CODEWITHSUNDEEP
c#.netvb.netvb6
Water Cooler v2
Water Cooler v2

Reputation: 33880

C# Equivalent of VB 6 DoEvents

VB6 had a DoEvents() method that you called to return control to the OS and mimic multi-threaded behavior in that single threaded environment.

What is the .NET framework equivalent of VB 6 DoEvents()?

Upvotes: 16

Views: 13991

Answers (5)

Christian Findlay
Christian Findlay

Reputation: 7712

You shouldn't use Application.DoEvents(). It will have reentrancy issues. You should call inside the loop:

await System.Windows.Threading.Dispatcher.Yield()

It will do the same thing. You will need to put it in a async method though. This has the added advantage of marking the method as asynchronous for calling methods. It's nice to suffix methods that call await Dispatcher.Yield with Async(). The method is not naturally async (i.e. it does have CPU bound work) but for all intents and purposes the method becomes async as it will not lock up the calling thread.

Upvotes: 0

Peter Smith
Peter Smith

Reputation: 5548

The following is a general DoEvents type method

using System;
using System.Windows.Threading;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Security.Permissions;

namespace Utilites
{
/// <summary>
/// Emulates the VB6 DoEvents to refresh a window during long running events
/// </summary>
public class ScreenEvents
{
    [SecurityPermissionAttribute(SecurityAction.Demand, Flags = SecurityPermissionFlag.UnmanagedCode)]
    public static void DoEvents()
    {
        DispatcherFrame frame = new DispatcherFrame();
        Dispatcher.CurrentDispatcher.BeginInvoke(DispatcherPriority.Background,
            new DispatcherOperationCallback(ExitFrame), frame);
        Dispatcher.PushFrame(frame);
    }

    public static object ExitFrame(object f)
    {
        ((DispatcherFrame)f).Continue = false;

        return null;
    }
}
}

It doesn't need to know about the application.

Upvotes: 5

user1704124
user1704124

Reputation: 94

If you call Application.DoEvents() in your code, your application can handle the other events. For example, if you have a form that adds data to a ListBox and add DoEvents to your code, your form repaints when another window is dragged over it. If you remove DoEvents from your code, your form will not repaint until the click event handler of the button is finished executing. For more information on messaging, see User Input in Windows Forms.

Unlike Visual Basic 6.0, the DoEvents method does not call the Thread.Sleep method.

Upvotes: 1

John Woo
John Woo

Reputation: 263893

you can use Application.DoEvents(). Why not use Threading class or simply Background Workers? If you are doing in .net environment, don't use DoEvents. Leave it on VB6.

Upvotes: 25

Zippit
Zippit

Reputation: 1683

Application.DoEvents() (part of WinForms)

Upvotes: 11

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