Re: Thread and listView - Managed C++/CLI Discussion Boards

Re: Thread and listView

Mark Salsbery27-Jul-07 14:03

Mark Salsbery

27-Jul-07 14:03

Use The Force Poke tongue | ;-P

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

Re: Thread and listView

Luc Pattyn27-Jul-07 14:06

Luc Pattyn

27-Jul-07 14:06

I do, if necessary.
I try the normal way first.

I bet it is an InvalidOperationException due to cross-thread violations
but dont want to waste message space, and everybody's time.

Luc Pattyn

try { [Search CP Articles] [Search CP Forums] [Forum Guidelines] [My Articles] }
catch { [Google] }

Re: Thread and listView

abbd27-Jul-07 23:33

abbd

27-Jul-07 23:33

Hi,

can you shwou me, how a use force, an exeemple if it's possible,

thank you verry mutch.

Re: Thread and listView

Luc Pattyn27-Jul-07 23:49

Luc Pattyn

27-Jul-07 23:49

I can not explain "The Force" to you; you will know when you have The Force,
not before that.

In the mean time, did you read my earlier reply, I was asking about the details
of the exception you are getting. That would bring us closer to a solution
for your problem.

Luc Pattyn

try { [Search CP Articles] [Search CP Forums] [Forum Guidelines] [My Articles] }
catch { [Google] }

Re: Thread and listView

abbd28-Jul-07 0:04

abbd

28-Jul-07 0:04

hi,

the exception was :

An unhandled exception of type 'System.InvalidOperationException' occurred in System.Windows.Forms.dll

Additional information: Cross-thread operation not valid: Control 'listView2' accessed from a thread other than the thread it was created on.

but when i put messageBox, he show message nurmously,

How i can add in listView?

Thank you verry mutch

Re: Thread and listView

Luc Pattyn28-Jul-07 0:21

Luc Pattyn

28-Jul-07 0:21

OK,

this is the problem: in Windows, each Control (such as a ListView) must be
handled by only one thread; the thread that creates the Control is the only
thread that successfully can read and write its properties, and execute its
methods. Violating this rule gives:
- on older .NET abnormal behavior, possibly a complete hangup
- on .NET 2.0 and better, by default, the exception you have got

Now typically each Control is linked somehow to another Control; a Button is
on a Form, a ListView is on a Form; clicking a Button that creates and shows
a dialog links that dialog to the original Button and Form, etc.

So normally all Controls belong to the main thread (also known as "GUI thread").

There are two ways to solve your problem:
- the easy way is have every Control be handled by the GUI thread, which
could mean, use a Forms.Timer, since that executes its Tick handler on the
GUI thread. The drawback is, if the Tick handler takes too long, your GUI
responsiveness will suffer
- use some other thread for calculating things, accessing a database, whatever,
but as soon as it needs to access a Control, let it ask the GUI thread to do
so. That can be organized by the Control.InvokeRequired property, and the
Control.Invoke or Control.BeginInvoke methods.

I suggest the latter; so read up on InvokeRequired and Invoke.
There are some good articles about it on CodeProject; my Sokoban article
shows a small example too (I used a Timers.Timer so I could demonstrate the
Invoke stuff).

Smile | :)

Luc Pattyn

try { [Search CP Articles] [Search CP Forums] [Forum Guidelines] [My Articles] }
catch { [Google] }

Re: Thread and listView

abbd28-Jul-07 0:48

abbd

28-Jul-07 0:48

hello,

In 1st, i used a Timer, who get a packets every tick, but my application became heavy, for this reason i would use a Thread.

With Timer:

private: System::Void button1_Click(System::Object^  sender, System::EventArgs^  e) {<br />
 timer5->Interval=10;<br />
 timer5->Start();<br />
}<br />
 <br />
private: System::Void timer5_Tick(System::Object^  sender, System::EventArgs^  e) {<br />
 <br />
While (there are packets which arrive ) {<br />
 <br />
listView->Items->add (one paquets)<br />
 <br />
}

Witht Thread { an exception on listView }

delegate void DelegateThreadTask();<br />
DelegateThreadTask ^ er;<br />
<br />
<br />
<br />
private: System::Void button1_Click(System::Object^  sender, System::EventArgs^  e) {<br />
	Threading::Thread(gcnew ThreadStart(this, &Form1::Traitement));<br />
             t->Start();<br />
			<br />
		 }<br />
.<br />
.<br />
.<br />
 <br />
void Traitement( )<br />
{   while(true)<br />
	{ThreadTask();<br />
              Thread::Sleep(100);		<br />
	}<br />
		<br />
	}<br />
.<br />
.<br />
.<br />
void ThreadTask()		<br />
{<br />
 <br />
While (there are packets which arrive ) {<br />
 <br />
listView->Items->add (one packets)<br />
 <br />
}<br />
 <br />
er = gcnew DelegateThreadTask(this, &Form1::ThreadTask);<br />
er->Invoke();		}<br />
 <br />
<br />
<br />

Please hlep me,to get packets without heavy my système

Thank you verry mutch

Re: Thread and listView

Luc Pattyn28-Jul-07 1:03

Luc Pattyn

28-Jul-07 1:03

Hi,

abbd wrote:
listView->Items->add (one packets)

this probably is the offending line. As I explained before, a thread other than
the GUI thread is not allowed to do this, lictView belongs to the GUI thread.

Read up on InvokeRequired and Invoke(); you will need a delegate.

Smile | :)

Luc Pattyn

try { [Search CP Articles] [Search CP Forums] [Forum Guidelines] [My Articles] }
catch { [Google] }

Re: Thread and listView

abbd28-Jul-07 2:39

abbd

28-Jul-07 2:39

I make this:

delegate void DelegateThreadTask();<br />
.<br />
.<br />
.<br />
<br />
private: System::Void button1_Click(System::Object^  sender, System::EventArgs^  e) {<br />
	Threading::Thread(gcnew ThreadStart(this, &Form1::Traitement));<br />
             t->Start();<br />
			<br />
		 }<br />
.<br />
.<br />
.<br />
 <br />
void Traitement( )<br />
{   while(true)	{ThreadTask();Thread::Sleep(100);}<br />
		<br />
}<br />
<br />
<br />
void ThreadTask()		<br />
{listView2->Items->Add("zezeze");<br />
 <br />
DelegateThreadTask ^ er = gcnew DelegateThreadTask(this, &Form1::ThreadTask);<br />
Invoke(er); <br />
}

but always there are an exception D'Oh! | :doh:

how i can resolve this great problem

Thank you very mutch.

Re: Thread and listView

Luc Pattyn28-Jul-07 3:07

Luc Pattyn

28-Jul-07 3:07

You did it again: what exception ?

anyhow I gave you the keywords, the suggestion to read some article,
and an example (in C#). I dont speak C++, I cant help you any further.

Bonne chance.

Luc Pattyn

try { [Search CP Articles] [Search CP Forums] [Forum Guidelines] [My Articles] }
catch { [Google] }

Re: Thread and listView

abbd28-Jul-07 11:20

abbd

28-Jul-07 11:20

Hi,

i do this

private: System::Void button1_Click(System::Object^  sender, System::EventArgs^  e) {<br />
			oa[0] = sender;<br />
                        oa[1] = e;<br />
<br />
<br />
			 Thread ^th = gcnew Thread(gcnew ThreadStart(this, &Form1::Traitement));<br />
		         th->Start();<br />
		<br />
			 <br />
  }<br />
.<br />
.<br />
.<br />
this->Invoke(gcnew DelegateThreadTask(this,&BHIDS00::Form1::ThreadTask), oa);

but unfortunately, there are always exception, he show me line of
this->Invoke(gcnew DelegateThreadTask(this,&BHIDS00::Form1::ThreadTask), oa);

Thank you verry mutch

Version Info in C++/CLI assemblies

Bartosz Bien27-Jul-07 11:07

Bartosz Bien

27-Jul-07 11:07

Hello All,

Although there is a wizard-generated AssemblyInfo.cpp file in my project, containing the default versioning directive:

[assembly:AssemblyVersionAttribute("1.0.*")];,

the generated assembly does not contain the version info resource (i.e. it does not get displayed as a tab in explorer's file properties).

I tried adding VersionInfo resource manually, but it uses hardcoded data, not the ones that are dynamically generated from the AssemblyInfo.cpp file.

How to set up a C++/CLI class library project to automatically include the appropriate version info?

Regards,
BB
http://spin.bartoszbien.com

Re: Version Info in C++/CLI assemblies

screanjap27-Apr-08 7:41

screanjap

27-Apr-08 7:41

Strange enough this seems to work fine if you use the C# compiler (the version information is included in the dll correctly) but the C++ compiler still needed the old-style RC, call it versioninfo.rc for instance.

There is an example of such a resource file at:
http://msdn2.microsoft.com/en-us/library/aa381058.aspx[^]

A problem that i have not solved is how to get the version from AssemblyInfo.cpp into the native resource-file.
A workaround i'm using now is: create a new file version.h the contains the version numbers and include it in both versioninfo.rc and AssemblyInfo.cpp.

Gr,

Jan

Why does Font class need full qualification?

BuckBrown27-Jul-07 10:28

BuckBrown

27-Jul-07 10:28

Hi, I am using Visual Studio 2005 C++/CLI. I was just curious about something. When I am 'using namespace System::Drawing' and I want to display some text on the screen I have the following two lines to setup my brush and font...

SolidBrush^ blackBrush = gcnew SolidBrush(Color::Black);
System::Drawing::Font^ myFont = gcnew System::Drawing::Font("Ariel", 16);

If I don't include System::Drawing:: in front of font, then this will not compile. If SolidBrush and Font are both classes in the System::Drawing namespace why do I have to include (for lack of a better term) the full path of the Font class? What makes the Font class different?

Thanks

Buck

Re: Why does Font class need full qualification?

Bartosz Bien27-Jul-07 10:51

Bartosz Bien

27-Jul-07 10:51

Hello Buck,

This is because Font is most probably also a member (a property) of the class you are editing (perhaps a Control-derived class).

Regards,
BB
http://spin.bartoszbien.com

Re: Why does Font class need full qualification?

Mark Salsbery27-Jul-07 12:44

Mark Salsbery

27-Jul-07 12:44

BuckBrown wrote:
"Ariel"

In addition to BB's reply...

You may want to use "Arial" Smile | :)

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

Why do some classes need full qualification

BuckBrown27-Jul-07 10:26

BuckBrown

27-Jul-07 10:26

OpenEx problem

CodeMaster_0527-Jul-07 4:15

CodeMaster_05

27-Jul-07 4:15

Hi all,I am having some problems with the OpenEx functin,the probelm is I don't know how to formulate the connection string.I've been using:
CDatabase con;
con.Open(_T( "DSN=;UID=sa" ),CDatabase::openReadOnly |CDatabase::noOdbcDialog );
But where do we pass the server name and the password?The program haults with an exception,this is my first application using afxdb and CDatabase,thanks in advance.

Re: OpenEx problem

Mark Salsbery27-Jul-07 7:14

Mark Salsbery

27-Jul-07 7:14

First, you're in the wrong forum if you're not using Managed C++/CLI.

Connection strings vary, depending on the ODBC driver you're using, and are generally documented
somewhere.

For example, when using the SQL Native Client for SQL Server, there's:

Using Connection String Keywords with SQL Native Client[^]

Also, CDatabase and related classes use exceptions for error handling. You'll probably want to catch
those exceptions and at least examine them - they provide fairly detailed error info from the ODBC
driver.

Mark

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

Re: OpenEx problem

CodeMaster_0527-Jul-07 9:43

CodeMaster_05

27-Jul-07 9:43

I am sorry,in my haste to post the question I posted it in the wrong form,I am using the .net frame work to create a visual C++ windows from application. I didn't want to use the sql adapter thing, i wanted to creat a connection the old fashioned way using cdatabase and afxdb.I am using sql server 2000 and thats what i want to connect to.Frankly I haven't had much time to research this at all,I was checking out this site and thought I might try it,I thank you all for your Smile | :)

help and time.

Re: OpenEx problem

Mark Salsbery27-Jul-07 9:49

Mark Salsbery

27-Jul-07 9:49

CodeMaster_05 wrote:
I am sorry,in my haste to post the question I posted it in the wrong form,

No problem! Everyone gets one chance... Poke tongue | ;-P

Did you find the connection string info you needed? I used to have it for SQL Server 2000 but I
can't find it....I'll let you know if I do.

Mark

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

Re: OpenEx problem

Mark Salsbery27-Jul-07 9:54

Mark Salsbery

27-Jul-07 9:54

Actually, it looks like the link I posted applies to 2000 as well (when using the native client).
Make sure you scroll down to the ODBC section Smile | :)

Mark

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

Re: OpenEx problem

CodeMaster_0527-Jul-07 10:03

CodeMaster_05

27-Jul-07 10:03

Thanks alot,it works perfectly, you people are great. Best regards Smile | :)

CreateProcess with write permission

slasktrat26-Jul-07 10:25

slasktrat

26-Jul-07 10:25

Hi
I'm trying to let my application run another application and give it write permission. At the moment i'm using CreateProcess, but can't figure out how to grant the process write permissions..
Tried googling alot, but can't find too many examples.. =/

Can anyone help me..?
Thanks!

Problem in reading data from any hardware device like Time access machine

pathak7825-Jul-07 22:47

pathak78

25-Jul-07 22:47

I want to read data from a hardware device like time access punching machine.

What is the complete process to read data and storing into a databse from any hardware device.

If any one have some idea, please guide me.

Thanks,

Pathak

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