World: r3wp

well, RL_GET_CHAR is probably better

all RL_* functions are safe to call from extensions

(macros, safe to use)

I did several extensions for windows, and you can find the source 
code and the dlls here: http://www.colineau.fr/rebol/R3_extensions.html
. This code may not be up to date, but recently I have compiled new 
versions. If necessary, I can upload them.

Oops, I forgot about your stuff jocko .. does it all still work?

I would appreciate a very simple example how to make extension using 
external DLL. So I could write for example ImageMagick extension.

Max was supposed to bing kind of R2 DLL interface in R3, but ... 
:-)

bing=bring

funny, I intended also to try interfacing with ImageMagick (maybe 
the ImageMagick Com + component.), as I have a need for another project.

Concerning the extensions dll's and source files, I think that they 
are no more compatible. I should check and put the latest versions.

pages updated with the new versions (binaries and sources) compatibles 
a110 :
http://www.colineau.fr/rebol/R3_extensions.html

I use IM extensively with R2 so I will need it with R3 as well. I 
think it must be easy.. if you know where to start.

if you download the OpenGL demo, there is a complete working setup. 
 it has a makefile and a visual studio 2008 setup .  it should help 
you out.

I'm completely C/C++ newbie, so I would like to know, how to make 
the extension, if I have precompiled DLL.
For example, In R2 I can simply download the DLL like this one:
http://zlib.net/zlib125-dll.zip

And simply do:

zlib.dll: load/library %zlib1.dll

zlib-version: make routine! [ return: [string!] ] zlib.dll "zlibVersion"
zlib-version
;== "1.2.5"


Is there someone who can write a simple tutorial - C extension with 
the zlib-version command?

I understand the REBOL part of it, but would like to see how to do 
the DLL trick part. Including the correct gcc command.

I would like to start with simple gcc instead of dealing with VS 
projects.

Oldes, I have uploaded an ImageMagick extension.

Nice

Oldes, I've built you a simple "zlib-version" extension.

Could you upload the C source as well? Btw.. I would rather use linkage 
to MagickWand.dll to be able use direct commands instead of command 
line like IM commands.

Great, I will check the zlib:) I'm looking forward to learn something.

No tutorial yet, but see I hope it helps nevertheless:
http://bolka.at/2010/rebol3/ext-zlib-20101108.zip

Extract this into your hostkit folder, so that you'll have an ext-zlib/ 
folder in the hostkit.

Then run make, and you should see something like the following:
$ make

gcc -DTO_WIN32 -I ../src/include -I include -mdll -L . -lzlib1 -o 
zlib.dll zlib.c

Afterwards you should have a fresh "zlib.dll" which is the extension.

Now run the accompanying zlib.r, and you should get:
$ r3-a110-3-1 -q zlib.r
1.2.5

it works.. thanks.. but I must say, that in R2 it was easier;-)

is there a reason why there is:
#include <stdio.h>
#include <string.h> 
?

stdio.h is a leftover and not needed.

string.h is for strlen.

And isn't the conversion to a REBOL string quite complicated?

Yes, a bit. There may be a simpler way. Or we could bundle a few 
such helper functions into a support library (as Max did in his OpenGL 
work).

Also note that this is not really comparable to using dlls with the 
/Library stuff in R2.

This facility simply did not exist in R2. On the other hand, /Library 
does not yet exist for R3 (but only because no one has written it 
yet).

I know. This is a good start for me:) btw. is it possible to create 
extzlib.dll which would contain the zlib1.dll? I don't need it, just 
asking.

Yes and no.

Yes, you can create an extension which contains the zlib library.

No, you can't do that from zlib1.dll, you'd have to use the zdll.lib 
in lib/.

You'd use

gcc -DTO_WIN32 -I ../src/include -I include -mdll -o zlib.dll zlib.c 
lib/zdll.lib


to statically link zlib into your extension (still called zlib.dll 
in the above).

are you sure? with this version the zlib1.dll is still required

Hmm, then zdll.lib probably is an import dll. Let me check.

developing an extension to wrap MagickWand is a huge work, because 
of the large number of functions, and data formats. It's better, 
in this case, to develop a full dedicated application in c, or, at 
least a dll with higher level functions ... wihch is approximately 
the case of ImageMagickObject. In other words, I am not convinced 
of the interest to program in Rebol if you want to use the full set 
of low level image processing functions.

yes, its VERY usefull... one doesn't want to have to compile applications 
and stuff... AFAIK there are binding to other languages which use 
the full IM suite.  

but yes its a lot of work.

(Yes, lib/zdll.lib seems to be an import library. So no static linking 
against it. Sorry for the confusion.)

Jocko, I don't think it's so much work. For example in R2 I use this: 
http://box.lebeda.ws/~hmm/rebol/im-min.r

Of course, better to use REBOL script to make the C code. Btw. your 
version is not working here. I get this result:
Error (null) (0x80040154)
Error (null) (0x80040154)
Error (null) (0x80040154)
Error (null) (0x80040154)
Error (null) (0x80040154)
Error (null) (0x80040154)

Also is it possible to use your version to for example load TIFF 
image into REBOL?

Have you installed ImageMagick , and ImageMagickObject ?

I have ImageMagick instaled. If installing ImageMagickObject means: 
regsvr32 /c /s ImageMagickObject.dll than I have it as well.

With this version, all the inputs and outputs are files. I'm waiting 
for more specs before loading directly into memory. It's possible 
to convert many file formats (including tiff) into may others.

hm.. but I don't see ImageMagickObject.dll in my Imagick folder.