Customized message box

[Vortex]

Attached is an example of a customized message box.

[CLR]

Very nice!

[CommonTater]

Hi Vortex... forgive my naivety on ASM... but wouldn't it be easier to just make a dialog box?

[TimoVJL]

Nice, now you can C it

[Vortex]

Hi CommonTater,

As you said, it's always much more easy to create a dialog box. My example is just a coding exercise as there is no any direct method \ API call to modify message boxes.

Here is an article based on Windows hooks :

Custom MessageBox

My approach is to move the message box creation to a separate thread.

Hi timovjl,

Thanks for the C code.

[CommonTater]

Hi CommonTater,

As you said, it's always much more easy to create a dialog box. My example is just a coding exercise as there is no any direct method \ API call to modify message boxes.

Ahhh... Now I see.  Actually it's a pretty clever trick.... 

I knew you'd know how to make dialog boxes, that's why I wondered what the point was.



 

[Vortex]

Another version using structures to pass data to the thread creating the message box.

Code: [Select]

include MBox.inc

MBOX STRUCT

    hWnd    DWORD ?
    msg     DWORD ?
    capt    DWORD ?

MBOX ENDS


MDATA STRUCT

    ThreadID DWORD ?
    hWnd     DWORD ?

MDATA ENDS

.data

capt        db "Hello!",0
msg         db 'Customized message box',0
msg2        db 'You clicked the Help button',0
ButtonText  db 'Click here',0
bclass      db 'Button',0
   
.data?
   
pOldProc    dd ?
HelpBtnID   dd ?
   
.code
   
start:
   
    invoke  CustMsgBox,0,ADDR msg,ADDR capt,ADDR ButtonText
    invoke  ExitProcess,0
   
CustMsgBox  PROC uses esi handle:DWORD,message:DWORD,caption:DWORD,button:DWORD

LOCAL ThreadID:DWORD
LOCAL hThread:DWORD
LOCAL hClick:DWORD
LOCAL mboxparam:MBOX
LOCAL mboxdata:MDATA

    lea     edx,mboxparam
   
    push    handle
    pop     MBOX.hWnd[edx]

    push    message
    pop     MBOX.msg[edx]

    push    caption
    pop     MBOX.capt[edx]

    invoke  CreateThread,0,0,ADDR ThreadProc,\
            edx,0,ADDR ThreadID
    mov     hThread,eax

    invoke  GetCurrentProcess

    invoke  WaitForInputIdle,eax,INFINITE

    lea     esi,mboxdata
   
    push    ThreadID
    pop     MDATA.ThreadID[esi]

    invoke  EnumWindows,ADDR EnumWndProc,\
            esi

    invoke  FindWindowEx,MDATA.hWnd[esi],\
            0,ADDR bclass,0
    mov     hClick,eax

    invoke  FindWindowEx,MDATA.hWnd[esi],\
            eax,ADDR bclass,0
    invoke  GetDlgCtrlID,eax
    mov     HelpBtnID,eax

    invoke  SetWindowText,hClick,button
    invoke  SetWindowLong,MDATA.hWnd[esi],GWL_WNDPROC,\
            ADDR MsgboxProc
    mov     pOldProc,eax
   
    invoke  WaitForSingleObject,hThread,INFINITE
    invoke  CloseHandle,hThread
    ret   
   
CustMsgBox ENDP


ThreadProc PROC pParams:DWORD
   
    mov     edx,pParams
    invoke  MessageBox,MBOX.hWnd[edx],\
            MBOX.msg[edx],MBOX.capt[edx],\
            MB_HELP
    ret
   
ThreadProc ENDP


EnumWndProc PROC hWnd:DWORD,lParam:DWORD
   
    LOCAL pid:DWORD
   
    invoke  GetWindowThreadProcessId,hWnd,ADDR pid
    mov     edx,lParam
    cmp     eax,MDATA.ThreadID[edx]
    jne     @f
    push    hWnd
    pop     MDATA.hWnd[edx]    ; get the handle of the window
    xor     eax,eax            ; displaying the message box
    ret
@@:
    mov     eax,TRUE
    ret
   
EnumWndProc ENDP
   
MsgboxProc PROC hWnd:DWORD,uMsg:DWORD,wParam:DWORD,lParam:DWORD
   
    .IF uMsg == WM_COMMAND
   
        mov     eax,wParam
        mov     edx,eax
        shr     edx,16
       
        .IF dx==BN_CLICKED
       
            mov  ecx,HelpBtnID
           
            .IF ax==cx

                invoke  MessageBox,0,ADDR msg2,ADDR capt,MB_OK

            .ENDIF
           
        .ENDIF
       
    .ENDIF
   
    invoke  CallWindowProc,pOldProc,hWnd,uMsg,wParam,lParam
    ret
   
    MsgboxProc    ENDP

END start