CODEWITHSUNDEEP
c#.netwindowswinforms
Mike
Mike

Reputation: 253

What is the Form "On_Load" equivalent for Controls?

I have a listBox that I would like to carry out a method when its loaded up, although I can't use the Form "On_Load" trigger, since the ListBox is within a TabControl.

Is there a way of getting a method to execute when the object initializes?

Upvotes: 2

Views: 3474

Answers (6)

Hasala Senevirathne
Hasala Senevirathne

Reputation: 67

You can use OnHandleCreated(EventArgs e). However, it triggers during design time too. You can override it too.

Upvotes: 1

SLaks
SLaks

Reputation: 887195

You can just put your code in the constructor.

You usually don't need to wait for any initialization.

Upvotes: -1

umlcat
umlcat

Reputation: 4143

Have the same problem, the previous answers apply well, for a single case.

But, I require to do something in most controls, in several forms, in an app. Solved by using an interface:

interface IOnLoad
{
  void OnLoad();
}

And added to descendant control:

public partial class MyButton : Button, IOnLoad
{
  void OnLoad() { // call "OnLoadDelegate" }
}

public partial class MyForm : Form
{

  public void MyForm_Load(...) {
    foreach(Control eachControl in Controls) {
      if (eachControl is IOnLoad) {
        IOnLoad eachOnLoadControl = (IOnLoad)eachControl;
        eachOnLoadControl.OnLoad();
      }
    } // foreach
  }
} // class

Its more complex, but it suit my requirements.

Upvotes: 1

DRapp
DRapp

Reputation: 48129

As @SLaks stated, you could put in your class's constructor. However, if what you want to prepare relies on other elements in the form, you can add to the event handler queue at the end of a form loading, but before its actually presented to the user.

In the constructor code of your form (not the designer code), add to the load event, then add your own custom function

public partial class frmYourForm : Form
{
    public frmYourForm()
    {
       Load += YourPreparationHandler;
    }

    private void YourPreparationHandler(object sender, EventArgs e)
    {
        // Do you code to prepare list, combos, query, bind, whatever
    }
}

Upvotes: 2

Adam Robinson
Adam Robinson

Reputation: 185583

The closest analog for controls is the HandleCreated event. This will fire when the underlying control handle is created, which is slightly before the Loaded event of the parent window would fire.

Upvotes: 3

Bala R
Bala R

Reputation: 108937

Can you use the HandleCreated event?

Upvotes: 0

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