Re: [LAD] [RFC] LADSPA 1.2

On Thu, Jun 18, 2009 at 06:28:32PM +0200, Jörn Nettingsmeier wrote:

> 2. addition of a port range hint flag LADSPA_HINT_ENUMERATED to inform
> hosts that an integer-type port (as denoted by LADSPA_HINT_INTEGER)
> should be annotated with a set of labels rather than numbers.
>
> LADSPA_HINT_ENUMERATED mandates the following:
> LADSPA_HINT_INTEGER is set.
> LADSPA_HINT_BOUNDED_BELOW and LADSPA_HINT_BOUNDED_ABOVE must be set.
> in LADSPA_PortRangeHint, LowerBound must be 0, UpperBound must be >0.
> the number of labels provided must be equal to (UpperBound - 1).

??? This should be (UpperBound + 1) AFAICS

Example: legal values = 0,1,2,3,4

Upperbound = 4, number of labels = 5

 
> some of these mandatory settings are redundant and could be handled
> as being implicit.
> however, for the sake of backwards compatibility and to to allow
> older hosts to display a meaningful UI even if they don't implement
> the new flag yet, all these items MUST be set.
>
> as to the location of the actual enum of labels: fons adriaensen
> suggests adding them to the end of the PortNames array.
> this implies that for multiple enum-labelled controls, the labels
> would have to be concatenated and the host would have to tell them
> apart by keeping track of the corresponding UpperBound offsets, which
> might become a little messy. your comments are welcome.

This makes is backwards compatible, as no new field is required
in the descriptor struct.

Host will need to use the value (UpperBound + 1) no matter
where these strings get stored. A host looping over the port
data should just initialise a pointer:

const char **enum_labels = descriptor->PortNames + descriptor->PortCount;

for (i = 0; i < descriptor->PortCount; i++)
{
    // ...
    if (enum_hint_is_set)
    {
         int nlabels = upperbound + 1;
         // Copy 'nlabels' and 'enum_labels' to where you want
         // them, normally something representing the widget.
         // Copy the strings to the widget if necessary.
         enum_labels += nlabels;
    }
    // ...
}

And that's all. The loop and everything in it, the 'if',
the 'nlabels' and the commented parts will be needed anyway,
the only 'typical' code are the two lines initialising and
incrementing 'enum_labels'. I don't think it could be any
simpler.

-- 
FA
Io lo dico sempre: l'Italia è troppo stretta e lunga.
_______________________________________________
Linux-audio-dev mailing list
Linux-audio-dev@email-addr-hidden
http://lists.linuxaudio.org/mailman/listinfo/linux-audio-dev