Re: [Vala] LADSPA bindings

[Victor Aurélio Santos <victoraur santos gmail com>]

Thank you very much, Aaron

There's only a thing to change, in the connect_port delegate
DataLocation is a pointer to a float not a float, but changing to
"Data?" solved.

2016-09-13 14:19 GMT-03:00 Aaron Andersen <aaron fosslib net>:
> Hello Victor,
>
> You have chosen one of the more difficult C libraries to bind to Vala. The
> way this library is setup so contrary to the GObject way of doing things it
> is certainly an edge case.
>
> Unfortunately this library requires a small C header "helper" file to
> accompany your vapi. The main reason for this is that Vala doesn't deal with
> unnamed function pointers.
>
> I've gone ahead and created ladspa.vapi, ladspa-vala.h (a C header "helper"
> file to make Vala work with the ladspa library), and main.vala (a test
> program I used to ensure the vapi was correct).
>
> main.vala - http://pastebin.com/VF9AXrLY
> ladspa.vapi - http://pastebin.com/WeaKPHnc
> ladspa-vala.h - http://pastebin.com/GB4kPzw1
>
> I placed all of these 3 files into a single directory and then ran this
> command to compile:
>
> valac --pkg ladspa --vapidir . main.vala --save-temps -X -L/usr/lib/ladspa/
> -X -l:amp.so -X -I.
>
> and this command to run the program:
>
> LD_LIBRARY_PATH=/usr/lib/ladspa/ ./main
>
> From reading the documentation I understand that the ladspa framework
> intends for the user to dynamically load plugins via dlopen but I hope you
> get the idea from the example.
>
> Please don't hesitate to ask any questions about this code.
>
> Thank you,
> Aaron
>
> Quoting Al Thomas <astavale yahoo co uk>:
>
> > > ----- Original Message -----
> > > From: Victor Aurélio Santos <victoraur santos gmail com>
> > > Sent: Tuesday, 13 September 2016, 15:55
> > > Subject: Re: [Vala] LADSPA bindings
> >
> >
> > > Now...
> >
> >
> > > [CCode (cname = "connect_port", has_target = false)]
> > >     public delegate void DescriptorConnectPort(Handle? instance, ulong
> > > port, ref double dataLocation);
> >
> >
> > > results in:
> > > src/CompressorBackend.c: In function ‘ajami_compressor_backend_connect’:
> > > src/CompressorBackend.c:674:2: error: unknown type name ‘connect_port’
> > >  connect_port _tmp2_ = NULL;
> >
> >
> >
> > I presume there's no typedef for it then. Instead try:
> >
> > [CCode (lower_case_cprefix = "", has_target = false)]
> > public delegate void ConnectPort(Handle? instance, ulong
> > port, ref double dataLocation);
> >
> > The lower_case_cprefix should remove the default namespace prefix
> > and then ConnectPort will be converted to connect_port in C.
> >
> > That's my interpretation of the last paragraph of:
> > https://wiki.gnome.org/Projects/Vala/LegacyBindings#Delegates
> >
> > If that doesn't work, I'm not sure what else to suggest. The paragraph
> > could
> > mean include an empty cname, e.g.
> >
> >
> > [CCode (cname = "", has_target = false)]
> > public delegate void DescriptorConnectPort(Handle? instance, ulong
> > port, ref double dataLocation);
> >
> >
> > Use the --ccode switch with valac to get the C code produced. Look at the
> > code and tweak it until it works then work back to the VAPI. You can use
> > valac to compile C. Just use valac --pkg xyz my_c_file.c
> > _______________________________________________
> > vala-list mailing list
> > vala-list gnome org
> > https://mail.gnome.org/mailman/listinfo/vala-list



-- 
Victor Aurélio Santos