Solved

VB.NET Loading Dialog crashes form

Posted on 2010-09-22
3
425 Views
Last Modified: 2012-05-10
Hi,

I have an application with a main form. On this page when a user click certain labels etc it will show another form, eg Form1. Form1 takes about 20 seconds to load the data in etc, so I have been trying to find a loading dialog. I have found one that is sort of working, but for some reason it crashes the just opened form. Here is the code for the loading form;

Imports System.ComponentModel
Public Class Loading
    Private _worker As BackgroundWorker
    Protected Overrides Sub OnLoad(ByVal e As System.EventArgs)
        MyBase.OnLoad(e)
        _worker = New BackgroundWorker()
        AddHandler _worker.DoWork, AddressOf WorkerDoWork
        AddHandler _worker.RunWorkerCompleted, AddressOf WorkerCompleted
        _worker.RunWorkerAsync()
    End Sub
    Private Sub WorkerDoWork(ByVal sender As Object, ByVal e As DoWorkEventArgs)
        Form1.Show()
    End Sub
    Private Sub WorkerCompleted(ByVal sender As Object, ByVal e As RunWorkerCompletedEventArgs)
        Me.DialogResult = Windows.Forms.DialogResult.OK
        Me.Close()
    End Sub
End Class

Open in new window



On the main page, I have the following code in the label;

Dim frm As New Loading()
frm.ShowDialog()

Open in new window


Now, when I click the Label on the main form, The loading box comes up and works fine. Once the data has finished loading the box disappears, as it should and leaves me with Form1. However Form1 will just hang and crash without any errors after it has been loaded.

Could anyone please help with this code?

Thank you kindly
0
Comment
Question by:DanielBlackmore
3 Comments
 
LVL 25

Accepted Solution

by:
Luis Pérez earned 250 total points
ID: 33733651
The reason is that Form1 has been started from the Loading thread. As the loading thread has finished, Form1 is orphan.

The best solution is that the Loading thread must not open Form1. Form1 must be open from the main form. First, open the Loading thread (that I suppose that shows any kind of "loading" message), and after that open Form1. As the Loading thread executes in it's own thread space, it will show the message anyway.

Hope that helps.
0
 
LVL 29

Assisted Solution

by:nffvrxqgrcfqvvc
nffvrxqgrcfqvvc earned 250 total points
ID: 33733725
You open the Form on a different thread so there is no message queue associated with that form. That is the reason your form  hangs around not responding. You will need to change your layout logic so that the form uses the original UI thread with the message queue.
 
0
 

Author Closing Comment

by:DanielBlackmore
ID: 33769978
Thanks!
0

Featured Post

Is Your Active Directory as Secure as You Think?

More than 75% of all records are compromised because of the loss or theft of a privileged credential. Experts have been exploring Active Directory infrastructure to identify key threats and establish best practices for keeping data safe. Attend this month’s webinar to learn more.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
Best way to handle data being sent over a serial COM 5 32
.net VBA word safemode 1 39
Round up to 100% in .NET 10 89
vb.net checkbox 7 41
If you're writing a .NET application to connect to an Access .mdb database and use pre-existing queries that require parameters, you've come to the right place! Let's say the pre-existing query(qryCust) in Access takes a Date as a parameter and l…
If you need to start windows update installation remotely or as a scheduled task you will find this very helpful.
This tutorial gives a high-level tour of the interface of Marketo (a marketing automation tool to help businesses track and engage prospective customers and drive them to purchase). You will see the main areas including Marketing Activities, Design …
Internet Business Fax to Email Made Easy - With  eFax Corporate (http://www.enterprise.efax.com), you'll receive a dedicated online fax number, which is used the same way as a typical analog fax number. You'll receive secure faxes in your email, f…

867 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

18 Experts available now in Live!

Get 1:1 Help Now