306410 - blocks with negative text-indent overlap at certain sizes

Status: RESOLVED FIXED

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

Description

[Rob Marshall [tH]]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8b4) Gecko/20050829 Firefox/1.0+
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8b4) Gecko/20050829 Firefox/1.0+

Using the font and text indent that I used on my website, some list items
overlap. Changing the font size or text indent by 0.01em fixes the problem.

Reproducible: Always

Steps to Reproduce:
1. Open testcase.
Actual Results:  
Some of the list items - April, June, and Tags - overlap the previous one.

Expected Results:  
No overlapping, all list items displayed with the same height.

Comment 1

[Rob Marshall [tH]]

Attachment: testcase

Comment 2

[Ronald Tilby]

Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9a1) Gecko/20051008
Firefox/1.6a1
Confirmed, testcase and URL exhibit the problem on current trunk build.

Comment 3

[Boris Zbarsky [:bzbarsky]]

This happens whenever the negative text-indent is exactly equal to the width of the text in the block.  The code I _think_ is to blame is in nsLineLayout::VerticalAlignFrames :

      if ((psd->mX != psd->mLeftEdge) || preMode || foundLI) {
...
      else {
        // XXX issues:
        // [1] BR's on empty lines stop working
        // [2] May not honor css2's notion of handling empty elements
        // [3] blank lines in a pre-section ("\n") (handled with preMode)
...
        minY = maxY = 0;
      }

In this case, psd->mX != psd->mLeftEdge tests false, since the text-indent exactly cancels out the width of the text...

Comment 4

[Boris Zbarsky [:bzbarsky]]

Attachment: 100% reproducible testcase; needs Ahem font

Comment 5

[shadytrees]

Attachment: Reproducible testcase that only needs Arial (ignore other stuff)

Reproducible on latest-trunk (2006.11.23), both Windows and Linux (Cairo on)

Comment 6

[Robert O'Callahan (:roc) (email my personal email if necessary)]

Fixed on trunk, almost certainly by bug 400813.