winforms - Show a child form in the centre of Parent form in C#

Question

I create a new form and call from the parent form as follows:

loginForm = new SubLogin();   
loginForm.Show();

I need to display the child form at the centre of the parent. So,in the child form load I do the foll:`

Point p = new Point(this.ParentForm.Width / 2 - this.Width / 2, this.ParentForm.Height / 2 - this.Height / 2);
this.Location = p;

But this is throwing error as parent form is null. I tried setting the Parent property as well, but didn't help. Any inputs on this?

Answer 1

Try:

loginForm.StartPosition = FormStartPosition.CenterParent;
loginForm.ShowDialog(this);

Of course the child for will now be a blocking form (dialog) of the parent window, if that isn't desired then just replace ShowDialog with Show..

loginForm.Show(this);

You will still need to specify the StartPosition though.