CODEWITHSUNDEEP
c#eventsdelegates
Aerith
Aerith

Reputation: 1

User Control to pass event back to parent form

I have a main form with 3 User Controls attached to it. How can I have events inside a specific User Control reach out and modify the UI of the other two User Controls without creating spaghetti code?

Main Form (Form1.cs) 

    public partial class Form1 : Form
   {
      private UserControl1 userControl11;
      private UserControl2 userControl21;
      private UserControl3 userControl31;

      public Form1()
      {
         InitializeComponent();
      }
   }

UserControl1.cs

public partial class UserControl1 : UserControl
{
    public UserControl1()
    {
        InitializeComponent();
    }

    private void button1_Click(object sender, EventArgs e)
    {
        // Change buttons around and fill in some data on user control 2 and 3
    }

    private void button2_Click(object sender, EventArgs e)
    {
        // Remove certain elements from control2 and 3
    }

    // .. So forth
}

I will have many events that do many different things on the other two user controls. I am creating a basic interface that's similar to Visual Studio where I can open projects, close them, add files, etc. These actions on one form should load up different windows and such in the other controls. What's the best method to achieve this? Creating custom events and parsing each event in the main form? Or accessing each user control directly from the first one? Or...?

Upvotes: 0

Views: 4222

Answers (2)

JWP
JWP

Reputation: 6963

The general pattern for events is:

public class MyClass{
public static EventHanlder<ofSomeType> MyEventHandler;

public void MyClass{
        MyEventHandler = _MyEventHandler;
}
public void _MyEventHandler(object sender, OfSomeType args){
      //do something with passed in args.
}
}

Other classes would use these eventhandlers like this...

public class myOtherClass{
   public void doSomething(){
      //do something here and signal the other class
      var ofSomeTypeData = GetData();        
      MyClass.MyEventHandler(ofSomeTypeData);        
   }
}

Some will argue this style is too closely coupled but it works flawlessly and is a good start.

Upvotes: 1

Moby Disk
Moby Disk

Reputation: 3851

Create an event inside each UserControl. Form1 should subscribe to events on those controls.

So suppose that UserControl1 allows the user to sort the data. Then you might write this:

public Form1()
{
   InitializeComponent();
   // I assume UserControl1 was created by this point
   userControl1.OnDataSorted = DataSorted;
}

// This will be called when the user wants to sort the data
private void DataSorted(UserControl1 sender, EventArgs e)
{
   // Change buttons around and fill in some data on user control 2 and 3
}

Then you will create an event and a delegate in the UserControl. 

public class UserControl1 {

   public delegate void DataSortedDelegate(UserControl1 sender, EventArgs e);

   public event DataSorted OnDataSorted;

   private void button1_Click(object sender, EventArgs e)
   {
      if (OnDataSorted != null)
         OnDataSorted(this, EventArgs.Empty);
      // Replace EventArgs.Empty above with whatever data Form1 needs
   }

This approach creates a separation of concerns between Usercontrol1 and Form1. The control does not need to actually modify the private controls inside Form1. It merely notifies Form1 that something has happened, and allows Form1 to make the changes.

Upvotes: 0

Related Questions