Re: kAudioUnitProperty_ContextName
Re: kAudioUnitProperty_ContextName
- Subject: Re: kAudioUnitProperty_ContextName
- From: William Stewart <email@hidden>
- Date: Tue, 27 Jul 2004 12:03:55 -0700
Stefan,
On 27/07/2004, at 9:58 AM, Stefan Gretscher wrote:
>
Am 27.07.2004 um 18:25 schrieb William Stewart:
>
> we'll add support to this in AUBase before we revise the SDK.
>
Great, thank you!
>
>
>>> 1) Should the text (the property's value) include the AU's name
>
>>> plus
>
>>> extra context info, or only the extra context info? In other words,
>
>>> let's say for example I had the plugin "Robocop FX" inserted on
>
>>> track
>
>>> 3. Would a possible ContextName be something like "Robocop FX:
>
>>> track
>
>>> 3" or just "track 3"?
>
>> In my opinion it only should contains "track 3", because each AU
>
>> knows
>
>> its name and can add it or not as applicable. Adding strings is
>
>> easier
>
>> then removing the name to get the pure context string.
>
> The AU shouldn't care what is in the String and furthermore the AU
>
> shouldn't modify the string in any way.
>
Ofcourse it is not allowed to modify the property string itself, I was
>
talking
>
about processing a copy of the string further for presenting it to the
>
user
>
in some appropriate way in a dialog or on the GUI.
>
>
> So either approach would be appropriate but I would think the common
>
> usage would be to just set the "track 3" string, rather than the full
>
> name
>
I think so too.
>
>
> The property can be cleared by setting the property with a NULL value
>
> (so the AU *has* to check for NULL before retaining the value when the
>
> property is set)
>
>
> I think it would be better if the current value of the property is
>
> NULL
>
> for the AU to return:
>
> kAudioUnitErr_InvalidPropertyValue
>
As it is legal for the host to set NULL to clear the context (as you
>
stated above),
>
I'd much prefer that the AU should not return an error if the current
>
context is
>
NULL. Why return an error if it's a legal, perfectly normal condition?
OK - the Carbon View already does look for this property and checks
both for noErr and the string is NULL, so I'll go with that.
Just a note to any AU Developers doing this - this string should *not*
be a part of a preset - its the host's responsibility to set this on an
AU when its using it based on the context of use..
Bill
>
>
> That way, if noErr is returned the host knows that the string returned
>
> is valid and doesn't have to check for NULL?
>
Checking for NULL is always a good idea when dealing with plug-ins. ;-)
>
>
Best,
>
>
Stefan Gretscher
>
>
plug-in development & 3rd party plug-in support
>
Emagic Soft- & Hardware GmbH
>
>
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