using System;
using System.Windows.Forms;
using System.Threading;
 
namespace UI_Threading_Example
{
    //declare the delegate that we'll use to launch our worker function in a separate thread
    public delegate void workerFunctionDelegate(int totalSeconds);
 
    //declare the delegate that we'll use to call the function that displays text in our text box
    public delegate void poplateTextBoxDelegate(string text);
 
    public partial class Form1 : Form
    {
       public Form1()
       {
          InitializeComponent();
       }
 
       //this function will simply write text to our text box
       //this function will later be called from a worker thread through the use of a delegate using the Invoke method on the form
       void populateTextBox(string text)
       {
          textBox1.Text = textBox1.Text + " " + text;
       }
 
       //this function simulates "work" by simply counting from 1 to totalSeconds
       void workerFunction(int totalSeconds)
       {
          for (int count = 1; count <= totalSeconds ; count++)
          {
             //we use this.Invoke to send information back to our UI thread with a delegate
             //if we were to try to access the text box on the UI thread directly from a different thread, there would be problems
             this.Invoke(new poplateTextBoxDelegate(populateTextBox), new object[] { count.ToString() });
             Thread.Sleep(1000);
          }
       }   
 
       //this function is executed when we click the first button in the windows form
       //this is the PROPER WAY to do work in a UI situation
       //the worker function is launched in a separate thread so that our UI will remain responsive while it does work
       private void buttonNewThread_Click(object sender, EventArgs e)
       {
          workerFunctionDelegate w = workerFunction;
          w.BeginInvoke(15, null, null);
       }
 
       //this function is executed when we click the second button in the windows form
       //it's an example of WHAT NOT TO DO because if we click this button
       //the UI will become completely unresponsive for 15 seconds while the worker fucntion is executed
       private void buttonCurrentThread_Click(object sender, EventArgs e)
       {
          workerFunction(15);
       }
 }