CWnd::EnableToolTips

Статья
10/16/2008

Enables tool tips for the given window.

BOOL EnableToolTips(
   BOOL bEnable = TRUE
);

Параметры

bEnable
Specifies whether the tool tip control is enabled or disabled. TRUE enables the control; FALSE disables the control.

Возвращаемое значение

TRUE if tool tips are enabled; otherwise FALSE.

Заметки

Override OnToolHitTest to provide the TOOLINFO struct or structs for the window.

Примечание.
Some windows, such as CToolBar, provide a built-in implementation of OnToolHitTest.

See TOOLINFO in the Windows SDK for more information on this structure.

Simply calling EnableToolTips is not enough to display tool tips for your child controls unless the parent window is derived from CFrameWnd. This is because CFrameWnd provides a default handler for the TTN_NEEDTEXT notification. If your parent window is not derived from CFrameWnd, that is, if it is a dialog box or a form view, tool tips for your child controls will not display correctly unless you provide a handler for the TTN_NEEDTEXT tool tip notification. See Tool Tips.

The default tool tips provided for your windows by EnableToolTips do not have text associated with them. To retrieve text for the tool tip to display, the TTN_NEEDTEXT notification is sent to the tool tip control's parent window just before the tool tip window is displayed. If there is no handler for this message to assign some value to the pszText member of the TOOLTIPTEXT structure, there will be no text displayed for the tool tip.

Пример

// From message map for CMdiView, a CView-derived class
ON_NOTIFY_EX_RANGE(TTN_NEEDTEXTW, 0, 0xFFFF, &CMdiView::OnToolTipNotify)
ON_NOTIFY_EX_RANGE(TTN_NEEDTEXTA, 0, 0xFFFF, &CMdiView::OnToolTipNotify)

void CMdiView::OnInitialUpdate()
{
   CView::OnInitialUpdate();

   m_Edit.Create(ES_MULTILINE | WS_CHILD | WS_VISIBLE | WS_TABSTOP | WS_BORDER,
      CRect(10, 10, 100, 100), this, IDC_TTEDIT);
   EnableToolTips(TRUE);   // enable tool tips for view
}

//Notification handler
BOOL CMdiView::OnToolTipNotify(UINT id, NMHDR* pNMHDR, LRESULT* pResult)
{
   UNREFERENCED_PARAMETER(id);
   UNREFERENCED_PARAMETER(pResult);

   // need to handle both ANSI and UNICODE versions of the message
   TOOLTIPTEXTA* pTTTA = (TOOLTIPTEXTA*)pNMHDR;
   TOOLTIPTEXTW* pTTTW = (TOOLTIPTEXTW*)pNMHDR;
   CStringA strTipText;
   UINT_PTR nID = pNMHDR->idFrom;
   if (pNMHDR->code == TTN_NEEDTEXTA && (pTTTA->uFlags & TTF_IDISHWND) ||
      pNMHDR->code == TTN_NEEDTEXTW && (pTTTW->uFlags & TTF_IDISHWND))
   {
      // idFrom is actually the HWND of the tool
      nID = ::GetDlgCtrlID((HWND)nID);
   }

   if (nID != 0) // will be zero on a separator
      strTipText.Format("Control ID = %d", nID);

   if (pNMHDR->code == TTN_NEEDTEXTA)
   {
      strncpy_s(pTTTA->szText, sizeof(pTTTA->szText), strTipText, 
         strTipText.GetLength() + 1);
   }
   else
   {
      ::MultiByteToWideChar(CP_ACP , 0, strTipText, strTipText.GetLength() + 1,
         pTTTW->szText, sizeof(pTTTW->szText)/(sizeof pTTTW->szText[0]));
   }

   return TRUE;    // message was handled
}