Cross-thread MessageBox.Show() ?

[Cheetah2003]

I've been working on a GUI for RunUO for a couple months now.

I discovered MessageBox.Show() and need to call this method from a few places in World.cs, but I get that irritating '{"Cross-thread operation not valid: Control 'RunUO_UI' accessed from a thread other than the thread it was created on."}'

So I had to disable the checking for this, currently. But I was wondering if anyone knew the proper way to cross-thread MessageBox.Show?

I know how to use delegates to do things like modify the text of a control and so forth, but creating a new control as a child of the form on another thread... I can't seem to locate any documentation on how to do that in MSDN.

[noobie]

there is a class called backgroundworker. there is lots of examples..

google:Cross-thread operation not valid

[o0_Sithid_0o]

You still looking for a way to avoid the "Cross-Thread Operation Not Valid" exception?

I happen to be looking for something to help me out of this paticular issue ... without screwing with some of the other stuff again.

SafeInvokeHelper.cs

using System;
using System.Collections;
using System.Reflection;
using System.Reflection.Emit;

public class SafeInvokeHelper
{
    static readonly ModuleBuilder builder;
    static readonly AssemblyBuilder myAsmBuilder;
    static readonly Hashtable methodLookup;

    static SafeInvokeHelper()
    {
        AssemblyName name = new AssemblyName();
        name.Name = "temp";
        myAsmBuilder = AppDomain.CurrentDomain.DefineDynamicAssembly(name, AssemblyBuilderAccess.Run);
        builder = myAsmBuilder.DefineDynamicModule("TempModule");
        methodLookup = new Hashtable();
    }

    public static object Invoke(System.Windows.Forms.Control obj, string methodName, params object[] paramValues)
    {
        Delegate del = null;
        string key = obj.GetType().Name + "." + methodName;
        Type tp;

        lock (methodLookup) 
        {
            if (methodLookup.Contains(key)) 
                tp = (Type)methodLookup[key];
            else
            {
                Type[] paramList = new Type[obj.GetType().GetMethod(methodName).GetParameters().Length];
                int n = 0;
                foreach (ParameterInfo pi in obj.GetType().GetMethod(methodName).GetParameters()) paramList[n++] = pi.ParameterType;
                TypeBuilder typeB = builder.DefineType("Del_" +  obj.GetType().Name + "_" + methodName, TypeAttributes.Class | TypeAttributes.AutoLayout | TypeAttributes.Public |  TypeAttributes.Sealed, typeof(MulticastDelegate), PackingSize.Unspecified);
                ConstructorBuilder conB = typeB.DefineConstructor(MethodAttributes.HideBySig | MethodAttributes.SpecialName |            MethodAttributes.RTSpecialName, CallingConventions.Standard, new Type[] { typeof(object), typeof(IntPtr) });
                conB.SetImplementationFlags(MethodImplAttributes.Runtime);
                MethodBuilder mb = typeB.DefineMethod( "Invoke", MethodAttributes.Public | MethodAttributes.Virtual | MethodAttributes.HideBySig, obj.GetType().GetMethod(methodName).ReturnType, paramList );
                mb.SetImplementationFlags( MethodImplAttributes.Runtime ); 
                tp = typeB.CreateType();
                methodLookup.Add(key, tp);
            }
        }

        del = MulticastDelegate.CreateDelegate(tp, obj, methodName);
        return obj.Invoke(del, paramValues);
    }
}

Usage:

SafeInvokeHelper.Invoke( Control, "the_method", parms )

Would look like this.

SafeInvokeHelper.Invoke( m_PatchSwapper, "Update_ProgressBar", percent <= 100 ? percent : 100, true );
SafeInvokeHelper.Invoke( m_PatchSwapper, "Update_Label", m_PatchSwapper._PercentLabel, String.Format( "{0}%", percent <= 100 ? percent : 100 ) );

Havnt tested it with a MessageBox before, not sure if it will even work with one. Its worth a shot though eh?


SafeInvokeHelper - Author/Original Article

[Jeff]

You should look into anonymous methods

for instance, lets say you want to invoke progress bar update from another thread.

int progress = 50;
progressBar.Invoke((MethodInvoker)delegate
{
   progressBar.Value = 50;
   progressBar.Invalidate();
});

its that simple.

I personally seen your code as more bloat but to each his own. Looks good tho.

@topic MessageBox.Show()

should simply do something like

myForm.Invoke( (MethodInvoker)delegate
{
  MessageBox.Show( "message", "caption" );
});

[o0_Sithid_0o]

I didnt write the SafeInvokeHelper class, I just happen to stumble onto it and decided to give it a try. Its been working fine for me.

SafeInvokeHelper

[Jeff]

Originally Posted by o0_Sithid_0o

I didnt write the SafeInvokeHelper class, I just happen to stumble onto it and decided to give it a try. Its been working fine for me.

SafeInvokeHelper

I dont doubt it works, but it is 1.0 code tbh 1.0 .net can lick my sack, ArrayList....:shutters:

[noobie]

why do you think it is 1.0 code?

@sithid:btw, there is a better solution on the same link if you havent noticed..

[Sep102]

System.Collections.HashTable, most likely.

[Jeff]

Originally Posted by noobie

why do you think it is 1.0 code?

ArrayList and Hashtable is why, tbh if u had 2.0 why in gods name would you use those. They do nothing but make room for error and slow your application.