Simple Word Processing with an Edit Control

The following example implements much of the functionality of a simple word processor by filling the client area of a window with a multiline edit control. The system automatically performs word wrap operations for this edit control and also handles the processing for the vertical scroll bar (created by specifying ES_AUTOVSCROLL in the call to the CreateWindow function). The WM_COMMAND message processes menu items; they allow the user to undo the previous action, cut or copy selections to the clipboard, paste text from the clipboard, and delete the current selection.

LONG APIENTRY MainWndProc( 
HWND hwnd,                // window handle 
UINT message,             // type of message 
WPARAM wParam,            // additional information 
LPARAM lParam)            // additional information 
{ 
    static HWND hwndEdit; 
 
    CHAR lpszTrouble[] = "When in the Course of human Events " 
                         "it becomes necessary for one People " 
                         "to dissolve the Political Bands which " 
                         "have connected them with another, and " 
                         "to assume among the Powers of the " 
                         "Earth, the separate and equal Station " 
                         "to which the Laws of Nature and of " 
                         "Nature's God entitle them, a decent " 
                         "Respect to the Opinions of Mankind " 
                         "requires that they should declare the " 
                         "causes which impel them to the " 
                         "Separation. "; 
 
    switch (message) 
    { 
        case WM_CREATE: 
            hwndEdit = CreateWindow( 
                "EDIT",     // predefined class 
                NULL,       // no window title 
                WS_CHILD | WS_VISIBLE | WS_VSCROLL | 
                    ES_LEFT | ES_MULTILINE | ES_AUTOVSCROLL, 
                0, 0, 0, 0, // set size in WM_SIZE message 
                hwnd,       // parent window 
                (HMENU) ID_EDITCHILD, // edit control ID 
                (HINSTANCE) GetWindowLong(hwnd, GWL_HINSTANCE), 
                NULL);                // pointer not needed 
 
             // Add text to the window. 
 
             SendMessage(hwndEdit, WM_SETTEXT, 0, 
                (LPARAM) lpszTrouble); 
 
            return 0; 
 
        case WM_COMMAND: 
            switch (wParam) 
            { 
                case IDM_EDUNDO: 

                    // Send WM_UNDO only if there is something 
                    // to be undone. 
 
                    if (SendMessage(hwndEdit, EM_CANUNDO, 0, 0)) 
                        SendMessage(hwndEdit, WM_UNDO, 0, 0); 
                    else 
                    {
                        MessageBox(hwndEdit, 
                            "Nothing to undo.", 
                            "Undo notification", MB_OK); 
                    }
                    break; 
 
                case IDM_EDCUT: 
                    SendMessage(hwndEdit, WM_CUT, 0, 0); 
                    break; 
 
                case IDM_EDCOPY: 
                    SendMessage(hwndEdit, WM_COPY, 0, 0); 
                    break; 
 
                case IDM_EDPASTE: 
                    SendMessage(hwndEdit, WM_PASTE, 0, 0); 
                    break; 
 
                case IDM_EDDEL: 
                    SendMessage(hwndEdit, WM_CLEAR, 0, 0); 
                    break; 
 
                case IDM_PASSWORD: 
                    DialogBox(hinst, // current instance 
                        "PassBox",   // resource to use 
                         hwnd,       // parent handle 
                         (DLGPROC) PassProc); 
                    break; 
 
                case IDM_WRAP: 
                    SendMessage(hwndEdit, 
                        EM_SETWORDBREAKPROC, 
                        (WPARAM) 0, 
                        (LPARAM) (EDITWORDBREAKPROC) WordBreakProc); 
                    SendMessage(hwndEdit, 
                        EM_FMTLINES, 
                        (WPARAM) TRUE, 
                        (LPARAM) 0); 
                    SendMessage(hwndEdit, 
                        EM_SETSEL, 
                        0, -1); // select all text 
                    SendMessage(hwndEdit, WM_CUT, 0, 0); 
                    SendMessage(hwndEdit, WM_PASTE, 0, 0); 
                    break; 
 
                case IDM_ABOUT: 
                    DialogBox(hinst, // current instance 
                        "AboutBox",  // resource to use 
                         hwnd,       // parent handle 
                         (DLGPROC) About); 
                    break; 
 
                default: 
                    return DefWindowProc(hwnd, message, wParam, lParam); 
            } 
            break; 
 
        case WM_SETFOCUS: 
            SetFocus(hwndEdit); 
            return 0; 
 
        case WM_SIZE: 
 
            // Make the edit control the size of the window's 
            // client area. 
 
            MoveWindow(hwndEdit, 
                0, 0,           // starting x- and y-coordinates 
                LOWORD(lParam), // width of client area 
                HIWORD(lParam), // height of client area 
                TRUE);          // repaint window 
            return 0; 
 
        case WM_DESTROY: 
            PostQuitMessage(0); 
            return 0; 
 
        default: 
            return DefWindowProc(hwnd, message, wParam, lParam); 
    } 
    return NULL; 
}