[PD-dev] Canvas and ojb/cnv arguments in .pd

[Martin Peach]

IOhannes m zmoelnig wrote:

> Dave S wrote:
>
>> Hello all,
>
>
>>
>> So, the question stands:
>> What is the last argument of [cnv] for?
>>
>> AS IN:
>> #X obj 0 0 cnv 15 768 22 cnv_heading_S cnv_heading_R 
>> All_About_Canvases 12
>> 12 0 14 -233017 -1 0;
>>
>>
>> Does anybody know?
>
>
> yes, thomas, who is the author of this object should know (tomorrow, 
> when he is in the office i could ask him)
>
> apart from that, the source-code should know....
>
> the arguments for the iemguis (these are the ones where you get the 
> fancy properties dialog) have undergone several generations of change.
> so it could be, that the last argument is just there for 
> compatibilites sake. (i tried talking thomas into putting an 
> "API-version"-argument into the argument list to make the parsing 
> simpler, but to no avail)
>
> furthermore, parts of the argument-handling are handled by a general
> "iemgui_args"-function. it might be, that this general approach has 
> some leftovers, e.g. unused arguments.
>
> looking at the c-code of the [cnv] (g_mycanvas.c, g_all_guis.c) it 
> seems, like the latter case is at least "not wrong". the value of the 
> 13th argument is used to turn on a "loadinit"-value (important for 
> [loadbang]-behaviour of e.g. [bng]; should be totally unused in the 
> [cnv]-case) and a "scale"-value (i think this turns on/off the "scale" 
> at the [vu])
>
> anything clear?


Almost. The function my_canvas_save in g_mycanvas.c stores the x_isa 
field of x_gui as an int.
x_isa is a 32-bit struct named t_iem_init_symargs, made up of the 
following (from g_mycanvas.h):

typedef struct _iem_init_symargs
{
    unsigned int x_loadinit:1;
    unsigned int x_rcv_arg_tail_len:6;
    unsigned int x_snd_arg_tail_len:6;
    unsigned int x_rcv_is_arg_num:6;
    unsigned int x_snd_is_arg_num:6;
    unsigned int x_scale:1;
    unsigned int x_flashed:1;
    unsigned int x_locked:1;
    unsigned int x_reverse:1; /* bugfix */
    unsigned int dummy:3;
} t_iem_init_symargs;

...so x_loadinit is one of 9 elements; are any of them actually used?

Martin