A Window with an Edit Field

The second example relates to the Edit field. The program is shown in Listing 3.2, and the result of its operation is shown in Fig. 3.1. When the Exit button is clicked, the program displays the message box with the edited string.

Figure 3.1: Running the program with the edit field (see Listing 3.2)

Notice how the message is sent to the window control. Mainly, two functions are used for this purpose: SendMessage and PostMessage. The difference between these two functions is that the first one calls window procedure with the appropriate parameters and waits until it returns the control; the second function places the message into the queue and returns the control immediately.

Listing 3.2: A window with an edit field

 ; The edit.inc file ; Constants WM_SETFOCUS          equ 7h ; The message that arrives when the window is closed WM_DESTROY           equ 2 ; The message that arrives when the window is created WM_CREATE            equ 1 ; The message that arrives when something happens ; to the window controls WM_COMMAND           equ 111h ; The message that allows you to send the string to the window WM_SETTEXT           equ 0Ch ; The message that allows you to receive the string WM_GETTEXT           equ 0Dh ; Window properties CS_VREDRAW           equ 1h CS_HREDRAW           equ 2h CS_GLOBALCLASS       equ 4000h WSJ_TABSTOP          equ 10000h WS_SYSMENU           equ 80000h WS_OVERLAPPEDWINDOW  equ 0+WS_TABSTOP+WS_SYSMENU STYLE                equ CS_HREDRAW+CS_VREDRAW+CS_GLOBALCLASS CS_HREDRAW           equ 2h BS_DEFPUSHBUTTON     equ 1h WS_VISIBLE           equ 10000000h WS_CHILD             equ 40000000h WS_BORDER            equ 800000h STYLBTN              equ WS_CHILD+BS_DEFPUSHBUTTON+WS_VISIBLE+WS_TABSTOP STYLEDT              equ WS_CHILD+WS_VISIBLE+WS_BORDER+WS_TABSTOP ; Standard icon identifier IDI_APPLICATION      equ 32512 ; Cursor identifier IDC_ARROW            equ 32512 ; Window display mode -- normal SW_SHOWNORMAL        equ 1 ; Prototypes of external procedures EXTERN SetFocus@4:NEAR EXTERN SendMessageA@16:NEAR EXTERN MessageBoxA@16:NEAR EXTERN CreateWindowExA@ 48:NEAR EXTERN DefWindowProcA@16:NEAR EXTERN DispatchMessageA@4:NEAR EXTERN ExitProcess@4:NEAR EXTERN GetMessageA@16:NEAR EXTERN GetModuleHandleA@4:NEAR EXTERN LoadCursorA@8:NEAR EXTERN LoadIconA@8:NEAR EXTERN PostQuitMessage@4:NEAR EXTERN RegisterClassA@4:NEAR EXTERN ShowWindow@8:NEAR EXTERN TranslateMessage@4:NEAR EXTERN UpdateWindow@4:NEAR ; Structures ; Message structure MSGSTRUCT STRUC     MSHWND          DD ?     MSMESSAGE       DD ?     MSWPARAM        DD ?     MSLPARAM        DD ?     MSTIME          DD ?     MSPT            DD ? MSGSTRUCT ENDS ;---- Window class structure WNDCLASS STRUC     CLSSTYLE        DD ?     CLWNDPROC       DD ?     CLSCBCLSEX      DD ?     CLSCBWNDEX      DD ?     CLSHINST        DD ?     CLSHICON        DD ?     CLSHCURSOR      DD ?     CLBKGROUND      DD ?     CLMENNAME       DD ?     CLNAME          DD ? WNDCLASS ENDS ; The edit.asm file .586P ; Flat memory model .MODEL FLAT, stdcall include edit.inc ; Directives for the linker to link libraries includelib c:\masm32\lib\user32.lib includelib c:\masm32\lib\kernel32.lib ;------------------------------------------ ; Data segment _DATA SEGMENT DWORD PUBLIC USE32 'DATA'     NEWHWND         DD 0     MSG             MSGSTRUCT <?>     WC              WNDCLASS <?>     HINST           DD 0 ; Application descriptor     TITLENAME       DB 'Application example - Edit window', 0     CLASSNAME       DB 'CLASS32', 0     CPBUT           DB 'Exit', 0 ; Exit     CPEDT           DB ' ', 0     CLSBUTN         DB 'BUTTON', 0     CLSEDIT         DB 'EDIT', 0     HWNDBTN         DWORD 0     HWNDEDT         DWORD 0     CAP             DB 'Message', 0     MES             DB 'Program termination', 0      TEXT           DB 'Edit string', 0                     DB 50 DUP(0) ; Buffer continuation _DATA ENDS ; Code segment _TEXT SEGMENT DWORD PUBLIC USE32 'CODE' START: ; Get the application descriptor     PUSH            0     CALL            GetModuleHandleA@4     MOV             [HINST], EAX     REG_CLASS: ; Fill the window structure ; Style     MOV  [WC.CLSSTYLE], STYLE ; Message-handling procedure     MOV  [WC.CLWNDPROC], OFFSET WNDPROC     MOV             [WC.CLSCBCLSEX], 0     MOV             [WC.CLSCBWNDEX], 0     MOV             EAX, [HINST]     MOV             [WC.CLSHINST], EAX ;----------Window icon     PUSH            IDI_APPLICATION     PUSH            0     CALL            LoadIconA@8     MOV             [WC.CLSHICON], EAX ;---------- Window cursor     PUSH            IDC_ARROW     PUSH            0     CALL            LoadCursorA@8     MOV             [WC.CLSHCURSOR], EAX ;----------     MOV             [WC.CLBKGROUND], 17 ; Window color     MOV             DWORD PTR [WC.CLMENNAME], 0     MOV             DWORD PTR [WC.CLNAME], OFFSET CLASSNAME     PUSH            OFFSET WC     CALL            RegisterClassA@4 ; Create a window of the registered class     PUSH            0     PUSH            [HINST]     PUSH            0     PUSH            0     PUSH            150 ; DY -- Window height     PUSH            400 ; DX -- Window width     PUSH            100 ; Y  -- Coordinate of the top left corner     PUSH            100 ; X  -- Coordinate of the top left corner     PUSH            WS_OVERLAPPEDWINDOW     PUSH            OFFSET TITLENAME ; Window title     PUSH            OFFSET CLASSNAME ; Class name     PUSH            0     CALL            CreateWindowExA@48 ; Check for error     CMP             EAX, 0     JZ              _ERR     MOV             [NEWHWND], EAX ; Window 'descriptor ;--------------------------------     PUSH            SW_SHOWNORMAL     PUSH            [NEWHWND]     CALL            ShowWindow@8 ; Show newly-created window ;--------------------------------     PUSH            [NEWHWND]     CALL            UpdateWindow@4 ; Command to redraw the visible                                    ; part of the window, the WM_PAINT message ; Message-handling loop MSG_LOOP:     PUSH            0     PUSH            0     PUSH            0     PUSH            OFFSET MSG     CALL            GetMessageA@16     CMP             EAX, 0     JE              END_LOOP     PUSH            OFFSET MSG     CALL            TranslateMessage@4     PUSH            OFFSET MSG     CALL            DispatchMessageA@4     JMP             MSG_LOOP END_LOOP: ; Exit the program (close the process)     PUSH            [MSG.MSWPARAM]     CALL            ExitProcess@4 _ERR:     JMP             END_LOOP ;-------------------------------Window procedure ; Position of parameters in the stack ; [EBP+014H] ; LPARAM ; [EBP+10H]  ; WAPARAM ; [EBP+0CH]  ; MES ; [EBP+8]    ; HWND WNDPROC PROC     PUSH            EBP     MOV             EBP, ESP     PUSH            EBX     PUSH            ESI     PUSH            EDI     CMP             DWORD PTR [EBP+0CH], WM_DESTROY     JE              WMDESTROY     CMP             DWORD PTR [EBP+0CH], WM_CREATE     JE              WMCREATE     CMP             DWORD PTR [EBP+0CH], WM_COMMAND     JE              WMCOMMND     JMP             DEFWNDPROC WMCOMMND:     MOV             EAX, HWNDBTN     CMP             DWORD PTR [EBP+14H], EAX     JNE             NODESTROY ; Get the edited string     PUSH            OFFSET TEXT     PUSH            150     PUSH            WM_GETTEXT     PUSH            HWNDEDT     CALL            SendMessageA@16 ; Display the edited string     PUSH            0     PUSH            OFFSET CAP     PUSH            OFFSET TEXT     PUSH            DWORD PTR [EBP+08H] ; Window descriptor     CALL            MessageBoxA@16 ; Exit     JMP             WMDESTROY NODESTROY:     MOV             EAX, 0     JMP             FINISH WMCREATE: ; Create the button window     PUSH            0     PUSH            [HINST]     PUSH            0     PUSH            DWORD PTR [EBP+08H]     PUSH            20 ; DY     PUSH            60 ; DX     PUSH            10 ; Y     PUSH            10 ; X     PUSH            STYLBTN     PUSH            OFFSET CPBUT ; Window name     PUSH            OFFSET CLSBUTN ; Class name     PUSH            0     CALL            CreateWindowExA@48     MOV             HWNDBTN, EAX ; Save the button descriptors ; Create the edit window     PUSH            0     PUSH            [HINST]     PUSH            0     PUSH            DWORD PTR [EBP+08H]     PUSH            20 ; DY     PUSH            350 ; DX     PUSH            50 ; Y     PUSH            10 ; X     PUSH            STYLEDT     PUSH            OFFSET CPEDT ; Window name     PUSH            OFFSET CLSEDIT ; Class name     PUSH            0     CALL            CreateWindowExA@48     MOV             HWNDEDT, EAX ;---------Place the string into the edit field     PUSH            OFFSET TEXT     PUSH            0     PUSH            WM_SETTEXT     PUSH            HWNDEDT     CALL            SendMessageA@16 ;---------Set the focus to the edit window     PUSH            HWNDEDT     CALL            SetFocus@4 ;------------------------------------------     MOV             EAX, 0     JMP             FINISH DEFWNDPROC:     PUSH            DWORD PTR [EBP+14H]     PUSH            DWORD PTR [EBP+10H]     PUSH            DWORD PTR [EBP+0CH]     PUSH            DWORD PTR [EBP+08H]     CALL            DefWindowProcA@16     JMP             FINISH WMDESTROY:     PUSH            0  ; MB_OK     PUSH            OFFSET CAP     PUSH            OFFSET MES     PUSH            DWORD PTR [EBP+08H] ; Window descriptor     CALL            MessageBoxA@16     PUSH            0     CALL            PostQuitMessage@4 ; WM_QUIT message     MOV             EAX, 0 FINISH:     POP             EDI     POP             ESI     POP             EBX     POP             EBP     RET             16 WNDPROC ENDP _TEXT ENDS END START