Re: Disposing a form in another thread? - C# Discussion Boards

23-Oct-04 13:32

There is no built-in way of doing this. What you have to do is create a new instance and copy all the properties to the new instance. You can use reflections to do this.

Take a look at this: www.dotnet247.com/247reference/msgs/58/292067.aspx[^]

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Alex Korchemniy

.net style

tom_dx23-Oct-04 11:35

23-Oct-04 11:35

how would you remove and add child and root items to a tree view through code?

Re: .net style

Alex Korchemniy23-Oct-04 13:39

Disposing a form in another thread?

23-Oct-04 13:39

MSDN[^] is your friend.

Use the Nodes property. Each node in turn has a Nodes property. You add more nodes (TreeNode) and build a tree. Smile | :)

More links:

msdn.microsoft.com/library/default.asp?url=/library/en-us/cpref/html/frlrfsystemwindowsformstreeviewclassnodestopic.asp[^]
msdn.microsoft.com/library/default.asp?url=/library/en-us/cpref/html/frlrfsystemwindowsformstreenodeclasstopic.asp[^]

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

Alex Korchemniy

Carl Mercier23-Oct-04 7:11

Carl Mercier

23-Oct-04 7:11

Hi,

I'm trying to close and dispose a form that is running in another process, but I get the error message "A first chance exception of type 'System.ObjectDisposedException' occurred in system.windows.forms.dll", "Additional information: Cannot access a disposed object named "frmProgressWindow".".

Here's what I'm trying to do basically...

My main UI thread launches another thread in which I show a modal Progress Window (form with a progress bar). When I'm done performing certain actions, I want to close the progress window from my main thread, so I call this code:

Private Sub CloseProgressWindow()<br />
  If _progressWindow Is Nothing Then Return<br />
  _progressWindow.Invoke(New CloseProgressWindowDelegate(AddressOf _progressWindow.Close))<br />
  _progressWindow.Invoke(New DisposeProgressWindowDelegate(AddressOf _progressWindow.Dispose))<br />
End Sub

The exception occurs on the "End Sub" (!) line. See the screenshot at http://www2.adonis.ca/disposeerror.png[^].

What am I doing wrong?

Thanks!

Carl

PS: I know the code is VB, and this is a C# forum, but I figured people in the VB forum wouldn't have enough knowledge for this question. Since I fully understand both languages, feel free to answer in C# Wink | ;)

Re: Disposing a form in another thread?

Carl Mercier23-Oct-04 7:30

Carl Mercier

23-Oct-04 7:30

I figured it out!

For the record, I created a method in my Progress Window that close and dispose itself, and I call this method from my main thread. Works like a charm!

Re: Disposing a form in another thread?

Dennis C. Dietrich23-Oct-04 9:19

Dennis C. Dietrich

23-Oct-04 9:19

Hi Carl!

I created a method in my Progress Window that close and dispose itself, and I call this method from my main thread.

Sounds like the mistake I made when implementing my first Dispose() method. Although you're not supposed to access normal members after disposing an object calling Dispose() more than once should not throw an exception. If you haven't already done so I strongly recommend using the Dispose Pattern[^].

Best regards
Dennis

How to get absolute value of the pixel cordinates using mouse position

Anonymous23-Oct-04 6:48

Anonymous

23-Oct-04 6:48

Hi all,

I want to get the absolute value of the pixel cordinates of an image using mouse position on the image. at present I can read the cordinates with respect to the active area of the image. But if the image is larer than the active window, we willbe havin scroll bars. for the remaining image, when we use the scroll bars, the remaining image will be shown in the actie area and when i read for the cordinates it is giving me relative tot he active area, which is not equal to the actual pixel cordinates of the image.

So, how can we read hte actual cordinates of the pixel cordinates on the image.

any ideas or suggestions,

Re: How to get absolute value of the pixel cordinates using mouse position

Alex Korchemniy23-Oct-04 12:33

Refresh DataGrid question

23-Oct-04 12:33

If you are using a control based on ScrollableControl check the AutoScrollPosition.

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

Alex Korchemniy

markdbd23-Oct-04 6:21

markdbd

23-Oct-04 6:21

Hi all,

I am making a little application where I am using a datagrid.
A menu displays when the user right click on the datagrid.
This menu has insert, update, delete options. And when the user clicks on one option it opens a new form so the user can edit or insert data. After filling this form and submiting the data, the form closes and the datagrid should refresh.

MY question is:

Is it better to make a new query to the database to see the new Information in the datagrid or to insert manually the submitted data into the old Dataset?

Another question?

Is there any good component that offers Image in Datagrid?

Thanks.

Re: Refresh DataGrid question

Alex Korchemniy23-Oct-04 12:40

Re: Refresh DataGrid question

23-Oct-04 12:40

Refreshing from the database is an extra round trip that is going to make your app run slower. If the only way of adding data to the database is through the form and you dont have any code updates the database based on what is attached to the DataGrid then its the way to go. Just make sure that you don't end up adding the same data twice.

Personally I don't use the DataGrid control that comes with .net. There are more powerful grids like Syncfusion's[^] grid.

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

Alex Korchemniy

markdbd24-Oct-04 2:13

markdbd

24-Oct-04 2:13

Thanks a lot for the Sungfusion grid tipo Smile | :)

I think the best way is to add, update, delete the dataset and finally update the database with the updated dataset.

Re: Refresh DataGrid question

Alex Korchemniy24-Oct-04 9:08

24-Oct-04 9:08

You can do it that way also. Depends on the way you do your business logic. Smile | :)

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

Alex Korchemniy

Calling an event

Anonymous23-Oct-04 5:46

Anonymous

23-Oct-04 5:46

I do some checking in the Validating event of a textbox. When I leave the form, I want to check the textboxes again to see if everything is correct. I have a recursive method that goes over all the controls on my form. Now I want to call the validating events for each control.

Is that possible? Is that good programming? And if not, how can I solve this?

Re: Calling an event

Alex Korchemniy23-Oct-04 13:21

Thread.Abort hangs the calling thread in VS .NET 2005

23-Oct-04 13:21

This is not exactly good programming but you can try this code bit:

public class Tasks
{
	public static void ForceControlValidation(Control c)
	{
		Type t = typeof(Control);

		// validate:
		MethodInfo m = t.GetMethod("NotifyValidating", BindingFlags.Instance | BindingFlags.InvokeMethod | BindingFlags.NonPublic);
		object obj = m.Invoke(c, new object[0]);

		// finish validating
		if (obj is bool && (bool)obj == false)
		{
			MethodInfo m2 = t.GetMethod("NotifyValidated", BindingFlags.Instance | BindingFlags.InvokeMethod | BindingFlags.NonPublic);
			m2.Invoke(c, new object[0]);
		}
	}
}

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

Alex Korchemniy

Ami Bar23-Oct-04 5:10

Ami Bar

23-Oct-04 5:10

I wrote an application that handles a few threads. (Thread Pool)
The application supports a Shutdown() method that calls to Thread.Abort() on all threads.

When I compile the application in VS .NET 2003 it works fine.
When I compile the same code in VS .NET 2005, the application deadlocks on the Thread.Abort() method.
As far as I know Thread.Abort() shouldn't lock the thread that called it.
Has anyone have the same problem ? or knows a way to solve this ?

Thanks,
Ami Bar

Re: Thread.Abort hangs the calling thread in VS .NET 2005

Dennis C. Dietrich23-Oct-04 9:36

Dennis C. Dietrich

23-Oct-04 9:36

Hi Ami!

Ami Bar wrote:
As far as I know Thread.Abort() shouldn't lock the thread that called it.

It's not explictly said that Thread.Abort() is asynchronous however the online version of the VS 2005 documentation does state that "the thread is not guaranteed to abort immediately, or at all. This situation can occur if a thread does an unbounded amount of computation in the finally blocks that are called as part of the abort procedure, thereby indefinitely delaying the abort. To ensure a thread has aborted, invoke a Join method on the thread after calling Abort." (see Thread.Abort Method ()[^]) I guess that paragraph only makes sense if Thread.Abort() does not wait for the thread to terminate.

Ami Bar wrote:
When I compile the application in VS .NET 2003 it works fine.
When I compile the same code in VS .NET 2005, the application deadlocks on the Thread.Abort() method.

Keep in mind that both VS 2005 and the .NET Framework 2.0 are still beta versions. If it works fine with VS 2003 but not with 2005 you should enter a new bug report (if it hasn't been already reported) at the MSDN Product Feedback Center[^]

Best regards
Dennis

mySQl Problem in C#. Suspect it's my mySQL config...

Admiral Ackbar23-Oct-04 3:59

Admiral Ackbar

23-Oct-04 3:59

I'm running mySQL locally on my coimputer. When I run my C# application I have the connect as

string MySQLDBConnect = "DRIVER={MySQL ODBC 3.51 Driver};" +
"SERVER=localhost;" +
"DATABASE=filetransfer;" +
"UID=********;" +
"PASSWORD=********;" +
"OPTION=3";

Everything works fine when it's set at localhost. But that's pretty useless as it onlly works on mmy PC. So instead I'll put in my IP adress. Let's say I change Localhost to 111.111.111.111. Then I get an error.

ERROR #0
Message: [MySQL][ODBC 3.51 Driver] Host '111.111.111.111' is not allowed to connect to this MySQL server.
Native: 1130
Source:
SQL: HY000

I assume this is a problem with my Mysql setup.

The database does get connected. I cna tell because I can see the connect going through my firewall. But I get a return error. I'm guessing it's with my database setup but I couldn't be sure.

is there a way??

tom_dx23-Oct-04 3:46

23-Oct-04 3:46

I'm using visual c# 2005 and would like to know if there is an easier way to process alot, about 35, checkboxes. Could you put the controls in an array or would you just have to process each one manually??

Do you want to know more?

Colin Angus Mackay23-Oct-04 4:14

Colin Angus Mackay

23-Oct-04 4:14

tom_dx wrote:
Could you put the controls in an array or would you just have to process each one manually??

Yes, put them in an array.

Vogon Building and Loan advise that your planet is at risk if you do not keep up repayments on any mortgage secured upon it. Please remember that the force of gravity can go up as well as down.

tom_dx23-Oct-04 4:39

23-Oct-04 4:39

How though I'm new to C# and I have never seen arrays contains any controls, can you show an example?

Do you want to know more?

Colin Angus Mackay23-Oct-04 4:41

Colin Angus Mackay

23-Oct-04 4:41

It is just like an array holding anything else. However there is a specialised class for holding Controls. See MSDN: ControlCollection[^]

Vogon Building and Loan advise that your planet is at risk if you do not keep up repayments on any mortgage secured upon it. Please remember that the force of gravity can go up as well as down.

Uwe Keim23-Oct-04 4:52

Uwe Keim

23-Oct-04 4:52

In one application where I had a lot of checkboxes, I put them into a list view control. You can advise the ListViewControl to have checkboxes left to each item.

Another solution would be to use reflection and a for loop, if your CheckBoxes are labeled with a running number like MyCheckBox1, MyCheckBox2, etc.

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tom_dx23-Oct-04 14:33