Question

I have an array of five threads. Each thread contains the same form, each form is put on to the screen in a different location (still working on that method :P).

I am trying to have each form load its contents (an image) before the other forms have finishing being placed. At the moment this works for the first form, but the others are blank or disappear 😛

Originally each form would be placed but the method would need to finish before all the forms contents were displayed.

Any help would be appreciated, thanks 🙂

public partial class TrollFrm : Form
{
    int number = 0;

    public TrollFrm()
    {
        InitializeComponent();

        startThreads();

    }

    private void TrollFrm_Load(object sender, EventArgs e)
    {

    }

    private void TrollFrm_FormClosing(object sender, FormClosingEventArgs e)
    {
        e.Cancel = true;
    }

    public void startThreads()
    {
        Thread[] ThreadArray = new Thread[5];

        for (int i = 0; i < 5; i++)
        {
            ThreadArray[i] = new Thread(new ThreadStart(createForm));

            ThreadArray[i].Start();
        }
    }

    public void createForm()
    {
        Form frm = new TrollChildFrm();

        Random randomX = new Random();

        Random randomY = new Random();

        number++;

        int xValue;

        int yValue;

        if (number % 2 == 0)    //number is even.
        {
            xValue = (Convert.ToInt32(randomX.Next(1, 1920))) + 200;

            yValue = (Convert.ToInt32(randomY.Next(1, 1080))) - 200;
        }

        else    //number is not even.
        {
            xValue = (Convert.ToInt32(randomX.Next(1, 1920))) - 200;

            yValue = (Convert.ToInt32(randomY.Next(1, 1080))) + 200;
        }

        frm.Show();

        frm.Location = new Point(xValue, yValue);

        Thread.Sleep(1000);
    }

Answer 1

Your forms are not displaying correctly because they are not running on a thread with a message loop. The general rule is that all UI element accesses must occur on the main UI thread.

Since you have a call to Thread.Sleep(1000) I am going to assume that you want to wait 1 second between the initial display of each form. In that case I would use a System.Windows.Forms.Timer who’s Tick event will call createForm directly. Enable the timer, let 5 Tick events come through, and then disable the timer. I see no need to create any threads at all.