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Return value of getSupportedConstraints (Re: [Bug 26654] WebIDL types needed in Constrainable application)

From: Harald Alvestrand <harald@alvestrand.no>
Date: Fri, 10 Oct 2014 10:36:19 +0200
Message-ID: <54379A83.8060305@alvestrand.no>
To: public-media-capture@w3.org
I think Jan-Ivar's request #36 is uncontroversial, but I'd like some 
list discussion on #37.

The important change is that we use MediaTrackConstraintSet as the 
return value for getCapabilities, getSettings and getSupportedConstraints.

What we previously thought, and what the change means:

- getCapabilities returns a constraint set that indicates "the maximum 
supportable values". I think using MediaTrackConstraintSet is 
uncontroversial here.

- getSettings returns something with the same keys as a constraint set, 
and values of the same type as the type of the constraint set. Returning 
bare values in a MediaTrackConstraintSet is a bit odd (since the 
semantic of a bare value is "ideal" when it's passed in the other 
direction), but seems not too odd to me.

- getSupportedContraints returned a dictionary where the keys are the 
same as for the constraint set, and where the values are all "true" for 
supported constraints (and missing for non-supported constraints, 
naturally). Using MediaTrackConstraintSet means that the values have to 
be of the corresponding types, and be "truthy" - which means that we 
need special treatment for constraints that have the possibility of 
being zero, empty string or other "falsy" things. This seems a bit iffy.

Are there other ways to skin this cat?


On 10/09/2014 04:14 PM, bugzilla@jessica.w3.org wrote:
> https://www.w3.org/Bugs/Public/show_bug.cgi?id=26654
> --- Comment #3 from Stefan Hakansson LK <stefan.lk.hakansson@ericsson.com> ---
> (In reply to Jan-Ivar Bruaroey [:jib] from comment #2)
>> Pull request: https://github.com/w3c/mediacapture-main/pull/22
> That one has been removed.
> New PR's: https://github.com/w3c/mediacapture-main/pull/36 and
> https://github.com/w3c/mediacapture-main/pull/37
Received on Friday, 10 October 2014 08:36:59 UTC

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