How to display text in system tray icon with win32 API?

Question

Trying to create a small monitor application that displays current internet usage as percentage in system tray in C using win32 API.

Also wanting to use colour background or colour text based on how much is used relative to days left in month.

EDIT: To clarify I am wanting the system tray icon to be dynamic. As the percentage changes I update the system tray icon. Looking for solution that uses just plain old win32 (ie. No MFC or WTL).

Answer 1

By text you mean "Tips" ?

Assuming you have your icon on the System Tray

NOTIFYICONDATA _stNotifyIconData;

// For a simple Tip
_stNotifyIconData.uFlags = NIF_TIP;
strcpy_s(_stNotifyIconData.szTip, "Little Tip"); // Copy Tip    
Shell_NotifyIcon(NIM_MODIFY, &_stNotifyIconData);

// For a Ballon Tip
_stNotifyIconData.uFlags = NIF_INFO;
strcpy_s(_stNotifyIconData.szInfoTitle, "Title of the Ballon"); // Title
strcpy_s(_stNotifyIconData.szInfo, "Text..." ); // Copy Tip
_stNotifyIconData.uTimeout = 3000;  // 3 Seconds
_stNotifyIconData.dwInfoFlags = NIIF_INFO;

Shell_NotifyIcon(NIM_MODIFY, &_stNotifyIconData);

Answer 2

The system tray only accepts icons to show, not text.

To get a text shown there, you have to first create a memory bitmap, draw your text on it, then convert that memory bitmap to a memory icon and have the system tray show that icon.

Example code below:

CDC dcMem;
dcMem.CreateCompatibleDC(NULL);

CBitmap* pOld = dcMem.SelectObject( &m_bmpIcon );

CBrush back( RGB(0,0,0) );
dcMem.FillRect( CRect(0,0,16,16), &back );

CBrush brush( COLORDOWN );
dcMem.FillRect( rcRecv, &brush );

dcMem.SelectObject( pOld );

HICON hIcon = CreateIconIndirect( &m_TaskBarIconInfo );

Answer 3

Okay here is my win32 solution:

HICON CreateSmallIcon( HWND hWnd )
{
    static TCHAR *szText = TEXT ( "100" );
    HDC hdc, hdcMem;
    HBITMAP hBitmap = NULL;
    HBITMAP hOldBitMap = NULL;
    HBITMAP hBitmapMask = NULL;
    ICONINFO iconInfo;
    HFONT hFont;
    HICON hIcon;

    hdc = GetDC ( hWnd );
    hdcMem = CreateCompatibleDC ( hdc );
    hBitmap = CreateCompatibleBitmap ( hdc, 16, 16 );
    hBitmapMask = CreateCompatibleBitmap ( hdc, 16, 16 );
    ReleaseDC ( hWnd, hdc );
    hOldBitMap = (HBITMAP) SelectObject ( hdcMem, hBitmap );
    PatBlt ( hdcMem, 0, 0, 16, 16, WHITENESS );

    // Draw percentage
    hFont = CreateFont (12, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
                    TEXT ("Arial"));
    hFont = (HFONT) SelectObject ( hdcMem, hFont );
    TextOut ( hdcMem, 0, 0, szText, lstrlen (szText) );

    SelectObject ( hdc, hOldBitMap );
    hOldBitMap = NULL;

    iconInfo.fIcon = TRUE;
    iconInfo.xHotspot = 0;
    iconInfo.yHotspot = 0;
    iconInfo.hbmMask = hBitmapMask;
    iconInfo.hbmColor = hBitmap;

    hIcon = CreateIconIndirect ( &iconInfo );

    DeleteObject ( SelectObject ( hdcMem, hFont ) );
    DeleteDC ( hdcMem );
    DeleteDC ( hdc );
    DeleteObject ( hBitmap );
    DeleteObject ( hBitmapMask );

    return hIcon;
}