[Help] i need code dll with Form.
lazarus / 31-LCL

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witawat · 2012-04-14 05:24

hello

i need code starter about dll with form .

thankyou

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now i get code but not work.

any one can help me? fix multitasking


aiLog.7z

than you in advanced

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KpjComp · 2012-04-16 20:22

You able to put your attachment somewhere we don't need to setup an
account to download.

eg. http://ge.tt/

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witawat · 2012-04-18 03:09

new link

http://ge.tt/8p5fkTG/v/0?c

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Martin_fr · 2012-04-18 10:36

See http://bugs.freepascal.org/view.php?id=1866

I haven't followed the topic, and don't know if there were changes to
it.

Last time I checked Forms could not be "used" in a DLL. (That is you
can not have a Form defined and created in the DLL.)

The main reason is, that such forms will get their own instance of
TApplication and with that, their own msg loop (communication control
to windows)
This msg loop in the DLL will not be run. So Forms will not react to
anything.

Not sure, if and how it can be worked around.

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KpjComp · 2012-04-18 11:15

Quote from: Martin_fr on April 18, 2012, 12:36:21 pmNot sure, if and
how it can be worked around.

Yeah, I've kind of come up with the same result.

In Delphi/Windows you had a couple of options.  That involved things
like SharedMem and setting the application window handle inside the
DLL. 

But the easiest way of creating plugins was with Delphi Packages,
unfortunately from what I can gather lazarus will only do statical
linked packages.  Here was some info I made on creating a very easy
plugin architecture for Delphi -> http://www.saxon.co.uk/SinglePkg/

One option I've though off is using interfaces that has Form/Control
creating that the EXE can pass onto the DLL.  The main Disadvantage
here is that Form design would have to be code only.

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Leledumbo · 2012-04-18 14:40

My solution for this is to have each dll maintain its own TApplication
instance. Data interchange is done through a procedural API expecting
opaque pointer (which is actually some kind of GUI element instance,
e.g. a form).

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KpjComp · 2012-04-18 15:55

Quote from: Leledumbo on April 18, 2012, 04:40:33 pmMy solution for
this is to have each dll maintain its own TApplication instance. Data
interchange is done through a procedural API expecting opaque pointer
(which is actually some kind of GUI element instance, e.g. a form).

There is of course a few problems with this, but I suppose it depends
on what your trying to achieve if its a problem or not.

1.  I don't believe MDI's are going to work.
2.  EXE & DLL size, are both going to have LCL overhead.
3.  Dialog's will need extra coding, aka. Your going to have 2
Tapplications running with there own messagepump.

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Leledumbo · 2012-04-19 01:17

Quote1.  I don't believe MDI's are going to work.Yes, of course. At
least without advanced hack.
QuoteEXE & DLL size, are both going to have LCL overhead.Indeed.
QuoteDialog's will need extra coding, aka. Your going to have 2
Tapplications running with there own messagepump.Plus, I can't make my
main form as parent of the dialog.

Those are the dark sides, but the plugin works anyway.

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witawat · 2012-04-21 12:11

Then use

http://wiki.freepascal.org/Multithreaded_Application_Tutorial

can work ?

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KpjComp · 2012-04-21 17:07

He's not asking how to multi-thread, he's wanting to use Forms within
DLL's.  It's most likely so he can create a plugin system or similar.