Call a function in main form from a User Control inside a flowpanellayout C# windowsforms

Question

can anyone answer my question in the title?

It goes like this

//Main Form

public partial class Main : Form
{

    public Main()
    {
        InitializeComponent();
    }


    public void Load_Main_Function()
    {
        MessageBox.Show("I'm called from the User Control inside flowpanellayout");
    }
}

---

//FlowPanel Form

public partial class FlowPanel : UserControl
{

    public FlowPanel()
    {
        InitializeComponent();
    }

    public void Load_Sample_Forms()
    {            
        for (int i = 0; i < 5; i++)
        {
            Item_User_Control Item = new Item_User_Control();

            Item.Name.Text = "Test Item " + i;
            Item.Price.Text = i;
            Item.button.Name = i; 

            flowLayoutPanel1.Controls.Add(Item);


        }
    }
}

---

//Item_User_Control (Main form function called from here)

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

    private void button_Click(object sender, EventArgs e)
    {
        //Here comes my problem..
        //The method I tried
        Main mainForm = new Main();
        mainForm.Load_Main_Function();
        //I was thinking that this Item_User_Control was cast inside the loop of Flowpanel Form   
        //that there must be a conflict somehow or this form can't be seen during the inialization
        //of Main Form and that's why the function in Main Form can't be called from             
        //Item_User_Control button event


    }
}

---

I'm making an POS using C# Windows Forms and I'm stuck in this problem:) The layout works it shows 5 Item_User_Control inside flowpanellayout, it's just when clicking the button, nothing happens

need help guys, thanks!!!

Answer 1

Basic information about the event system can be found here

In your code you could do it something like:

//Main Form

public partial class Main : Form
{

    public Main()
    {
        InitializeComponent();

        FlowPanel.FlowItemClicked += FlowPanel_FlowItemClicked;
    }

    private void FlowPanel_FlowItemClicked(object sender, EventArgs e)
    {
        MessageBox.Show("I'm called because A flow item in the flow panel was clicked."); 
    }
}

---

//FlowPanel Form

public partial class FlowPanel : UserControl
{
    public event EventHandler FlowItemClicked; // Event to notify any item getting clicked.

    public FlowPanel()
    {
        InitializeComponent();
    }

    public void Load_Sample_Forms()
    {            
        for (int i = 0; i < 5; i++)
        {
            Item_User_Control Item = new Item_User_Control();

            Item.Name.Text = "Test Item " + i;
            Item.Price.Text = i;
            Item.button.Name = i; 

            // Handle FlowItemClicked event from this item.
            item.ItemClicked += (o,e) => { FlowItemClicked?.Invoke(this, EventArgs.Empty;) };

            flowLayoutPanel1.Controls.Add(Item);
        }
    }
}

---

//Item_User_Control (Main form function called from here)

public partial class Item_User_Control : UserControl
{

    public event EventHandler ItemClicked; // Event to notify the item getting clicked.

    public Item_User_Control()
    {
        InitializeComponent();
    }

    private void button_Click(object sender, EventArgs e)
    {
        // When the button gets clicked, raise the ItemClicked event.
        ItemClicked?.Invoke(this, EventArgs.Empty);
    }
}

---

Answer 2

You can try to make an instance of your Main Form "Globally Accessible":

// On Main Form

public partial class Main : Form
{
    public static Main Instance { get; private set; }

    public Main()
    {
        InitializeComponent();
        Instance = this; // Initiate an instance of your form
    }

    public void Load_Main_Function()
    {
        MessageBox.Show("I'm called from the User Control inside flowpanellayout");
    }
}

// On FlowPanel - your custom control. Remember to call your Load_Sample_Forms() method.

public partial class FlowPanel : UserControl
{
    public FlowPanel()
    {
        InitializeComponent();
        Load_Sample_Forms();
    }

    public void Load_Sample_Forms()
    {
        for (int i = 0; i < 5; i++)
        {
            Item_User_Control Item = new Item_User_Control();

            Item.Name = "Test Item " + i;
            Item.Price.Text = i.ToString();
            Item.button.Name = i.ToString();

            flowLayoutPanel1.Controls.Add(Item);
        }
    }
}

// On Item_User_Control

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

    private void button_Click(object sender, EventArgs e)
    {
        Main.Instance.Load_Main_Function(); // Execute any main function regardless of signature;
    }
}