box.