Cleartype used even when Cleartype is disabled

NEW
Unassigned

Status

()

Core
Graphics
6 years ago
9 months ago

People

(Reporter: jtd, Unassigned)

Tracking

Trunk
x86
Windows 7
Points:
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Firefox Tracking Flags

(Not tracked)

Details

(URL)

(Reporter)

Description

6 years ago
When D2D is disabled and DirectWrite is enabled, Cleartype is *always* used, even if Cleartype is explicitly disabled.  With D2D enabled, Cleartype is not used when explicitly disabled.

Steps:

1. Control Panel > Fonts, disable Cleartype
2. In 'about:config', set 'gfx.direct2d.disabled" to true and set 'gfx.font_rendering.directwrite.enabled' to true
3. Open the testcase

Result: text is drawn with Cleartype enabled

Comment 1

6 years ago
Not sure if this is related, but after upgrading from 5 to 6, I'm seeing ClearType forced on some text but not all.  ClearType is disabled at the OS level, and both Direct2D and DirectWrite are enabled.

Comment 2

6 years ago
(In reply to John Daggett (:jtd) from comment #0)
> When D2D is disabled and DirectWrite is enabled, Cleartype is *always* used,
> even if Cleartype is explicitly disabled.

Sure that it's Cleartype (sub-pixel AA) and not greyscale font AA? Because AFAIK Firefox in this case simply let's DirectWrite decide if and what AA type should be used and Directwrite decides to do greyscale AA even if it's disabled system-wide. You should see the same with IE9 (in standards mode). [CJK fonts with bitmaps are an exception to this.]

(In reply to James Arnold from comment #1)
> Not sure if this is related, but after upgrading from 5 to 6, I'm seeing
> ClearType forced on some text but not all.

Only text in fonts not listed in gfx.font_rendering.cleartype_params.force_gdi_classic_for_families?
(In reply to [Baboo] from comment #2)
> (In reply to John Daggett (:jtd) from comment #0)
> > When D2D is disabled and DirectWrite is enabled, Cleartype is *always* used,
> > even if Cleartype is explicitly disabled.
> 
> Sure that it's Cleartype (sub-pixel AA) and not greyscale font AA? Because
> AFAIK Firefox in this case simply let's DirectWrite decide if and what AA
> type should be used and Directwrite decides to do greyscale AA even if it's
> disabled system-wide. You should see the same with IE9 (in standards mode).
> [CJK fonts with bitmaps are an exception to this.]

DirectWrite in general does not appear to respect system cleartype settings.

Comment 4

6 years ago
(In reply to [Baboo] from comment #2)
> Only text in fonts not listed in
> gfx.font_rendering.cleartype_params.force_gdi_classic_for_families?

No, I have no such setting.  But I already reluctantly turned on ClearType system-wide because of this problem.
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