Managed C++/CLI

Lighter Joul23-May-11 4:37

23-May-11 4:37

Thanks for your kind reply.

hello!

Luc Pattyn23-May-11 4:38

23-May-11 4:38

You're welcome.

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles] Nil Volentibus Arduum

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Lighter Joul23-May-11 5:00

23-May-11 5:00

BTW，I did some test right now, I added some painting codes in panel's on_paint function. However, the painting can not be double buffered, and the panel's double buffered property is private.

If I want to do some painting in the panel, there are some blinks when painting.

How about your idea about this?

Thanks. Smile | :)

Joul

Luc Pattyn23-May-11 5:30

23-May-11 5:30

There are two ways I know of:

1.
you derive your own DoubleBufferedPanel from the normal Panel, then in its constructor you can set the double-buffered property (as it is protected). Once you build a project with such DoubleBufferedPanel class present (but still unused), Visual Designer should have it available and now you can replace the Panel by a DoubleBufferedPanel.

2.
you can change the properties of a regular Panel at run-time, something akin to:

panel.SetStyle(System.Windows.Forms.ControlStyles.DoubleBuffer,true);
panel.SetStyle(System.Windows.Forms.ControlStyles.AllPaintingInWmPaint,true);
panel.SetStyle(System.Windows.Forms.ControlStyles.UserPaint,true);
oanel.UpdateStyles();

This also works on pre-2.0 .NET versions where Control.DoubleBuffered didn't exist.

Smile | :)

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Lighter Joul24-May-11 3:33

24-May-11 3:33

Hi,

I did some test again, but panel.SetStyle is the private function, and I can not use that function.

For the first way, I can make a DoubleBufferedPanel class, but it's not convinent for visual designer.

I don't know if there is another way. Thanks.

hello!

Luc Pattyn24-May-11 9:07

24-May-11 9:07

Indeed, SetStyle isn't public either, my mistake. So you have to create your own Panel.

Here[^] is an article where I did exactly that; there is a download near the end. It is in C#, I trust it would be basically the same in C++//CLI. Getting Visual Designer to find the new controls depends on a number of factors, I don't think I know them all; one is your code has to compile; another may well be the new Control has to be the first (or only?) class in its source file.

Smile | :)

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Lighter Joul24-May-11 16:55

Static and Global Variables?

24-May-11 16:55

Hi Luc,

I had created a user constrol derived from panel class. and it's easy to add the new Control to the Visual Designer.

I provide a method named setDB to set if the panel can be doublebuffered. And it works.

Thanks for your kind help.

BTW, I had read your article about animation demo, it's greate. Smile | :)

Joul

VonHagNDaz19-May-11 3:08

Re: Static and Global Variables?

19-May-11 3:08

Hey guys,

I have a question that's been plaguing me for a day or so. I'll try to explain as best as possible. No code this time, just some general questions.

I have a hierarchy of Windows forms, MainForm->AdminForm->JobDetailsForm. JobDetailsForm requires objects from MainForm, and AdminForm is just a middle man. Is there a slick way to get information from an object in MainForm to JobDetails form without passing the object through AdminForm? The object is an ArrayList of Objects called Users. I set information in the MainForm, and then I get that information inside of JobDetailsForm. Currently I'm doing something similar to

Pseudo Code:

MainForm
ArrayList users;
...
new AdminForm(users);

AdminForm
...
//no operations on users
new JobDetailsForm(users)

JobDetailsForm
...
//some operations on users

AdminForm has no use for users, it simply displays some information unrelated to users. If possible, I'd also like the operations preformed in JobDetailsForm to be reflected in the users object used in MainForm. I'm thinking a global or static variable could solve this, but from what I understand, there are no global or static variables in managed C++/CLI. Any ideas or suggestions?

[Insert Witty Sig Here]

Mark Salsbery19-May-11 8:28

Mark Salsbery

19-May-11 8:28

VonHagNDaz wrote:
I'm thinking a global or static variable could solve this, but from what I understand, there are no global or static variables in managed C++/CLI.

If you choose that route, you can have a ref class with a static constructor and static member methods/properties/fields...How to: Define Static Constructors in a Class or Struct[^]

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

DateTime->Parse

VonHagNDaz16-May-11 4:34

Re: DateTime->Parse [modified]

16-May-11 4:34

Hey Guys,

I'm having a little problem parsing a date and time from a string.

DateTime^ start = gcnew DateTime();

temp = "";
this->thisJob->getStartDate(temp);
start->Parse(temp);

temp is "5/16/2011"

however, after start->parse(temp) the value of start is always "1/1/1 0 Blush | :O

" I'm only interested in the date "5/26/2011". MSDN has several differnt "Parse" methods, and I've tried a few others, but the result is always "1/1/1 0 Blush | :O

"

Sorry for the smileys, I think CP website is taking my returned string I'm typing into the question and converting it into some kind of smiley code.

[Insert Witty Sig Here]

Mark Salsbery16-May-11 7:26

Mark Salsbery

16-May-11 7:26

Try something like this...

String ^temp = "5/26/2011";
DateTime start;
if (DateTime::TryParse(temp, start))
{
    // do something with start
}

...or this...

String ^temp = "5/26/2011";
try
{
    DateTime start = DateTime::Parse(temp);

    // do something with start
}
catch (Exception ^)
{
}

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

modified on Monday, May 16, 2011 2:32 PM

Re: DateTime->Parse

VonHagNDaz16-May-11 10:56

16-May-11 10:56

That works! I'm a bit confused as to why your code works and mine doesn't. What is the difference between SomeDateTimeObject.Parse, and DateTime::Parse?

[Insert Witty Sig Here]

Re: DateTime->Parse

Mark Salsbery16-May-11 12:57

Mark Salsbery

16-May-11 12:57

All the Parse() methods are static (AFAIK) so they return a new DateTime object instead of altering the one you were calling Parse() on.

This would have worked;

start = start->Parse(temp);

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: DateTime->Parse

VonHagNDaz17-May-11 1:57

[C++/CLI]problem with unmanaged C library and callback functions

17-May-11 1:57

I see, MSDN wasn't too clear on that. It lead me to believe temp would be modified. Thank you, 5's for both.

[Insert Witty Sig Here]

re dei giovani16-May-11 3:39

Re: [C++/CLI]problem with unmanaged C library and callback functions

16-May-11 3:39

Hi,
I've got this problem and I don't try to solve it.
I'm using Microsoft Studio 2008 and I want to build a managed application.
This application uses a C unmanaged library.

In particular the library function that I must use is:

error_status TED_PixRad_RegisterEventCallback( eventCallback_t eventCallbackProc,void* customData = NULL ).
(I must use it to hook the event returned by a device).

This function has a callback function parameter with this syntax:

typedef void (*eventCallback_t)( const event_id eventID, const Event *eventData,void* customData );

I' ve found that I must build a wrapper class to use my managed application and the unmanaged library.

I try to build a wrapper class:

file wrapper.h:
#pragma once
#include "stdafx.h"
#include "gcroot.h"

namespace Pixium {

using namespace System;
using namespace System::Runtime::InteropServices;

void cdeclEventCallback(const event_id eventID, const Event *eventData, void* customData );

public ref class Library
{
public:
delegate void eventRegistered(const event_id eventID);

internal:

eventRegistered ^_event_registered;
private:

gcroot<Library^> *_native_handle;
public:
Library();
~Library();
error_status registerEvent(eventRegistered ^evento);
};
}

file wrapper.cpp:
#include "stdafx.h"
#include "wrapper.h"

namespace Pixium {
Library::Library()
{
_native_handle = new gcroot<Library^>();
_event_registered=nullptr;
}
Library::~Library()
{
delete _native_handle;
}
error_status Library::registerEvent(eventRegistered ^evento)
{
_event_registered=evento;
return TED_PixRad_RegisterEventCallback(cdeclEventCallback,_native_handle);
}

void cdeclEventCallback(const event_id eventID, const Event *eventData, void* customData )
{
gcroot<Library^> & native_handle = *((gcroot<Library^>*)customData);
native_handle->_event_registered(eventID);
}
}

In an application class I try to use this wrapper to receive the values event returned.

In particular in the constructor I initialize the wrapper object:
Form1(void)
{
InitializeComponent();
this->lib=gcnew Library(); //istanzio il wrapper
//event_registered= gcnew Library::eventRegistered(this,&Form1::processEvent);
this->registerEvent();
}
and in the function I call a wrapper event register funciotn:

void Form1::registerEvent()
{
//error_status err_reg_event=TED_PixRad_RegisterEventCallback((eventCallback_t)Marshal::GetFunctionPointerForDelegate(del).ToPointer(),_native_handle);
error_status err_reg_event=this->lib->registerEvent(); //utilizzo il wrapper
if (this->TestError(err_reg_event)){
this->button2->Visible=true;
}
}

The problem: I think a mistake to use the wrapper by my application or also in wrapper building.
Infact I' ve got error on the callback function when I try to receive event message.

I apologize for my bad English, hoping to be able to explain problem

Someone can indicates me an example or tutorial to learn how can I work with managed C++/CLI and unmanaged C type?
Thanks

John Schroedl16-May-11 5:22

John Schroedl

16-May-11 5:22

I think the MSDN topic: How to: Marshal Callbacks and Delegates Using C++ Interop addresses what you need to do.

I think the key will be placing the #pragma managed/unmanaged and using Marshal::GetFunctionPointerForDelegate

John

Re: [C++/CLI]problem with unmanaged C library and callback functions

re dei giovani17-May-11 3:27

Re: [C++/CLI]problem with unmanaged C library and callback functions

17-May-11 3:27

Hi John,
thanks to help me.
I followed your advice and I've read How to: "Marshal Callbacks and Delegates Using C++ Interop"
I've tried to work on my application.
I' ve done this:

1) I decided to create a simple example without wrapper.h. So I' working only in a Form1.h.
2) Since my form1.exe work with the library of an electronic device and I constantly receive
the events returned by this device, I thinked to put the define of delegate, IntPtr and the callback unmanaged function as form1 private attributes and I declared them in the Form1 constructor:

Form1(void)
{
InitializeComponent();
_native_handle=new gcroot<Form1^>();
evento=gcnew eventRegistered(cdeclEventCallback);
gch =GCHandle::Alloc(evento);
ip=Marshal::GetFunctionPointerForDelegate(evento);
cb=static_cast<eventCallback_t>(ip.ToPointer());
GC::Collect();
this->registerEvent();

}

3) After, in constructor, I call the function registerEvent(). In this function I put the calling at the library function "TED_PixRad_RegisterEventCallback":

void Form1::registerEvent()
{
error_status er_return=TED_PixRad_RegisterEventCallback(cb,_native_handle);
if (this->TestError(er_return)){
this->button2->Visible=true;
}

}

4) the callback implementation in my Form1 is this:
void cdeclEventCallback(const event_id eventID, const Event *eventData, void* customData )
{
gcroot<Form1^> & native_handle = *((gcroot<Form1^>*)customData);
native_handle->processEvent(eventID,"evento");
}

Oss1: I think I must using _native_handle and not passing this (Form1 refer).
Oss3: processEvent is an internal function of Form1 that receive the code eventID and write the code mean in a form1 label.
Oss2: The compilation is without errors or warnings.

Assuming that I can not debug because the device connected to a machine other than the development,I have seen that the device gives me error event handling return
In particular, writing message on Form1 labels I' ve seen that I cannot enter in cdeclEventCallback function and I cannot call processEvent().

I can not understand what could be in error and this is a logic error in using Marshal:: GetFunctionPointerForDelegate in my example.

Have you got any advice for me?

Thanks for the help

re dei giovani17-May-11 3:55

Re: [C++/CLI]problem with unmanaged C library and callback functions

17-May-11 3:55

OSS1:
I find that probably the error lies in the way the gcroot, because if I pass NULL in place of _native_handle and put processEvent () outside of Form1, I do not come back errors on callback events in the logs of the device;

OSS2: I used gcroot to pass ref of FORM1 between the managed and unmanaged code;

OSS3: I remember that the prototype of "TED_PixRad_RegisterEventCallback" library function is:

error_status TED_PixRad_RegisterEventCallback( eventCallback_t eventCallbackProc,
void* customData = NULL )

and the protorype of callback function by unmanaged library to my managed applicaiton is:

typedef void (*eventCallback_t)( const event_id eventID, const Event *eventData,
void* customData );

and customData for me is my Form1 (in general my object class).

PROBLEM:
I must implements processEvent like object function (then as Form1 funciotn) and so I must to pass FORM1 refer in TED_PixRad_RegisteredEventCallback that is the function of unmanaged library.
Any ideas?

Luc Pattyn17-May-11 4:22

Re: [C++/CLI]problem with unmanaged C library and callback functions

17-May-11 4:22

I've never done this with C++/CLI but I've done it quire frequently between C# (managed) and C (native), and the one thing to remember is in the native world you must declare the callback function as StdCall.

You can read some about C#-C in this article of mine[^].

Smile | :)

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re dei giovani18-May-11 2:15

Re: [C++/CLI]problem with unmanaged C library and callback functions

18-May-11 2:15

Hi luc,
thantks for advice.
Reading your article, I had an idea:
- I haven't used gcroot but directly GCHandle.
- I must casting because parameter library function is void*.

This is what I've done:
1) I 've used GCHandle to build an handle to object (for my example FORM1) and I've used GCHandle.Alloc() to reserve memory when i send object refer from managed code to unmanaged library. I' ve done this in the constructor. So it is:

Form1(void)
{
    InitializeComponent();
    evento=gcnew eventRegistered(Form1::cdeclEventCallback);
    gch =GCHandle::Alloc(evento);
    ip=Marshal::GetFunctionPointerForDelegate(evento);
    cb=static_cast<eventCallback_t>(ip.ToPointer());
    GC::Collect();
    gch3=GCHandle::Alloc(this);  //<-**************
    this->registerEvent();
}

2) I've used GCHandle::ToIntPtr to obtain pointer of handle to send like parameter.I've done this in my registerEvent() function when i call library funciton. registerEvent() now is:

void Form1::registerEvent()
{
    error_status er_return=TED_PixRad_RegisterEventCallback(cb,(void*)(GCHandle::ToIntPtr(gch3)));  //<******

    if (this->TestError(er_return)){
        this->button2->Visible=true;
    }
}

3) Since library function receives void* customData parameter and it returns this in callback function, I must cast my pointer Form1 refer from IntPtr to void*. After, in the callback function I must casting from void* to IntPtr and in second time I must casting from intPtr to Form1^.
The implementation of the callback funciton now is:

static void Form1::cdeclEventCallback(const event_id eventID, const Event *eventData, void* customData )
{
    GCHandle gch4 = GCHandle::FromIntPtr((IntPtr)(customData)); //<-***************
    Form1^ frm = (Form1^)gch4.Target;                           //<-***************
    frm->label3->Text="GESTIONE EVENTO";
    frm->label3->Refresh();
    frm->processEvent(eventID,"");                           //<-***************

}

Now I must call processEvent like an object function and not like Form1 external function.
---------------------------------------------------------------

I compiled without problems and doing some tests I've seen that behavior is correct, that the occurrence of an event correctly calls the callback function and that this uses the correctly reference at Form1.
Less than denials I think the problem is solved, thank you all for your help.

Smile | :)

Luc Pattyn18-May-11 2:46