Question

Can someone please let me know by some code how I can call a function located in the Form class from another class?

Some code will be of great help!

thanks

EDIT: This is my current code

 public partial class frmMain : Form
 {
    //*******Class Instances*******
    ImageProcessing IP = new ImageProcessing();


    //********************
    public void StatusUpdate(string text)
    {
        tlsStatusLabel.Text = text;
    }//


    public frmMain()
    {
        InitializeComponent();            
    }//
}


class ImageProcessing
{

    private void UpdateStatusLabel(frmMain form, string text)
    {
        form.StatusUpdate(text);
    }//

   private UpdateLabel()
   {
        UpdateStatusLabel(frmMain, "Converting to GreyScale");
   }
}

the problem i am having is with frmMain.

Answer 1

A quick and dirty way is to create a reference of the MainForm in your Program.cs file as listed above.

Alternatively you can create a static class to handle calls back to your main form:

    public delegate void AddStatusMessageDelegate (string strMessage);

    public static class UpdateStatusBarMessage
        {

        public static Form mainwin;

        public static event AddStatusMessageDelegate OnNewStatusMessage;

        public static void ShowStatusMessage (string strMessage)
            {
            ThreadSafeStatusMessage (strMessage);
            }

        private static void ThreadSafeStatusMessage (string strMessage)
            {
            if (mainwin != null && mainwin.InvokeRequired)  // we are in a different thread to the main window
                mainwin.Invoke (new AddStatusMessageDelegate (ThreadSafeStatusMessage), new object [] { strMessage });  // call self from main thread
            else
                OnNewStatusMessage (strMessage);
            }

        }

Put the above into your MainForm.cs file inside the namespace but separate from your MainForm Class.
Next put this event call into your MainForm.cs main class.

     void UpdateStatusBarMessage_OnNewStatusMessage (string strMessage)
     {
          m_txtMessage.Caption = strMessage;
     }

Then when you initialise the MainForm.cs add this event handle to your form.

     UpdateStatusBarMessage.OnNewStatusMessage += UpdateStatusBarMessage_OnNewStatusMessage;

In any UserControl or form associated with the form (MDI) that you want to call, just us the following…

     UpdateStatusBarMessage.ShowStatusMessage ("Hello World!");

Because it is static it can be called from anywhere in your program.