Open Bug 1233361 Opened 8 years ago Updated 2 years ago

upright-orientation glyphs should not protude out of border box

Categories

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

defect

Tracking

()

Tracking Status
firefox46 --- affected

People

(Reporter: bugzilla, Unassigned)

References

(Blocks 1 open bug, )

Details

(Keywords: testcase)

Attachments

(1 file)

Test
----

http://www.gtalbot.org/BrowserBugsSection/CSS3WritingModes/upright-oriented-glyphs-cross-border.xht


Expected results
----------------

No part of the "月" glyph protudes outside border box; no part of the "月" glyph crosses over the thin blue line at the top


Actual results
--------------

The "月" glyph protudes outside border box; the "月" glyph crosses over the thin blue line at the top


Explanations
------------

Several other tests, eg
http://www.gtalbot.org/BrowserBugsSection/CSS3WritingModes/text-orientation-mixed-002-GT-mplus-1p.xht
show that upright-orientation glyphs are very close to border box. 

If 'font-weight: bold' is applied, eg
http://www.gtalbot.org/BrowserBugsSection/CSS3WritingModes/text-orientation-mixed-001-GT.xht
then the "T" glyph touches the top border. I see none of this happening in Chrome 49.0.2587.3. 

I am not a typography expert (vertical text frame, glyphRect, glyph extent, etc) but, when the "月" glyph protudes outside border box as in the provided test, then it seems to me that this must be a bug of some sort. 

Setting 'font-weight: bold' seems to be a necessary contributing factor in getting the actual results; it may also increase or worsen an already too tight design...

In
http://www.gtalbot.org/BrowserBugsSection/CSS3WritingModes/text-orientation-mixed-002-GT-mplus-1p.xht
there is a *_5px gap_* between the top of each 3 "T" glyphs and the top border in Firefox 46 while there is a *_35px gap_* between the top of each 3 "T" glyphs and the top border in Chrome 49.0.2587.3 . I do not know if this is a spec violation of some sort somewhere but I think Chrome's rendering is more appropriate, expected and more natural.

Notes
-----

- I get actual result with Firefox 46.0a1 buildID=20151216080148
- I get expected result with Chrome 49.0.2587.3
- I use Linux 3.16.0-71-generic x86_64, Qt: 4.8.6, KDE 4.14.3; Kubuntu (trusty) 14.04.03 LTS
- I can upload screenshots if requested
- I've searched for duplicates and did not find any.
Screenshot of test in (from left to right):

Firefox 49.0a1 buildID=20160522030240 under Windows XP SP3, 800x600 screen resolution

Firefox 49.0a1 buildID=20160522030240 under Linux KDE 4.14.3, 1440x900 screen resolution

Chrome 52.0.2739.0 under Linux KDE 4.14.3, 1440x900 screen resolution

Firefox 49.0a1 buildID=20160522030240 under Windows XP SP3, 1280x1024 screen resolution
From what I can see in attachment 8755237 [details], in Firefox 49, the top of the "月" glyph overlaps the blue border under Windows XP but it does not protude outside like it does under Linux.
It looks like all characters are placed higher than where they should be indicated by the selection rect.
I went over many tests today and I am convinced there is some sort of bug here. I think there is a too tight design somewhere and that setting 'font-weight: bold' makes things worse. 

Also, enlarging (Zoom In, Text Only) text size with Ctrl++ will also show that latin glyphs will protude outside border box as well.
Severity: normal → S3
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