Want to protect your cyber security and still get fast solutions? Ask a secure question today.Go Premium

x
  • Status: Solved
  • Priority: Medium
  • Security: Public
  • Views: 449
  • Last Modified:

VB.NET Loading Dialog crashes form

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
DanielBlackmore
Asked:
DanielBlackmore
2 Solutions
 
Luis PérezSoftware Architect in .NetCommented:
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
 
nffvrxqgrcfqvvcCommented:
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
 
DanielBlackmoreAuthor Commented:
Thanks!
0

Featured Post

Receive 1:1 tech help

Solve your biggest tech problems alongside global tech experts with 1:1 help.

Tackle projects and never again get stuck behind a technical roadblock.
Join Now