760248 - Disabling subpixel anti-aliasing in Windows doesn't disable it in Firefox

Status: UNCONFIRMED

(Core :: Graphics, defect)

Description

[D. A.]

User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:15.0) Gecko/15.0 Firefox/15.0a1
Build ID: 20120529052711

Steps to reproduce:

Windows 7 x64
Nightly 15.0a1

Visit any webpage with text.


Actual results:

Font smoothing/subpixel antialiasing can't be disabled.

Font smoothing looks bad on my monitor and I have subpixel AA disabled in the operating system.
Subpixel AA can be disabled in the nightly by disabling hardware acceleration, but that's not needed for the latest stable (not to mention a pathetic workaround)

A few days ago I somehow managed to disable subpixel AA until Nightly closed but I can't reproduce it; I've tried changing and resetting all the about:config keys I touched yesterday to no avail.


Expected results:

The latest Firefox stable does not have this issue

Comment 1

[Joe Drew (not getting mail)]

This has *got* to be a dupe; I clearly remember this, but can't find the bug.

Comment 2

[D. A.]

I performed several searches before I created the bug and found nothing.
I mentioned it a couple times on IRC before filing the bug report; you may be remembering that.
Though I kind of hope it's a dupe since that means someone else has run into the same problem independently.

Comment 3

[Jonathan Kew [:jfkthame]]

In bug 719410, we landed a patch that was supposed to stop us using ClearType (subpixel) AA when it's disabled at the OS level, and just use grayscale instead.

That bug also discusses the problem that when font smoothing is *completely* disabled at the OS level (not even grayscale AA is enabled), the rendering can look quite blurry because DW doesn't seem to be able to reproduce GDI's pixel-snapped aliased rendering when drawing to a target with pixel depth > 1, which is why we didn't resolve it.

It's possible there are additional issues when Azure is enabled; IIRC, the patch in bug 719410 was specific to the cairo backend.

Comment 4

[neb1236]

I confirm the issues; it’s between 36e938e51481 and f43e8d300f21 changeset (http://forums.mozillazine.org/viewtopic.php?f=23&t=2477267)
The same problem happened when d2d and dw was first introduced, see Bug 574976
But here the problem is slightly different, some chrome element are aliased correctly (menu, and context menu only)
Is screencap needed?

Comment 5

[neb1236]

Attachment: Example of the Regression

Left is before, and intended behaviour; everything is aliased since cleartype is deactivated in windows
Right is after, content and some chrome element have cleartype applied, except context menu, and main menu

Comment 6

[Jonathan Kew [:jfkthame]]

The regression in content was probably triggered by Azure being enabled, bug 715768.

I'd guess this means the subpixel-AA-management code from bug 717393 doesn't pay attention to the Windows system setting properly.

Comment 7

[neb1236]

Some update, from now menus are also cleartype (don't have the exact regression range, needed?)
And just to know, will this be confirmed & fixed or ignored? Dropping HW isn’t a very nice workaround.

Comment 8

[neb1236]

Some update again, setting gfx.content.azure.enabled to false resolve the problem too, content and interface (better than turning HW totally)
And https://addons.mozilla.org/fr/firefox/addon/anti-aliasing-tuner/ work for the content but not for Firefox interface

Comment 9

[D. A.]

gfx.content.azure.enabled false solved the problem.