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Here is a scenario where you must know DACL, because the NULL will not work.
If you have two processes, one of which is running as a service under the local system account, and you want each one to be able to open a mutex, but you do not want the mutex to have 'wide open' access, then you must apply a DACL. This is all well and good, but suppose the process which is running as a service created the mutex, and the other process is running under the security context of the logged on user. The logged on user process will not be able to open the mutex if it was created under the context of the service (which usually runs as local system) - it will get access denied. So, then you have to apply the correct kinds of DACL to not only secure the object, but to allow it to be opened by the correct types of users.
Typically, the NULL DACL will either assign the object the security context of the process which created it, or give the object access to 'everyone'. In some cases, like the one mentioned here, neither case is a workable solution, so a non-NULL DACL must be applied.
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Hiya I have dropped an IPAddress Control from the toolbox onto my form. But when I use GetAddress() or IsBlank() methods of the IPAddress control, the program crashes with:
Debug Assertion Failed!
Program:
File: f:\vs70builds\3077\vc\MFCATL\ship\atlmfc\include\afxcmn2.inl
Line: 344
Does anyone know how to fix this??
Thanks.
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Seems like your dialog is closed the time u call this method
Papa
while (TRUE)
Papa.WillLove ( Bebe ) ;
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Did you try running under the debugger and hitting Retry when prompted? That takes you to the line firing the assertion.
Also, look in the vc7\atlmfc\include directory under Visual Studio .NET's install directory.
The source line reads:
_AFXCMN_INLINE BOOL CIPAddressCtrl::IsBlank() const
{ ASSERT(::IsWindow(m_hWnd)); return (BOOL) ::SendMessage(m_hWnd, IPM_ISBLANK, 0, 0L); }This indicates that you tried to call it on an object whose m_hWnd member isn't a valid window handle. Usually this means that either you tried to use an object you haven't initialised (m_hWnd is NULL), that you stored a pointer returned from GetDlgItem and then later tried to use that pointer in a different message handler, or, more rarely, that some kind of memory corruption has occurred (typically through a buffer overrun). You'll also get problems passing CWnd pointers between threads, particularly if they point to temporary objects.
You must not store pointers to temporary CWnd objects. Any MFC function returning a CWnd* may return a pointer to a temporary object; these temporary objects are cleaned up the next time your program is idle. If you need to reference a window for a period longer than the duration of the current function, create a CWnd-derived object and call Attach.
You can use the DDX_Control function in your DoDataExchange override to automatically hook up a member variable to a control. You can do this through the Visual Studio environment by right-clicking the control in the dialog designer and choosing Add Variable.
Stability. What an interesting concept. -- Chris Maunder
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Hi,
For the moment I'm working on a lockscreen feature. This works fine except for the fact that if dialogs (with choices and options and stuff) are opened, these are not closed. How can I get a handle to these dialogs (so that I can close them)?
(Note: these dialogs can call dialogs themselves).
tnx!
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Read the documentation on the EnumWindows, EnumDesktopWindows, and EnumChildWindows APIs in MSDN. I don't follow exactly what you're trying to do, but these are the APIs you would want to use to get HWND values of existing windows.
Hope this helps you get started.
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tnx for your help. It worked although I had to do some workarounds (but as long as the boss is happy  )
What I'm trying to do:
I'm working on a medical dossier for hospitals. => privacy of the patient. So all viewable data should be hidden when a doctor is not working on his computer....
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Why would you want to close an open dialog? That doesn't sound very user friendly!
"The pointy end goes in the other man." - Antonio Banderas (Zorro, 1998)
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I have subclassed an the EDIT control in my active x project.
How can I get at the base class data and methods, from within my super active x class?
its really annoying, it must be so simple!!!;P
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 hi,
i am creating a sample for testing interop.
i am having one .net(c#) class. i am going to expose this to Com Client.
i am having one MFC client program.
in that i am referring the .tlb file which is created from .net( with the Register for COM property of project is true).
it is working fine.
my problem is:
if i set that property(register for COM) to false, and i create a dll and thro' regasm/tlbexp i create a tlb.
and finaly i refer it in the MFC client program , then i will get the error "Class not registered".
could u anybody let me know what will the problem be?
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The CLSID for .NET classes, if not explicitly set, is derived from your class's assembly version numbers (among other things). A wizard-generated project has the AssemblyVersion attribute set to 1.0.*, which instructs the compiler to generate new numbers for the last two components of the version number when you compile (the numbers are derived from the compile date and time).
Either set the Guid attribute (see GuidAttribute), or use a fixed version number.
[EDIT] In case it wasn't clear, the consequence of the first paragraph is that the CLSID changes every time you recompile the component. [/EDIT]
Stability. What an interesting concept. -- Chris Maunder
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Hi,
For the last few days I've been trying to create a small DLL using the IActiveDesktop interface without avail.
What I want to do is create a dll which contains a method that when passed the location of a file, sets the wallpaper to that file.
I need this to integrate with a Java application I'm writing. Just on that note, I am strictly a Java developer with some C++ experience. However! Until this week I had never opened VS.NET nor tried to perform Windows coding of any kind.
Now, I managed to create a small .exe that does this as per the COM tutorial on this site. I'd like to take this code and compile a DLL.
Alas, I'm having no end of problems. I don't know which template project I'm supposed to be using and I'm generally finding this IDE very difficult to cope with especially the linker errors! argh!
MSDN is proving a poor substitute to my beloved Javadoc and I'm at a point where I'm ready to pull my hair out from frustration.
Could someone *please* write me a small step-by-step guide as to how I should approach this?? What templates do I need to use? I tried the MFC DLL template to no avail. Maybe I'm not configuring it right? I just don't know. 
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OK. Assuming that a Java program can call into a 'flat' DLL (and that's a big assumption from what I've read), you need to do:
File > New > Project
Under Visual C++ Projects > Win32, select Win32 Project. Type a name for the project and hit OK.
In the Win32 Application Wizard dialog, select Application Settings in the left-hand bar, then select DLL under Application Type. Check the 'Export Symbols' checkbox. Hit Finish.
VS.NET generates a project containing five files: stdafx.h, stdafx.cpp, <projectname>.h, <projectname>.cpp and a readme.txt.
The stdafx files are used to produce a precompiled header. This is a binary file used by the compiler to speed up the main compilation by only reading commonly-used header files once. If you're going to use a system header, it's often handy to put the #include statement in stdafx.h.
Let's assume that you called your project NewDll. In newdll.h, VS.NET has generated an exported class, CNewDll, an exported variable, nNewDll, and a function, fnNewDll. To export a function, we want to follow the fnNewDll example; however, to make it easier to import from other languages, it's best to add extern "C" to the beginning of the declaration. This tells the compiler not to 'mangle' the function's name (produce an encoded name that includes all the type information).
If you're using the Microsoft VM for Java, that's probably enough and you need to look up J/Direct. However, the standard mechanism for including C++ code with your Java program is Java Native Interface[^]. You'll have to look up Sun's documentation for this.
Stability. What an interesting concept. -- Chris Maunder
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When I have a lot of text in my Control (lager then 64k)
I can not handle this anymore.
CString is to small, Richedit will not take any more letters.
What can I do?
is there a alternative?
GermanGeorge
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GermanGeorge wrote:
CString is to small,
What do you mean by this? A CString object can store up to 231-1 characters.
GermanGeorge wrote:
Richedit will not take any more letters
By chance are you sending the control a EM_LIMITTEXT message?
"The pointy end goes in the other man." - Antonio Banderas (Zorro, 1998)
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hello,
thank you for yout idea.
i used LimitText (which I thought was a limitation) and it works well right now.
GermanGeorge
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I have a Dialog based application, which uses file type say *.chl now i want to associate all *.chl files with my dialog based application,
what changes do i have to make in registry ?
i can't even remember what my point is now, but anyway, i'm correct
Barring unforeseen acts of God and Adminstrators, my server will be up tomorrow. I'm more worried about the Adminstrators.
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searching at google revealed this
works like a charm
-----
All you need to do is create a registry entry for your
extension containing the command to run. Have a look at
the Reg... API functions used for writing registry entries.
For example, if your extension, is ".xxx", then create a
registry entry like this:
HKEY_CLASSES_ROOT
.xxx
shell
open
command="c:\x\y\z\myapp.exe %1"
i can't even remember what my point is now, but anyway, i'm correct
Barring unforeseen acts of God and Adminstrators, my server will be up tomorrow. I'm more worried about the Adminstrators.
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Have you looked at CWinApp::RegisterShellFileTypes()? This is the function that is normally called to do registering. It handles all registry updates.
"The pointy end goes in the other man." - Antonio Banderas (Zorro, 1998)
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I just did the same thing yesterday. But I did the registry changes in the installer, that way the entries are undone when the app is unistalled. have a look at:
http://www.jrsoftware.org/isfaq.php#assoc[^]
Sonork 100.11743 Chicken Little
"You're obviously a superstar." - Christian Graus about me - 12 Feb '03
Within you lies the power for good - Use it!
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yup did it in installer (inno setup)
thanks 
i can't even remember what my point is now, but anyway, i'm correct
Barring unforeseen acts of God and Adminstrators, my server will be up tomorrow. I'm more worried about the Adminstrators.
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Is it possible to detect all installed codecs without using DirectShow ??
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Would it available in WMI?
Sonork 100.41263:Anthony_Yio
Life is about experiencing ...
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There are, I have discovered, various sorts of codec. The older sort were designed originally for Video for Windows. The newer sort actually run in kernel space and can be accessed with DirectShow. Some programs (e.g. Windows Media Player) can use both sorts. Others (e.g. Windows Media Encoder) can only use DirectShow-style codecs. A third set (e.g. VirtualDub) can only use the older VfW sort.
To enumerate VfW codecs, use ICInfo.
Note that the Windows Media codecs are DirectShow-only.
Stability. What an interesting concept. -- Chris Maunder
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I have a BYTE array of pixels, which describes am image. Image is black - white. Pixels have 255 and 0 values. If pixels are white - this is object, black - background. I wanna know sizes and locations of all objects on image.
If i use standart recursive floodfill algorithm for every object by turns it takes too much time to scan whole image, find object, use to object floofill and to get size and location of the object.
Do anybody know fast algoritmh for simultaneously detecting of all objects on image(BYTE array)?
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