从用户控件表单更新父表单控件

Question

i have one user control gridview which value changes every second, so I put one-timer of interval 1sec and updating gridview,

now I want to update its parent form label value as per gridview total number of rows, inside timer

i tried below code in user control form

  if (ParentFormInstance != null)
                    {

                        Label mylabel = (ParentFormInstance.Controls["lblTotalDevices"] as Label);                     
                        mylabel.Text = totalcount.ToString();
                    }

i have one property in user control

 public FormEmuHost ParentFormInstance { get; set; }

this property value I am setting in parent form constructor: Parent form code

 public FormEmuHost(string ISdeveloper, EmuSettings emuSettings)
            {
                InitializeComponent();
            this.emuDeviceListControl1.ParentFormInstance = this;
            }

Problem is, I always get label control value null in the user control form

Answer 1

You can create an Event and fire it off inside your User Control

public partial class CustomMapShapeEditor : UserControl
{
        public CustomMapShapeEditor()
        {
            InitializeComponent();
        }

        public EventHandler Ev_BTN_Pressed ;

        private void BTN_Click(object sender, EventArgs e)
        {
            if (Ev_BTN_Pressed != null)
                Ev_BTN_Pressed (this, e);
        }

}

And then in your parent form Subscribe to the event and handle the event.

this.childForm.Ev_BTN_Pressed += HandleChildBtnPress;

internal void HandleChildBtnPress(object sender, EventArgs e)
{

}