How to format tooltip in win32?

Question

Hi,
After initializing the tooltip, I want to set up few custom formats.
my part1 code as follow:

m_hWndTooltip = ::CreateWindowEx(0, TOOLTIPS_CLASS, 0, dwStyle,  
            CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT,  
            m_hParent, 0, m_hInstance, 0);  
TOOLINFO ti;  
//...setup ti;  
::SendMessage(m_hWndTooltip, TTM_ADDTOOL, 0, (LPARAM)&ti);  
if (SendMessage(m_hWndTooltip, TTM_TRACKACTIVATE, (WPARAM)TRUE, (LPARAM)&ti))  
{  
    NMTTCUSTOMDRAW nmh; //Initialize setting  
    RECT rec;  
    GetWindowRect(m_hWndTooltip, &rec);  
    ::SendMessage(m_hWnd, WM_NOTIFY, idFrom, (LPARAM)&nmh);  
}  

in part2, the NOTIFY called passed to winproc as follows:

case WM_NOTIFY:  
{  
switch (((LPNMHDR)lParam)->code)  
{  
  
    case NM_CUSTOMDRAW:  
        const auto& lpNMCustomDraw = (LPNMTTCUSTOMDRAW)lParam;   
        OnToolTipCustomDraw(lpNMCustomDraw);  
          
    break;  
}  

}
//--------------------------------------------------------------

LRESULT OnToolTipCustomDraw(NMTTCUSTOMDRAW* pcd)  
{  
  
 LRESULT result = CDRF_DODEFAULT;  
 switch (pcd->nmcd.dwDrawStage)  
 {  
 case CDDS_PREPAINT:  
 {  
  
 auto result1 = SetTextColor(pcd->nmcd.hdc, 0x000000FF);  
 if (CLR_INVALID == result1)  
 outputA("\nSet textcolor failded.");  
  
 result = CDRF_NOTIFYPOSTPAINT;  
 break;  
 }  
 }  
 return result;  
}  

however, after showing, the tooltip does not change format.
my question is:
Is the call setup for OnNotify correct or not? (i called it right after showing the tooltip)
Also, does the return value of OnToolTipCustomDraw work with winproc?

Thanks you!

Answer 1

What is in DrawToolTipContent ?
(CDDS_PREPAINT is not used for the colors with Tooltips)

A quick test with FillRect and DrawText in CDDS_POSTPAINT :