Re: How do you obtain a Window Handle?

From:

Hans-J. Ude <news@hajue-ude.de>

Newsgroups:

microsoft.public.vc.mfc

Date:

Tue, 05 Feb 2008 02:36:38 +0100

Message-ID:

<g5efq3dqpbe84k05joeh8aqr8tlhd7n5g0@4ax.com>

"Check Abdoul" <check abdoul at mvps dot org> wrote:

Take a look at the CWnd::GetWindow() member function. You should be able to
pass GW_CHILD and then GW_NEXT in a loop to get all the child windows of a
given main window. If you want to do it without MFC, then use the
GetWindow() API. Something like

TCHAR sClassName[MAX_PATH+1] = {0};

HWND hWndChild = ::GetWindow( hWndParent, GW_CHILD);
while ( hWndChild != NULL )
{
   // Do something with the hWndChild. For example call
   // GetClassName(hWndChild, sClassName, MAX_PATH );
   // to get its window class name

    hWndChild = ::GetWindow(hWndChild, GW_HWNDNEXT);
}

I once wrote some code based on that method. It's recursive and
displays all windows in the system in a CTreeCtrl. Just like Spy++.
Since results are sometimes slightly different I'm wondering what's
buggy. Spy++ or my code. I guess Spy++ ;)

Hans

////////// Top of file ////////////////////
void CWindowDlg::PopulateWinTree()
{
    CString str;
    TVINSERTSTRUCT tvi;

    c_winTree.DeleteAllItems();
    HWND hwnd = ::GetDesktopWindow();
    str = FormatEntry(hwnd);
    str += _T("(Desktop)");

    tvi.hParent = TVI_ROOT;
    tvi.hInsertAfter = TVI_ROOT;
    tvi.item.mask = TVIF_PARAM | TVIF_TEXT;
    tvi.item.lParam = (LPARAM) hwnd;
    tvi.item.pszText = (LPTSTR) LPCTSTR(str);
    HTREEITEM hRoot = c_winTree.InsertItem (&tvi);

    hwnd = ::GetWindow(::GetDesktopWindow(), GW_CHILD);
    RecurseWindows(hwnd, hRoot);
    c_winTree.Expand(hRoot, TVE_EXPAND);
}

HTREEITEM CWindowDlg::RecurseWindows(HWND hwnd, HTREEITEM hParent)
{
    TVINSERTSTRUCT tvi;
    HTREEITEM hTree = 0;
    CString str;

    if (hwnd == 0)
        return 0;

    hwnd = ::GetWindow(hwnd, GW_HWNDFIRST);
    tvi.hParent = hParent;
    tvi.hInsertAfter = TVI_LAST;
    tvi.item.mask = TVIF_PARAM | TVIF_TEXT ;

    while (hwnd)
    {
        if (::GetWindowLong(hwnd, GWL_STYLE) & WS_VISIBLE)
        {
            // Visible Window
        }
        else
        {
            // Hidden Window
        }
        str = FormatEntry(hwnd);
        tvi.item.pszText = (LPTSTR) LPCTSTR(str);
        tvi.item.lParam = (LPARAM) hwnd;
        hTree = c_winTree.InsertItem (&tvi);
        c_winTree.SetItem (&tvi.item);

        RecurseWindows(::GetWindow(hwnd, GW_CHILD), hTree);
        hwnd = ::GetWindow(hwnd, GW_HWNDNEXT);
    }
    return hTree;
}

CString& CWindowDlg::FormatEntry(HWND hwnd)
{
    static CString str;
    TCHAR wndtext[256];
    TCHAR classname[256];

    wndtext[0] = classname[0] = _T('\0');
    ::GetWindowText(hwnd, wndtext, sizeof(wndtext)/sizeof(TCHAR));
    ::GetClassName(hwnd, classname,
sizeof(classname)/sizeof(TCHAR));
    str.Format (_T("%08Xh \"%s\" \'%s\' "), hwnd, wndtext,
classname);
    return str;
}

void CWindowDlg::OnRefresh()
{
    PopulateWinTree();
}
////////// Bottom of file ////////////////////