1416479 - Some characeters are truncated

Status: UNCONFIRMED

(Core :: Layout: Text and Fonts, defect, P3)

Description

[Julien Palard]

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:57.0) Gecko/20100101 Firefox/57.0
Build ID: 20171018030234

Steps to reproduce:

Version 47b09, I was reviewing a PR on github : https://github.com/python/python-docs-fr/pull/77/files




Actual results:

Some characeters were truncated.

I tried to take a screenshot via the new screenshot utility but the rendered screenshot was *not* affected by the issue.

So I took a picture of my screen with my phone: https://www.dropbox.com/s/fasee8khzsg4sqv/2017-11-11%2015.24.43.jpg?dl=0

In the "utilisation" word, the "l" letter is missing some pixels, It may not be obvious at first glance, but I noticed later a more obvious case, right after "options" there's:

``[ -V |

But the double backtick is just not rendered, and the upper part of the bracket isn't.


Expected results:

I expected character to be rendered, I almost commented with "please don't forget the double backticks" before realising.

Comment 1

[Mathieu Leplatre [:leplatrem]]

Attachment: Screenshot from 2018-08-14 15-13-33.png

Comment 2

[Mathieu Leplatre [:leplatrem]]

I have the same problem on Nightly Linux (see screenshot)

Note: WebRender is unavailable by runtime: Hardware compositing is disabled

Comment 3

[Jonathan Kew [:jfkthame]]

Is the font being used here Liberation Mono, by any chance? If so, I suspect this may be due to bad "typographic ascent/descent" metrics in the font, as noted in bug 1480420.

Comment 4

[Mathieu Leplatre [:leplatrem]]

Bingo! Indeed, it is. I saw this on Github.

Comment 5

[Jonathan Kew [:jfkthame]]

Aha, that helps to explain it. OK, so I believe this is being caused by a flaw in the Liberation Mono font, as described in bug 1480420 comment 10.

We may be able to work around this somehow, but the other thing that would be worth doing is to report the issue to the Liberation font developers so that it can be improved for a future release.