C# Discussion Boards - CodeProject

Daniel Turini23-Nov-04 8:05

23-Nov-04 8:05

Heath Stewart wrote:
Why generate an extra call on the stack just to "redirect" to another method?
To avoid duplicating defaults and/or code (which could lead to inconsistent behavior).
Actually, if you Google for it you'll notice that this is one of those religious things. Personally, I agree with you, with the added annoyance that single-stepping through code like this is really boring.

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Persist ListViewItem backColor when using HideSelection= false

the last free name23-Nov-04 0:05

the last free name

23-Nov-04 0:05

Anynoe know how to keep the backColor of listview items (View=Details) when HideSelection is set to false?
The problem is when selectedItems.Count == 0, it seems to redraw the last selected item with a clear background after the selectedIndex changed event.
Any ideas how I can get around this?

Thanks

Re: Persist ListViewItem backColor when using HideSelection= false

mhmoud rawas23-Nov-04 1:37

mhmoud rawas

23-Nov-04 1:37

try to override paint function ...

Mhmoud Rawas
------------
Software Eng.

Calling C# functions from a DLL from within unmanaged C++

Uwe Keim22-Nov-04 22:18

Uwe Keim

22-Nov-04 22:18

This is a question for Heath [^], I guess Smile | :)

I want to write a managed C# DLL and call functions/classes from a unmanaged C++ application.

I could write a COM component in C#, register it and then #import it in the unmanaged C++ application to generate wrappers.

But: I want to avoid having the need to register the C# COM component, since the C# DLL and the unmanaged C++ application both are located inside the same folder and there is no need for other applications to access the COM component.

What I already tried (results in error C1083 [^]) was to

<a href="http://msdn.microsoft.com/library/en-us/vclang/html/_predir_The_.23.import_Directive.asp">#import</a> [<a href="http://msdn.microsoft.com/library/en-us/vclang/html/_predir_The_.23.import_Directive.asp" target="_blank" title="New Window">^</a>]

the C# COM DLL by referencing the complete DLL via

#import "C:\Test\MyCSharpClassLib.dll"

, but witthout success.

Also, I looked at the way this example does it: www.perfectxml.com/articles/msxml/TipsAugust02.asp [^], but that didn't help me either.

Question: Is it possible for me to call a C# COM-component from unmanaged C++, without registering it?

Thanks
Uwe

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Re: Calling C# functions from a DLL from within unmanaged C++

mhmoud rawas23-Nov-04 1:47

mhmoud rawas

23-Nov-04 1:47

Dear Sir,

as i have try it before i think that you don't have to register that com dll cuz it is self registration dll which can be generated from C# compiler using COM option, i have put them in the same foler with no-need to register it just you can call that dll from unmaneged c++ directlly with wout registration and you will have an error message just if you have used any crystal report objects in that C# dll

Mhmoud Rawas
------------
Software Eng.

Re: Calling C# functions from a DLL from within unmanaged C++

Mike Dimmick23-Nov-04 2:20

Mike Dimmick

23-Nov-04 2:20

Two options I can think of: first, to use side-by-side assemblies[^] to produce an isolated application. Second, to use the CLR Hosting[^] APIs to host the .NET Framework in your C++ application.

The second option looks like a lot of work, so I'd look into the first technique first. However, if you need it to work on Windows 2000 or earlier, I think it'll have to be the second.

Stability. What an interesting concept. -- Chris Maunder

Re: Calling C# functions from a DLL from within unmanaged C++

Uwe Keim23-Nov-04 19:29

Uwe Keim

23-Nov-04 19:29

Just tried your "CLR Hosting" suggestion: I looked at the "CLR Hosting Sample [^]" at the bottom of the link you suggested, slightly modified it and, it now works fantastic, without any additional registering.

Thank you! Big Grin | :-D

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Re: Calling C# functions from a DLL from within unmanaged C++

Nick Parker23-Nov-04 4:57

Nick Parker

23-Nov-04 4:57

Uwe, here's a thought, create an CCW a la my article[^], but you could control the registration from your application with the command line tool Regasm.exe[^], this way you could unregister it if you wanted (this idea seems brittle though). Also, CLR Hosting would be an interesting mechanism to consider as well. I've been wanting to write an article cover this topic, maybe I can sit down over the holiday weekend and put some notes together for it.

[EDIT]
You may also want to look into using the Tlbexp.exe[^] as it will generate the type library for you, however it won't register the assembly as regasm.exe will above.
[/EDIT]

- Nick Parker
My Blog | My Articles

Re: Calling C# functions from a DLL from within unmanaged C++

Uwe Keim23-Nov-04 5:02

Uwe Keim

23-Nov-04 5:02

That would be great! Thanks for your feedback Nick, I will try out and post my results.

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Re: Calling C# functions from a DLL from within unmanaged C++

Heath Stewart23-Nov-04 5:58

Heath Stewart

23-Nov-04 5:58

Both Mike's and Nick's answers are correct, but I wanted to explain what #import - the way you're using it - is. It serves two purposes - including assembly references in Managed C++ and importing typelibs, which generates a header and allows you to specify options for how that header file is generated.

Even if you have a typelib a la regasm.exe /tlb MyAssembly.dll and import that (as I did in my Java/.NET interop article), the classes still need to be registered. A typelib - as I'm sure you know - only describes types, nothing more.

If you go with Mike's approach about using manifests and don't want to register the components to be used by other COM clients (although, since that is the easiest, ask yourself "why not?". there's lots of "private" COM components registered on your system), understand that it'll only work on XP and newer and make sure that down-level platforms get a user-friendly error for when that type won't be found (off-hand, I'd bet you'd get either a TypeLoadException or TargetInvocationException).

Hosting the CLR is another good idea and isn't too much work for the basic functionality.

This posting is provided "AS IS" with no warranties, and confers no rights.

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Developer Division Sustained Engineering
Microsoft

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Re: Calling C# functions from a DLL from within unmanaged C++

Uwe Keim23-Nov-04 6:11

Uwe Keim

23-Nov-04 6:11

Thanks for your reply, Heath, really fantastic explained, as always! What makes me wonder is this newsgroup posting: http://groups.google.de/groups?q=getDllClassObject&hl=de&lr=&selm=OLWwtP%244CHA.1740%40TK2MSFTNGP12.phx.gbl&rnum=1 [^].

The guy metions a function getDllClassObject, which must be written by the autor of the book he mentions. Since I don't have the book, maybe I should buy it? Or do you know how the function probably works?

Thanks
Uwe

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Re: Calling C# functions from a DLL from within unmanaged C++

Nick Parker23-Nov-04 7:22

Nick Parker

23-Nov-04 7:22

Uwe Keim wrote:
The guy metions a function getDllClassObject, which must be written by the autor of the book he mentions. Since I don't have the book, maybe I should buy it? Or do you know how the function probably works?

No it's probably just a VB wrapper around the native call, he is refering to DllGetClassObject[^] which you can implement yourself. It's returning a class factory based on the CLSID of the coclass and the interface being requested.

- Nick Parker
My Blog | My Articles

Re: Calling C# functions from a DLL from within unmanaged C++

Uwe Keim23-Nov-04 7:34

Uwe Keim

23-Nov-04 7:34

Sounds reasonable, thanks! Do you know any way to implement this function (DllGetClassObject) from a managed COM DLL?

E.g. I once wrote a managed COM DLL where I applied the [System.Runtime.InteropServices.ComRegisterFunctionAttribute()] to a function to provide the registering functionality.

So I guess there must be a similar attribute or something like that in the System.Runtime.InteropServices namespace?!?

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Re: Calling C# functions from a DLL from within unmanaged C++

Nick Parker23-Nov-04 8:02

Nick Parker

23-Nov-04 8:02

Uwe Keim wrote:
Sounds reasonable, thanks! Do you know any way to implement this function (DllGetClassObject) from a managed COM DLL?

You can simply create a class factory in your .NET code. Make sure you just return an interface pointer to the created class. You can use the standard C-style casting mechanism as well.

private IFun GetFunObject(string strType)
{
    IFun iFun;
    if(string.Compare(strType, "SomeClassName") == 0)
    {
        // explicit cast
        iFun = (IFun) new Fun();
    }
    return iFun;
}
//....
interface IFun
{
   void HaveFun();
}
//....
class Fun : IFun
{
   void HaveFun()
   {
   //...
   }
}

- Nick Parker
My Blog | My Articles

Re: Calling C# functions from a DLL from within unmanaged C++

Heath Stewart23-Nov-04 8:40

Heath Stewart

23-Nov-04 8:40

Remember that VB6 (or older) != VB.NET...er, <> VB.NET! Smile | :)

Completely different runtime.

GetDllClassObject has to be a natively exported function, just like DllRegisterServer, DllUnregisterServer, etc. This isn't possible with the managed compilers, though if you wrote your own compiler you could inject implementations or relocate calls to a bootstrap DLL (this is actually how VB6 and many other executables work - the entry point is actually a redirect to another library that calls back into the PE/COFF executable).

This posting is provided "AS IS" with no warranties, and confers no rights.

Software Design Engineer
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Microsoft

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Drawing & Scaling

Prof AKA22-Nov-04 21:37

Prof AKA

22-Nov-04 21:37

I need to show a drawing surface that is the same size as the default printer page but which is a user control. Then I need to scale it for better viewing. What would be the best approach to take on this one? I am a little bit stymied.

Thanks

Re: Drawing & Scaling

Gary Thom23-Nov-04 3:17

Gary Thom

23-Nov-04 3:17

Try this one as a starting point.

Creating a Design Surface Using Windows Forms and GDI+ in Microsoft .NET[^]

Gary

While you're waiting, read the free novel we sent you. It's a Spanish story about a guy named 'Manual.'
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Get the command line parameters of an external process.

Matt Philmon22-Nov-04 19:42

Matt Philmon

22-Nov-04 19:42

Does anyone know how to get the commandline parameters of an externally created process?

The Process class gives you the StartInfo property which includes "Arguments". This works great if I want to start my own process. However, I've found that it never contains the arguments used to start an external process that my program didn't start. It's always empty.

In C, there's a Win32 call for GetCommandLine() which would work great... except it only works for the calling process, not an external one.

SysInternals' "Process Explorer" does this without any trouble for any process so I know it can be done. Any help? I don't care if it's C/C++, VB, VB.NET, or C#.

Thanks

Re: Get the command line parameters of an external process.

Guinness4Strength9-Sep-06 6:53

Guinness4Strength

9-Sep-06 6:53

Did you ever figure this out ?

Re: Get the command line parameters of an external process.

Matt Philmon9-Sep-06 9:51

Matt Philmon

9-Sep-06 9:51

Yeah, I ultimately did in C++. I wrote a wrapper in ATL COM so I could easily use it in a C# project I was working on at the time. Unfortunately the hard drive it existed on was lost when the project was shelved a couple years back. I MAY have a backup still on another drive at the office. I can dig that up for you if you really need it, but it will need to wait until Monday. If you can't, then look into examining the PEB (process environment block). I think it had something to do with NtQueryInformationProcess but I'm not sure. You can get the processID of the process you want to query with the .NET classes, then jump into the lower level API calls to get the rest.

Hmmm, maybe there's an actual article in there for CP. I hadn't thought about that before.

Datagrid?

murali_utr22-Nov-04 19:08

murali_utr

22-Nov-04 19:08

hi,
how to use datagrid for making invoice and purcase orders and so on. any one help to me. if possible with small sample.

Thanks in advace!

Have A Nice Day!
Murali.M

Re: Datagrid?

sreejith ss nair22-Nov-04 19:20

sreejith ss nair

22-Nov-04 19:20

It's very tough to get a ready made customizable Grid. What you need to do is, play around with your logic.

I wrote an article on DataGrid formattings. This will help you to customize your figures(numbers) in desided fasion. apart from this please check this link, which contain lot of tips and sample tutorials which will guide you to reach your place.DataGrid Gal Wink | ;)

Sreejith Nair
[ My Articles ]

Re: Datagrid?

Gary Thom23-Nov-04 3:20

Gary Thom

23-Nov-04 3:20

This is a great Windows Forms FAQ and has a few examples of datagrid formatting:

WinForms FAQ[^]

Gary

While you're waiting, read the free novel we sent you. It's a Spanish story about a guy named 'Manual.'
- Dilbert

Object Writer?

Rafferty Uy22-Nov-04 18:37

Rafferty Uy

22-Nov-04 18:37

Hi,

I remember that there's an object stream writer in Java which makes it easy to save objects into files. What class is this in C#? Smile | :)

Rafferty

Re: Object Writer?

Daniel Turini22-Nov-04 19:14

Daniel Turini

22-Nov-04 19:14

You can use the BinaryWriter, or, for a higher level solution, BinaryFormatter with the [Serializable] attribute on the class.

Yes, even I am blogging now!

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