172661 - nsIFrame::CheckVisibility() doesn't handle enough cases

Status: RESOLVED INVALID

(Core :: Layout, defect)

Description

[Aaron Leventhal]

CheckVisibility() is not checking to see if a frame has visibility:hidden or
visibility:collapsed. 

Shouldn't CheckVisibility() return false when something is hidden that way?

I haven't tested what happens when something is hidden via zindex, but I guess
that should be supported as well, if it isn't.

Comment 1

[Aaron Leventhal]

Does CheckVisibility say something is invisible if it's scrolled off screen?
If so, I suppose we can't just simply use CheckVisibility from nsFind to
determine if a range returned is visible, because it needs to find things that
are off-screen too.

Comment 2

[Aaron Leventhal]

Why is attinasi still the owner for layout bugs. Is he still active in Mozilla?

Comment 3

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

CheckVisibility seems to be used for selection.  Should we still be able to
select things with 'visibility: hidden'?  Should we scroll to them?  I think the
answer to both is yes.  (See CSS2 11.2 for the little text to go by.)

(BTW, layout is going to be split, with new component owners, whenever the split
is actually done.  See bug 160347.)

Comment 4

[Aaron Leventhal]

CheckVisibility is a bad name then, because it sounds like it has something to
do with the "visibility: blah" styles.

Maybe the various CheckVisibility methods should take another argument?
Either
 out boolean invisibleeViaStyle
or
 in boolean allowInvisibleViaStyle
 (which would affect how the return value is computed)

Comment 5

[Aaron Leventhal]

CC'ing mjudge, to comment on whether elements invisible through CSS should be
selectable.

Personally I don't think visibility: hidden or visibility: collapse should be
selectable. Currently, display: none stuff is not selectable, and I think it
should behave like that.

What if a user selects text and gets a bunch of stuff that's not on the page?

Comment 6

[Aaron Leventhal]

Aha, why we have IsVisibleForPainting(), although it requires the creation of a
device context to use it. It's just easier to use frame->GetStyleContext and go
from there.

Marking INVALID