WinForms raise event from another Form

Question

I have a main form named: MainForm and a child form named: ChildForm I want to fill ChildForm\'s textboxes and in MainForm_ButtonClick i want to fire ChildForm_ButtonClick e

Answer 1

Child form

public partial class ChildForm : Form
{
    public ChildForm()
    {
        InitializeComponent();
        MainForm.OnChildTextChanged += MainForm_OnChildTextChanged;
        MainForm.OnButtonClick += MainForm_OnButtonClick;
        bttn1.Visible = false;
    }

    void MainForm_OnButtonClick(object sender, EventArgs e)
    {
        this.bttn1.PerformClick();
    }

    void MainForm_OnChildTextChanged(string value)
    {
        this.textBox1.Text = value;
    }

    private void bttn1_Click(object sender, EventArgs e)
    {
        MessageBox.Show("I am hide. But shows message");
    }

}

public class Bttn : Button
{
    public new void PerformClick()
    {
        this.OnClick(EventArgs.Empty);
    }
}

Create a Parent Form

public partial class MainForm : Form
{
    public delegate void OnMyTextChanged(string value);
    public delegate void ButtonClicked(object sender, EventArgs e);

    public static event OnMyTextChanged OnChildTextChanged;
    public static event ButtonClicked OnButtonClick;

    ChildForm frm = new ChildForm();

    public MainForm()
    {
        InitializeComponent();
        frm.Show();
    }

    public void button1_Click(object sender, EventArgs e)
    {
        OnChildTextChanged("this is new value");
        OnButtonClick(sender, e);
    }
}

Answer 2

To access a textbox in another form:

1. Set Modifier property of the the textbox to public in child form.

2. In main form, access the textbox by an object of the child form.

   Eg:

   obj.txtBox.Text="MyValue";
   

To access an event in another form:

1. Set the event handling function to public.

2. Invoke the function by passing null as parameters by the object of the form.

   Eg:

   obj.MyButton_Click(null, null);