Use DOMPoint instead of Point2D?

[dontcallmedom]

from @w3ctag 's review @travisleithead:

Consider allowing a DOMPoint in places where a Point2D dictionary could be used (DOMPoint from http://www.w3.org/TR/geometry-1/#DOMPoint). The DOMPoint handles points in 3d space, but the 'z' and 'w' coordinates are not required, and this may be useful for platform consistency.

[yellowdoge]

DOMPoint is an interface needing all its attributes x,y,z,w (I don't see any indication of z and w being not required), whereas Point2D is a dictionary with just x and y.

Moreover, DOMPoint is not 'just' a cartesian point but a 3D point with a perspective w attached to it (although this is by default 1.0) --The reason for this pseudo-quaternion situation is that DOMPoint is meant to play nicely with transformation DOMMatrixes.

Using DOMPoint would be confusing for users, since two of the said DOMPoint attributes are not used in this case but they actually relate to the mathematics of perspective cameras. Perhaps DOMPoint should be renamed to DOMPoint3D and a DOMPoint2D added to the Geometry interfaces Spec.

Finally, if any of the Geometry Interfaces would be needed, DOMRect would be the least removed one.

[domenic]

Because Point2D is only used in dictionaries, the distinction is very slight. If DOMPointInit was used (not DOMPoint; that would be bad) then inputs like { x: 1, y: 2, get z() { throw new Error("z"); } } would throw when being converted to a DOMPointInit, even though the plan is to ignore the z (and w). Whereas in the current spec, given such input the z (and w) are ignored, so it would not throw. So I think Point2D as used here is the right choice.

However, if the points were ever exposed externally (e.g. as attribute values or method return values), then DOMPoint might be a better choice, for platform harmony. I can't find any such instances in the spec right now.

[yellowdoge]

getSettings() returns a MediaTrackSettings that has a sequence<Point2D> representing the current points/areas used for A3 calculation.

[yellowdoge]

@domenic I'm closing this issue, plz reopen or shout if this is not intended, thanks!

[travisleithead]

Works for me.