[fxtf-drafts] [css-masking] Definition of `mask-clip` not compatible with SVG masks

AmeliaBR has just created a new issue for https://github.com/w3c/fxtf-drafts:

== [css-masking] Definition of `mask-clip` not compatible with SVG masks ==
The [`mask-clip` property](https://drafts.fxtf.org/css-masking-1/#the-mask-clip) as defined in CSS Masking 1:

> Determines the mask painting area, which determines the area that is affected by the mask. The painted content of an element must be restricted to this area.

The initial value and fallback rules mean that the default for elements with SVG layout is `fill-box`.  However, for SVG `<mask>` element masks, the exact clipping region is set by attributes on the `<mask>` element (`x`, `y`, `width`, `height` and `maskUnits`).  The default (if those attributes aren't specified) is to use the fill-box plus 10% padding on each side.

I think the easiest solution is to update the definition of `mask-clip` to make it clear that it does not apply to SVG `<mask>` element masks, which define their own clipping region.

(Note, however, that I'd still want [`mask-origin`](https://drafts.fxtf.org/css-masking-1/#the-mask-origin) to apply to `<mask>` element masks, to define whether the "object bounding box" used to scale the mask should be the `fill-box`, `stroke-box`, or one of the CSS layout boxes.  But that definition should probably also be made more explicit.)


Please view or discuss this issue at https://github.com/w3c/fxtf-drafts/issues/185 using your GitHub account

Received on Sunday, 4 June 2017 17:52:12 UTC