I've found that example (Communicate between two windows forms in C#) that works fine but not when the two forms are in different thread.
I've got an "System.NullReferenceException" at line 20 in MainForm (this.splashy.LabelText = i;)
The point of this script is to modified the width of the progressBar in the splashscreen when MainForm is doing his job.
Thanks in advance!
Here are the two c# classes and program file:
//Program.cs
using System;
using System.Threading;
using System.Windows.Forms;
namespace GIS
{
static class Program
{
public static SplashScreen splashy = null;
/// <summary>
/// Point d'entrée principal de l'application.
/// </summary>
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Thread splashThread = new Thread(new ThreadStart(
delegate
{
//SplashScreen splashy = new SplashScreen();
splashy = new SplashScreen();
Application.Run(splashy);
}
));
splashThread.SetApartmentState(ApartmentState.STA);
splashThread.Start();
//run form - time taking operation
MainForm mainForm = new MainForm(splashy);
mainForm.Load += new EventHandler(mainForm_Load);
Application.Run(mainForm);
}
static void mainForm_Load(object sender, EventArgs e)
{
//close splash
if (splashy == null)
{
return;
}
splashy.Invoke(new Action(splashy.Close));
splashy.Dispose();
splashy = null;
}
}
}
//SplashScreen.cs
using System;
using System.Windows.Forms;
namespace GIS
{
public partial class SplashScreen : Form
{
public SplashScreen()
{
InitializeComponent();
}
public int LabelText
{
get
{
return rectangleShape1.Width;
}
set
{
rectangleShape1.Width = value;
}
}
}
}
//MainForm.cs
using System.Threading;
using System.Windows.Forms;
namespace GIS
{
public partial class MainForm : Form
{
private SplashScreen splashy = null;
public MainForm(Form callingForm)
{
splashy = callingForm as SplashScreen;
InitializeComponent();
doWork();
}
private void doWork()
{
for(int i = 0; i < 100; i++)
{
this.splashy.LabelText = i;
Thread.Sleep(10);
}
}
}
}
You need to invoke the
SplashScreen
to change it's value from an other thread likeNote that the constructor
allows
splashy
to be null - this causes your currentNullReferenceException
.This problem is locaed in this snipped:
The new thread you are start is not fast enought to create the instance of
SplashScreen
before you pass it. The result - you are passingnull
.Fix it by create the splashy before your thread starts: