Implementation method of WinForm child form access to parent form control

public delegate void SetVisableHandler();//Define the delegate type

private void button1_Click(object sender,EventArgs e)//Click event to open the child form
{
    Form2 frm = new Form2(new SetVisiableHandler(SetVisiable));
    ();
}

private void SetVisiable()
{
    ("123","456","789");
}

private SetVisableHandler m_setVisable;//Declare the delegate variable
public Form2(SetVisiableHandler  setvisiable)
{
    InitializeComponent();
    this.m_setVisiable = setvisiable;
}

public void butten1_Click(object sender,EventArgs e)
{
    if(this.m_setVisiable != null)
    {
        this.m_setVisiable();
    }
}