Hi,

I want to use som functions from the imagemagick C api. How do I do that? How do I call the functions and objects and how do I link with the dll's?

here's a templated class lib I wrote to help with dll loading ('cos I like
the delphi extern "foo.dll"; )
and an example (loads winmm.dll to all access to multimedia timers)
due to D's templateing its a little verbose, but works ...

first make instances of the types of functions you want to import
e.g. `extern (windows) DWORD func();`
instance DynFunc( Windows, DWORD ) noParamReturnsDword;

the declare a func pointer to it (using the template instance)
`<instance>.fp` e.g. ....
noParamReturnsDword.fp myFunc;

// now write a static initialiser to your module to load the dll and get the
function.
// there are two ways to do this both have the same result but its personal
preference which you use
static this()
{
// fp = <template>.require( <dll name>, <func_name> ); // I perfer this
myFunc = I_I_Ldr.require( "foo.dll", "someFuncname" );
// <template>.use( fp, <dll name>, <func_name> );
noParamReturnsDword.use( myFunc,   "foo.dll", "someFuncname" );
}

for C fucntions use
instance DynFunc( C, <return_type>, <param1>, <param2> .... ) somename;
if the return type is void due to D templates you can't use
instance DynFunc( C, void, int );
instead you have to use DynProc( C, int );
or DyncProc( C ) => extern(C) void func( void );

to do it manually here the code that loads up and gets a directx d3d
interface from the function
`Direct3DCreate8` in `d3d8.dll`

extern(Windows) alias IDirect3D8 function( UINT ) start_up_fp;

IDirect3D8 loadD3DLibs() {
 HMODULE sysModule;
 sysModule = LoadLibraryA( "d3d8.dll" );   // load a dll
 FARPROC fp = GetProcAddress( sysModule, cast(char*)"Direct3DCreate8" ); //
get a function pointer
 assert(fp);
 start_up_fp dxfp = cast(start_up_fp)fp;
 return dxfp(D3D_SDK_VERSION);
}

failing all that .... use implib to convert the dll to a .lib and just write
the functions as
extern( C ) .....
or extern(Windows) .....
the linker will the link correctly against <foo>.dll if you link against the
created lib file.


"Mårten Ask" <majbritt37@hotmail.com> wrote in message news:bhb9cs$1eq3$1@digitaldaemon.com...
> Hi,
>
> I want to use som functions from the imagemagick C api. How do I do that? How do I call the functions and objects and how do I link with the dll's?
>
>

Thanks!

I haven't had time to try it out yet..

There's still one thing that puzzles me though. Structs. how do I declare that I want a struct from the dll? From the imagemagick api:

typedef struct _MagickWand
  MagickWand;
  ...
extern MagickExport MagickWand
  *MagickCloneWand(const MagickWand *),
  *MagickCoalesceImages(MagickWand *),
  *NewMagickWand(void);
  ...

Obviously I need to declare those functions as 'extern (C) MagickWand
NewMagickWand()' but then the compiler complains about not knowing what a
MagickWand is. Do I write 'extern (C) struct MagickWand'? Or 'extern (C)
typedef MagickWand'?



"Mike Wynn" <mike.wynn@l8night.co.uk> skrev i meddelandet news:bhbaa0$1ftb$1@digitaldaemon.com...
>
> here's a templated class lib I wrote to help with dll loading ('cos I like
> the delphi extern "foo.dll"; )
> and an example (loads winmm.dll to all access to multimedia timers)
> due to D's templateing its a little verbose, but works ...
>
> first make instances of the types of functions you want to import
> e.g. `extern (windows) DWORD func();`
> instance DynFunc( Windows, DWORD ) noParamReturnsDword;
>
> the declare a func pointer to it (using the template instance)
> `<instance>.fp` e.g. ....
> noParamReturnsDword.fp myFunc;
>
> // now write a static initialiser to your module to load the dll and get
the
> function.
> // there are two ways to do this both have the same result but its
personal
> preference which you use
> static this()
> {
> // fp = <template>.require( <dll name>, <func_name> ); // I perfer this
> myFunc = I_I_Ldr.require( "foo.dll", "someFuncname" );
> // <template>.use( fp, <dll name>, <func_name> );
> noParamReturnsDword.use( myFunc,   "foo.dll", "someFuncname" );
> }
>
> for C fucntions use
> instance DynFunc( C, <return_type>, <param1>, <param2> .... ) somename;
> if the return type is void due to D templates you can't use
> instance DynFunc( C, void, int );
> instead you have to use DynProc( C, int );
> or DyncProc( C ) => extern(C) void func( void );
>
> to do it manually here the code that loads up and gets a directx d3d
> interface from the function
> `Direct3DCreate8` in `d3d8.dll`
>
> extern(Windows) alias IDirect3D8 function( UINT ) start_up_fp;
>
> IDirect3D8 loadD3DLibs() {
>  HMODULE sysModule;
>  sysModule = LoadLibraryA( "d3d8.dll" );   // load a dll
>  FARPROC fp = GetProcAddress( sysModule, cast(char*)"Direct3DCreate8" );
//
> get a function pointer
>  assert(fp);
>  start_up_fp dxfp = cast(start_up_fp)fp;
>  return dxfp(D3D_SDK_VERSION);
> }
>
> failing all that .... use implib to convert the dll to a .lib and just
write
> the functions as
> extern( C ) .....
> or extern(Windows) .....
> the linker will the link correctly against <foo>.dll if you link against
the
> created lib file.
>
>
> "Mårten Ask" <majbritt37@hotmail.com> wrote in message news:bhb9cs$1eq3$1@digitaldaemon.com...
> > Hi,
> >
> > I want to use som functions from the imagemagick C api. How do I do
that?
> > How do I call the functions and objects and how do I link with the
dll's?
> >
> >
>
>
>

"Mårten Ask" <majbritt37@hotmail.com> wrote in message news:bhjaf3$348$1@digitaldaemon.com...
> Thanks!
>
> I haven't had time to try it out yet..
>
> There's still one thing that puzzles me though. Structs. how do I declare that I want a struct from the dll? From the imagemagick api:

the compiler only needs to know about the struct layout, this is usually in
the c header
some times you will find typedef struct _foo { } * ApiToken;
either way the dll does not "export" the struct layout.

if the dll contains a struct then I assume its
struct foo { int a; }
extern (C) foo in_dll;
I've only every used "getProcAddress" or implicit linking I'm not sure what
VC++/Windows does with dll's contain data too, guess I better read some docs
might be useful!!

read on about how to declare the struct;
>
> typedef struct _MagickWand
>   MagickWand;
>   ...
> extern MagickExport MagickWand
>   *MagickCloneWand(const MagickWand *),
>   *MagickCoalesceImages(MagickWand *),
>   *NewMagickWand(void);

you need to know what the _MagicWand struct looks like .. also note the use of align.

struct Foo { align(1):
    byte a, b;
    int missaligned;
};

struct Foo2 { align(4):
    byte a, b;
    int aligned;
    align(1):
    byte c;
    int offby1;
};

(the default for D and C is to align items at their size (works on CISC and
RISC then))

only the functions need to be extern(C) etc

extern(C) :
    Foo * getFooFromFoo2( Foo2* );
    Foo*  getContext();
etc...

asfaik (Walter correct me here if I'm wrong) the only time making a struct,
alias or typedef
as extern(CONV) is if it contains a pointer to func that you want to have
that calling convention.

although is does help document the code to have
extern(C) struct MyStruct { align(4):
    int a, b, c, d;
}
(implies that its for use with extern(C) funcs).

>   ...
>
> Obviously I need to declare those functions as 'extern (C) MagickWand
> NewMagickWand()' but then the compiler complains about not knowing what a
> MagickWand is. Do I write 'extern (C) struct MagickWand'? Or 'extern (C)
> typedef MagickWand'?
>
>
>
> "Mike Wynn" <mike.wynn@l8night.co.uk> skrev i meddelandet news:bhbaa0$1ftb$1@digitaldaemon.com...
> >
> > here's a templated class lib I wrote to help with dll loading ('cos I
like
> > the delphi extern "foo.dll"; )
> > and an example (loads winmm.dll to all access to multimedia timers)
> > due to D's templateing its a little verbose, but works ...
> >
> > first make instances of the types of functions you want to import
> > e.g. `extern (windows) DWORD func();`
> > instance DynFunc( Windows, DWORD ) noParamReturnsDword;
> >
> > the declare a func pointer to it (using the template instance)
> > `<instance>.fp` e.g. ....
> > noParamReturnsDword.fp myFunc;
> >
> > // now write a static initialiser to your module to load the dll and get
> the
> > function.
> > // there are two ways to do this both have the same result but its
> personal
> > preference which you use
> > static this()
> > {
> > // fp = <template>.require( <dll name>, <func_name> ); // I perfer this
> > myFunc = I_I_Ldr.require( "foo.dll", "someFuncname" );
> > // <template>.use( fp, <dll name>, <func_name> );
> > noParamReturnsDword.use( myFunc,   "foo.dll", "someFuncname" );
> > }
> >
> > for C fucntions use
> > instance DynFunc( C, <return_type>, <param1>, <param2> .... ) somename;
> > if the return type is void due to D templates you can't use
> > instance DynFunc( C, void, int );
> > instead you have to use DynProc( C, int );
> > or DyncProc( C ) => extern(C) void func( void );
> >
> > to do it manually here the code that loads up and gets a directx d3d
> > interface from the function
> > `Direct3DCreate8` in `d3d8.dll`
> >
> > extern(Windows) alias IDirect3D8 function( UINT ) start_up_fp;
> >
> > IDirect3D8 loadD3DLibs() {
> >  HMODULE sysModule;
> >  sysModule = LoadLibraryA( "d3d8.dll" );   // load a dll
> >  FARPROC fp = GetProcAddress( sysModule, cast(char*)"Direct3DCreate8" );
> //
> > get a function pointer
> >  assert(fp);
> >  start_up_fp dxfp = cast(start_up_fp)fp;
> >  return dxfp(D3D_SDK_VERSION);
> > }
> >
> > failing all that .... use implib to convert the dll to a .lib and just
> write
> > the functions as
> > extern( C ) .....
> > or extern(Windows) .....
> > the linker will the link correctly against <foo>.dll if you link against
> the
> > created lib file.
> >
> >
> > "Mårten Ask" <majbritt37@hotmail.com> wrote in message news:bhb9cs$1eq3$1@digitaldaemon.com...
> > > Hi,
> > >
> > > I want to use som functions from the imagemagick C api. How do I do
> that?
> > > How do I call the functions and objects and how do I link with the
> dll's?
> > >
> > >
> >
> >
> >
>
>