[geometry] DOMQuad is weird

DOMQuad seems like the odd one out of the Geometry interfaces. It doesn’t have a ReadOnly variant, and, unlike DOMRect, its points are 3D DOMPoints (with x,y,w,z). In the WebKit implementation, we never have a need to store quads in 3D space; they only ever exist in the plane of an element. We do have code that tracks an accumulated matrix along with a planar quad when mapping through 3D rendering contexts, but the quads are only ever used once you flatten into the plane of an element.

Also, I think [SameObject] readonly attribute DOMPoint cause unwanted behavior for JS authors.


var quad = DOMQuad.fromQuad({ p1:{ x:11, y:12 }, p2:{ x:22, y:23 }, p3:{ x:33, y:34 }, p4:{ x:44, y:45 } });

var firstPoint = quad.p1;
firstPoint.x = 9999;

if (quad.p1.x == 9999)
    console.log(“what the hey”); <— this happens

I think it’s very counterintuitive for JS authors to have the points be “live” if you pass them to other parts of the code and then modify them.


Received on Tuesday, 18 October 2016 18:29:53 UTC