How to use threading for Loading Bar WinForm? - vb.net

Question

I am wanting to have a an infinite loop progress bar, just to give the user something to stare at during long load times. Currently the user will select a SQL query to execute, and results get displayed onto another winform that contains a gridview for the query results. My goal is to have another winform(loading form) that just has a progress bar on it that just infinitely fills to end and resets over and over until the gridview on the results form finishes rendering. I tried a background worker because i believe this will need multi threading for performance but the load form never shows up. Basically the execution plan should be this:
User clicks execute button, show progress bar on load form(infinite loop), Executes query and loads result form
Closes progress bar on load form
The above execution is called from my Main form
Private Sub LoadingForm_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
pbSqlCall.Minimum = 0
pbSqlCall.Maximum = 100
pbSqlCall.Step = 10
Dim Counter As Integer = 0
While Counter < 100
pbSqlCall.Increment(10)
Counter += 10
If Counter = 100 Then
Counter = 0
pbSqlCall.Value = 0
End If
End While
End Sub
BackgroundWorker1.RunWorkerAsync()
ExecuteQuery(Parameters, Queries.Item(ddlQueries.SelectedIndex))
'Not sure how to close the form using the thread
Private Sub BackgroundWorker1_DoWork(sender As System.Object, e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork
lf.ShowDialog() 'Load form
End Sub

Answer 1

You can do the following given a form called 'Loader' and a form called 'Main'
Loader:
Public Class Loader
Private Sub Loader_Load(sender As Object, e As EventArgs) Handles MyBase.Load
pbSqlCall.Style = ProgressBarStyle.Marquee
pbSqlCall.MarqueeAnimationSpeed = 30
End Sub
End Class
Main:
Imports System.Threading.Tasks
Public Class Main
Private Sub DoWork_Click(sender As Object, e As EventArgs) Handles Button1.Click
Dim lf As New Loader
lf.Show(Me)
Task.Factory.StartNew(Sub()
'go get the data for the grid
System.Threading.Thread.Sleep(6000)
End Sub) _
.ContinueWith(Sub(result As task)
'check the aggregate exception
Dim aex As System.AggregateException = result.Exception
If aex IsNot Nothing Then
MessageBox.Show(String.Format("something bad happened: ", aex.Flatten.Message))
End If
'bind the data to the grid
lf.Close()
lf.Dispose()
End Sub, TaskScheduler.FromCurrentSynchronizationContext)
End Sub
Private Sub Main_Load(sender As Object, e As EventArgs) Handles MyBase.Load
End Sub
End Class