MDI (Multiple Document Interface) Demo

#include <windows.h>
#include <commctrl.h>

#define IDI_ICON            101

#define IDC_CHILD_EDIT      200

#define IDM_FILE_EXIT       1000
#define IDM_FILE_NEW        1001

#define ID_MDI_CLIENT       1002
#define ID_MDI_FIRSTCHILD   1003


const TCHAR MainClassName[]  = TEXT("MainWindowClass");
const TCHAR ChildClassName[] = TEXT("ChildWindowClass");


HWND hWndClient = NULL;


// Forward declarations
LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);
LRESULT CALLBACK ChildProc(HWND, UINT, WPARAM, LPARAM);


//------------------------------------------------------
// MDI CHILD WINDOW PROCEDURE
//------------------------------------------------------

LRESULT CALLBACK ChildProc(HWND hWnd, UINT Msg, WPARAM wParam, LPARAM lParam)
{

    switch(Msg)
    {

    case WM_CREATE:
        {
            HWND hEdit;

            hEdit = CreateWindowEx(
                WS_EX_CLIENTEDGE,
                TEXT("EDIT"),
                TEXT(""),
                WS_CHILD |
                WS_VISIBLE |
                WS_VSCROLL |
                WS_HSCROLL |
                ES_MULTILINE |
                ES_AUTOVSCROLL |
                ES_AUTOHSCROLL,

                0,
                0,
                100,
                100,

                hWnd,
                (HMENU)IDC_CHILD_EDIT,
                GetModuleHandle(NULL),
                NULL
            );


            if(hEdit == NULL)
            {
                MessageBox(
                    hWnd,
                    TEXT("Could not create edit control"),
                    TEXT("Error"),
                    MB_OK
                );
            }

        }
        break;



    case WM_SIZE:
        {
            RECT rc;
            HWND hEdit;


            GetClientRect(hWnd,&rc);

            hEdit = GetDlgItem(hWnd,IDC_CHILD_EDIT);


            if(hEdit)
            {
                SetWindowPos(
                    hEdit,
                    NULL,
                    0,
                    0,
                    rc.right,
                    rc.bottom,
                    SWP_NOZORDER
                );
            }

        }
        break;


    case WM_MDIACTIVATE:
        {
            // Code here runs when child activates
        }
        break;


    }


    return DefMDIChildProc(hWnd,Msg,wParam,lParam);
}



//------------------------------------------------------
// MAIN FRAME WINDOW PROCEDURE
//------------------------------------------------------

LRESULT CALLBACK WndProc(HWND hWnd, UINT Msg, WPARAM wParam, LPARAM lParam)
{

    switch(Msg)
    {


    case WM_CREATE:
        {

            HMENU hMenuBar;
            HMENU hFileMenu;


            hMenuBar = CreateMenu();

            hFileMenu = CreateMenu();


            AppendMenu(
                hFileMenu,
                MF_STRING,
                IDM_FILE_NEW,
                TEXT("&New")
            );


            AppendMenu(
                hFileMenu,
                MF_STRING,
                IDM_FILE_EXIT,
                TEXT("&Exit")
            );


            AppendMenu(
                hMenuBar,
                MF_POPUP,
                (UINT_PTR)hFileMenu,
                TEXT("&File")
            );


            SetMenu(hWnd,hMenuBar);



            CLIENTCREATESTRUCT ccs;


            ccs.hWindowMenu =
                GetSubMenu(hMenuBar,0);

            ccs.idFirstChild =
                ID_MDI_FIRSTCHILD;



            hWndClient = CreateWindowEx(
                WS_EX_CLIENTEDGE,
                TEXT("MDICLIENT"),
                NULL,

                WS_CHILD |
                WS_VISIBLE |
                WS_CLIPCHILDREN |
                WS_VSCROLL |
                WS_HSCROLL,

                0,
                0,
                0,
                0,

                hWnd,
                (HMENU)ID_MDI_CLIENT,
                GetModuleHandle(NULL),
                (LPVOID)&ccs
            );


            if(hWndClient == NULL)
            {
                MessageBox(
                    hWnd,
                    TEXT("Cannot create MDI client"),
                    TEXT("Error"),
                    MB_OK
                );
            }

        }

        break;



    case WM_COMMAND:
        {

            switch(LOWORD(wParam))
            {


            case IDM_FILE_NEW:
                {

                    HWND hChild;


                    hChild = CreateWindowEx(
                        WS_EX_MDICHILD,
                        ChildClassName,
                        TEXT("Document"),

                        WS_CHILD |
                        WS_VISIBLE |
                        WS_OVERLAPPEDWINDOW,

                        CW_USEDEFAULT,
                        CW_USEDEFAULT,
                        300,
                        200,

                        hWndClient,
                        NULL,
                        GetModuleHandle(NULL),
                        NULL
                    );


                    if(hChild == NULL)
                    {
                        MessageBox(
                            hWnd,
                            TEXT("Cannot create child window"),
                            TEXT("Error"),
                            MB_OK
                        );
                    }

                }

                break;



            case IDM_FILE_EXIT:

                SendMessage(
                    hWnd,
                    WM_CLOSE,
                    0,
                    0
                );

                break;



            default:

                if(LOWORD(wParam)>=ID_MDI_FIRSTCHILD)
                {
                    DefFrameProc(
                        hWnd,
                        hWndClient,
                        Msg,
                        wParam,
                        lParam
                    );
                }

                break;

            }

        }

        break;



    case WM_SIZE:

        if(hWndClient)
        {
            MoveWindow(
                hWndClient,
                0,
                0,
                LOWORD(lParam),
                HIWORD(lParam),
                TRUE
            );
        }

        break;



    case WM_CLOSE:

        DestroyWindow(hWnd);

        break;



    case WM_DESTROY:

        PostQuitMessage(0);

        break;



    default:

        return DefFrameProc(
            hWnd,
            hWndClient,
            Msg,
            wParam,
            lParam
        );

    }


    return 0;
}



//------------------------------------------------------
// PROGRAM ENTRY
//------------------------------------------------------

int WINAPI WinMain(
    HINSTANCE hInstance,
    HINSTANCE hPrevInstance,
    LPSTR lpCmdLine,
    int nCmdShow
)
{

    WNDCLASSEX wc;
    MSG Msg;
    HWND hWnd;



    ZeroMemory(&wc,sizeof(wc));


    //--------------------------------------------------
    // Register MAIN frame window
    //--------------------------------------------------

    wc.cbSize = sizeof(WNDCLASSEX);

    wc.style = CS_HREDRAW | CS_VREDRAW;

    wc.lpfnWndProc = WndProc;

    wc.hInstance = hInstance;

    wc.hIcon =
        LoadIcon(NULL,IDI_APPLICATION);

    wc.hIconSm =
        LoadIcon(NULL,IDI_APPLICATION);

    wc.hCursor =
        LoadCursor(NULL,IDC_ARROW);

    wc.hbrBackground =
        (HBRUSH)(COLOR_WINDOW+1);

    wc.lpszClassName =
        MainClassName;



    if(!RegisterClassEx(&wc))
    {
        return 0;
    }



    //--------------------------------------------------
    // Register MDI CHILD window
    //--------------------------------------------------

    ZeroMemory(&wc,sizeof(wc));


    wc.cbSize = sizeof(WNDCLASSEX);

    wc.style = CS_HREDRAW | CS_VREDRAW;

    wc.lpfnWndProc = ChildProc;

    wc.hInstance = hInstance;

    wc.hIcon =
        LoadIcon(NULL,IDI_APPLICATION);

    wc.hCursor =
        LoadCursor(NULL,IDC_ARROW);

    wc.hbrBackground =
        (HBRUSH)(COLOR_WINDOW+1);

    wc.lpszClassName =
        ChildClassName;



    if(!RegisterClassEx(&wc))
    {
        return 0;
    }



    //--------------------------------------------------
    // Create main frame window
    //--------------------------------------------------

    hWnd = CreateWindowEx(
        WS_EX_CLIENTEDGE,

        MainClassName,

        TEXT("MDI Application"),

        WS_OVERLAPPEDWINDOW,

        CW_USEDEFAULT,
        CW_USEDEFAULT,

        700,
        500,

        NULL,
        NULL,

        hInstance,
        NULL
    );


    if(!hWnd)
        return 0;



    ShowWindow(hWnd,nCmdShow);

    UpdateWindow(hWnd);



    //--------------------------------------------------
    // Message loop
    //--------------------------------------------------

    while(GetMessage(&Msg,NULL,0,0))
    {

        if(!TranslateMDISysAccel(hWndClient,&Msg))
        {
            TranslateMessage(&Msg);

            DispatchMessage(&Msg);
        }

    }


    return Msg.wParam;
}