CODEWITHSUNDEEP
c#winformsinvoke
Ivan Prodanov
Ivan Prodanov

Reputation: 35522

C# How to invoke with more than one parameter

I use the code below to access the properties on my form,but today I'd like to write stuff to a ListView,which requires more parameters.

    public string TextValue
    {
        set
        {
            if (this.Memo.InvokeRequired)
            {
                this.Invoke((MethodInvoker)delegate
                {
                    this.Memo.Text += value + "\n";
                });
            }
            else
            {
                this.Memo.Text += value + "\n";
            }
        }
    }

How to add more than one parameter and how to use them(value,value)?

Upvotes: 14

Views: 28027

Answers (2)

Antonio Leite
Antonio Leite

Reputation: 480

Generically, You can do as follow

  • In C# 2012/Net 4.5 Create a Windows Forms Application project called Lambda1
  • In the Form1 Form, insert a Label called label1
  • Press F4 to open the Form1 properties (not the label1 properties)
  • Click on the Events view (Icon with a thunder)
  • Double click on the Form Closing event. An event handler will be created.
  • Don't mind about the event handler for now. It will be replaced by another one later;
  • Select and erase all the code in Form.cs (Ctrl-A/Delete key)
  • Copy and paste the following code to Form1.cs;
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Linq.Expressions;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Diagnostics;
namespace Lambda1
{
public partial class Form1 : Form
{

    System.Timers.Timer t = new System.Timers.Timer(1000);
    Int32 c = 0;
    Int32 d = 0;
    Func<Int32, Int32, Int32> y;

    public Form1()
    {

        InitializeComponent();           
        t.Elapsed += t_Elapsed;
        t.Enabled = true;
    }

    void t_Elapsed(object sender, System.Timers.ElapsedEventArgs e)
    {
        c = (Int32)(label1.Invoke(y = (x1, x2) => 
              { label1.Text = (x1 + x2).ToString(); 
                               x1++;  
                               return x1; },  
                               c,d));
        d++;
    }

    private void Form1_FormClosing(object sender, FormClosingEventArgs e)
    {
        t.Enabled = false;
    }
}

}

What this code do is:

A timer is created. The Elapsed Event Handler 

void t_Elapsed(object sender, System.Timers.ElapsedEventArgs e)

will be called every 1000ms

The label1.Text will be updated inside this event handler. Without the Invoke, there will be a thread issued

To update the label1.Text with a new value, the code was used

c = (Int32)(label1.Invoke(y = (x1, x2) => { label1.Text = (x1 +
x2).ToString(); x1++; return x1; }, c,d));

Please see that c and d are being passed as argument to x1 and x2 in the the Invoke function and x1 is returned in the Invoke call.

The variable d was inserted in this code just to show how to pass more than one variable when Invoke is called.

Upvotes: 0

Marc Gravell
Marc Gravell

Reputation: 1062770

(edit - I think I misunderstood the original question)

Simply make it a method instead of a property:

public void DoSomething(string foo, int bar)
{
    if (this.InvokeRequired) {
        this.Invoke((MethodInvoker)delegate {
            DoSomething(foo,bar);
        });
        return;
    }
    // do something with foo and bar
    this.Text = foo;
    Console.WriteLine(bar);
}

Upvotes: 33

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