1045877 - vertical offset of absolutely positioned box ignores vertical positioning of its relatively positioned inline parent

Status: NEW

(Core :: Layout: Block and Inline, defect)

Description

[Greg Whitworth]

User Agent: Mozilla/5.0 (Windows NT 6.4; WOW64; Trident/7.0; .NET4.0E; .NET4.0C; .NET CLR 3.5.30729; .NET CLR 2.0.50727; .NET CLR 3.0.30729; InfoPath.3; rv:11.0) like Gecko

Steps to reproduce:

http://css-class.com/test/css21testsuite/abs-pos-child-inside-rel-pos-inline-offset-002.html

Open up the test case and compare with Chrome and IE. This was discussed on the W3C mailing list and it was resolved that IE and Chrome are setting the offsets correctly. http://lists.w3.org/Archives/Public/www-style/2014Jul/0218.html


Actual results:

Firefox is moving the abs box horizontally based on the offset of its parent but not vertically.


Expected results:

It should move both horizontally and vertically based on its parent. In the test case it is only testing vertically as that is what was discussed on the mailing list.

Comment 1

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

It looks like we get the expected behavior if the inline is in some way non-empty (for example, if I add a 1px left border to the #rel-pos-inline).  It seems like the empty inline is somehow ignoring its relative positioning.

Comment 2

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

Er, never mind, it's not about emptiness , and the original description was better.

Comment 3

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

Attachment: testcase

current contents of http://css-class.com/test/css21testsuite/abs-pos-child-inside-rel-pos-inline-offset-002.html

Comment 4

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

I suspect the basic problem is order of computation.  In inline layout we do:
 1. Reflow
 2. nsBlockFrame::PlaceLine
    a. nsLineLayout::VerticalAlignLine
    b. nsLineLayout::RelativePositionFrames

We presumably position the absolutely position descendants inside (1), but we need to wait until after 2b.