We are creating controls dynamically in our application, and when you create
a combobox control dynamically, the default style = 0(Dropdown Combo).  Is
there a way to dynamically create a control with the default style =
2(Dropdown List).  Since you can't set this property at Runtime, we need
another way to 'default' this style at creation.

I have investigated using Windows Hooks(VBPJ - July 1999) to change the
style at Creation time, as that is probably when it needs to be done, but
can't seem to set this style.

Has anybody done this?

TIA,

Mark Essex

The easy way is to simply build a user control that has a style 2 combo box
as a constituent control. All you would have to do is mirror the properties.
Yes, there is a slight memory/performance hit in doing this, but if dynamic
is your primary concern, then it isn't a major problem.

I have a "Swiss Army Knife" control that not only has this kind of combo,
but a textbox, listbox, date selection, and a few others in it. This allows
my main "shell" program to use it to build out forms based on definitions
stored in a database. If it didn't have this functionality, I would have had
to have written and distributed 40 or so similar applications.

If you want to pursue the more difficult method, I think you're on the right
track. Keep it mind that it is a difficult endeavor.

Frank Carr

Mark,

I am generateing controls run-time as well.  However, I have not experienced
a problem with chaging the style during run-time.  Don't know what version
of VB you are using, but I found that I had to add my controls in the form's
initialize event or they would not display properly.  In this event I also
set the style property without any problems.

Au contraire, mon ami!  'Loading' - which is really cloning - an additional
member of a control array is a far faster and more efficient method of adding a
control at run-time than is Controls.Add . . .

The speed hit I'm talking about comes from the overhead of loading a user
control with about a dozen constituent controls, not from the loading
method. Therefore, I'm cloning 13 controls rather than just one, thus the
extra processing overhead.

In the app I mentioned, I am using the Load method, not the Controls.Add
method. I have the typical "zero/template" element that's never used and I
load the controls from there. Fields in the database determines load order
and placement of the controls.

Frank Carr

Okay, we've gone from one style-2 combo box to a user control with 13 controls
on it . . .  You're right, your method does seem exorbitant in terms of
resources, but (1) do you really notice the time expended in cloning this user
control,  (2) what is the cost of loading via Controls.Add a single combo box in
comparison to the time you are spending, and (3) how quickly is any time-savings
from using Controls.Add expended in late-binding references?

There is no way to do what you are asking without recreating the control
from scratch,  this is just the nature of the combo box, a usercontrol wont
help either cause the Combo box already.

The Windows Hook aspect sounds like the way to proceed, thats if you can get
it to work.

Tarek

Actually, the user control worked very well.  I just set the DataCombo Style
property = 2 on the user control BEFORE I compiled the user control into an
OCX.  So, when the user control is created, either dynamically, or by being
drawn on the screen, it has a style = 2.  So, my user control is used to
dynamically create combo boxes with Style = 2.  I couldn't use it to create
dynamic combos of style = 0 or style = 1 for the same reason as the original
problem presented.

So, I have decided to go with this method, as it was pretty simple to
implement, and works like a champ.

Thanks to all that contributed answers to this thread...

Mark

I am working on a similar project but having a different problem.  I am
creating forms dynamically.  But I get my initial setting for the
dynamic form from an existing form.  After scraping the form, I remove
it from my project and create it from the database entries.

My problem is that I cannot scrape the datasource property.   I create
a new instance of the target form and loop thru the controls.  When I
try to read the datasource property, I don't get anything.  No object
ref.  When I perform the same loop in the form_load event, I can
reference the datasource property with no problem.

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