Adding ActiveX controls at runtime and threading

[Toe Dipper]

In short we have a lengthy process when a form is loaded that adds
activex controls to our windows form. This process in itself works
fine however we would like to push this processing to a thread but are
stumped so far.

Our goal is simply to allow the form to fully display while the
controls are being added. Preferrably with a progressbar to let them
know that the form is still being built.

Here are some snippets.

Private Sub Form_Shown(ByVa l sender As Object, ByVal e As
System.EventArg s) Handles Me.Shown
Dim myThread As Threading.Threa d
myThread = New Threading.Threa d(AddressOf load_udfSection s)
myThread.SetApa rtmentState(Thr eading.Apartmen tState.STA)
myThread.Start( )
End Sub

Private Sub load_udfSection s()
...
udfSection = New AxTdF_DynamicUD F.AxDynUDF

udfSection.Begi nInit()
udfSection.Anch or =
CType(((System. Windows.Forms.A nchorStyles.Top Or
System.Windows. Forms.AnchorSty les.Left) _
Or System.Windows. Forms.AnchorSty les.Right),
System.Windows. Forms.AnchorSty les)
udfSection.Enab led = True
udfSection.Visi ble = False
udfSection.Loca tion = New
System.Drawing. Point(ToolStrip Container1.Cont entPanel.Margin .Left,
currentTop)
udfSection.Name = "AxDynUDF" & CStr(controlInd ex + 1)

With ToolStripContai ner1.ContentPan el
axWidth = .Width - (.Margin.Left + .Margin.Right)
End With

udfSection.Size = New System.Drawing. Size(axWidth, 1)

ToolStripContai ner1.ContentPan el.Invoke(New
addControl(Addr essOf addControlToToo lstrip), udfSection)
udfSection.EndI nit()

udfSection.load _Controls(CShor t(reader("Contr olGroupID")), True)

.....
End Sub
There is a delegate called addcontroltoToo lstrip for the following
function.

Private Sub addControlToToo lstrip(ByVal activexControl As
AxTdF_DynamicUD F.AxDynUDF)
ToolStripContai ner1.ContentPan el.Controls.Add (activexControl )
End Function

The invoke on the toolstrip seems to work fine but then when we try to
call endinit() it errors telling us that the control has been modified
in a different thread.

Any ideas? Only been using .NET for a week so there is no chance of
offending me. In VB6 we would have just started a timer in the show
event of the form which would let the event exit and then the timer
would process our lengthy code. Ugly but it at least allowed the form
to fully display before adding the remaining controls. Looking for
something a little bit more interactive.

Glenn Welker

[gene kelley]

On Mon, 26 Jun 2006 08:47:53 -0400, Toe Dipper
<to*******@disc ussions.microso ft.com> wrote:

In short we have a lengthy process when a form is loaded that adds
activex controls to our windows form. This process in itself works
fine however we would like to push this processing to a thread but are
stumped so far.

Our goal is simply to allow the form to fully display while the
controls are being added. Preferrably with a progressbar to let them
know that the form is still being built.

Here are some snippets.

Private Sub Form_Shown(ByVa l sender As Object, ByVal e As
System.EventAr gs) Handles Me.Shown
Dim myThread As Threading.Threa d
myThread = New Threading.Threa d(AddressOf load_udfSection s)
myThread.SetApa rtmentState(Thr eading.Apartmen tState.STA)
myThread.Start( )
End Sub

Private Sub load_udfSection s()
...
udfSection = New AxTdF_DynamicUD F.AxDynUDF

udfSection.Begi nInit()
udfSection.Anch or =
CType(((System .Windows.Forms. AnchorStyles.To p Or
System.Windows .Forms.AnchorSt yles.Left) _
Or System.Windows. Forms.AnchorSty les.Right),
System.Windows .Forms.AnchorSt yles)
udfSection.Enab led = True
udfSection.Visi ble = False
udfSection.Loca tion = New
System.Drawing .Point(ToolStri pContainer1.Con tentPanel.Margi n.Left,
currentTop)
udfSection.Name = "AxDynUDF" & CStr(controlInd ex + 1)

With ToolStripContai ner1.ContentPan el
axWidth = .Width - (.Margin.Left + .Margin.Right)
End With

udfSection.Size = New System.Drawing. Size(axWidth, 1)

ToolStripContai ner1.ContentPan el.Invoke(New
addControl(Add ressOf addControlToToo lstrip), udfSection)
udfSection.EndI nit()

udfSection.load _Controls(CShor t(reader("Contr olGroupID")), True)

.....
End Sub
There is a delegate called addcontroltoToo lstrip for the following
function.

Private Sub addControlToToo lstrip(ByVal activexControl As
AxTdF_DynamicU DF.AxDynUDF)
ToolStripContai ner1.ContentPan el.Controls.Add (activexControl )
End Function

The invoke on the toolstrip seems to work fine but then when we try to
call endinit() it errors telling us that the control has been modified
in a different thread.

Any ideas? Only been using .NET for a week so there is no chance of
offending me. In VB6 we would have just started a timer in the show
event of the form which would let the event exit and then the timer
would process our lengthy code. Ugly but it at least allowed the form
to fully display before adding the remaining controls. Looking for
something a little bit more interactive.

Glenn Welker

Based on what you posted, you are essentially continuing what would
normally happen in the Load Event, so I'm not sure why you want to use
a separate thread to continue loading controls. Is there some other
background process going on that is not shown in your code?

In VB6, I used a similar concept which worked fine - show the main
form ASAP, then continue with the load event. In VB2005, my
experience, so far, hs been that this is a bit more difficult to
implement from app to app as, in some cases, the main form has a
tendency to do an undesirable repaint when adding and positioning
controls after the main form is visible particularly when I have code
in the Layout Event.

Gene

[Toe Dipper]

Based on what you posted, you are essentially continuing what would
normally happen in the Load Event, so I'm not sure why you want to use
a separate thread to continue loading controls. Is there some other
background process going on that is not shown in your code?

In VB6, I used a similar concept which worked fine - show the main
form ASAP, then continue with the load event. In VB2005, my
experience, so far, hs been that this is a bit more difficult to
implement from app to app as, in some cases, the main form has a
tendency to do an undesirable repaint when adding and positioning
controls after the main form is visible particularly when I have code
in the Layout Event.

Gene

We were really just trying to clean up a hack that has been in our
code too long.

You are right we are trying to continue the load event. The code I
have referenced takes up to 10 seconds. Without any progress
indication to the user, it appears that the form has locked up. It
seemed like I could load the controls in a background process while
updating a progress bar in the main thread. This would have enabled
the user to move the gui and get feedback on the progress while the
background process finished.

Our solution for VB6 seems to be less robust under vb 2005. Since the
documentation for doevents points to multithreading it seems possible,
although quite complicated.

I appreciate your feedback.

[gene kelley]

On Tue, 27 Jun 2006 09:13:18 -0400, Toe Dipper
<to*******@disc ussions.microso ft.com> wrote:

Based on what you posted, you are essentially continuing what would
normally happen in the Load Event, so I'm not sure why you want to use
a separate thread to continue loading controls. Is there some other
background process going on that is not shown in your code?

In VB6, I used a similar concept which worked fine - show the main
form ASAP, then continue with the load event. In VB2005, my
experience, so far, hs been that this is a bit more difficult to
implement from app to app as, in some cases, the main form has a
tendency to do an undesirable repaint when adding and positioning
controls after the main form is visible particularly when I have code
in the Layout Event.

Gene

We were really just trying to clean up a hack that has been in our
code too long.

You are right we are trying to continue the load event. The code I
have referenced takes up to 10 seconds. Without any progress
indication to the user, it appears that the form has locked up. It
seemed like I could load the controls in a background process while
updating a progress bar in the main thread. This would have enabled
the user to move the gui and get feedback on the progress while the
background process finished.

Our solution for VB6 seems to be less robust under vb 2005. Since the
documentatio n for doevents points to multithreading it seems possible,
although quite complicated.

I appreciate your feedback.

A common technique for a long load time (10 seconds is long) is to
display a sort of spash screen (not the VB2005 splash screen) as soon
as the main form is displayed where the splash form contains a label
that is updating iindicating to the user that there is activity.
PhotoShop is a good example if you are familiar with that program.

Gene