C# Discussion Boards - CodeProject

Re: Reading files

Alan Balkany17-Apr-09 3:42

Alan Balkany

17-Apr-09 3:42

You need to put a '@' before the string to handle the back slashes correctly:

@"c:\mydir\myfile.exe"

A security exception was not handled in your code

lachu00917-Apr-09 2:07

lachu009

17-Apr-09 2:07

Hi,

I got an error "A security exception was not handled in your code" when i try to open a page using server.transfer.But when changed the application server it worked perfectly. what could be the issue? Is it an IIS configuration issue ,Server configuration issue or any other..

Thanks in advance

cross thread operation not valid, when closing a windows form

But_Im_a_Lady17-Apr-09 1:19

But_Im_a_Lady

17-Apr-09 1:19

Hi All,

After spending ages on google trying to understand & recify my problem, and having no success, I am hoping someone here can point me in the right direction.

Here is my problem...

I have a windows form, which has a selection of standard toolbox controls and custom User controls, some of which are added at design time & some of which are added at run time.

This all works fine, but when I close the form I get this message:-

"Cross-thread operation no valid: Control 'chkShowSparesMatrix' accessed from a thread other than the thread it was created on".

This control is a standard MS check box which is added at design time. None of its properties are changed in code, the only event which is acted upon is 'checkedchanged':-

private void chkShowSparesMatrix_CheckedChanged(object sender, EventArgs e)
{
    if (chkShowSparesMatrix.Checked)
    {
        usrSparesMatrix1.IsStandAlone = false;
        usrSparesMatrix1.Visible = true;
    }
    else
    {
        usrSparesMatrix1.IsStandAlone = false;
        usrSparesMatrix1.Visible = false;
    }
}

If I remove this control, I get the same message on another control.

If anyone can throw light on this for me I would be grateful, or if you need more info to understand my problem I can forward you this.

Thanks in advance,

Janet

Lady Programmers are a rare breed!

Re: cross thread operation not valid, when closing a windows form

Henry Minute17-Apr-09 1:55

Henry Minute

17-Apr-09 1:55

And are you doing anything in another thread?

Henry Minute

Do not read medical books! You could die of a misprint. - Mark Twain
Girl: (staring) "Why do you need an icy cucumber?"
“I want to report a fraud. The government is lying to us all.”

Re: cross thread operation not valid, when closing a windows form

But_Im_a_Lady17-Apr-09 2:05

But_Im_a_Lady

17-Apr-09 2:05

The only thing I do on another thread is 'faxing', which is subject to the user saying they want to 'fax' a document, so this doesn't always get fired, unless they answer Yes to a series of questions.

I get the error message, regardless of choosing to Fax or not!

Lady Programmers are a rare breed!

Re: cross thread operation not valid, when closing a windows form

Henry Minute17-Apr-09 2:12

Henry Minute

17-Apr-09 2:12

Have a look at the link that 12Code gave you. I haven't looked at it, so don't know if it will help. If it doesn't help, feel free to come back.

Re: cross thread operation not valid, when closing a windows form

But_Im_a_Lady17-Apr-09 2:14

But_Im_a_Lady

17-Apr-09 2:14

Thanks - will do

Janet

Lady Programmers are a rare breed!

Re: cross thread operation not valid, when closing a windows form

But_Im_a_Lady17-Apr-09 2:25

But_Im_a_Lady

17-Apr-09 2:25

My first step was to comment out all references to 'faxing' (this was the other thread in my form) and I still get this error.

So now I am confused Confused | :confused:

Janet

Lady Programmers are a rare breed!

Re: cross thread operation not valid, when closing a windows form

Henry Minute17-Apr-09 2:39

Henry Minute

17-Apr-09 2:39

The only thing that makes any sense is as 12Code said in his OP. Somehow the 'faxing' thread is getting started, and then causes the error when you close the app.

What sort of threading are you using? Is it a BackgroundWorker, or are you creating it in code?

Whichever type, one way might be to handle the FormClosing event of your main form and close/de-activate the thread there.

Re: cross thread operation not valid, when closing a windows form

But_Im_a_Lady17-Apr-09 2:49

But_Im_a_Lady

17-Apr-09 2:49

I am using 'System.Threading', the code is below:-

private void FaxEngineersRequest()
        {
            try
            {
                //SendZetaFax sendZetaFax = new SendZetaFax ();
                //sendZetaFax.FaxBody = _processingModule.CreateEngineerCallSheet ( _callNumber ).ToString ();
                //sendZetaFax.FaxNumber = usrAddressDetailsEngineer.Fax;
                //sendZetaFax.RecipientName = usrAddressDetailsEngineer.Contact;
                //sendZetaFax.From = _sysCNDR.Name;

                ////Since the processing for Zeta fax can be v.slow - do processing on a separate thread.
                //Thread thread = new Thread ( new ThreadStart ( sendZetaFax.SendFaxMessage ) );
                //thread.Start ();
            }
            catch (Exception ex)
            {
                _commonValidation.DisplayErrorGracefully ( ex );
            }
        }

As you can see I have commented this part of the code out - so it will never run, but I still get the cross thread operation not valid error.

<blockquote class="FQ"><div class="FQA">Henry Minute wrote:</div>Whichever type, one way might be to handle the FormClosing event of your main form and close/de-activate the thread there. </blockquote>
Not quite sure how / if / why I need to do this Confused | :confused:

Janet

Lady Programmers are a rare breed!

Re: cross thread operation not valid, when closing a windows form

Henry Minute17-Apr-09 2:59

Henry Minute

17-Apr-09 2:59

If your 'faxing' thread does not run, and it certainly shouldn't from the code you posted, then there has to be another thread running to cause the exception.

If you don't know about this thread, you obviously cannot close it in the FormClosing handler. You might however put a break point there and use the debugger to search for the 'Thread With No Name'. I would suggest Googling for 'Debugging Threads C#' for methods to do this.

As always, come back if no joy.

Re: cross thread operation not valid, when closing a windows form

But_Im_a_Lady20-Apr-09 1:16

But_Im_a_Lady

20-Apr-09 1:16

For completeness of this message - I have now fixed my problem.

I made a STUPID D'Oh! | :doh:

mistake...

Rushing to finish the project I had put Close() inside the formclosing event!!!

Won't be doing that again in a hurry Smile | :)

Lady Programmers are a rare breed!

Re: cross thread operation not valid, when closing a windows form

12Code17-Apr-09 2:06

12Code

17-Apr-09 2:06

The other thread that you created has directly update the form control, which is not allowed.

You need to use Invoke. I have a thread might help you.
http://www.codeproject.com/script/Forums/View.aspx?fid=1649&select=2972472&tid=2972413#xx2972472xx[^]

*12Code

Re: cross thread operation not valid, when closing a windows form

But_Im_a_Lady17-Apr-09 2:15

But_Im_a_Lady

17-Apr-09 2:15

Thanks - will look at this & try & get it to work.

Janet

Lady Programmers are a rare breed!

Re: cross thread operation not valid, when closing a windows form

But_Im_a_Lady17-Apr-09 2:22

But_Im_a_Lady

17-Apr-09 2:22

Just to prove your theory I commented out all references to 'faxing' (this was the other thread in my form) & I still get this error.

So now I am confused Confused | :confused:

Lady Programmers are a rare breed!

Re: cross thread operation not valid, when closing a windows form

0x3c017-Apr-09 2:46

0x3c0

17-Apr-09 2:46

What about the if-clause? Doesn't that access chkShowSparesMatrix?

Re: cross thread operation not valid, when closing a windows form

But_Im_a_Lady17-Apr-09 2:54

But_Im_a_Lady

17-Apr-09 2:54

Yeah I suppose it does.

Even if I comment out the single method which uses System.Threading to send a fax (this method isn't always called in code anyway), I still get the 'cross threading operation not valid error message.

I have no idea why Confused | :confused:

Lady Programmers are a rare breed!

Re: cross thread operation not valid, when closing a windows form

Luc Pattyn17-Apr-09 4:01

Luc Pattyn

17-Apr-09 4:01

Hi,

here is my standard reply on cross-thread problems, I hope it helps:

Controls are not thread-safe, hence they should be touched (that is: their methods or properties called) only by the thread that created them, which normally is the main thread (aka GUI thread). Creating some controls on a different thread is unlikely to be successful, since all Controls get linked somehow: they reside on Forms, Forms are related to each other (by Parent, by Z-Order, etc), so normally all are created on a single thread.

If you violate the “don’t touch Controls from another thread” rule and are running .NET version 2.0 or above you will get an InvalidOperationException (“Cross-thread operation not valid”), which should be remedied by changing the code.

Do not set Control.CheckForIllegalCrossThreadCalls false, since that does hide the exception but does not cure the fundamental flaw in your code, so it just postpones the moment of failure, which typically will show as a non-responsive and possibly badly painted GUI.

Here are some ways to get another thread:
- explicitly launching a Thread instance
- exclicitly delegating some work to a ThreadPool thread
- using a BackgroundWorker; a BGW is a separate thread with the advantage that two of its events (ProgressChanged and RunWorkerCompleted) execute on the GUI thread; however the bulk of the work normally is handled in the DoWork handler which runs on a distinct thread.
- using timers other than System.Windows.Forms.Timer; the Forms timer ticks on the GUI thread, all other use different threads to handle the periodic event;
- using asynchronous input/output, such as the DataReceived event of the SerialPort class

Any of these touching a single method or property of a Control is sufficient to create havoc; there are 5 exceptions:
- the InvokeRequired property
- the Invoke, BeginInvoke, EndInvoke and CreateGraphics methods (the latter only if the handle for the control has already been created).

If there is a need to touch the Control from another thread, one must use an Invoke pattern, which basically looks like this:

public void SetText(string text) {
    if (myControl.InvokeRequired) {
        // this runs on the foreign thread and causes the
        // invocation of this same method on the GUI thread
        myControl.Invoke(new Action< string >(SetText),
            new object[] {text});
    } else {
        // this runs on the GUI thread only
        myControl.Text=text;
    }
}

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Need Help For Reading and Sending SMS Through SonyEricsson Mobile Using C# Language

A.Q.Ghouri17-Apr-09 1:15

A.Q.Ghouri

17-Apr-09 1:15

Hi Everybody There!
I need help regarding Reading & Sending SMS Through SonyEricsson Mobile Modem.. I did alot of research and found some helpfull topics on the Net but still i am missing the .How actually C# Application Do Communicate with The GSM modem..

I will be thankful for any body who helps me out in this problem

Regards
A.Q.Ghouri

Re: Need Help For Reading and Sending SMS Through SonyEricsson Mobile Using C# Language

Rajesh Anuhya17-Apr-09 1:22

Rajesh Anuhya

17-Apr-09 1:22

search for serial port communication in Google

--------------

Before Writing A C# Application U have to know about the Properties of your Modem like Buad Rate, parity,Flow control..,

and also know about the AT commands.

Write Your Application Using Serial Port Class

Thanks

Rajesh B --> A Poor Workman Blames His Tools <--

Re: Need Help For Reading and Sending SMS Through SonyEricsson Mobile Using C# Language

A.Q.Ghouri20-Apr-09 18:06

A.Q.Ghouri

20-Apr-09 18:06

thanks buddy for letting me know that how to do that.. i have all the stuff but now i have to focus on how to deal with it.. infact i have 2 problems.. some gsm does not support Text mode,and some do so i have to make a flexible app which will delt both of them..

Re: Need Help For Reading and Sending SMS Through SonyEricsson Mobile Using C# Language

Giorgi Dalakishvili17-Apr-09 2:07

Giorgi Dalakishvili

17-Apr-09 2:07

Here you are: Sending short messages (SMS) via GSM mobile phones[^]

Giorgi Dalakishvili

#region signature
My Articles

Asynchronous Registry Notification Using Strongly-typed WMI Classes in .NET [^]

My blog
#endregion

Re: Need Help For Reading and Sending SMS Through SonyEricsson Mobile Using C# Language

A.Q.Ghouri20-Apr-09 18:29

A.Q.Ghouri

20-Apr-09 18:29

Thanks alot buddy really help full.....

Why the line disappear?

lune1217-Apr-09 1:15

lune12

17-Apr-09 1:15

Hi,

I use the following code for drawing line on a panel, but after few seconds the line disappear.
Can someone help with this?

Graphics formGraphics = panel1.CreateGraphics();
//p1 and p2 are well defined points.
formGraphics.DrawLine((Pens.Red, p1, p2);

Thanks in advance.
Lune

Re: Why the line disappear?

Luc Pattyn17-Apr-09 1:18

Luc Pattyn

17-Apr-09 1:18

Hi,

that indicates you didn't paint it in the right way.
there are several steps to correctly draw something so it becomes visible on the screen:

1.
decide upon what object you want to draw; it normally is a Control (e.g. a Panel) or a
Form itself. I prefer to add a Panel to a Form, then draw on the Panel.

2.
create some variables (Rectangle, struct, class, whatever) that hold the parameters of
your drawing. For a rectangle that could be top and left coordinate, and width+height,
or just a Rectangle. etc.

3.
create a Paint handler (either add your own paint handler to the Paint event, or
override the OnPaint method) for that Panel, and do all your drawing in there,
using the Graphics class and your variables.

4.
when you want to change things, modify the variables and call Panel.Invalidate() or
one of its overloads (for selective invalidation).

5.
If you want to animate things, perform the move (step 4) inside the Tick handler
of a Windows.Forms.Timer

BTW: if you need to create some objects (Fonts, Pens, Brushes, ...) either keep them
alive in class members (hence create them only once); or create them inside the Paint
handler and don't forget to call Dispose() on them.

Smile | :)

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