1465988 - clip-path: <geometry-box> (e.g., border-box, margin-box, padding-box, content-box) makes content disappear

Status: NEW

(Core :: Layout, enhancement, P3)

Description

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

Per the spec at https://drafts.fxtf.org/css-masking-1/#the-clip-path the <geometry-box> values of 'clip-path' can be specified with a shape or on their own.  With a shape, they seem to work reasonably, but on their own, the spec says:

  If specified by itself, uses the edges of the specified box, including
  any corner shaping (e.g. defined by border-radius [CSS3BG]), as clipping
  path. See also “Shapes from box values” [CSS-SHAPES].

Instead, Gecko seems to make the shape disappear.

In other words, 'border-box' alone should behave the same as 'inset(0 0 0 0)' or similar, but it doesn't appear to do so.  (With border-radius, things should be a little more interesting.)

Comment 1

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

Attachment: testcase

Comment 2

[Boris Chiou [:boris]]

It seems Gecko doesn't implement "Shapes from box values" properly, either. There is a recent wpt update and these tests are failed: https://bugzilla.mozilla.org/show_bug.cgi?id=1852288