创建子菜单

Question

我想制作一个像Mozilla Firefox子菜单一样的子菜单：

现在就是这样（在我的程序中）：

但是我希望它看起来像Firefox，当你把鼠标放在它上面时它会有一个额外的菜单。

#define ID_SM 1

LRESULT CALLBACK WindowProcedure (HWND hwnd,
                                  UINT message,
                                  WPARAM wParam,
                                  LPARAM lParam)
{
    switch (message)
    {
        case WM_CREATE:
            HMENU hMenubar = CreateMenu();
            HMENU hMenu = CreateMenu();

            AppendMenu(hMenubar, MF_POPUP, (UINT_PTR)hMenu, "Menu");
            AppendMenu(hMenu, MF_STRING, ID_SM, "Sub Menu");

            /* Would I put it here? How? */

            SetMenu(hwnd, hMenubar);
            break;

        case WM_COMMAND:
            if (LOWORD(wParam) == ID_SM) {
                /* Not sure if this should be here,
                   cause I want it to pop up when you mouse over */
            } 
            break;
    }
}

Answer 1

您只需创建另一个菜单并将其附加为子菜单。您可以通过调用相同的AppendMenu function来执行此操作，只需将uFlags参数设置为MF_POPUP，然后将句柄作为uIDNewItem参数传递给子菜单。

例如：

case WM_CREATE:
    HMENU hMenubar = CreateMenu();
    HMENU hMenu = CreateMenu();
    HMENU hSubMenu = CreatePopupMenu();

    AppendMenu(hMenubar, MF_POPUP, (UINT_PTR)hMenu, "Menu");
    AppendMenu(hMenu, MF_STRING, ID_SM, "Sub Menu");
    AppendMenu(hMenu, MF_STRING | MF_POPUP, (UINT_PTR)hSubMenu, "Sub-Sub Menu");

    SetMenu(hwnd, hMenubar);
    break;

响应WM_COMMAND消息，您无需执行任何特殊操作。将鼠标悬停在父菜单项上时，Windows将自动显示弹出菜单。当然，您将需要处理子菜单上 上显示的项目的命令。

Answer 2

首先，创建一个新菜单并向其中添加项目。例如：

HMENU hSubmenu = CreatePopupMenu();
// Insert or append items to hSubmenu here

然后将创建的菜单附加到hMenu：

AppendMenu(hMenu, MF_POPUP | MF_STRING, (UINT_PTR)hSubmenu, "My Submenu");