C# Discussion Boards - CodeProject

Gary Kirkham9-Jan-04 7:21

9-Jan-04 7:21

Is there a way in .Net to get a reference to the applications Main Form (Window)? Similar to what you would do in a MFC app:

AfxGetApp()->GetMainWnd();

Gary Kirkham

A working Program is one that has only unobserved bugs

I thought I wanted a career, turns out I just wanted paychecks

Re: Main Form

Alex Korchemniy9-Jan-04 9:16

Alex Korchemniy

9-Jan-04 9:16

In your startup method (main) just change it to be like this:

form = new MainForm();
Application.Run(form);

Where "form" is a static field that you can get to from anywhere.

Comparing dates

jnngill9-Jan-04 5:57

jnngill

9-Jan-04 5:57

Hi I'am having trouble converting a string containing date and time info to a DateTime for comparison. The string is in this format "Thu, 03 Jan 2002 00:00:00 GMT". Any help would be greatly welcomed.

Thanks,

James Gill

Re: Comparing dates

TigerNinja_9-Jan-04 6:39

TigerNinja_

9-Jan-04 6:39

jnngill wrote:
The string is in this format "Thu, 03 Jan 2002 00:00:00 GMT".

try this, where s is your date string.

DateTime.Parse(string s);

R.Bischoff
.NET, Kommst du mit?

Re: Comparing dates

Richard Deeming9-Jan-04 6:40

Richard Deeming

9-Jan-04 6:40

Try:

DateTime theDate = DateTime.ParseExact("Thu, 03 Jan 2002 00:00:00 GMT", "r", null);

Standard DateTime Format Strings[^]

"These people looked deep within my soul and assigned me a number based on the order in which I joined." - Homer

Re: Comparing dates

jnngill9-Jan-04 7:46

jnngill

9-Jan-04 7:46

Thanks, it worked like a charm.

Thanks,

James Gill

Help Pls

extremeg9-Jan-04 5:39

extremeg

9-Jan-04 5:39

Good day to all u programmers out there. Pls could you offer help on the following:
1. I enjoying programming and I also have a great love for database administration...where do I fit in?
2. I seldom use a tool for long before moving around to something new - low persistence...where do I fit in?

I know some of u are professions. Pls help me discover myself (direction and clear advice without any biase)...where do I fit in? Sleepy | :zzz:

...the mind is not a vessel to be filled but a fire to ignited

Re: Help Pls

TigerNinja_9-Jan-04 6:42

TigerNinja_

9-Jan-04 6:42

You will get more responses by posting in the correct board.

I would recommend posting in one of the following:
Lounge
Work Issues
SoapBox

This board is for C# related questions, hence coding with C#.

Wink | ;)

R.Bischoff
.NET, Kommst du mit?

Tabpages

Jonathan Slenders9-Jan-04 1:40

Jonathan Slenders

9-Jan-04 1:40

Ive some problems with tabpages

i have one form with one tabcontrol with one tabpage
The first tabpage contain a button.

When you click the button a new tabpage will be created and added to the tabcontrol.
This works.

But the second created tabpage contain a button to for closing that page. I used the next code:

((Tabcontrol)this.parent).Tabpages.remove (this);

It works but after i used these code i connot close the form (the close button doesnt work anymore) However a "Application.exit" command in the menus works.

Can anyone help me?

Ive another problem:

When i click the button in the first tabpage, how con i focus the second?

I used the

tabpage.focus ();

command but it doesnt work

Jonathan Slenders

Re: Tabpages

Heath Stewart9-Jan-04 3:34

Heath Stewart

9-Jan-04 3:34

When remove a TabPage or Control from a collection like this, make sure you do it in the main UI thread, no another thread. This can lead to problems processing the message loop that internally dispatches messages to the appropriate windows. There are other causes of this behavior and we've discussed it before. You could try searching the comments to find more causes.

Instead of TabPage.Focus, use TabControl.SelectedIndex or TabControl.SelectedTab:

// Initialize the TabPage and its contents
TabPage page = new TabPage("Second");
//...

tabControl1.TabPages.Add(page);
tabControl1.SelectedTab = page;

-----BEGIN GEEK CODE BLOCK-----
Version: 3.21
GCS/G/MU d- s: a- C++++ UL@ P++(+++) L+(--) E--- W+++ N++ o+ K? w++++ O- M(+) V? PS-- PE Y++ PGP++ t++@ 5 X+++ R+@ tv+ b(-)>b++ DI++++ D+ G e++>+++ h---* r+++ y+++
-----END GEEK CODE BLOCK-----

Re: Tabpages

Jonathan Slenders10-Jan-04 4:42

Jonathan Slenders

10-Jan-04 4:42

// The TabControl.SelectedIndex Property works good. Thanks for that.

// But i doesnt know how i can do it in another thread.

// Now i have created an instance of a class inheritted from the Tabpage.
// That class contain a property which refer to a function with the delegate:

public delegate void delRemoveTabPage (TabPage tabPage1);

// When i create that instance i set the RemoveTabPage property

TabPage1.RemoveTabPage += new delRemoveTabPage (RemoveTabpage);

// My RemoveTabPage function is these

void RemoveTabpage (TabPage tabPage1)
{
tabCtrlMain1.TabPages.Remove (tabPage1);

}

// It works (This tabpage disapears but the close butten doesnt work anymore like i said before.)

// Well, i have an other possibility but i don't know if this is good:
// the TabPage.Hide ( ) method works perfect. And if i add code in the tabpage thad set his childs

null i think there will be not mush memory used for thad hidden tabpage. Is this a good method?

Re: Tabpages

Heath Stewart10-Jan-04 6:23

Heath Stewart

10-Jan-04 6:23

Next time you post, please do not prefix each sentance with "//". It's very hard to read and completely unnecessary.

See the Control.InvokeRequired and Control.Invoke methods. These make sure that the action is performed in the main thread by invoking it from another method. For instance:

private delegate void RemoveHandler(TabPage);
//...
private void removeButton_Click(object sender, EventArgs e)
{
  Button b = sender as Button; if (b == null) return;
  TabPage tab = b.Parent as TabPage; if (tab == null) return;
  if (this.tabControl1.InvokeRequired)
  {
    RemoveHandler handler =
      new RemoveHandler(this.tabControl1.TabPages.Remove);
    this.tabControl1.Invoke(d, new object[] {tab});
  }
  else this.tabControl1.TabPages.Remove(tab);
}

And no, simply hiding the tab is not a very good idea unless you plan on showing it again. When you're done with objects, dispose of them.

DateTimePicker Display Case

Ben Swann8-Jan-04 23:05

Ben Swann

8-Jan-04 23:05

I have a custom format, however, I want the abbreviated Month to be displayed all in uppercase. DateTime doesn't like this and I am a bit suck in how to accomplish this. I don't want to override the paint method.

Anyone got any ideas? Is there a helpfile class or something that the datetimepicker uses?

Re: DateTimePicker Display Case

Mazdak9-Jan-04 0:54

Mazdak

9-Jan-04 0:54

If you can't set your custom format with DateTimePicker.CustomFormat and DateTimePickerFormat.Custom properties you can implement IFormattable interface. Look into MSDN for more information.

Mazy

No sig. available now.

fonts (maybe)

brain2cpu8-Jan-04 19:57

brain2cpu

8-Jan-04 19:57

Basically I want to print some stuff from my program, it works just great on every single test machine, but Mad | :mad:

on customer's computer when the printing should start I got an Arithmetic underflow or overflow exception at System.Drawing.Font.Init. The same error shows up when selecting some fonts (but I can still use those fonts from Word, ...) and closing the font dialog. To be even more strange if I print from an other program before starting my own printing it will work like a charm.
Does anybody meet something like this? Any hint would be great, I'm Confused | :confused:

how to reject the invalid row adding to datatable?

wangier8-Jan-04 16:39

wangier

8-Jan-04 16:39

dataTable1.RowChaging += new DataRowChangeEventHandler(dataTable1_rowChaing)

private void dataTable1_RowChanging(object sender, DataRowChangeEventArgs e)
{
if ( e.Action == DataRowAction.Add )
{
if (...)
throw new ApplicationException("不合法的检查项目！");
}
}

------------
the problem is :
this dataTable is associated to a datagrid, when add a new row through the datagrid, the rowchanging event can be trigered. If the row is invalid, the exception will be throwed, and the new row cannot be added to the dataTable1.
But when should I handle this Exception? I can't catch this exception.

Re: how to reject the invalid row adding to datatable?

Heath Stewart8-Jan-04 17:15

Heath Stewart

8-Jan-04 17:15

You could create a handler for AppDomain.UnhandledException, but it might be simpler to just display an error or warning message box to the user with MessageBox.Show. With Windows XP and higher, they are now using balloons when invalid characters are typed, such as a backslash in a filename or another invalid character somewhere. You could always do something like that, too.

Basically, just don't throw the exception and instead provide feedback to the user.

Re: how to reject the invalid row adding to datatable?

wangier8-Jan-04 17:20

wangier

8-Jan-04 17:20

But if I don't throw the exception in RowChaging event, i can't prevent the new row to be added to the data table.
Or some way to do that?

Re: how to reject the invalid row adding to datatable?

Heath Stewart8-Jan-04 18:53

Heath Stewart

8-Jan-04 18:53

Sorry about that. I've been doing so much control development lately I'm too used to such events being CancelEventHandler events (or similar)!

Yes, you'll have to throw the exception so add a handler to AppDomain.UnhandledException like I mentioned before. I recommend you also create a custom exception class that derives from ApplicationException (typically used for custom exceptions to give them a common, application-based base class) that you throw from the DataTable.RowChanging event handler. This way, you can easily just catch this exception in the handler for the AppDomain.UnhandledException event and handle appropriately, which is better than throwing such a oft-used exception and trying to determine where it came from and why it was thrown.

Re: how to reject the invalid row adding to datatable?

wangier8-Jan-04 21:45

wangier

8-Jan-04 21:45

I did that. And I throw a ErrorDataRowException which inherits from Application in the data table's RowChanging event.
But when the ErrorDataRowException is thrown, the application didnot enter the method UnHandledExceptionHandler. Instead, the application still popup an window in which told me there is an unhandled exception.
why? pls help me.

[STAThread]
static void Main()
{
AppDomain currentAppDomain = AppDomain.CurrentDomain;
currentAppDomain.UnhandledException += new UnhandledExceptionEventHandler(UnHandledExceptionHandler);

FormRegisterConsole fmMain = new FormRegisterConsole();
Application.Run(fmMain);
}

private static void UnHandledExceptionHandler(object sender, UnhandledExceptionEventArgs args)
{
Exception e = (Exception) args.ExceptionObject;
if (e.GetType() == typeof(Health.ApplicationLibrary.RIS.Register.ErrorDataRowException))
{
MessageBox.Show(e.Message, "data updating", MessageBoxButtons.OK, MessageBoxIcon.Error);
}
else
{
MessageBox.Show("出现未处理错误： " + e.Message, "未处理错误", MessageBoxButtons.OK, MessageBoxIcon.Error);
}
}

Re: how to reject the invalid row adding to datatable?

Heath Stewart9-Jan-04 3:50

Heath Stewart

9-Jan-04 3:50

Try Application.ThreadException then. I use the same thing in our program I designed at work but couldn't remember which event I was using. It's been a long time since I wrote that section of the container application.

Also, just a helpful tip: try the is keyword instead of obj.GetType() == typeof(SomeClass). It results in fewer IL instructions (better performance) and, IMO, is a little easier to read:

public static void Main(string[] args)
{
  Application.ThreadException +=
    new ThreadExceptionEventHandler(UnhandledException);
  Application.Run(new FormRegisterConsole());
}
 
private static void UnhandledException(object sender,
  ThreadExceptionEventArgs e)
{
  if (e.Exception is ErrorDataRowException)
  {
    //...
  }
  else
  {
    //...
  }
}

Re: how to reject the invalid row adding to datatable?

wangier11-Jan-04 18:24

wangier

11-Jan-04 18:24

It's OK, Thanks lot! ^|^

how to prevent changing columns' width in datagrid?

wangier8-Jan-04 16:38

wangier

8-Jan-04 16:38

how to prevent changing columns' width in datagrid?

Re: how to prevent changing columns' width in datagrid?

Heath Stewart8-Jan-04 17:12

Heath Stewart

8-Jan-04 17:12

You could derive from DataGridColumnStyle (or one of the derivative classes to avoid extra work) and override the Width property so that the set accessor does nothing. You'll have to have an internal property or a param in the constructor so you can set the initial width, though, which you can do by setting base.Width. This works in a quick test but still allows the user to drag the splitters (just doesn't actually change the width).

Upon inspection, the members you'd need to override are both private and are not virtual, nor do they use anything relevent that is overridable.

About the only thing I can think of is to override WndProc and handle mouse messages over the column header (which you can get the bounds of through various properties), not passing those to the base.WndProc.

Re: how to prevent changing columns' width in datagrid?

wangier8-Jan-04 20:51

wangier

8-Jan-04 20:51

thanks!

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.