Control invalidated on new thread start.

Why is that? I have an Outlook style bar (ComponentOne) and whenever I click on a button on my form (whether or not it's in the toolbar is irrelevant) that starts a new thread with a call to a private sub in my form, the toolbar is invalidated and won't refresh after the thread has completed. While I can add code to refresh it after the thread completes, I can't figure out how to refresh it BEFORE the thread completes (that's my goal), and any attempt to do this is ignored.

Again, the control will only refresh after the thread has completed and only if I tell it to do so.

I have tried inserting code immediately after the thread is started to refresh just the control or the whole form, and I'm still not having much luck. Does anyone out there have any idea why?

Thanks in advance,

KT

Ok, apparently that control isn't the only one being invalidated. I have a progress bar on the form that's having the same problem. So I think I need a timer or something to refresh a few or all of the controls (at least the ones I am having trouble with) every so often while the thread is executing. Any ideas on how I can do that? Never done it before.

It sounds like you are doing something funky with the threading. You may want to post that part of the code. Also keep in mind that all UI is on the same thread, if it is being altered in another thread it will still be marshalled over to the main or UI thread when it goes to update an UI elements like controls. So be careful when using threading because lots of marshalling can actually slow the application down and ruin the whole point of multithreading.

Ok. But first, I must apologize for the coding style as I'm still learning.

I click a button on my form that corresponds to a section. For instance, "Games."

VB Code:

Private Sub showGames_Click(ByVal sender As System.Object, ByVal e As C1.Win.C1Command.ClickEventArgs) Handles showGames.Click
        navBar.Enabled = False
        sectionSelected = 2
        Label2.Text = "Games"
        Dim viewThread As New System.Threading.Thread(New System.Threading.ThreadStart(AddressOf Me.UpdateView))
        viewThread.Start()

Which calls this:

VB Code:

Private Sub UpdateView()
 
        If sectionSelected = 1 Then
           'omitted as I'm still working on this.
        ElseIf sectionSelected = 2 Then
            view.ParseTable(gamesTable, ListView1, mainBar)
        ElseIf sectionSelected = 3 Then
            view.ParseTable(moviesTable, ListView1, mainBar)
        ElseIf sectionSelected = 4 Then
            view.ParseTable(showsTable, ListView1, mainBar)
        ElseIf sectionSelected = 5 Then
            view.ParseTable(animeTable, ListView1, mainBar)
        ElseIf sectionSelected = 6 Then
            view.ParseTable(musicTable, ListView1, mainBar)
        ElseIf sectionSelected = 7 Then
            view.ParseTable(appsTable, ListView1, mainBar)
        ElseIf sectionSelected = 8 Then
            view.ParseTable(comicsTable, ListView1, mainBar)
        ElseIf sectionSelected = 9 Then
            view.ParseTable(macTable, ListView1, mainBar)
        ElseIf sectionSelected = 10 Then
            view.ParseTable(miscTable, ListView1, mainBar)
        End If
        navBar.Enabled = True
 
    End Sub

Here's the ViewManager class that contains the ParseTable sub (called by the instance "view" as shown above):

VB Code:

Public Class ViewManager
 
    Public Sub ParseTable(ByVal table As DataTable, ByVal list As ListView, ByVal _
    progress As ProgressBar)
 
        list.Visible = False
        list.Items.Clear()
 
        Dim rows As DataRowCollection
        Dim row As DataRow
        rows = table.Rows
 
        progress.Maximum = rows.Count
 
        For Each row In rows
            Dim lvi As New ListViewItem(CType(row(1), String))
 
            lvi.SubItems.Add(CType(row(2), String))
            lvi.SubItems.Add(CType(row(3), String))
            lvi.SubItems.Add(CType(row(5), String))
            lvi.SubItems.Add(CType(row(6), String))
            lvi.SubItems.Add(CType(row(7), String))
            lvi.SubItems.Add(CType(row(8), String))
 
            list.Items.Add(lvi)
            progress.Value += 1
 
        Next row
        list.Visible = True
        progress.Visible = False
        progress.Value = 0
 
    End Sub
 
End Class

And that's that, right? But what about the tables that are being loaded into the listview? Well, there's another button on my form called "Update Section."

VB Code:

Private Sub Button1_Click_1(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles buttonUpdate.Click
 
        navBar.Enabled = False
        mainBar.Visible = True
        ListView1.Visible = False
        Dim updateThread As New System.Threading.Thread(New System.Threading.ThreadStart(AddressOf Me.updateTable))
        updateThread.Start()

The updateTable() sub is almost identical to the updateView() sub shown above, the only exceptions being.. well, I'll show you:

VB Code:

Private Sub updateTable()
 
        buttonUpdate.Enabled = False
 
        If sectionSelected = 1 Then
           ' again I'm still working on the newslister function as the news section is different from other sections, such as games.
            newsTable = newsLister.List(newsUrl)
        ElseIf sectionSelected = 2 Then
            gamesTable = sectionLister.List(gamesUrl, Me.mainBar, Me.Label1)
            Me.UpdateView()
        ElseIf sectionSelected = 3 Then
            moviesTable = sectionLister.List(moviesUrl, Me.mainBar, Me.Label1)
            Me.UpdateView()
        ElseIf sectionSelected = 4 Then
            showsTable = sectionLister.List(showsUrl, Me.mainBar, Me.Label1)
            Me.UpdateView()
        ElseIf sectionSelected = 5 Then
            animeTable = sectionLister.List(animeUrl, Me.mainBar, Me.Label1)
            Me.UpdateView()
        ElseIf sectionSelected = 6 Then
            musicTable = sectionLister.List(musicUrl, Me.mainBar, Me.Label1)
            Me.UpdateView()
        ElseIf sectionSelected = 7 Then
            appsTable = sectionLister.List(appsUrl, Me.mainBar, Me.Label1)
            Me.UpdateView()
        ElseIf sectionSelected = 8 Then
            comicsTable = sectionLister.List(comicsUrl, Me.mainBar, Me.Label1)
            Me.UpdateView()
        ElseIf sectionSelected = 9 Then
            macTable = sectionLister.List(macUrl, Me.mainBar, Me.Label1)
            Me.UpdateView()
        ElseIf sectionSelected = 10 Then
            miscTable = sectionLister.List(miscUrl, Me.mainBar, Me.Label1)
            Me.UpdateView()
        End If
 
        navBar.Enabled = True
        buttonUpdate.Enabled = True
 
    End Sub

And finally, in case you're curious, here's the sectionLister.List function that is called above.

VB Code:

Public Class SectionLister
    Dim lastEntry As Boolean = False
    Dim nextEntry As Integer
    Dim lastItem As Boolean = False
    Dim nextItem As Integer
 
    Dim torrentTable As DataTable
    Dim subProgress As ProgressBar
    Dim subLabel As Label
 
 
 
 
    Function List(ByVal sectionUrl As String, ByVal subProgress As ProgressBar, ByVal subLabel As Label) As DataTable
 
        torrentTable = New DataTable
 
        Dim _id As DataColumn = New DataColumn("ID")
        _id.DataType = System.Type.GetType("System.Int32")
        torrentTable.Columns.Add(_id)
 
        Dim _time As DataColumn = New DataColumn("Time")
        _time.DataType = System.Type.GetType("System.String")
        torrentTable.Columns.Add(_time)
 
        Dim _section As DataColumn = New DataColumn("Section")
        _section.DataType = System.Type.GetType("System.String")
        torrentTable.Columns.Add(_section)
 
        Dim _name As DataColumn = New DataColumn("Name")
        _name.DataType = System.Type.GetType("System.String")
        torrentTable.Columns.Add(_name)
 
        Dim _url As DataColumn = New DataColumn("URL")
        _url.DataType = System.Type.GetType("System.String")
        torrentTable.Columns.Add(_url)
 
        Dim _size As DataColumn = New DataColumn("Size")
        _size.DataType = System.Type.GetType("System.String")
        torrentTable.Columns.Add(_size)
 
        Dim _seeds As DataColumn = New DataColumn("Seeds")
        _seeds.DataType = System.Type.GetType("System.Int32")
        torrentTable.Columns.Add(_seeds)
 
        Dim _peers As DataColumn = New DataColumn("Peers")
        _peers.DataType = System.Type.GetType("System.Int32")
        torrentTable.Columns.Add(_peers)
 
        Dim _quality As DataColumn = New DataColumn("Quality")
        _quality.DataType = System.Type.GetType("System.String")
        torrentTable.Columns.Add(_quality)
 
        Dim _donor As DataColumn = New DataColumn("Donor")
        _donor.DataType = System.Type.GetType("System.String")
        torrentTable.Columns.Add(_donor)
 
        Dim _donorrank As DataColumn = New DataColumn("Donor Rank")
        _donorrank.DataType = System.Type.GetType("System.String")
        torrentTable.Columns.Add(_donorrank)
 
        Dim _info As DataColumn = New DataColumn("Info URL")
        _info.DataType = System.Type.GetType("System.String")
        torrentTable.Columns.Add(_info)
 
        Dim getsubs As New SubsectionLister
        Dim http As New Connecter
 
 
        Dim subsectionList As Hashtable = getsubs.List(sectionUrl)
        subProgress.Maximum = subsectionList.Count
 
        Dim entry As DictionaryEntry
 
        For Each entry In subsectionList
 
            Dim url As String = CType(entry.Value, String)
            Dim title As String = CType(entry.Key, String)
            subProgress.Update()
            subProgress.Value += 1
            subLabel.Text = "Listing: " & title
            Dim html As String = http.Download(url)
            ListSingleSection(html)
 
        Next entry
        subProgress.Value = 0
        subLabel.Text = ""
        Return torrentTable
 
    End Function

There's more child functions under this one but I omitted them because, quite frankly, they're boring and I'm positive they have nothing to do with the problem I'm experiencing. I should note that you can actually see how I implemented the progress bar as you suggested to me in another post. I'm a quick learner, but again I must stress I've only been learning how to program for only a month, so I must apologize if the code isn't to standard. But, it's not bad for a month of learning, right?

Progress bar works great, although it has some strange quirks like I'm experiencing with the navBar (ComponentOne Outlook style bar). At first I wasn't able to get it to show properly but adjusting the location of the calls to turn on and off its visibility property fixed that.

Now, it seems, it loses its Windows XP style randomly. Can't explain that either. That happened to me with the "Update Section" button much earlier in my project (before ever implementing threading) but I gave up and changed it to the flat style button. Any ideas at all? I really would appreciate all of your help.

Thanks in advance,

KT

So why are you threading this?

This falls in line with what I mentioned, since you call the threaded method which fills the listview then it has to keep marshalling back to the UI thread to update the control. This will lock the control which make it seem invalidated. Why not just ditch the threading and have it fill synchronously (normal)? You could also use a callback to the main thread to make it safe multithreading.

Okay, slow down, I'm not sure I understand what you're saying.

Before I threaded this application, I couldn't minimize it or move the window while it was running the UpdateTable or UpdateView routines. Additionally, before the threading code, the progress bar worked fine but label1 (which shows which section is being updated as called by the For Each loop in the SectionLister.List function) was not being refreshed every time a new section was parsed. It would not show anything, period. Threading the application made it more responsive while the updates were occuring.

Additionally, what you're saying about the progress bar doesn't make any sense. At first I thought it was being invalidated, but after changing the design-time visibility property to true and calling visibility = false on the Form Load subroutine, that fixed the issues I was having with it losing its XP style function, which I think is very, very strange. However, it works, and it looks good.

I'd still like to find out why it was doing that, but that's another issue. Now, why is it that my Outlook style bar gets invalidated when I don't have any references to it in a new thread? That's my question. What is wrong with my threading code? I don't need a callback for the progress bar, this happened before I even implemented the progress bar.

And if you can't help me with that, at least maybe we can figure out why the progress bar would sometimes lose its XP style when the design-time visibility property was set to false.

This is only guessing but I think the Outlook bar seems to be invalidating because of lag - Actually first a question, can you move the form around while the listview is being updated and while the Ooutlook bar appears invalidated?

I'm not saying anything is 'wrong' with the threading code just that it is going to have to marshal back and forth between the background thread and the UI thread everytime it updates the ListView. This cause more work and a slow down for the threading.

If it's not too much trouble, could I post the project and have you take a look at it? I just found another anomoly, disabling the updateButton after a click on the C1Commands instead of the UpdateTable subroutine as I have it above makes the progress bar invisible. I don't understand it at all. I changed it back and it fixed it, only using Undo would do it, changing the code back manually did not do it. Am I finding bugs in VS.NET?

Let me know if I can post it real quick, it's a half a meg compressed.

Thanks,

KT

Sure go ahead and post it. If it doesn't fit on the forums then you can email it [email protected]