Re: window from win32 dll

See below...
On Mon, 1 Sep 2008 04:45:21 -0700 (PDT), keralafood@xxxxxxxxx wrote:

I really fed up with this problem,i have to create one window from
win32 DLL,
BOOL Derived::InitWindow(int left,int top,int width,int
height,HINSTANCE h)
{
****
Snip
****
WNDCLASSEX wc = { sizeof(WNDCLASSEX), CS_CLASSDC, MsgProc, 0L,
0L,
h, NULL, NULL, NULL, NULL,
L"Renderer", NULL };
RegisterClassEx( &wc );
****
Move these two lines to your DllMain/DLL_PROCESS_ATTACH handler. I'm not sure why you
would write "0L" when "0" is sufficient. Also, what is h? It should the the instance
handle of the DLL, according to the documentation. Why aren't you passing in a const
CRect& instead of explicit width and height?

I notice that you seem to have failed to see if this actually worked; I did not see
anything of the form
ATOM at = ::RegisterClassEx(&wc);
if(at == NULL)
return FALSE;
so how do you know this worked?

But after moving it to DllMain/DLL_PROCESS_ATTACH, you will then add

case DLL_PROCESS_DETACH:
UnregisterClassEx(L"Renderer");
return TRUE;

Also, is there some reason you are using CS_CLASSDC, which is a very, very strange
technique, and probably extremely dangerous to use. Is there some reason you want every
instance of the window to share the one-and-only DC that is a class DC? (This style
probably hasn't made sense since Win32 came out, since its purpose was to reduce GDI
memory usage on an 8088 running Windows 1.0)

Note that returning FALSE from DllMain is generally poor practice in production code, but
it takes a 10-minute lecture to explain why, and what you have to do to get around it,
which I don't want to go into right now.
****

// Create the application's window
_hRenderWnd = CreateWindow(L"Renderer",0,
WS_POPUPWINDOW, left, top, width, height,
NULL, NULL, h,
NULL);
return TRUE;
}

msgProc declared diclared in Derived class.static LRESULT WINAPI
MsgProc( HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam );
****
A strange thing to want to do; why are you declaring a window handler in a derived class,
when you could just as easily use MFC in a non-extension DLL? Note that using this class
in the .exe file can lead to potential confusion. The handler for your messages has to be
in the DLL (or why bother using a DLL). What kind of class are you using? CWnd? If
CWnd, why are you mixing raw Win32 API with MFC?

I note that you have not actually said anything about what is going wrong, or if anything
failed, what the GetLastError values are. For example, you are presuming RegisterClassEx
succeeds without actually testing that it does, or that the CreateWindow works, without
actually testing that it does.

Perhaps you are seeing no window? Is that what is happening? If you don't say WS_VISIBLE
as a window style, it happily creates an invisible window. You have neglected to explain
what failures you are seeing, which is why testing the RegisterClassEx and CreateWindow
calls is sort of critical to the analysis...all you've said is "my program doesn't work"
followed by some highly questionable code, but given no basis for the analysis.
****

.HINSTANCE storing in dllmain HMODULE

CreateWindow always fail..

i tried this way also
WNDCLASSEX wc = { sizeof(WNDCLASSEX), CS_CLASSDC|CS_HREDRAW |
****
Please try to put spaces around binary operators
****
CS_VREDRAW | CS_OWNDC | CS_GLOBALCLASS, MsgProc, 0L, 0L,
GetModuleHandle(NULL), NULL, NULL, NULL, NULL,
szWindowClass, NULL };
RegisterClassEx( &wc );
****
GetModuleHandle(NULL) returns the module handle of the executable, but your handler
function is in the DLL, so why do you go out of your way to make the same error as in the
first case? You want to save the HMODULE/HINSTANCE parameter of DllMain and use that
here, as the documentation carefully states.

// Create the application's window
hwnd = CreateWindow(szWindowClass,L"Title",
WS_POPUPWINDOW| CS_GLOBALCLASS, left, top, width,
height,
GetDesktopWindow(), NULL,GetModuleHandle(NULL),
NULL);
****
Is szWIndowClass set to the same value you used when you did the RegisterClassEx. I see
no evidence here that it is.

It is always a mistake to create a window as a child of the desktop window; take that as
your guideline and the few exceptions will be obvious.

Have you tried
hwnd = ::CreateWIndow(szWindowClass, // window class
NULL, // caption
WS_POPUPWINDOW | WS_VISIBLE,
left, top, width, height,
parent,
NULL,
dllsinstance,
NULL);
if(hwnd == NULL)
return FALSE;

There is no such thing as a "static dll". A dll is either implicitly linked dynamically
or explicitly linked dynamically, and from your viewpoint there is no difference between
these two styles.
*****
return TRUE;
but all are avail..
this dll is a static dll(lib and header file)
any rule for creating window inside dll?
i must create another thread ?should i call in dllmain?
****
You can't call it from DllMain. RTFM. Creating from another thread is somewhere between
silly and dangerous; if you can't create it using the code you have, the code you have is
wrong. Note that you also cannot create a window in a function *called* from DllMain.
****
please help me ..
NB: second post (afterwin32 UI )
Joseph M. Newcomer [MVP]
email: newcomer@xxxxxxxxxxxx
Web: http://www.flounder.com
MVP Tips: http://www.flounder.com/mvp_tips.htm
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