DrawToDC

re: DrawToDC

Geoff Appleby — Tue, 12 Oct 2004 18:10:00 GMT

Without actually going and trying it myself, i would hazard a guess that the IHTMLElementRender interface isn't an actual inherited interface of the body element.

QueryInterface somtimes does more than just cast the object to a different interface, I'd make a bet that the QueryInterface for IHtmlElementRender is acting like a factory, and returning a new object. So therefore, when you just try and cast to that render interface, you get back null.

Try calling QueryInterface directly on your body element, and see what that gives you. Let me know how you :)

--Geoff

re: DrawToDC

Geoff Appleby — Tue, 12 Oct 2004 18:11:00 GMT

how you go, i mean to say.

re: DrawToDC

Darron — Wed, 13 Oct 2004 00:05:00 GMT

I tried this real quick and it works. I threw together a form with an IE control and a panel. There is an issue with import of the MSHTML interface so just redeclare it locally and you will have no problems. If render is null, you may have a frame to deal with.

using System;
using System.Drawing;
using System.Runtime.InteropServices;
using SHDocVw;
using mshtml;

namespace ScreenGrab
{
[
Guid("3050f669-98b5-11cf-bb82-00aa00bdce0b"),
InterfaceTypeAttribute(ComInterfaceType.InterfaceIsIUnknown),
ComVisible(true),
ComImport
]
interface IHTMLElementRender
{
void DrawToDC([In] IntPtr hDC);
void SetDocumentPrinter([In, MarshalAs(UnmanagedType.BStr)] string bstrPrinterName, [In] IntPtr hDC);
};

public class IEElementCapture
{
private IWebBrowser2 webBrowser = null;

public IEElementCapture(IWebBrowser2 webBrowser)
{
this.webBrowser = webBrowser;
}

public bool Capture(ref Graphics g)
{
if ( null == webBrowser )
{
return false;
}

IHTMLDocument2 htmlDocument = (IHTMLDocument2) webBrowser.Document;
if ( null != htmlDocument )
{
IHTMLElement bodyElement = (IHTMLElement) htmlDocument.body;
if ( null != bodyElement )
{
IHTMLElementRender render = (IHTMLElementRender) bodyElement;
if ( null != render )
{
IntPtr memDC = g.GetHdc();
render.DrawToDC(memDC);
return true;
}
}
}

return false;
}
}
}

re: DrawToDC

Ryan — Wed, 13 Oct 2004 09:12:00 GMT

This is perfect. Thank you. It is interesting that it doesn't pick up the custom DHTML filters like the gradients applied on www.microsoft.com home page.

re: DrawToDC

dd — Wed, 10 Nov 2004 12:05:00 GMT

Is there a VB.net version of this code?

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