[svgwg] Support for 3D ancestor transforms in `getScreenCTM()`

BigBadaboom has just created a new issue for 
https://github.com/w3c/svgwg:

== Support for 3D ancestor transforms in `getScreenCTM()` ==
https://svgwg.org/svg2-draft/single-page.html#types-__svg__SVGGraphicsElement__getScreenCTM

Should the definition of `getScreenCTM()` make any comment on how 3D 
transforms on ancestor (HTML) elements should be handled?  From my 
experimentation, it seems Chrome does attempt to support this (but is 
currently bugged).  Firefox does not seem to have updated 
`getScreenCTM()` for SVG2 yet.

https://jsfiddle.net/r8887x05/1/

```
<div id="mydiv" style="transform: translate(1px,0) scale(2)">
  <svg>
    <circle id="mycircle" cx="50" cy="50" r="10"/>
  </svg>
</div>

var div = document.getElementById('mydiv');
var circle = document.getElementById('mycircle');
console.log("before=", circle.getScreenCTM());
div.setAttribute("style", "transform: translate3D(1px,0,0) scale(2)");
console.log("after=", circle.getScreenCTM());
```

Chrome results *(bug? scale transform is reflected in e and f, but not
 a and d)*:
```
before= SVGMatrix { a: 1, b: 0, c: 0, d: 1, e: -335.5, f: -69 }
after= SVGMatrix { a: 1, b: 0, c: 0, d: 1, e: -335.5, f:-69 }
```

Firefox results *(ancestor transforms have no effect)*:
```
before= SVGMatrix { a: 1, b: 0, c: 0, d: 1, e: 8, f: 8 }
after= SVGMatrix { a: 1, b: 0, c: 0, d: 1, e: 8, f: 8 }
```


Please view or discuss this issue at 
https://github.com/w3c/svgwg/issues/302 using your GitHub account

Received on Wednesday, 4 January 2017 06:38:10 UTC