682709 - inflated and inconsistent character spacing in input boxes and text areas (under certain circumstances) when harfbuzz is disabled

Status: RESOLVED INVALID

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

Description

[al_9x]

Attachment: normal and abnormal spacing

1. xp sp3, Fx 7.0b2 (nightly as well)
2. start with a new profile, leave a single tab, maximize window
3. set gfx.font_rendering.harfbuzz.scripts to 0
4. in the same tab open http://crisislanding.appspot.com/
5. after it loads, in the same tab, open http://slashdot.org/
6. paste "abcdefghijklmnopqrstuvwxyz"into the search box at the top of the page
7. the character spacing in the search box is off, comparison attached

step 4 is what triggers the problem, without it, spacing is ok

Comment 1

[al_9x]

not reproducible with browser.display.auto_quality_min_font_size=0

Comment 2

[Jonathan Kew [:jfkthame]]

Those who are experiencing this bug: Please test with the tryserver build at https://ftp.mozilla.org/pub/mozilla.org/firefox/try-builds/[e-mail]-9d3ee39d7727/try-win32/ and confirm whether it fixes the problem.

(See bug 672456 for the patch being tested.)

Comment 3

[al_9x]

I will try the build, I want to let you know, though:

I've been running with browser.display.auto_quality_min_font_size=0 for a while, and even though it does cure this specific bug (Comment 0), in my main profile, after running for some time, spacing goes bad in text areas such as this (http://forums.informaction.com/posting.php?mode=post&f=7)

restarting Fx resets it to normal and I don't what triggers it, any ideas?

Comment 4

[Jonathan Kew [:jfkthame]]

It's possible this will turn out to be the same issue, as there are some cases where we go via the GDI text path regardless of the auto_quality_min_font_size setting (because Uniscribe fails on certain fonts) - it may be that you're hitting this. It's difficult to investigate thoroughly without more concrete steps to reproduce, but please see whether the tryserver build still exhibits the problem.

Comment 5

[al_9x]

(In reply to Jonathan Kew (:jfkthame) from comment #4)
> It's possible this will turn out to be the same issue, as there are some
> cases where we go via the GDI text path regardless of the
> auto_quality_min_font_size setting (because Uniscribe fails on certain
> fonts) - it may be that you're hitting this. It's difficult to investigate
> thoroughly without more concrete steps to reproduce, but please see whether
> the tryserver build still exhibits the problem.

The specific (Comment 0) reproducible bug is still present with the try build.  It is also still curable with auto_quality_min_font_size=0

Were it fixed, I would not be able to test the difficult to repro problem, because it requires extensive browser use with my main profile, until I run into it, or not.  To do that, I need a beta build with a possible fix.  When you do fix the specific bug, please try to get it into the beta so I can test more extensively.

Comment 6

[al_9x]

I found a way to repro the textarea spacing problem consistently.  Like the comment 0 issue, it is not addressed by the try build, but unlike it, auto_quality_min_font_size=0 does not help.

1. start Fx
2. load http://noscript.net/
3. load http://forums.informaction.com/posting.php?mode=post&f=7
4. spacing in the textarea will be off with some letter combinations more than others, type "dddddddddddddddddddd," 'd' shows increased spacing better.

Comment 7

[al_9x]

an important detail I just noticed, auto_quality_min_font_size=0 actually causes the comment 6 problem, without it the bug does not manifest.

So to be clear, the comment 6 issue is in a new profile with gfx.font_rendering.harfbuzz.scripts=0 and browser.display.auto_quality_min_font_size=0

Comment 8

[Jonathan Kew [:jfkthame]]

Aha, so this is actually an entirely separate issue from the crazy GDI font spacing, I believe. Thanks for the clarification.

Comment 9

[al_9x]

One more detail, as I mentioned in comment 7, the specific synthetic bug from comment 6 does not manifest with the default auto_quality_min_font_size, however in normal use I am running into bad spacing in the http://forums.informaction.com/ textareas even with auto_quality_min_font_size at default.

Of the three harfbuzz disabled spacing bugs this is the more annoying since it happens in html content.  Please investigate it.  The whole point of the simple/fast/dumb/gdi rendering path is to provide a presumably reliable, time tested fallback.

Comment 10

[Behdad Esfahbod]

HarfBuzz cannot be disabled anymore.