[mediacapture-screen-share] Clarify that we only process (including TypeError) applicable constraints (#95)

jan-ivar has just created a new issue for https://github.com/w3c/mediacapture-screen-share:

== Clarify that we only process (including TypeError) applicable constraints  ==
Spec says: *"For each member present in constraints whose value, value, is a dictionary, run the following steps:"*

This is too broad a pre-processing of constraints, and goes against https://github.com/w3c/mediacapture-main/pull/542.

It's also hard to implement, as WebIDL bindings typically map dictionaries to `struct` in c++, with no obvious way to enumerate dictionary members—nor should we do this, as it's a design problem that MediaTrackConstraintSet cuts across spec domains like this.

For example, screen sharing has no audio constraints (because audio constraints are *microphone* constraints). Terminology baggage.

I'll add a PR to clarify that we only throw on "applicable" constraints, which are the [ones explicitly listed in the screen share spec](https://w3c.github.io/mediacapture-screen-share/#constrainable-properties).

Please view or discuss this issue at https://github.com/w3c/mediacapture-screen-share/issues/95 using your GitHub account

Received on Thursday, 20 December 2018 15:07:33 UTC