Opening multiple instances of a child form in a MDI Form with unique identifiers

Question

In my application I want to be able to open a new instance of a form as a child multiple times while they have a unique identifier.

At the moment I do like this:

private int _consoleWindowCount = 0;

private void tsBtNewConsole_Click(object sender, EventArgs e)
{
    _consoleWindowCount++;
    var consoleForm = new ConsoleForm(_consoleWindowCount) { MdiParent = this };
    consoleForm.FormClosing += delegate { _consoleWindowCount--; };
    consoleForm.Show();

    //This will open a new ConsoleForm with Text: Console #_consoleWindowCount 
    //Like:
    // Console #1
    // Console #2

}

I have 2 problems at the moment:

How is it possible that from MDIForm (mainForm) I can programatically doe stuff like BringToFront or Close or ... by the Text property of child forms currently open in the main form
I should not be a genius to find out this way of unique naming of the child forms is not working. If I open 5 child forms (of same form) they will be numbered like Console #1 to Console #5. But if I close lets say Console #4 and if I open a new form (of same form!) it will be named Console #5 then I will have two forms with same name. if this can be fixed, it will be great for forms being distinguishable by user.

Looking forward to your tips in such a case!

LarsTech LarsTech · Accepted Answer · 2011-12-21T16:55:37

I think the logic is a bit broken with the _consoleWindowCount variable.

Since you are passing in an ID number in the ConsoleForm constructor, just add a ReadOnly property to that form so you can use the id number:

Example:

public class ConsoleForm : Form {
  private int _FormID;

  public ConsoleForm(int formID) {
    _FormID = formID;
    this.Text = "Console #" + _FormID.ToString();
  }

  public int FormID {
    get { return _FormID; }
  }
}

Creating new forms would require you to iterate through your children collection and looking for the available id to create:

private void tsBtNewConsole_Click(object sender, EventArgs e) {
  int nextID = 0;
  bool idOK = false;

  while (!idOK) {
    idOK = true;
    nextID++;
    foreach (ConsoleForm f in this.MdiChildren.OfType<ConsoleForm>()) {
      if (f.FormID == nextID)
        idOK = false;
    }
  }

  var consoleForm = new ConsoleForm(nextID);
  consoleForm.MdiParent = this;
  consoleForm.Show();
}

You would use the same iteration to determine which form you want to work on:

private void ShowChildForm(int formID) {
  foreach (ConsoleForm f in this.MdiChildren.OfType<ConsoleForm>()) {
    if (f.FormID == formID)
      f.BringToFront();
  }
}

Opening multiple instances of a child form in a MDI Form with unique identifiers

2 Answers