VC8 GDI+ dll in VC6

  • Thread starter Thread starter Asfar
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A

Asfar

Hi,

Can I write a VC8 dll which used GDI+ and then use this dll in VC6.
I will be using GDI+ to basically load a image in memory and annotate it
with some text and save the image.

Any pointers on how I can do this?

Thanks,
-Asfar
 
Asfar said:
Hi,

Can I write a VC8 dll which used GDI+ and then use this dll in VC6.
I will be using GDI+ to basically load a image in memory and annotate
it with some text and save the image.

Any pointers on how I can do this?
Click to expand...

You can, as long as you expose a pure C (or COM) interface to your VC8 DLL.
If you expose functions that have MFC, ATL or STL types in the interface,
you won't be able to call those functions from VC6. If you expose functions
that have GDI+ types in their interface, it _might_ work, depending on
whether VC6 and VC8 can both compile the exact same version of GDI+ and
whether you have all the options for the two compilers set in a compatible
way.

In your case, if all you want to do is load, annotate and save an image,
your exported function probably needs little more than a path, so it should
be doable.

-cd
 
Can I write a VC8 dll which used GDI+ and then use this dll in VC6.
I will be using GDI+ to basically load a image in memory and annotate it
with some text and save the image.
Click to expand...

The functionality itself should not be difficult to figure out.
www.codeproject.com has plenty of GDI+ articles and code samples.

build a class that does what you want to do. after that you can either build
a C style wrapper that exposes the desired functionality of that class, you
can build an activeX control that exports that functionality, or you can
build a managed class library and use it via COM interop.

Should you go for the C style wrapper dll, then you also have to be careful
to respect memory ownership. I.e. do not let the dll allocate memory that
will be deleted by your VC6 app, or vice versa.

--

Kind regards,
Bruno.
(e-mail address removed)
Remove only "_nos_pam"
 
Can I write a VC8 dll which used GDI+ and then use this dll in VC6.

Why do you want to ? GDI+ is an unmanaged library that you could call much
more easily direct from VC6 unmanaged code.

Cheers
Doug Forster
 
Doug Forster said:
Why do you want to ? GDI+ is an unmanaged library that you could call much
more easily direct from VC6 unmanaged code.
Click to expand...

What's that got to do with VC8, which is just as capable of generating
native code as VC6 was?

-cd
 
What's that got to do with VC8, which is just as capable of generating
native code as VC6 was?
Click to expand...

Nothing at all. I was presuming the OP had some undisclosed reason for
wanting to work within VC6.
 
Just to continue...

I also supposed the reason the OP wanted to use VC8 for the dll was because
he was under the common misapprehension that GDI+ was a managed library and
that he needed managed code to use it.
 
Doug said:
Just to continue...

I also supposed the reason the OP wanted to use VC8 for the dll was
because he was under the common misapprehension that GDI+ was a
managed library and that he needed managed code to use it.
Click to expand...

Good call :) I'd never heard the misperception that GDI+ was managed, but
apparently it is common!

-cd
 
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