MDI app (keep track of opening/closing forms)

[RiverX]

Hi all,

I'm fairly new to c# and have currently been working on a project containing mdi forms.
This is how the project is layed out.
Parent form is called Street_Index. This contains a menu strip which can open 2 different forms.
* Street_Search
* Office_Search

Within the Street_search form there is a button that i click that returns the results in another form called Search_Results.
Search Results contains a grid and on double clicking the column of the grid it returns the results of that row back to Street_Search form which displays them in textboxes, grid, combobox, etc..

Within the Office_Search form there is also a button that opens the Search_Results form and then from there you can double click on the grid within Search_Results and open up Street_Search form which will display the results as previous.


Now on to the question. What is the cleanest possible way to check to see if a childform is open or not and if it is bring it into focus/refresh it?

Thanks in advance
Take care all.

[nmadd]

If I read it correctly, you only ever want ONE instance of Search_Results open correct?

Search for "singleton form" on the forums and you will find multiple examples of how to make this happen. Good luck.

[RiverX]

I would like one instance of all of them. Say for example i click on office_search and hit search it brings up the results_form. From there i double click on a cell in the grid and it brings up the street search form. Now if i clear the street search form and decide to run a search again i get 2 results form open and if i click on a grid cell within any of the results form i get 2 search_street forms open, or if i click on the menu bar for office search again in the parent form i get 2 office_search forms open etc..
You see what im getting at lol. I think i confused myself.

[nmadd]

Alright. Then you can use the Singleton pattern for all of your forms. Here are a couple of posts about them but you can fine a whole lot more.
http://vbforums.com/showthread.php?t...ight=singleton
http://vbforums.com/showthread.php?t...ight=singleton

[RiverX]

Hi, Thanks for the links. I got it to work for the parent form.
Heres what i did. I put the following in the child forms

   1.
      public partial class Form2 : Form
   2.
      {
   3.
          private static Form2 _instance;
   4.
       
   5.
          public static Form2 Instance
   6.
          {
   7.
              get
   8.
              {
   9.
                  if (_instance == null || _instance.IsDisposed)
  10.
                  {
  11.
                      _instance = new Form2();
  12.
                  }
  13.
       
  14.
                  return _instance;
  15.
              }
  16.
          }
  17.
       
  18.
          private Form2()
  19.
          {
  20.
              InitializeComponent();
  21.
          }
  22.
      }

And this in the parent forms on the menuitemclick event.

   1.
      private void ShowChildForm()
   2.
      {
   3.
          Form2.Instance.MdiParent = this;
   4.
          Form2.Instance.Show();
   5.
          Form2.Instance.Activate();
   6.
      }

What would i need to do to check it within the other child forms as well?

[RiverX]

Okay what i did was replace form frm = new form() with form frm = form.Instance and it seems to be working correctly.
Is this what i am supposed to do or is the method im using wrong?