Question

How does one access WinForm controls such as ProgressBar properties from another class?

Please see my code below. I know this might not be the best option to expose WinForm class and its members as public but I am trying to clear the concept at this point.

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        public void button1_Click(object sender, EventArgs e)
        {
            Class1 c = new Class1();
            c.loop();
        }

        public void PBSetup()
        {
            progressBar1.Minimum = 0;
            progressBar1.Maximum = 100;
        }

        public void PBUpdate(int recno)

        {
            progressBar1.Value = Class1.recno;
        }
    }
}

namespace WindowsFormsApplication1
{
    class Class1
    {

        public static int recno;

        public void loop()
        {
            //How do I access Form1.PBSetup()??

            for (recno = 0; recno <= 100; recno++)
            {
                //How do I access Form1.PBUpdate(recno)??
            }
        }
    }
}

Answer 1

You do not want your business logic (your class) interacting with your UI (your form). The business logic should be agnostic of the presentation layer.

If you want the form to respond to things that happen inside the class, you could consider exposing an Event inside the class that the form could subscribe to, much like it would subscribe to a button’s click event. The class instance could fire off the event completely unaware of who might be listening, and any subscribers would be notified.