468137 - printing reftests cut of part of the content

Status: NEW

(Testing :: Reftest, defect)

Description

[David Baron :dbaron: (⌚️UTC-5, no longer working on Mozilla)]

Attachment: reftest image showing problem

When looking at the images for the media query tests that are going to land for bug 466171, one of the paragraphs on the second page is partly cut off.  This seems quite odd, since the markup and style applied are quite simple.  Given that we're not getting massive numbers of bugs on problems like this, I suspect it's a problem specific to the reftest harness's way of doing printing.

Attached is the image that reftest is using for comparison.  Note that the bottom part of the "o" is cut off.  Since it's only part of a line, it's not interfering with the function of these tests, but it could be interfering with others.

Comment 1

[Eli Friedman]

One possibility is that font metrics are off... I thought I had that working consistently, but there might be issues; it's naturally confusing because screen and print fonts aren't consistent.  It should be easy to test if that's the issue, though: just put an outline around all the paragraphs, and if the characters leak out, that's the issue.

The other possibility I can think of is just that the layout and paint rectangles aren't being computed consistently in the layout mode the reftests use, like maybe some wrong computation in nsPageFrame; this somehow strikes me as unlikely, but it's quite possible.