660448 - Subpixel antialiasing too strong/incorrect everywhere

Status: VERIFIED FIXED

(Core :: Graphics, defect)

Description

[echogene.alpha]

User-Agent:       Mozilla/5.0 (X11; Linux i686; rv:7.0a1) Gecko/20110526 Firefox/7.0a1
Build Identifier: Mozilla/5.0 (X11; Linux i686; rv:7.0a1) Gecko/20110526 Firefox/7.0a1

Subpixel antialiasing has become too strong/wrong in the latest builds of Nightly.  That is, where it is red and blue, it is too red and too blue.  This happens on both web pages and the entire user interface (menu bar and below).

Reproducible: Always

Steps to Reproduce:
1. Open Firefox
2. Look at text

Actual Results:  
Text looks weird.  Upon zooming in, it's easy to see that subpixel antialiasing is wrong.

Expected Results:  
Text should look like it did in previous builds.

Comment 1

[echogene.alpha]

Attachment: Comparison of antialiasing

A comparison of subpixel antialiasing in Nightly and Firefox 4.

Comment 2

[Jonathan Kew [:jfkthame]]

That's a pretty glaring difference. Jeff, might this possibly be related to the recent cairo update (bug 562746)?

Comment 3

[Timothy Nikkel (:tnikkel)]

The cairo update alone is definitely responsible for a change in text rendering on my Linux machine.

Comment 4

[Ahmad Samir]

Since cairo 1.9.10, this change is in effect http://cgit.freedesktop.org/cairo/commit/?id=7a023a62f7517ad0d54f4d59c99909fadcc05e82

I think it maybe related, https://bugs.freedesktop.org/show_bug.cgi?id=34886#c3
(disclaimer: I am not an expert in cairo, freetype, fontconfig or mozilla; so don't take what I say to heart... :)).

Comment 6

[Joe Drew (not getting mail)]

OK, I'm going to undupe this for a short-term patch. The long-term fix is bug 456448, but we're blocked on releng for that.

Comment 7

[Joe Drew (not getting mail)]

Attachment: dlsym FT_Library_SetLcdFilter for now

OK, let's just dlsym() FT_Library_SetLcdFilter for now. This is not a long-term fix, because on computers that don't have this symbol we'll be a rainbowy mess. (We have to stop supporting distributions with old freetypes.) But until all the infrastructural work to upgrade Freetype and stop supporting old versions of it is done, this'll do.

Comment 8

[Joe Drew (not getting mail)]

Attachment: dlsym FT_Library_SetLcdFilter for now

Forgot to qrefresh.

Comment 9

[Karl Tomlinson (:karlt)]

Comment on attachment 538346 [details] [diff] [review]
dlsym FT_Library_SetLcdFilter for now

I probably would have replaced initialized_setLcdFilter with

  static setLcdFilterFunc setLcdFilter =
      (setLcdFilterFunc) dlsym (RTLD_DEFAULT, "FT_Library_SetLcdFilter");

in the code block scope but I haven't checked the C standard to make sure that is called on first pass, and what you have does the right thing.

Comment 10

[Joe Drew (not getting mail)]

That's how I started out, but it seems you can't initialize statics with a non-constant.

Comment 11

[Karl Tomlinson (:karlt)]

Oh, interesting, thanks.

Comment 12

[Daniel C]

Mozilla/5.0 (X11; Linux i686; rv:7.0a1) Gecko/20110610 Firefox/7.0a1

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This comment works as a testcase for me. These are all quite distinctly coloured on my screen. It's almost likeable.

Comment 13

[Daniel C]

Attachment: Pretty!

Note that I have my monospace font size set to 16 in Firefox as the default is too small for me. Zooming in and out changes the colours :-)

Comment 14

[Joe Drew (not getting mail)]

http://hg.mozilla.org/integration/mozilla-inbound/rev/76d7b28ca1ba

Comment 15

[Marco Bonardo [:mak]]

http://hg.mozilla.org/mozilla-central/rev/76d7b28ca1ba

Comment 17

[Daniel C]

Attachment: Fixed

Confirming that this is fixed for me (compare with attachment 538565 [details]).