XTipComboBox - Display tooltips for combobox

• Download demo project - 31 Kb

Introduction

Here is how the tooltips look - note that the tooltip colors will match what is being tooltipped:

Implementation Notes

• PreSubclassWindow() - this virtual function allows us to create tooltip window, add combobox as its tool, and perform other initialization. Note use of TTF_TRANSPARENT. This flag tells tooltip control to forward mouse messages (including mouse clicks) to the parent window. In the case of the listbox, this will prevent two CBN_SELENDOK messages from being sent to the parent dialog.
  
  
• OnCtlColor() - This is not what you think. According to MSDN article HOWTO: Subclass CListBox and CEdit Inside of CComboBox (Q174667), this is actually recommended way of subclassing listbox of a combobox. We use this to subclass listbox only - for edit box, it is simpler to handle inside CXTipComboBox.
  
  
• OnMouseMove() - This message handler catches mouse moves, and when mouse is inside combo client rect, tooltip will be activated.
  
  
• OnTimer() - A timer is used only when a tooltip is being displayed. When code in OnTimer() detects that mouse is no longer inside client rect, tooltip is removed.
  
  
• OnDestroy() - Unsubclasses the listbox.
  
  

Note that nearly identical code is implemented for first four functions in XTipComboBox.cpp and XTipListBox.cpp.

Tooltip Notes

    // create tooltip
    m_hWndToolTip = ::CreateWindowEx(WS_EX_TOPMOST,
                              TOOLTIPS_CLASS,
                              NULL,
                              TTS_NOPREFIX | TTS_ALWAYSTIP,
                              CW_USEDEFAULT,
                              CW_USEDEFAULT,
                              CW_USEDEFAULT,
                              CW_USEDEFAULT,
                              m_hWnd,
                              NULL,
                              NULL,
                              NULL);
    ASSERT(m_hWndToolTip);

    // initialize toolinfo struct
    memset(&m_ToolInfo, 0, sizeof(m_ToolInfo));
    m_ToolInfo.cbSize = sizeof(m_ToolInfo);
    m_ToolInfo.uFlags = TTF_TRACK | TTF_TRANSPARENT;
    m_ToolInfo.hwnd = m_hWnd;

    // add combo box
    ::SendMessage(m_hWndToolTip, TTM_SETMAXTIPWIDTH, 0, SHRT_MAX);
    ::SendMessage(m_hWndToolTip, TTM_ADDTOOL, 0, 
                                          (LPARAM) (LPTOOLINFO) &m_ToolInfo);
    ::SendMessage(m_hWndToolTip, TTM_SETTIPBKCOLOR, 
                                          ::GetSysColor(COLOR_HIGHLIGHT), 0);
    ::SendMessage(m_hWndToolTip, TTM_SETTIPTEXTCOLOR, 
                                      ::GetSysColor(COLOR_HIGHLIGHTTEXT), 0);

    // reduce top & bottom margins
    CRect rectMargins(0,-1,0,-1);
    ::SendMessage(m_hWndToolTip, TTM_SETMARGIN, 0, (LPARAM)&rectMargins);

    // set font
    CFont *pFont = GetFont();
    ::SendMessage(m_hWndToolTip, WM_SETFONT, (WPARAM)(HFONT)*pFont, FALSE); 

How To Use

To integrate CXTipComboBox into your app, you first need to add following files to your project:

• XTipComboBox.cpp
• XTipComboBox.h
• XTipListBox.cpp
• XTipListBox.h

Next, include header file XTipComboBox.h in appropriate project files (usually, dialog header files). Now you are ready to start using CXTipComboBox. If you already have a dialog box with combobox controls, just replace CComboBox with CXTipComboBox in the dialog header file. There is no extra initialization you need to do.

Demo App

Revision History

Version 1.0 - 2003 June 30

• Initial public release.

Usage

This software is released into the public domain. You are free to use it in any way you like. If you modify it or extend it, please to consider posting new code here for everyone to share. This software is provided "as is" with no expressed or implied warranty. I accept no liability for any damage or loss of business that this software may cause.

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)