Owner-drawn context menu in WTL

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Introduction

I was looking for a code to implement an owner-drawn context menu in WTL, but could not find any; everything I found would modify the behavior of the CCommandBarCtrl, and could not be used in a context menu displayed by, let's say, an edit control.

In this article, I�ll show you how to implement an owner-drawn context menu, and how to add cool-looking menus to your application real easy, using my class CCoolContextMenu.

Implementation

In order to make an item an owner-drawn item, you must create a new menu item, or modify an existing one by setting the MFT_OWNERDRAW menu flag.

You can use the InsertMenuItem or SetMenuItemInfo functions to set or change information about a menu item. When calling these two functions, you must specify a pointer to a MENUITEMINFO structure, which specifies the properties of the menu item.

You need to specify the MFT_OWNERDRAW value for the fType member, for an item to become an owner-drawn item. You can also associate an application-defined value, which is called item data, with each menu item. The CCoolContextMenu class defines the MenuItemData structure that contains the information used to draw a menu item. The application uses the dwItemData member to store a pointer to this structure.

The MenuItemData structure is sent to the menu's owner window with the WM_MEASUREITEM and WM_DRAWITEM messages. The GetMenuItemInfo function is used to retrieve the item data for a menu at any time.

LRESULT InitMenuPopupHandler(UINT uMsg, WPARAM wParam, 
                             LPARAM lParam, BOOL& bHandled)
{
    // System menu, do nothing

    if ((BOOL)HIWORD(lParam))   
    {
        bHandled = FALSE;
        return 1;
    }

    CMenuHandle menuPopup = (HMENU)wParam;
    ATLASSERT(menuPopup.m_hMenu != NULL);

    TCHAR szString[MAX_MENU_ITEM_TEXT_LENGTH];
    BOOL bRet = FALSE;

    for (int i = 0; i < menuPopup.GetMenuItemCount(); i++)
    {
        CMenuItemInfo mii;
        mii.cch = MAX_MENU_ITEM_TEXT_LENGTH;
        mii.fMask = MIIM_CHECKMARKS | MIIM_DATA | MIIM_ID | 
                    MIIM_STATE | MIIM_SUBMENU | MIIM_TYPE;
        mii.dwTypeData = szString;
        bRet = menuPopup.GetMenuItemInfo(i, TRUE, &mii);
        ATLASSERT(bRet);

        if (!(mii.fType & MFT_OWNERDRAW))
        // not already an ownerdraw item

        {
            MenuItemData * pMI = new MenuItemData;
            ATLASSERT(pMI != NULL);

            if (pMI)
            {
                // Make this menu item an owner-drawn

                mii.fType |= MFT_OWNERDRAW;

                pMI->fType = mii.fType;
                pMI->fState = mii.fState;

                // Associate an image with a menu item

                static_cast<T*>(this)->AssociateImage(mii, pMI);

                pMI->lpstrText = new TCHAR[lstrlen(szString) + 1];
                ATLASSERT(pMI->lpstrText != NULL);

                if (pMI->lpstrText != NULL)
                    lstrcpy(pMI->lpstrText, szString);
                mii.dwItemData = (ULONG_PTR)pMI;

                bRet = menuPopup.SetMenuItemInfo(i, TRUE, &mii);
                ATLASSERT(bRet);
            }
        }
    }

    // Add it to the list

    m_stackMenuHandle.Push(menuPopup.m_hMenu);
    
    return 0;
}

Internally, CCoolContextMenu implements WM_MEASUREITEM, WM_DRAWITEM, WM_INITMENUPOPUP, and WM_MENUSELECT messages so you do not have to worry about anything.

Using the code

To use the CCoolContextMenu class, all you have to do is to derive your class from CCoolContextMenu and follow the next few steps:

class CCoolEdit : public CWindowImpl<CCoolEdit, CRichEditCtrl>,
                  public CRichEditCommands<CCoolEdit>,
                  public CCoolContextMenu<CCoolEdit>

In the message map, use CHAIN_MSG_MAP to redirect messages to CCoolContextMenu's message map:

BEGIN_MSG_MAP(CCoolEdit)
    ...
    CHAIN_MSG_MAP(CCoolContextMenu<CCoolEdit>)
END_MSG_MAP()

In the OnInitDialog() function of your dialog class, or in the OnCreate() function of the window class, call the GetSystemSettings() method of CCoolContextMenu:

LRESULT OnInitDialog(UINT uMsg, WPARAM wParam, 
                     LPARAM lParam, BOOL& bHandled)
{
    ...
    GetSystemSettings();
    ...
}

But wait! What about images? Don't worry, just create the image list and implement the AssociateImage(CMenuItemInfo& mii, MenuItemData * pMI) function in your CCoolContextMenu derived class:

void AssociateImage(CMenuItemInfo& mii, MenuItemData * pMI)
{
    switch (mii.wID)
    {
    case ID_EDIT_UNDO:
        pMI->iImage = 17;
        break;
    case ID_EDIT_CUT:
        pMI->iImage = 3;
        break;
    case ID_EDIT_COPY:
        pMI->iImage = 4;
        break;
    case ID_EDIT_PASTE:
        pMI->iImage = 5;
        break;
    case ID_EDIT_CLEAR:
        pMI->iImage = 20;
        break;
    default:
        pMI->iImage = -1;
        break;
    }
}

Conclusion

CCoolContextMenu allows you to add nice looking context menus to your application with just a few lines of code; and by combining my code with Jean-Michel's, your windows will look completely different.

My Thanks To

• Jean-Michel LE FOL for the menu customization code in CMenuXP - The OfficeXP menu (WTL version)[^]
• Do Young KIM for the bitmaps in XP Style - MainFrame in WTL[^]
• Bjarke Viks�e and Justin Tay for answering my questions on the WTL Group[^]

History

• March 13, 2006 - Initial release.
• March 15, 2006 - Put a message map in the CCoolContextMenu class. Thanks to J�rgen Sigvardsson for suggesting it.
• April 24, 2006 - Added a default implementation of the AssociateImage function to the CCoolContextMenu class.

Disclaimer

THIS SOFTWARE AND THE ACCOMPANYING FILES ARE DISTRIBUTED "AS IS" AND WITHOUT ANY WARRANTIES WHETHER EXPRESSED OR IMPLIED. NO RESPONSIBILITIES FOR POSSIBLE DAMAGES CAN BE TAKEN. THE USER MUST ASSUME THE ENTIRE RISK OF USING THIS SOFTWARE.