Question

Explanation:

Structure: Windows form – three components: Text box, Text box Response and button.

Problem: I am moving motor with C# windows form: I am starting the motor and reversing
the direction of movement of motor with single button click with 10 second delay in the middle. i.e. I start the motor, have 10 sec delay and then reverse the motor. I want to display “Start” at the beginning and “End” at the end of the 10 second delay. I have tried using thread but it does not work. But I am only able to see “Finish” not “Start” in text box. The code is below:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Threading;

namespace SampleThreadProgram
{
     public partial class Form1 : Form
     {
          static EventWaitHandle _waitHandle = new AutoResetEvent(false);
          delegate void SetTextCallback(string text);

     void SetText(string text)
     {
          if (textBox.InvokeRequired)
          {
             SetTextCallback d = new SetTextCallback(SetText);
             BeginInvoke(d, new object[] { text });
          }
          else
          {
             textBox.Text = text;
          }
     }

    void UpdateTextBox(string message)
    {
        SetText(message);
        _waitHandle.Set();
    }

    void Wait()
    {
        for (ulong i = 0; i < 10000; i++)
        {
            for (ulong j = 0; j < 100000; j++)
            {
            }
        }

    }
    public Form1()
    {
        InitializeComponent();
    }

    private void Form1_Load(object sender, EventArgs e)
    {

    }

    private void button1_Click(object sender, EventArgs e)
    {

        UpdateTextBox("Start");
        _waitHandle.WaitOne();
        Thread.Sleep(10000);
        UpdateTextBox("Finish");

    }

    }
}

Answer 1

There’s not enough time for the UI to update. Add an Application.DoEvents(); after the SetText(message); in UpdateTextBox.