Hello all,
Been reading for some time now and thought I'd post a quickie.
Why can I not open an instance of a form from within a child thread?
I can open it when not using multi threading so why can't I use threading to open a separate form?
The aim is to have one main form (form2) to do a DB update and a clock form (Clock) to display some graphics that will spiral around to show the processing time.
Please help.
Many thanks.
Dan.
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Threading;
namespace WindowsApplication5
{
public partial class Form2 : Form
{
Thread thread1;
private bool _stopThreads = false;
public Form2()
{
InitializeComponent();
}
private void Form2_Load(object sender, EventArgs e)
{
thread1 = new Thread(new ThreadStart(DisplayThread1));
}
private void GO_Click(object sender, EventArgs e)
{
thread1.Start();
}
void DisplayThread1()
{
Clock ClockForm = new Clock();
ClockForm.Show();
}
}
}
Daniel PritchardPosted Nov 18, 2010, 5:29 AM
Sam HobbsPosted Nov 13, 2010, 11:21 PM
You ask why "can I not open an instance of a form from within a child thread". Why can't you? Who is telling you that you cannot? I assume you are not familiar with the concept of a message queue so instead of me explaining that, it would help if you could be more clear about the problem you are encountering.
JurePosted Nov 12, 2010, 8:58 PM
this.BeginInvoke(new WaitCallback(display_function), 0);
Put your new-form-stuff in display_function, or just write anonymous method inside those parentheses ((object o) => { //your code here }).
0 is there because you need to pass something else than null to WaitCallback, otherwise an exception will be thrown.
The above will create yet another thread (or so I read) that has the access to the STAThread (the GUI thread), which your thread1 doesn't.