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Programmatically scrolling WebBrowser control from Visual C/C++

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22 Aug 2001 254.2K   48   45
Article describes how to obtain IHTML interfaces to prrogrammatically scroll WebBrowser control from Visual C/C++.

Introduction

For some time I struggled to do these simple tasks in Visual C++:

  1. How to get browser window to scroll programmatically?

    It does not accept Windows scroll messages. Calling the MFC GetScrollInfo APIs does not do anything. But there is a way.

  2. To scroll we use IHTMLElement2 API get_scrollTop/put_scrollTop... but how do I obtain IHTMLElement2?

The way is a bit obscure...

Now, the code

//
// All this code does is what
// "m_browser.Document.Body.ScrollTop = 100;"
// does in VB. Gotta love COM in C++.
//

// let's say m_browser is the WebBrowser's member variable.

HRESULT hr;

// get the document dispatch from browser
IDispatch *pDisp = m_browser.GetDocument();
ASSERT( pDisp ); //if NULL, we failed

// get document interface
IHTMLDocument2 *pDocument = NULL;
hr = pDisp->QueryInterface( IID_IHTMLDocument2, (void**)&pDocument );
ASSERT( SUCCEEDED( hr ) );
ASSERT( pDocument );

//
// this is the trick!
// take the body element from document...
//
IHTMLElement *pBody = NULL;
hr = pDocument->get_body( &pBody );
ASSERT( SUCCEEDED( hr ) );
ASSERT( pBody );

// from body we can get element2 interface,
// which allows us to do scrolling
IHTMLElement2 *pElement = NULL;
hr = pBody->QueryInterface(IID_IHTMLElement2,(void**)&pElement);
ASSERT(SUCCEEDED(hr));
ASSERT( pElement );

// now we are ready to scroll
// scroll down to 100th pixel from top
pElement->put_scrollTop( 100 );

// try to get the whole page size - but the returned number
// is not allways correct. especially with pages that use dynamic html
// tricks...
long scroll_height;
pElement->get_scrollHeight( &s );

// we can use this workaround!
long real_scroll_height;
pElement->put_scrollTop( 20000000 ); // ask to scroll really far down...
pElement->get_scrollTop( &real_scroll_height );
real_scroll_height += window_height; // will return the scroll height
// for the first visible pixel, to get whole html page size must
// add the window's height... (to obtain window_height is
// left as an exercise for the reader)


// print to debug output
TRACE( "real scroll height: %ld, get_scrollHeight: %ld\n",
                 real_scroll_height, scroll_height );

And there we have it.

License

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Comments and Discussions

 
Generalie7 crash for scrolling [modified] Pin
castielle_alana14-Oct-10 21:09
castielle_alana14-Oct-10 21:09 
Generalno shtypes.h file.... Pin
Aric Wang24-Mar-10 18:59
Aric Wang24-Mar-10 18:59 
QuestionUsing this code with new versions of IE? Pin
Trapper300129-Jan-10 8:33
Trapper300129-Jan-10 8:33 
AnswerRe: Using this code with new versions of IE? [modified] Pin
Trapper30012-Feb-10 5:39
Trapper30012-Feb-10 5:39 
QuestionHow to do it in BCB6 Pin
Chriz_z26-Oct-06 1:57
Chriz_z26-Oct-06 1:57 
GeneralApplet in WebBrowser Pin
colin-12312-Sep-06 23:50
colin-12312-Sep-06 23:50 
GeneralThanks heaps. I spent hours looking for how to do that. Pin
jai20024-May-05 16:26
jai20024-May-05 16:26 
GeneralThanks (works with CDHtmldialog as well) Pin
richard sancenot4-Apr-05 5:08
richard sancenot4-Apr-05 5:08 
Thanks for saving me valuable time Big Grin | :-D .

To scroll to the bottom with CDHtmlDialog, simply call the CDhtmlFunction GetInterface memberfunction

IHTMLElement2 *pElement = NULL;
if(SUCCEEDED(GetElementInterface(_T("SpanList"),IID_IHTMLElement2,(void**)&pElement)))
{
long lHeight;
pElement->get_scrollHeight(&lHeight);
pElement->put_scrollTop(lHeight);
pElement->Release();//It's not a smart pointer
}


Tout programme dont la fiabilité dépend de l'homme n'est pas fiable
GeneralChanging the size of Scrollbar in WebBrowser control Pin
Wasif Ali4-Apr-05 1:10
Wasif Ali4-Apr-05 1:10 
GeneralRe: Changing the size of Scrollbar in WebBrowser control Pin
richard sancenot4-Apr-05 5:00
richard sancenot4-Apr-05 5:00 
GeneralUsing Scroll Pin
unidentify26-Mar-05 22:19
unidentify26-Mar-05 22:19 
Questionhow to seperate pictures? Pin
Member 46991628-Feb-05 6:48
Member 46991628-Feb-05 6:48 
GeneralAny Help on how to do it with C# Pin
ggmemo8-Feb-05 5:19
ggmemo8-Feb-05 5:19 
GeneralRe: Any Help on how to do it with C# Pin
Boyan N. Rabchev26-Mar-05 0:02
Boyan N. Rabchev26-Mar-05 0:02 
GeneralRe: Any Help on how to do it with C# Pin
pinkyNet13-Apr-07 10:38
pinkyNet13-Apr-07 10:38 
Generalhow to make webbrowser scroll with vb.net Pin
JohannNutter6-Sep-09 17:50
JohannNutter6-Sep-09 17:50 
GeneralRe: Any Help on how to do it with C# Pin
Bojan Sala23-Aug-06 14:31
professionalBojan Sala23-Aug-06 14:31 
GeneralRe: Any Help on how to do it with C# Pin
Knightrunner21-Sep-07 1:45
Knightrunner21-Sep-07 1:45 
GeneralWant IE automate and IpHelper Help Pin
eiteit24-Nov-04 7:21
eiteit24-Nov-04 7:21 
QuestionCan we get the total scroll Height and width Pin
eacho.woo13-Oct-04 17:31
eacho.woo13-Oct-04 17:31 
QuestionAllow ActiveX execution in browser? Pin
dragomir10-Sep-04 20:33
dragomir10-Sep-04 20:33 
GeneralCatching Scroll Bar Events Pin
Humphrey Chakma6-Apr-04 19:45
Humphrey Chakma6-Apr-04 19:45 
QuestionHow to get scroll bar position? Pin
w1424331-Mar-04 18:48
w1424331-Mar-04 18:48 
AnswerRe: How to get scroll bar position? Pin
Humphrey Chakma31-Mar-04 22:43
Humphrey Chakma31-Mar-04 22:43 
GeneralA version that does not use IHTMLElement2 Pin
mrxeng23-Feb-04 20:45
mrxeng23-Feb-04 20:45 

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