Threading Questions - Object Ownership - C# Discussion Boards

Re: adding more than one control to the single cell in datagridview control

19-Mar-09 2:20

Can you even add one?

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myms.net19-Mar-09 2:24

myms.net

19-Mar-09 2:24

I can add one control but i cant add more than one.

my requrement is to add more one control to the single cell and select each control

Tqs for the response

Re: adding more than one control to the single cell in datagridview control

musefan19-Mar-09 2:37

Re: adding more than one control to the single cell in datagridview control

19-Mar-09 2:37

How do you add one control? As far as im aware the different controls you mention are just different styles of datagridview cells.

In which case the same question could be asked. how do i add 2 textboxes to 1 textbox? answer is you cant

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myms.net19-Mar-09 2:45

myms.net

19-Mar-09 2:45

its not to add 1 control to another control
add to cell those controls and select each control individually.
when you select single control, need to show some properties.

Re: adding more than one control to the single cell in datagridview control

musefan19-Mar-09 2:48

Threading Questions - Object Ownership

19-Mar-09 2:48

I know what you are trying to achieve, but my point is that controls cant be added to datagridview cells. Maybe i am mistaken, that why i ask how you can add one control?

Post come code showing how you have managed to add one control to a datagridview cell then maybe i can help you better with your needs

Life goes very fast. Tomorrow, today is already yesterday.

Jammer19-Mar-09 1:33

Jammer

19-Mar-09 1:33

Hi All,

I have very little experience with threading and have been building an object that creates a thread internally (not sure this is even a good design idea). Just as an example I have created this class (with a delegate):

public delegate void ThreadCompleterEventHandler(object sender, ThreadCompleteEventArgs args);

public class ObjectThatCreatesAThread
{
    public event ThreadCompleterEventHandler ThreadCompleted;
    private Thread t;

    public ObservableCollection<string> StringsCollection;

    public ObjectThatCreatesAThread()
    {
        StringsCollection = new ObservableCollection<string>();
    }

    public void PopulateStringsCollectionOnOtherThread()
    {
        t = new Thread(delegate()
            {
                DoWork();
            });
        t.Name = "Populate StringsCollection Thread";
        t.Start();
    }

    private void DoWork()
    {
        StringsCollection.Add("String1");
        StringsCollection.Add("String2");
        StringsCollection.Add("String3");
        OnThreadCompleted();
    }

    private void OnThreadCompleted()
    {
        ThreadCompleted(this, new ThreadCompleteEventArgs());
    }
}

This object is created by a button click on a WPF UI. Like:

private void RunThread_Click(object sender, RoutedEventArgs e)
{
    obj = new ObjectThatCreatesAThread();
    obj.ThreadCompleted += new ThreadCompleterEventHandler(obj_ThreadCompleted);
    obj.PopulateStringsCollectionOnOtherThread();
}

In the eventhandler in the UI I have:

void obj_ThreadCompleted(object sender, ThreadCompleteEventArgs args)
{
    StringsListBox.ItemsSource = obj.StringsCollection;
}

Which throws a InvalidOperationException "The calling thread cannot access this object because a different thread owns it.". Which is easily rectified by doing this instead:

void obj_ThreadCompleted(object sender, ThreadCompleteEventArgs args)
{
    Dispatcher.BeginInvoke(DispatcherPriority.Normal, new Action(delegate()
    {
        StringsListBox.ItemsSource = obj.StringsCollection;
    }));
}

My question is why does the DoWork() method running on the spawned thread gain ownership of the StringCollection object that was in fact constructed on the UI thread?

Is there any way to move this collection back to the ownership of the UI thread without the need for the Dispatcher.BeginInvoke()

Am I actually just trying to code around a bad practise?

I would prefer to make this object as user friendly as possible so that even though it is spawning a thread internally at the end of the threads execution the collection is made available to other threads to work with, I guess specifically the UI thread. Is there anything I can set at thread construction time to facilitate this?

Thanks,

Jammer
My Blog | Article(s)

Fayu19-Mar-09 3:09

19-Mar-09 3:09

Change the signature for the OnThreadCompleted method and try the following.. I have not tested the code:

private void OnThreadCompleted(object sender, ThreadCompleteEventArgs e)
{
    System.ComponentModel.ISynchronizeInvoke sync;

    if (ThreadCompleted != null)
    {
        foreach (Delegate d in this.ThreadCompleted.GetInvocationList())
        {
            sync = d as System.ComponentModel.ISynchronizeInvoke;
            if (sync != null)
            {
                if (sync.InvokeRequired)
                {
                    ThreadCompleterEventHandler del = new ThreadCompleterEventHandler(OnThreadCompleted);
                    object[] args ={ sender, e };
                    sync.BeginInvoke(del, args);
                    return;
                }
            }
            this.ThreadCompleted(sender, e);
        }
    }
}

Jammer19-Mar-09 4:44

Jammer

19-Mar-09 4:44

Wow ... thanks for this ...

I just tried this code and I'm getting a StackOverflowException on:

this.ThreadCompleted.GetInvocationList();

If I put a breakpoint on this line and look at the ThreadCompleted object the _invocationList has a count of 0 even though I know there is at least one subscription to the event ...

Jammer
My Blog | Article(s)

Fayu19-Mar-09 5:33

19-Mar-09 5:33

If you email me your solution, i can assist you further.

Jammer19-Mar-09 8:57

Jammer

19-Mar-09 8:57

Thanks for this offer Fayu, where should I send the solution?

Thanks,

Jammer
My Blog | Article(s)

Fayu19-Mar-09 9:44

Re: Threading Questions - Object Ownership [modified]

19-Mar-09 9:44

Check your email. I sent you my e-mail address.

Fayu19-Mar-09 13:40

Using Rejex to validate user name

19-Mar-09 13:40

I looked at your code and it seems like you are using WPF. This changes things. Multithreading is a little different in WPF. The code below should resolve your issue:

if (ThreadCompleted != null) //Check to see if event is subscribed to
{
    //Get the calling window object
    Window caller = (Window)this.ThreadCompleted.Target;

    //Check to see if syncronization is required
    //The CheckAccess method will not be visible by Intellisence but it's there...
    if (!caller.Dispatcher.CheckAccess())
    {
        //Create delegate
        ThreadCompleterEventHandler del = new ThreadCompleterEventHandler(OnThreadCompleted);

        //paramers that you want to pass
        object[] args = { sender, e };

        //"Syncronize"
        caller.Dispatcher.Invoke(del, args);

        //Make a call to OnThreadCompleted using delegate
        return;
    }
    //Threads will be synced above.  This code will run after threads are synced
    this.ThreadCompleted(sender, e);
}

Hope this helps.

modified on Friday, March 20, 2009 8:53 AM

shabya19-Mar-09 1:24

19-Mar-09 1:24

hello ,
i would like to use Rejex to validate a user name.
my user name rules are as follows:
1. first character is a letter : a-z, A-Z
2. other characters can be letters , numbers and _
3. a space can be used only once.

i tried this one but it didnt work :

Boolean Result = false;
string PatternString = @"[_-zA-Z0-9\s]$";
Result = Regex.Match(UserNameString, PatternString).Success;

tnx in advance,

avi

musefan19-Mar-09 1:40

19-Mar-09 1:40

im not 100% but try...

"[a-zA-z][a-zA-z0-9_]*[ ]?[a-zA-Z0-9_]$"

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shabya19-Mar-09 2:42

19-Mar-09 2:42

hi,
its semi working.
there is a problem with the initial value.
i can enter the following string: ,jukj
and it will also be successfull.

tnx,
avi

musefan19-Mar-09 2:46

19-Mar-09 2:46

oh yes, you need to make it specify to use the start of the string, i think ^ does that job...

"^[a-zA-z][a-zA-z0-9_]*[ ]?[a-zA-Z0-9_]$"

Life goes very fast. Tomorrow, today is already yesterday.

Ian Shlasko19-Mar-09 3:27

Ian Shlasko

19-Mar-09 3:27

You also probably need another asterisk in there right before the $. Otherwise it'll only allow one more character after the optional space.

musefan19-Mar-09 3:31

19-Mar-09 3:31

cool

Life goes very fast. Tomorrow, today is already yesterday.

shabya19-Mar-09 3:59

19-Mar-09 3:59

thanks musefan , it works fine Thumbs Up | :thumbsup:

Eslam Afifi19-Mar-09 3:26

Eslam Afifi

19-Mar-09 3:26

shabya wrote:
1. first character is a letter : a-z, A-Z
2. other characters can be letters , numbers and _
3. a space can be used only once.

Based on that, I suggest a little modification to musefan's regex.

"^[a-zA-z][a-zA-z0-9_]*\s?[a-zA-Z0-9_]*$"

Eslam Afifi

shabya19-Mar-09 3:57