[css3-images] Generalize the notion of 'invalid images' for image() fallback

This is something I meant to file on myself a while ago, but forgot about. :/

Before this morning, the image() function only skipped an image if it
was a format that the UA couldn't decode or knew wasn't an image.
While addressing some LC feedback, I broadened this to also skip an
image if it's a URL that uses a fragment identifier syntax the UA
doesn't understand.

I'd like to slightly broaden this "invalid image" definition so that
other features can hook into it.  Specifically, I'd like to allow
element() to trigger fallback in image() if it hits one of the "error"
cases that currently produce a transparent image.  If element() is
used alone, it would still produce a transparent image as currently
specified; it would just trigger fallback if used in image().

With an explicit hook, other sources of <image> could potentially hook
into this as well, though I'm not currently aware of anything else
that would want to.

Any objections?


Received on Wednesday, 22 February 2012 18:58:19 UTC