Suggestions on porting some Mingw code, to call from Xailer

[Guest]

Hi,
Are there some general guidelines, for porting over third-party
libraries, which are mingw compatible (meaning, they are compiled with
gcc), to interface with Xailer? For example, some mappings between C
data types and Xailer?
I had a nightmare of a time, trying to interface some Borland code with
Xailer, a few years ago. If there are some tips to start with, to avoid
wasting time, that would be appreciated.
Just some general suggestions, would be fine. Thanks.

[Guest]

As an example of something more specific, here are the results of trying
to compile some example .c. code, in Xailer:
Compiling: XailerYap.prg...
Compiling: frmXailerYap.prg...
Compiling: TestCInterface.prg...
C:xailer3ProjectsXailerYapSourceTestCInterface.prg:28:7 : warning:
implicit declaration of function 'umask' [-Wimplicit-function-declaration]
Compiling: TestYInterface01.c...
C:xailer3Include/core.h:19:19: error: unknown type name 'DWORD'
C:xailer3Include/core.h:20:20: error: unknown type name 'HWND'
C:xailer3Include/core.h:20:31: error: unknown type name 'HWND'
C:xailer3Include/graphics.h:18:1: error: unknown type name 'BOOL'
C:xailer3Include/graphics.h:18:21: error: unknown type name 'HDC'
C:xailer3Include/graphics.h:18:30: error: unknown type name 'HBITMAP'
C:xailer3Include/Xailer.h:69:57: error: unknown type name 'BOOL'
....
....
4 Files, 4 Warnings, 126 Errors
Now, I know what the errors mean, of course. But where does Xailer have
the basic types defined?
#include "xailer.ch" is at the top of the source file, but it doesn't
seem to be sufficient to include any of the headers which define all of
these basic types.

[Guest]

fyi,
For anyone who has had these kinds of problems in the past, but were
simply ignored when they asked about it, and finally just gave up -
In the case of the type errors in core.h, they can be mostly resolved,
by including windef.h, in the core.h file.
You shouldn't have to include it there, but I don't see any other way.

[jfgimenez]

Dwayne,
> Are there some general guidelines, for porting over third-party
> libraries, which are mingw compatible (meaning, they are compiled with
> gcc), to interface with Xailer? For example, some mappings between C
> data types and Xailer?
When writing any C routine for [x]Harbour and/or Xailer, it's needed to
use the Harbour API in order to send and receive data between C and PRG
level. That API includes functions like hb_par*(), hb_ret*() and so on.
Xailer adds a few more ones, like XA_ObjSend*() and XA_ObjGet*().
Also, any function written in C which may be called from PRG level must
be declared as HB_FUNC( <funcname> ), HB_FUNC_STATIC( <funcname> ) or
XA_FUNC( <funcname> ). It's usual to write those functions in the same
PRG module, guarded by a #pragma BEGINDUMP and #pragma ENDDUMP
directives block.
Of course, it's needed at least a basic C knowledge. That's all. If you
have any problem when writing a "wrapper" or any other C routine, you
may ask here, providing, if possible, a small sample.
Regards,
Jose F. Gimenez
http://www.xailer.com
http://www.xailer.info

[jfgimenez]

Dwayne,
> C:xailer3ProjectsXailerYapSourceTestCInterface.prg:28:7 : warning:
> implicit declaration of function 'umask'
> [-Wimplicit-function-declaration]
Just #include the header file where that function is declared. In this
case, it's io.h
> Compiling: TestYInterface01.c...
> C:xailer3Include/core.h:19:19: error: unknown type name 'DWORD'
> C:xailer3Include/core.h:20:20: error: unknown type name 'HWND'
> C:xailer3Include/core.h:20:31: error: unknown type name 'HWND'
> C:xailer3Include/graphics.h:18:1: error: unknown type name 'BOOL'
> C:xailer3Include/graphics.h:18:21: error: unknown type name 'HDC'
> C:xailer3Include/graphics.h:18:30: error: unknown type name 'HBITMAP'
> C:xailer3Include/Xailer.h:69:57: error: unknown type name 'BOOL'
You have to #include "windows.h" just before #include "xailer.h". In
most cases, those are the only header files which have to be included
(in that specific order). That is:
#include "windows.h"
#include "xailer.h"
Regards,
Jose F. Gimenez
http://www.xailer.com
http://www.xailer.info

[jfgimenez]

Dwayne,
> For anyone who has had these kinds of problems in the past, but were
> simply ignored when they asked about it, and finally just gave up -
>
> In the case of the type errors in core.h, they can be mostly resolved,
> by including windef.h, in the core.h file.
>
> You shouldn't have to include it there, but I don't see any other way.
You have to #include "windows.h", as I've stated in the previous message.
Regards,
Jose F. Gimenez
http://www.xailer.com
http://www.xailer.info

[jfgimenez]

Dwayne,
> #include "xailer.ch" is at the top of the source file, but it doesn't
> seem to be sufficient to include any of the headers which define all
> of these basic types.
Xailer.ch is valid for PRG level, not for C level. Moreover, C and PRG
are at different levels, so, any header file included at PRG level is
not visible to C level, and viceversa. So, if you're using a #pragma
BEGINDUMP / #pragma ENDDUMP block, you have to #include any needed
header file inside that block. I.e.:
#include "Xailer.ch"
// here goes PRG code
#pragma BEGINDUMP
#include "windows.h"
#include "xailer.h"
// and here goes C wrappers and other C routines
#pragma ENDDUMP
// here continue the PRG code
Regards,
Jose F. Gimenez
http://www.xailer.com
http://www.xailer.info

[Guest]

Jose,
Sorry, I mean Xailer.h. That's what I placed in the c sources, but it
still generated the error.
However, after following your suggestion and placing the windows.h
BEFORE the Xailer header, it mostly worked.
There's still a couple of errors specifically related to the third party
library, but I can handle those.
Thanks for the suggestions. Can we put some of these general tips in an
official doc, or in wiki? Just this one tip - the order of the header
files - saves a lot of frustration.

[Guest]

Jose,
Yes, I understand the the hbapi is needed for interfacing directly to
third party libraries, as opposed to just calling one of their
DLL-supplied functions.
And yes, I have some c knowledge, although it's been years since doing
anything hard-core.
However, it shouldn't be necessary to review C, in order to compile some
simple code, that is already mingw-compatible, inside Xailer. If you
ask me to compile or modify some standalone c code, it's not difficult.
Just looking for some general tips, for interfacing with Xailer - like
putting windows.h before xailer.h, and maybe a link to some mappings
between the C types that we find, and how we use those in Xailer/Harbour.
Anyway, the code is much closer now, thanks.