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How can I get information about the scrollbars of an instance of a Webbrowser or IE Webrowser control?

I need to get information about scrollbars (position, size, visibility) of an external application's Webbrowser control , I tried to use GetScrollBarInfo from my previous question , but the function always returns false, I have tested this function with other applications and it worked fine, but not with IE or with the Webbrowser control.So how I can get information about the scrollbars of an Webbrowser control instance or the IE Webbrowser?

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This is how you can tell if scrollbars are visible or not. Some error checking has been omitted for brevity.

LPDISPATCH      lpDispatch;
lpDispatch      = m_Browser.GetDocument();

IHTMLDocument2 *doc2 = NULL;
disp->QueryInterface(IID_IHTMLDocument2,(void**)&doc2);

IHTMLElement *lpBodyElement; 
IHTMLBodyElement *lpBody; 

doc2->get_body(&lpBodyElement); 
if ( lpBodyElement )
{
lpBodyElement->QueryInterface(IID_IHTMLBodyElement,(void**)&lpBody); 
if ( lpBody )
{
    BSTR bstrText; 
            pBody->get_scroll(&bstrText);
    lpBody->Release(); 
}
lpBodyElement->Release(); 
}
doc2->Release();

Possible values ​​for bstrText are yes, no, auto (scrollbars are displayed when the page content exceeds the client area)



And this is how you can find out the current scroll position:

IHTMLElement2 *pElement = NULL;
hr = pBody->QueryInterface(IID_IHTMLElement2,(void**)&pElement);
ASSERT(SUCCEEDED(hr));
ASSERT( pElement );
long scroll_pos;
pElement->get_scrollTop( &scroll_pos);
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You can send a message WM_HTML_GETOBJECT

to the "Internet Explorer_Server"

external application class window to receive IHtmlDocument2

, and then using IServiceProvider

you can get the interface IWebBrowser2

.
Here's some sample code in Delphi:

uses
  ActiveX, MSHTML;

type
  TObjectFromLResult = function(LRESULT: lResult; const IID: TIID;
    wParam: wParam; out pObject): HRESULT; stdcall;

function GetIEFromHWND(WHandle: HWND; var IE: IWebbrowser2): HRESULT;
var
  hInst: HWND;
  lRes: Cardinal;
  Msg: Integer;
  pDoc: IHTMLDocument2;
  ObjectFromLresult: TObjectFromLresult;
begin
  Result := S_FALSE;
  hInst := LoadLibrary('Oleacc.dll');
  @ObjectFromLresult := GetProcAddress(hInst, 'ObjectFromLresult');
  if @ObjectFromLresult <> nil then
  try
    Msg := RegisterWindowMessage('WM_HTML_GETOBJECT');
    SendMessageTimeOut(WHandle, Msg, 0, 0, SMTO_ABORTIFHUNG, 1000, lRes);
    Result := ObjectFromLresult(lRes, IHTMLDocument2, 0, pDoc);
    if Result = S_OK then
      (pDoc.parentWindow as IServiceprovider).QueryService(
        IWebbrowserApp, IWebbrowser2, IE);
  finally
    FreeLibrary(hInst);
  end;
end;

procedure TForm1.Button1Click(Sender: TObject);
var
  Wnd, WndChild: HWND;
  IE: IWebBrowser2;
  Document: IHtmlDocument2;
  ScrollTop, ScrollLeft: Integer;
begin
  Wnd := FindWindow('IEFrame', nil); // top level IE
  if Wnd = 0 then Exit;
  WndChild := FindWindowEX(Wnd, 0, 'Shell DocObject View', nil);
  if WndChild = 0 then Exit;
  WndChild := FindWindowEX(WndChild, 0, 'Internet Explorer_Server', nil);
  if WndChild = 0 then Exit;

  GetIEFromHWnd(WndChild, IE);
  if IE <> nil then
  begin
    ShowMessage(IE.LocationURL);
    Document := IE.Document as IHtmlDocument2;
    ScrollTop := ((Document as IHTMLDocument3).documentElement as IHTMLElement2).scrollTop;
    ScrollLeft := ((Document as IHTMLDocument3).documentElement as IHTMLElement2).scrollLeft;
    ShowMessage(Format('%d;%d', [ScrollTop, ScrollLeft]));

    // visible|hidden|scroll|auto|no-display|no-content
    ShowMessage(OleVariant(Document).documentElement.currentStyle.overflowX);
    ShowMessage(OleVariant(Document).documentElement.currentStyle.overflowY);
  end;
end;


Edit: when the page uses the directive <!DOCTYPE>

to switch IE6 to strict standard use mode document.documentElement

. ( IHTMLDocument3

) in pre-standard mode, the body is a scrollable area, so you can get the scroll position with document.body.scrollTop

. In standard mode, the HTML element is scrolled, so you should use document.documentElement.scrollTop

.

If you document.documentElement.clientWidth <> 0

use element documentElement

for else properties, use element body

.
Useful properties relating to information on scrolling, as clientHeight

, scrollWidth

, scrollHeight

.

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