C / C++ / MFC

7-Jan-07 11:21

Using VS2005/SP1 and MFC...

I have a SDI app and I'm trying to use a CView-derived class from a MFC extension DLL in the document template object. Everything compiles fine with no warnings).

When the app hits the CDocTemplate constructor, it asserts on this line:

ASSERT(pViewClass == NULL ||
    pViewClass->IsDerivedFrom(RUNTIME_CLASS(CView)));

The pViewClass pointer isn't NULL, so the assert is triggering on the IsDerivedFrom() function. The view I'm trying to use IS derived from CView. Why would it assert? What am I not seeing?

NOTE: If I move the view into the application project, it starts up just fine. And yes, I'm exporting the class, using class __declspec(dllexport) CTestView : public CView.

"Why don't you tie a kerosene-soaked rag around your ankles so the ants won't climb up and eat your candy ass..." - Dale Earnhardt, 1997
-----
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PJ Arends7-Jan-07 12:18

7-Jan-07 12:18

Have you stepped through the IsDerivedFrom() function?

How are you calling the CSingleDocTemplate c'tor?

You may be right
I may be crazy
-- Billy Joel --

Within you lies the power for good, use it!!!

#realJSOP7-Jan-07 13:55

7-Jan-07 13:55

It's a nothing-fancy MFC SDI app. The only thing I changed in the CDocTemplate was the view class.

What's really stupid is I've done this before, and I can't think of anything I'm forgetting.

The trace through IsDerivedFrom doesn't make any sense. It's comparing pointers to objects instead of doing something like checking the results of a dynamic_cast to the desired base class. Here's that function - the bold parts are the lines executed:

BOOL CRuntimeClass::IsDerivedFrom(const CRuntimeClass* pBaseClass) const
{
	ENSURE(this != NULL);
	ASSERT(AfxIsValidAddress(this, sizeof(CRuntimeClass), FALSE));
	ENSURE(pBaseClass != NULL);
	ASSERT(AfxIsValidAddress(pBaseClass, sizeof(CRuntimeClass), FALSE));

	// simple SI case
	const CRuntimeClass* pClassThis = this;
#ifdef _AFXDLL
	for ( ; ; )
#else
	while (pClassThis != NULL)
#endif
	{
		if (pClassThis == pBaseClass)
			return TRUE;
#ifdef _AFXDLL
		if (pClassThis->m_pfnGetBaseClass == NULL)
			break;
		pClassThis = (*pClassThis->m_pfnGetBaseClass)();
#else
		pClassThis = pClassThis->m_pBaseClass;
#endif
	}
	return FALSE;       // walked to the top, no match
}

If checks the following classes:

CTestGridView3
CView <------------ !!!!!
CCmdTarget
CObject
NULL

#realJSOP7-Jan-07 14:24

7-Jan-07 14:24

In the DLL, I had to set the "Characterset" property (under Configuration Properties/General) to "Not Set". Then everything works. :/

PJ Arends7-Jan-07 14:55

7-Jan-07 14:55

Yeah, I tried it and noticed that I get the same error if the DLL and main app are built with different settings. I guess that means you can not mix MBCS and DBCS.

You may be right
I may be crazy
-- Billy Joel --

Within you lies the power for good, use it!!!

Michael Dunn7-Jan-07 18:48

Michael Dunn

7-Jan-07 18:48

I'm guessing that "not set" means that the build falls back to the default of SBCS, which should not be used anymore. Dead | X|

--Mike--
Visual C++ MVP Cool | :cool:

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#realJSOP7-Jan-07 23:25

Detecting doubleclick on a desktop window - part 2.

7-Jan-07 23:25

The app is set to MBCS. If I set the DLL to "not set" or "MBCS", it works. If I set the DLL to Unicode, it doesn't work.

PatrykDabrowski7-Jan-07 10:43

PatrykDabrowski

7-Jan-07 10:43

Hello,

I have some questions about using global (system wide) hooks in Win32. I've got a simple app loading my simple DLL which sets up a WH_MOUSE hook:

m_hhook=SetWindowsHookEx(WH_MOUSE,MouseProc,m_hmod,0); (inside DLL)

My MouseProc is: (also inside DLL)

HOOKTEST2DLL_API LRESULT CALLBACK MouseProc(int nCode, WPARAM wParam, LPARAM lParam)
{
MOUSEHOOKSTRUCT *mhs=(MOUSEHOOKSTRUCT *)lParam;

if(nCode < 0) // do not process the message
return CallNextHookEx(m_hhook, nCode, wParam, lParam);
else
{
if((nCode==HC_ACTION) && (wParam==WM_LBUTTONDBLCLK))
{
PostThreadMessage(m_appthreadid,WM_APP+1,0,0);
m_mouseproc_counter++;
}
return CallNextHookEx(m_hhook, nCode, wParam, lParam);
}
}

I have also some variables in shared section of DLL which are initialised using:

HOOKTEST2DLL_API void fnInit()
{
m_hwnd_app=NULL; //main application window HWND
m_hhook=NULL; //WH_MOUSE hook handle
m_hwnd_desktop=::GetDesktopWindow(); //desktop window handle
m_mouseproc_counter=0; //mouse-dblclicks counter
m_appthreadid=NULL; //main application's thread ID
m_hmod=GetModuleHandle("HookTest2DLL.dll"); //DLL module handle
}

My questions are:

1) Why PostMessage(m_hwnd_app,WM_APP+1,0,0) doesn't work? Variable m_hwnd_app is set up after DLL is loaded and points to the main window of my simple MFC app. PostThreadMessage(m_appthreadid,WM_APP+1,0,0) works fine.

2) When I detect a doubleclick on desktop screen, in my MOUSEHOOKSTRUCT structure hwnd is set to 0x10094 (::GetDesktopWindow() returns 0x10014) but even when I double-click on any desktop icon (ie My Computer) I'm getting this event. Is it possible to filter out those events connected with double-clicking on desktop icons??

3) What is the best way of communicating between DLL and host application in case, when DLL could be injected into other threads/processes? Can I use variables in shared data section of my DLL or only PostThreadMessage() should be used?

Thank for any help Smile | :)

Pat.

Re: Detecting doubleclick on a desktop window - part 2.

PatrykDabrowski7-Jan-07 12:03

PatrykDabrowski

7-Jan-07 12:03

To my question 2)

Using Spy++ I have figured out, that capturing additional message LVM_HITTEST could solve my problem. When double-clicking on desktop, Windows generates LVM_HITTEST message with nIndex set to icon which we are clicking on, or -1 when we click on desktop. Messages come in this order (in case of doubleclick)

1.LVM_HITTEST (first click)
2.LVM_HITTEST (second click)
3.WM_LBUTTONDBLCLK

...so it's safe to cache last LVM_HITTEST message and when WM_LBUTTONDBLCLK happen, just check nIndex of last cached message, if it's -1 we have a double-click on desktop.

Any faster/simpler solution?? (it would be nice if I could detect it based on only one message)

Another question is how to capture LVM_HITTEST message? Another system-wide hook?:/

Thanks for any help Smile | :)

Pat.

Re: Detecting doubleclick on a desktop window - part 2 - solution?

PatrykDabrowski7-Jan-07 16:37

PatrykDabrowski

7-Jan-07 16:37

Finally I've found a way to filter-out all icons connected WM_LMOUSEDBLCLK messages. My MouseProc() now looks like this:

HOOKTEST2DLL_API LRESULT CALLBACK MouseProc(int nCode, WPARAM wParam, LPARAM lParam)
{
MOUSEHOOKSTRUCT *mhs=(MOUSEHOOKSTRUCT *)lParam;
LVHITTESTINFO pinfo;

if(nCode < 0) // do not process the message
{
return CallNextHookEx(m_hhook, nCode, wParam, lParam);
}
else
{
if((nCode==HC_ACTION) && (wParam==WM_LBUTTONDBLCLK))
{
if(mhs->hwnd==m_hwnd_desktop) //==0x10094
{
pinfo.pt=mhs->pt;
if(SendMessage(m_hwnd_desktop,LVM_HITTEST,0,(LPARAM)&pinfo)==-1)
{
PostThreadMessage(m_appthreadid,WM_APP+1,mhs->pt.x,mhs->pt.y);
m_mouseproc_counter++;
}
}
}

return CallNextHookEx(m_hhook, nCode, wParam, lParam);
}
}

It seems to be fine, I'm getting WM_APP+1 messages only when I double-click on desktop window and not on any desktop icon Smile | :)

Well, this leads me to another question:

4) How to find in a system-friendly and Windows compatible way this 'magic' window handle 0x00010094? Using Spy++ I could find out the class name and window name. My current code looks like this:

HWND h1=::FindWindowEx(NULL,NULL,"Progman","Program Manager");
HWND h2=::FindWindowEx(h1,NULL,"SHELLDLL_DefView",NULL);
m_hwnd_desktop=::FindWindowEx(h2,NULL,"SysListView32",NULL);

...and it's working fine, but that's strange that a single line:
m_hwnd_desktop=::FindWindowEx(NULL,NULL,"SysListView32","ListView");

...does NOT work (returns NULL). Is this method 'safe and compatible'?

Pat.

Re: Detecting doubleclick on a desktop window - part 2.

Naveen7-Jan-07 16:55

Naveen

7-Jan-07 16:55

PatrykDabrowski wrote:
PostThreadMessage(m_appthreadid,WM_APP+1,0,0);

instead of using the WM_APP+1, use RegisterWindowMessage to create a unique message.

nave

Multithreading? Help!

Yonggoo7-Jan-07 8:37

Yonggoo

7-Jan-07 8:37

Hi All,
I am studying multithreading with Visual Studio 2005.
I have an error with one sample from "Multithreading Applications in Win32 - Jim Beveridge & Robert"

1>.\SearchFile.cpp(44) : error C2664: '_beginthreadex' : cannot convert parameter 3 from 'DWORD (__stdcall *)(void *)' to 'unsigned int (__stdcall *)(void *)'

/*
SerarhFil.cpp
*/

#include <windows.h>
#include <process.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include "MtVerify.h"

DWORD WINAPI SearchProc(void *arg);
#define MAX_THREADS 3

HANDLE hThreadLimitSemaphore;
char szSearchFor[1024];

int main(int argc, char *argv[])
{
WIN32_FIND_DATA* lpFindData;
HANDLE hFindFile;
HANDLE hThread;
DWORD dummy;
int i;

if(argc != 2)
{
printf("Usage: %s <search-string>\n", argv[0]);
return EXIT_FAILURE;
}

strcpy(szSearchFor, argv[1]);

lpFindData = (WIN32_FIND_DATA*) calloc(1, sizeof(WIN32_FIND_DATA));

MTVERFY(hThreadLimitSemaphore = CreateSemaphore(NULL, MAX_THREADS, MAX_THREADS, NULL));

hFindFile = FindFirstFile("*.c", lpFindData);
if(hFindFile == INVALID_HANDLE_VALUE);
return EXIT_FAILURE;

do{
WaitForSingleObject(hThreadLimitSemaphore, INFINITE);

//HERE
MTVERFY(hThread = (HANDLE) _beginthreadex(NULL, 0, SearchProc, lpFindData, 0, &dummy));
MTVERFY(CloseHandle(hThread));
lpFindData =(WIN32_FIND_DATA*)calloc(1, sizeof(WIN32_FIND_DATA));
}while(FindNextFile(hFindFile, lpFindData));

FindClose(hFindFile);

for(i=0; i<max_threads;i++)
waitforsingleobject(hthreadlimitsemaphore,="" infinite);

="" mtverfy(closehandle(hthreadlimitsemaphore));

="" return="" exit_success;
}

dword="" _stdcall="" searchproc(void="" *arg)
{
="" win32_find_data="" *lpfinddata="(WIN32_FIND_DATA*)arg;
" char="" buff[1024];
="" file*="" ptrfile;
="" ptrfile="fopen(lpFindData-">cFileName, "r");
if(!ptrFile)
return EXIT_FAILURE;

while(fgets(buff, sizeof(buff), ptrFile))
{
if(strstr(buff,szSearchFor))
printf("%s: %s", lpFindData->cFileName, buff);
}

fclose(ptrFile);
free(lpFindData);

MTVERFY(ReleaseSemaphore(hThreadLimitSemaphore, 1, NULL));
}

Yonggoo

Re: Multithreading? Help!

PJ Arends7-Jan-07 9:12

Using Resource ID's [modified]

7-Jan-07 9:12

Yonggoo wrote:
1>.\SearchFile.cpp(44) : error C2664: '_beginthreadex' : cannot convert parameter 3 from 'DWORD (__stdcall *)(void *)' to 'unsigned int (__stdcall *)(void *)'

Yonggoo wrote:
MTVERFY(hThread = (HANDLE) _beginthreadex(NULL, 0, SearchProc, lpFindData, 0, &dummy));

Yonggoo wrote:
DWORD _stdcall SearchProc(void *arg)

_beginthreadex requires the thread proc that it calls to return an unsigned int. You are passing it a function that returns a DWORD. There is no built in conversion from a DWORD to an unsigned int. Change the return type of the SearchProc to an unsigned int.

You may be right
I may be crazy
-- Billy Joel --

Within you lies the power for good, use it!!!

BlitzPackage7-Jan-07 7:45

BlitzPackage

7-Jan-07 7:45

Greetings,

I have a custom class I'm building in an MDI application. How do I use a resource ID (i.e. IDB_CAR1) in my class? I called a method using that resource ID, but my application can't find it even though it is a resource. Is there an "#include" I'm missing somewhere for my custom class? What's really strange, is that when I hover the mouse over the offending variable, it gives me a tooltip stating "define IDB_CAR1 130" so it knows what it is, but when I try to compile it, it tells me that it is an unknown identifier.

Any help would be greatly appreciated.

Thanks,
BP

-- modified at 13:57 Sunday 7th January, 2007

Re: Using Resource ID's

PJ Arends7-Jan-07 9:13