Calling Functions in Other Forms. - C# Discussion Boards

2-Feb-05 4:17

I have a Form (MainForm) that loads a usercontrol (UserMenu) as a main menu, I do NOT want to show this as a dialog, but I have no way to fire an event on MainForm from a command button on UserMenu without instantiating a new MainForm.

There are properties set on the MainForm that need to be used. This is why I cannot simply instantiate a new MainForm.

I have considered delegates, but honestly struggling to wrap my mind around the concepts. Also, I know the showDialog is the simplist way, but cannot use it for various other reasons.

Any suggestions would be appreciated.

Michael Potter2-Feb-05 4:57

2-Feb-05 4:57

The best mechinism is delegates/events. The are pretty simplistic to use but, if you want to wimp out Wink | ;-)

, just pass the form to the UserMenu and make the necessary methods public.

Dwayner792-Feb-05 6:25

2-Feb-05 6:25

I definitely want to learn... do you know any good resources/tutorials on delegates/events. I have read through c# Unleashed and Windows Forms Programming in c#, but still am struggling to comprehend. Perhaps I am over analyzing this...

I will continue to read up on it.

Michael Potter2-Feb-05 7:32

2-Feb-05 7:32

This not MS way (they use EventArgs as the base) but here is a short snippet from one of my early project that may lead you in the right direction.

#namespace TabCode
{
public class TabChoice
{
     public string Text;
     public bool Active;	

     public TabChoice(string text, bool active)
     {
          Text = text;
          Active = active;
     }
}

public delegate void TabPanelChangeEvent(TabChoice choice);

public class TabPanel : Panel
{
     private ArrayList _choices;
     public TabPanelChangeEvent Change = null;

     private void FireChange(int index)
     {
          if (Change != null)
          {
               Change((TabChoice)_choices[index]);
          }
     }

     // Skipping alot of code for brevity.......
}
}

Dwayner792-Feb-05 8:10

2-Feb-05 8:10

Thanks,

I was able to build a working delegate, the problem is I still have to instantiate a new copy of the form. I need to use the already instanciated copy of it because it has parameters and values that I need to use.

Any other thoughts??

Michael Potter2-Feb-05 10:08

2-Feb-05 10:08

Why don't you just tell the UserControl the parameters. If they change, update the UserControl.

I am not clear on what you are attempting to do but, creating a new copy of the form does not seem like a proper solution.

Dwayner792-Feb-05 11:19

2-Feb-05 11:19

OK... my form loads a usercontrol that has a list of radiobuttons. This is not a modal form as they are always available for clicking. A command button on that form launches code on the main form. I have to know what radio button was selected and pass that back to the main form.

Here is the code so far:

In usercontrol:

public delegate void delRunStep(string name);

private void cmdRunStep_Click(object sender, System.EventArgs e)
{
//find out what radiobutton is selected
MainForm mf = new MainForm();
//This does not work as it makes new Mainform and looses all Data.
delRunStep run = new delRunStep(mf.RunStep);
run(myString);

}

In the main form:
public void RunStep(string StepName)
{
//do code
}

Michael Potter2-Feb-05 11:36

2-Feb-05 11:36

Why does the UserControl need to know what radio button is selected on the main form? Could it not just pass back that the command button was clicked and let the main form decide what to do with the information?

Otherwise:
If the UserControl has to be notified of the state of the radio buttons then let it listen.

public void RegistureRadioButton(RadioButton rb)
{
    rb.CheckChanged += new EventHandler(OnCheckChange);
}

private void OnCheckChange(object sender, EventArgs ea)
{
    RadioButton rb = (RadioButton)sender;
    if (rb.Checked) 
    {
        if (rb.Text == "Choice 1")
        {
             //Choice 1 active
        }
    }
}

Dwayner793-Feb-05 1:37

3-Feb-05 1:37

The Userform has the Radiobuttons. But what you are saying will work,if I switch it around and make the main form know what radiobutton is selected. I will keep on working on it. I think I have enough info to make it work.

Thanks.

Robert Rohde2-Feb-05 8:44

Robert Rohde

2-Feb-05 8:44

It may be that I dont really get the problem but as Micheal already mentioned you could just pass the existing form to your user control. Give the usercontrol a property where the form can be set and than use this instance:
(within MainForm)

<br />
UserMenu menu = new UserMenu();<br />
menu.MyMainForm = this;<br />

This is probably the easiest way, but an event should be better. For that you have to decalre an event in UserMenu and consume it on the MainForm (just like you would handle the Click event of a Button).

Dwayner792-Feb-05 11:21