594889 - [Dwrite] wrong margins between characters in text and overlapping chars with no Cleartype

Status: RESOLVED FIXED

(Core :: Graphics, defect)

Description

[René Schwarz]

User-Agent:       Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0b5) Gecko/20100101 Firefox/4.0b5
Build Identifier: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0b5) Gecko/20100101 Firefox/4.0b5

Since I installed Firefox 4 Beta 5 today I noticed that the ugly font rendering, which was present in Beta 4 with activated gfx.font_rendering.directwrite.enabled in about:config, has been replaced with the a new, better looking rendering.

But there is a problem with incorrect margins between the chars of a text, sometimes the chars too near each other, sometimes there are big spaces between them. I could think of a problem with this new way of font rendering in Beta 5.

I've attached two screenshots with orange markers showing examples for the wrong margins.

Reproducible: Always

Steps to Reproduce:
load a random website
Actual Results:  
described above

Expected Results:  
Good font rendering.

For the sake of completeness I have to remark that gfx.font_rendering.directwrite.enabled is actually set to false, but I've webgl.enabled_for_all_sites set to true (despite if it is relevant or not).

Comment 1

[René Schwarz]

Attachment: example No. 1 of the wrong font rendering

Comment 2

[René Schwarz]

Attachment: example No. 2 of the wrong font rendering

Comment 3

[(mostly gone) XtC4UaLL [:xtc4uall]]

Please post your Graphics Info from about:support (at the Bottom).

Comment 4

[René Schwarz]

Adapter Description       NVIDIA GeForce GTX 260
Vendor ID                 10de
Device ID                 05e2
Adapter RAM               896
Adapter Drivers           nvd3dumx,nvwgf2umx,nvwgf2umx nvd3dum,nvwgf2um,nvwgf2um
Driver Version            8.17.12.5896
Driver Date               7-9-2010
Direct2D Enabled          true
DirectWrite Enabled       true

Comment 5

[Rich Parker]

Same problem here with a GTX 275 in Windows 7 x64.  The problem is noticeably worse on some pages.

Adapter Description       NVIDIA GeForce GTX 275
Vendor ID                 10de
Device ID                 05e6
Adapter RAM               896
Adapter Drivers           snvd3dumx,nvwgf2umx,nvwgf2umx nvd3dum,nvwgf2um,nvwgf2um
Driver Version            8.17.12.5896
Driver Date               7-9-2010
Direct2D Enabled          true
DirectWrite Enabled       true

Comment 6

[Rich Parker]

Attachment: News item from dslreports.com

Comment 7

[René Schwarz]

Problem still exists in Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:2.0b7pre) Gecko/20100925 Firefox/4.0b7pre.

Adapter Description      NVIDIA GeForce GTX 260
Vendor ID                10de
Device ID                05e2
Adapter RAM              896
Adapter Drivers          nvd3dumx,nvwgf2umx,nvwgf2umx 
                         nvd3dum,nvwgf2um,nvwgf2um
Driver Version           8.17.12.5896
Driver Date              7-9-2010
Direct2D Enabled         true
DirectWrite Enabled      true
GPU Accelerated Windows  1/1 Direct3D 9

Comment 8

[Bas Schouten (:bas.schouten)]

The screenshots look like Cleartype Quality is disabled on the systems that are showing this bug, correct?

Comment 9

[René Schwarz]

Yes, this is correct for mine.

Comment 10

[Bas Schouten (:bas.schouten)]

So the cause of this issue is that although we've updated the rendering code to use the lower quality setting for people who have that in their system settings. The glyph placement code is still using high quality settings. Because the low quality rendering setting will force glyphs to be placed on pixel aligned positions, this doesn't work well together.

This is a known bug and will be fixed at some point before release.

Comment 11

[René Schwarz]

OK, so can you set the bug to NEW or mark it as a duplicate of the bug you refer to?

Comment 12

[Bas Schouten (:bas.schouten)]

Let's keep it as new for now. I'm not sure if a bug was ever created. If someone else knows of one please dupe.

Comment 14

[Joe Drew (not getting mail)]

I think that we need Harfbuzz to know that we're rasterizing without AA.

Comment 15

[Omer Kehri]

Attachment: Comparison of Segoe UI with and without harfbuzz enabled

Harfbuzz also affects some letters of the chrome font Segoe UI even with ClearType enabled. The screenshot shows different kerning of the letter "y" with Harfbuzz on/off. D2D/DirectWrite is disabled. Disabling D3D layers does not make any difference.

UA: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0b8pre) Gecko/20101009 Firefox/4.0b8pre

Graphics info:
Adapter Description: NVIDIA GeForce Go 7400
Vendor ID: 10de
Device ID: 01d8
Adapter RAM: 128
Adapter Drivers: nvd3dum,nvd3dumx nvwgf2um,nvwgf2umx
Driver Version: 7.15.11.6904
Driver Date: 10-28-2007
Direct2D Enabled: false
DirectWrite Enabled: false
GPU Accelerated Windows: 1/1 Direct3D 9

Comment 17

[Alex Faaborg [:faaborg] (Firefox UX)]

Joe Drew: is this bug causing the text in the Firefox button to slightly change on hover?  I want to make sure we are tracking that.

Comment 18

[Joe Drew (not getting mail)]

The bug tracking that is bug 613696.

Comment 19

[zgf1]

This (594889) bug:
http://zgf1.e-net24.pl/screensender/img/img_4011596.png
http://zgf1.e-net24.pl/screensender/img/img_4117115.png

ATI Radeon 4850, Windows 7 64 bit, ClearType - Disabled, D2D - On.

Comment 20

[Jonathan Kew [:jfkthame]]

Attachment: patch v1 - use hinted widths when ClearType is turned off

In my testing, this greatly improves the appearance of non-ClearType text.

(Note that after changing the system's font smoothing setting to enable or disable ClearType, you need to restart the browser to see the effect.)

Comment 21

[zgf1]

When will the patch be generally available?
Will it arrive in the nightlies?

Comment 22

[Jonathan Kew [:jfkthame]]

There should be a tryserver build available at http://ftp.mozilla.org/pub/mozilla.org/firefox/tryserver-builds/[e-mail]-ee6f7b9e348d in a couple of hours or so.

As for any patch, whether/when it will appear in nightlies depends on review, and any further work that we decide is necessary before it goes into the tree.

Comment 23

[Bas Schouten (:bas.schouten)]

Comment on attachment 500882 [details] [diff] [review]
patch v1 - use hinted widths when ClearType is turned off

I can't say all this extra code makes me superhappy! But it looks like it should do the trick to me.

Just one comment:

+static bool
+UsingClearType()
+{
+    BOOL fontSmoothing;
+    UINT type;
+
+    return (SystemParametersInfo(SPI_GETFONTSMOOTHING, 0, &fontSmoothing, 0) &&
+            fontSmoothing &&
+            HasClearType() &&
+            SystemParametersInfo(SPI_GETFONTSMOOTHINGTYPE, 0, &type, 0) &&
+            type == FE_FONTSMOOTHINGCLEARTYPE);
+}

I can live with this, but personally I'd rather see this split out in several conditionals that each do an early return. In optimized builds this will be optimized to the same code anyway, and in debug builds it actually makes debugging issues a little easier.

And it looks nicer.

Comment 24

[Jonathan Kew [:jfkthame]]

Attachment: patch v2 - also make equivalent fix for the dwrite shaper

Split up the conditional as requested.

Requesting re-review because I have also added an equivalent fix in gfxDWriteShaper, for those scripts that we don't send through harfbuzz. (The effect can also be seen in Latin script by setting gfx.font_rendering.harfbuzz.level = 0.) By using "GDI compatible" placement when ClearType is turned off, we get much better glyph spacing through that path as well.

Comment 25

[Jonathan Kew [:jfkthame]]

http://hg.mozilla.org/mozilla-central/rev/d0141c1310ff

Comment 26

[zgf1]

Still is not ok:
http://zgf1.e-net24.pl/screensender/img/img_18742786.png
http://zgf1.e-net24.pl/screensender/img/img_18581949.png
http://zgf1.e-net24.pl/screensender/img/img_19017613.png


Screens from WWW:
http://www.devilpage.pl/
http://forum.pclab.pl/


4.0b9pre (2011-01-05)

Comment 27

[neb1236]

Attachment: Comparison between after/before the patch + GDI reference

Comment 28

[neb1236]

The patch as done something and definitely fixed most of it. Not perfect but way better.

The image is made with size 8 Tahoma font.
Top line is today build, second et yesterday bottom is GDI render
There is some issues on the overall spacing, but to be honest, it’s better than having letters touching each-others

Additionally I can confirm that there is no more decimal placing of the letter (for testing, on the about:home page resize windows horizontally on look at the text in the centre, before patch; spacing between letter were changing, and now it’s only between words)

For zgf1 case there is something strange about the first example, it looks like it’s because of justify in such a small space.

Comment 29

[zgf1]

Big problems with the font:

4.0b9pre (2011-01-05):
http://zgf1.e-net24.pl/screensender/img/img_4081469.png

Internet Explorer 8:
http://zgf1.e-net24.pl/screensender/img/img_4108442.png

Look at the words: spRZedam, dreamER, booMBo, wgRAne, geMIni...

Spacing issues.

Comment 30

[zgf1]

The issue with letter spacing occurs mostly after the letter 'm' (low caps)

Firefox4 ct off, d2d on:
http://zgf1.e-net24.pl/screensender/img/img_25752785.png

Firefox4 ct off, d2d off:
http://zgf1.e-net24.pl/screensender/img/img_25798368.png


WWW: http://sport.onet.pl/boks/adamek-o-walce-z-kliczka-tak-robia-prawdziwi-wojow,1,4099489,wiadomosc.html

Comment 31

[Jonathan Kew [:jfkthame]]

I was going to reopen this bug on the basis of the screenshots still showing poor spacing, but I see you've filed a new bug 623974, so we'll follow up there.