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If anyone has scratched their head over superclassing a window they will know what I mean by this. It is always preferable, at least to me to store as much information with a window as possible, that way you aren't dealing with alot of memory variables. So generally in a subclassing I will store the oldWndProc in the GWL_USERDATA parameter of the window. This is fine and works well enough. However when you superclass a window you cannot affect class memory until *after* the window has been created. This is because Set/GetClassLong require a window handle of the class and not a class atom. So it would seem that there is no way to store the oldWndProc for a class in it's class memory allocated in WNDCLASSEX.cbClsExtra. Here is a solution to that connundrum if you are not assigning a class menu...

First assign the string representation of the old WndProc to the lpszMenuName parameter:

; In the superclassing routine

mov D[wcx.cbClsExtra],4

mov eax,[wcx.lpfnWndProc]

invoke wsprintf,offset buffer,"%u",eax

add esp,12

lea eax,buffer

mov [wcx.lpszMenuName],eax

mov D[wcx.lpfnWndProc],OFFSET newWndProc



invoke RegisterClassEx,ADDR wcx

Then in your newWndProc you must process the WM_NCCREATE message to set the class DWORD:

cmp D[uMsg],WM_NCCREATE

jne >.NXTMSG

	; we stored the old proc in the menu name

	; that way there is no need to create a variable for it

	; This must be processed as the first message

	invoke GetClassLong,[hwnd],GCL_MENUNAME

	invoke ascii2dw,eax

	invoke SetClassLong,[hwnd],0,eax

Once that is done there is no longer a need to track the oldWndProc pointer:

invoke GetClassLong,[hwnd],0

invoke CallWindowProc,eax,[hwnd],[uMsg],[wParam],[lParam]

(Offtopic)

If GoAsm needs 'add esp' after 'invoke wsprintf' -
why it uses name "invoke" like MASM ...

2 M.O.R.R.I.S.:


My offtopic wasn't about calling conventions.
It was note about name "invoke" for macros in Masm and GoAsm.

In case of GoAsm we must wright

1) invoke wsprintf,offset buffer,"%u",eax
2) add esp,12

In case of Masm we must write only
1) invoke wsprintf,offset buffer,"%u",eax

- do you guess what will be after 2) in Masm ?

So again:
if macros "invoke" in Masm and "invoke" in GoAsm are such different -
why GoAsm didn't use another name instead of Masm's "invoke"...

2 Morris:

i'm afraid we created flame in Donkey's thread...

Let's go to my thread "Need test code on XP/2k3 ..."
(http://www.asmcommunity.net/board/showthread.php?threadid=18853)
- i use there 'wsprintfA proto C' and 33 arguments in my utility without add esp etc


But at first just play with code bellow:


.386
.model flat,stdcall
option casemap:none


include masm32includewindows.inc
include masm32includeuser32.inc
include masm32includekernel32.inc
includelib masm32libuser32.lib
includelib masm32libkernel32.lib

wsprintfA proto C :DWORD,:DWORD,:VARARG
wsprintf equ <wsprintfA>

.data
tt db "OK",0
ft db "%d",0
.data?
br db 16 dup (?)

.code
start:
push offset tt
invoke wsprintf,addr br,addr ft,0

; add esp,4*3 ; TRY SWITCH ON/OFF THIS LINE

pop eax
cmp eax,offset tt
jz @f
xor eax,eax
@@:
invoke MessageBox,0,addr br,eax,0
invoke ExitProcess,0
end start