List of available com ports in menu of MFC dialog - c++

Question

I am stuck. I have just a little experience with MFC and inherited a MFC program from a former coworker.
I want to add a list of available com ports in the menu bar, so the user can select whatever he wants. During the further runtime of the program, this menu should be locked.
I already created the Menu and added it to my Dialog. But:
How can I dynamically show the list of available com ports during the initialization?
How can I figure out which Port was selected? Is there something. like a return value?
Actually the second question bugs me the most.
Edit1:
to be more clear: I already know how to get the list of available com ports and currently I am displaying them in a combo box. But I want to do it with a Menu instead.
Edit2: This is what I got so far. Question 1 is solved!
//create a menu object for main menu
CMenu *menu = new CMenu();
menu->CreateMenu();
//another menu object for submenu
CMenu *subMenu = new CMenu();
subMenu->CreateMenu();
//create subsubmenus
CMenu *ComPortSelect = new CMenu();
CMenu *ModeSelect = new CMenu();
ComPortSelect->CreateMenu();
ModeSelect->CreateMenu();
//append available ports (portlist created earlier)
for (INT_PTR i = 0; i < portlist.GetCount(); i++)
{
ComPortSelect->AppendMenu(MF_POPUP, ID_SHOW, portlist[i]);
}
ModeSelect->AppendMenu(MF_POPUP, ID_SHOW, _T("User"));
ModeSelect->AppendMenu(MF_POPUP, ID_SHOW, _T("Expert"));
//append subsubmenu to submenu
subMenu->AppendMenu(MF_POPUP | MF_STRING, (UINT)ComPortSelect->m_hMenu, _T("ComPorts"));
subMenu->AppendMenu(MF_POPUP | MF_STRING, (UINT)ModeSelect->m_hMenu, _T("Mode"));
//append submenu to menu
menu->AppendMenu(MF_POPUP | MF_STRING, (UINT)subMenu->m_hMenu, _T("Advanced"));
SetMenu(menu);

Answer 1

I played with interfacing a program to an Arduino some time ago. Different models of Arduinos that I had used different COM ports so I also had a need to scan for available ports.
I forget the exact ins and outs of it now, but you an use one syntax when opening COM ports upto about 8 or 10 I think, and a different one for any higher numbered ports. Fortunately, the syntax that works for higher numbered ports also works for the lower numbered ones - my code uses the higher-numbered port syntax and works fine for both.
The code I used for a non-mfc win32 project follows:
void initPortCombo(HWND combo)
{
int curPort;
char mPortName[16];
HANDLE hCom;
for (curPort=1; curPort<=20; curPort++)
{
sprintf(mPortName, "\\\\.\\COM%d", curPort);
hCom = CreateFile(mPortName, GENERIC_READ | GENERIC_WRITE, 0, 0, OPEN_EXISTING, 0, 0);
if (hCom != INVALID_HANDLE_VALUE)
{
sprintf(mPortName, "COM%d", curPort);
CloseHandle(hCom);
SendMessage(combo, CB_ADDSTRING, 0, (LPARAM)mPortName);
}
}
}
As for your second question, when you dynamically add a menu option, you need to specify the ID that the menu item has. So with that in mind, when your WM_COMMAND handler fires, you simply need to reverse the logic you used at the time you added the menu items.
For instance, if you assign the menu items an ID of (4000 + com_port_number), you can subtract 4000 from the ID of the control that fired the WM_COMMAND handler. If this results in a valid number (I guess from 1 to 20 or whatever port number you scan up to) then you know it was the menu item that corresponds to one of your com-ports.
Just have a play with adding dynamic menu items and then determining which one was selected. I dont MFC, so cant help you there.

Answer 2

One way to find the installed COM ports is to call the GetDefaultCommConfig API. There is some sample code for this at http://www.naughter.com/enumser.html
When a menu command is selected by the user you receive a WM_COMMAND message from the menu, with parameters that include the ID of the chosen menu item. You put an ON_COMMAND_RANGE statement in your message map to route these messages to a message handler function.