Bug 206573 – [WinCairo] -webkit-font-smoothing:antialiased makes fonts blurry

• Status: RESOLVED
• Resolution: FIXED
• Component: Platform

[Fujii Hironori]

[WinCairo] small MS Gothic font with -webkit-font-smoothing:antialiased is blurry

r254506 (Bug 54763) added -webkit-font-smoothing support. Since then some texts in Google News of Japanese are rendered blurry.

1. Start WinCairo MiniBrowser
2. Go to https://news.google.com/?hl=ja&gl=JP&ceid=JP%3Aja

[Fujii Hironori]

Created attachment 388403 [details]
[Screenshot] Google News (Japan) of WinCairo port (150% display scale factor)

[Fujii Hironori]

Created attachment 388406 [details]
test case

[Fujii Hironori]

Created attachment 388502 [details]
[screenshot] GMail in WinCairo (with -webkit-font-smoothing support, r254899)

I realized GMail also looks blurry even for alphabet.

[Fujii Hironori]

Created attachment 388504 [details]
[screenshot] GMail in WinCairo (without -webkit-font-smoothing support, r254326)

Old WinCairo renders clearly.

[Fujii Hironori]

I'm spoofing Safari User-Agent string to use GMail in WinCairo.

[Fujii Hironori]

Created attachment 402626 [details]
[screenshot] https://www.apple.com/ in WinCairo (with -webkit-font-smoothing support, r254899)

[Fujii Hironori]

-webkit-font-smoothing:antialiased is mapped to CAIRO_ANTIALIAS_GRAY.
And CAIRO_ANTIALIAS_GRAY is mapped to ANTIALIASED_QUALITY.

If I changed to use DEFAULT_QUALITY instead of
ANTIALIASED_QUALITY by applying the following patch to Cairo, the
font looked good.

diff --git a/src/win32/cairo-win32-font.c b/src/win32/cairo-win32-font.c
index 1f217573b..355192dc0 100644
--- a/src/win32/cairo-win32-font.c
+++ b/src/win32/cairo-win32-font.c
@@ -347,7 +347,7 @@ _win32_scaled_font_create (LOGFONTW                   *logfont,
 	case CAIRO_ANTIALIAS_GRAY:
 	case CAIRO_ANTIALIAS_FAST:
 	case CAIRO_ANTIALIAS_GOOD:
-	    f->quality = ANTIALIASED_QUALITY;
+	    f->quality = DEFAULT_QUALITY;
 	    break;
 	case CAIRO_ANTIALIAS_SUBPIXEL:
 	case CAIRO_ANTIALIAS_BEST:

This issue seems a Windows API issue.

[Fujii Hironori]

Created attachment 402627 [details]
Patch

[Fujii Hironori]

Created attachment 402628 [details]
[screenshot] https://www.apple.com/ in WinCairo with the proposed patch

[Alex Christensen]

Comment on attachment 402627 [details]
Patch

This seems fine.

[Fujii Hironori]

Committed r263471: <https://trac.webkit.org/changeset/263471>

[Radar WebKit Bug Importer]

<rdar://problem/64716389>