1351332 - Needs hack for Meiryo to render italic/oblique style

Status: RESOLVED FIXED

(Core :: Layout: Text and Fonts, enhancement)

Description

[Masayuki Nakano [:masayuki] (he/him)(JST, +0900)]

Meiryo, Japanese font of Windows, is odd font. It has same glyph for both normal style and italic/oblique style because MS claims that italic/oblique style isn't in Japanese culture.  However, this is really problem if we take it as default font and web pages use <em>/<i> etc.

If we specify:

> @font-face {
>   font-family: "Meiryo";
>   src: local("Meiryo");
>   font-weight: normal;
> }
> @font-face {
>   font-family: "Meiryo";
>   src: local("Meiryo Bold");
>   font-weight: bold;
> }
> @font-face {
>   font-family: "\30E1 \30A4 \30EA \30AA"; /* メイリオ */
>   src: local("Meiryo");
>   font-weight: normal;
> }
> @font-face {
>   font-family: "\30E1 \30A4 \30EA \30AA"; /* メイリオ */
>   src: local("Meiryo Bold");
>   font-weight: bold;
> }

we see forcibly tilted characters, see following test cases on Windows:

testcases without hack:
https://jsfiddle.net/d_toybox/8vsv97k6/
https://jsfiddle.net/d_toybox/8vsv97k6/2/

testcases with hack:
https://jsfiddle.net/d_toybox/8vsv97k6/4/
https://jsfiddle.net/d_toybox/8vsv97k6/3/

So, we should take this hack with ua.css or hard coded hack in gfx.

Any ideas?

Comment 1

[Masayuki Nakano [:masayuki] (he/him)(JST, +0900)]

Note that on Windows 10, you need to install Japanese language pack of Windows for Meiryo. IIRC, Win7 and Win8.1 has Meiryo even without Japanese language pack.

Comment 2

[Masatoshi Kimura [:emk]]

Maybe we should also specify unicode-range so that latin characters in Meiryo can use the real italic glyphs instead of simulated ones.

Comment 3

[Masayuki Nakano [:masayuki] (he/him)(JST, +0900)]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=5db86447e26d01e1dc99c889d4a8806a04672c8e

Comment 4

[Masayuki Nakano [:masayuki] (he/him)(JST, +0900)]

(In reply to Masayuki Nakano [:masayuki] from comment #3)
> https://treeherder.mozilla.org/#/jobs?repo=try&revision=5db86447e26d01e1dc99c889d4a8806a04672c8e

Hmm, adding @font-face to ua.css causes a lot of assertions...

Comment 5

[Masayuki Nakano [:masayuki] (he/him)(JST, +0900)]

(In reply to Masatoshi Kimura [:emk] from comment #2)
> Maybe we should also specify unicode-range so that latin characters in
> Meiryo can use the real italic glyphs instead of simulated ones.

Hmm, I don't like to do that because:
1. It requires a lot of time to investigate which glyph should be included/excluded...
2. I worry about the performance to use unicode-range (and also @font-face too).

Comment 6

[Masayuki Nakano [:masayuki] (he/him)(JST, +0900)]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=4259192140462cc5f47f0903850ed505e966f4ca

Comment 7

[Masayuki Nakano [:masayuki] (he/him)(JST, +0900)]

If we use @font-face hack, looks like that it's stored at every document. So, perhaps, we shouldn't use it. Additionally, I see odd rendering result changes on non-Windows platforms. So, using it really risky.

Comment 8

[Masatoshi Kimura [:emk]]

(In reply to Masayuki Nakano [:masayuki] from comment #7)
> If we use @font-face hack, looks like that it's stored at every document.
> So, perhaps, we shouldn't use it.

Yes, I presented the @font-face hack only for demonstration purpose. We should make some C++ changes if we fix this bug.

> Additionally, I see odd rendering result
> changes on non-Windows platforms. So, using it really risky.

Isn't it a bug itself? Meiryo is unavailable on other platforms, so any rendering changes should not happen.

Comment 9

[Masayuki Nakano [:masayuki] (he/him)(JST, +0900)]

(In reply to Masatoshi Kimura [:emk] from comment #8)
> (In reply to Masayuki Nakano [:masayuki] from comment #7)
> > Additionally, I see odd rendering result
> > changes on non-Windows platforms. So, using it really risky.
> 
> Isn't it a bug itself? Meiryo is unavailable on other platforms, so any
> rendering changes should not happen.

Yeah, probably so but I don't have much time to investigate it for now.

My current patches being tested on tryserver ignore italic style Meiryo faces at creating font list on Windows.

Comment 10

[Jonathan Kew [:jfkthame]]

How does Meiryo behave in IE/Edge? In general, I'd be a bit reluctant to add special-case code that is basically working around a design decision from the platform.

Comment 11

[Masayuki Nakano [:masayuki] (he/him)(JST, +0900)]

(In reply to Jonathan Kew (:jfkthame) from comment #10)
> How does Meiryo behave in IE/Edge?

On the other browsers, they are not rendered as italic/oblique (i.e., rendered as "font-style: normal;"). However, neither IE nor Edge uses Meiryo as default Japanese font.

> In general, I'd be a bit reluctant to add
> special-case code that is basically working around a design decision from
> the platform.

I agree with that. However, Meiryo developers designed the font as so intentionally. However, some designers complain about that (I googled "Meiryo Italic" in Japanese). So, this is the most risky point at switching Japanese default font to Meiryo. If web sites use <em>, <i>, font-style: italic; and font-style: oblique, user will not be able to distinguish such element and the others in Japanese text.

If we could "Yu Gothic", which is available Win8 and later, it's better if there is no rendering trouble I asked you at bug 548311 comment 21. ("Yu Gothic" and "Yu Mincho" have italic style, even though they're newer Windows' default font.)

Comment 12

[Masayuki Nakano [:masayuki] (he/him)(JST, +0900)]

Attachment: Bug 1351332 gfxDWriteFontList and gfxGDIFontList should ignore italic face of Meiryo for using synthetic italic style

Meiryo has same glyph for both normal style and italic/oblique style.  Therefore, if we will use it as default Japanese font, italic/oblique style won't be used in Japanese text.  It's too bad for <em>, <i> and backward compatibility with MS PGothic.

This patch makes gfxDWriteFontList and gfxGDIFontList ignore italic style face(s) of Meiryo at creating Meiryo's font face list.

Note that in GDI mode, font names are localized.  Therefore, we need to compare with both English name and Japanese name.  However, in DirectWrite mode, face names are not localized.  Therefore, it's enough to compare only with English face names.

Review commit: https://reviewboard.mozilla.org/r/124720/diff/#index_header
See other reviews: https://reviewboard.mozilla.org/r/124720/

Comment 13

[Jonathan Kew [:jfkthame]]

Comment on attachment 8852534 [details]
Bug 1351332 gfxDWriteFontList and gfxGDIFontList should ignore italic face of Meiryo for using synthetic italic style

https://reviewboard.mozilla.org/r/124720/#review128450

Comment 14

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/b2cbd8ef4c84
gfxDWriteFontList and gfxGDIFontList should ignore italic face of Meiryo for using synthetic italic style r=jfkthame

Comment 15

[Wes Kocher (:KWierso) (Not reading bugmail; email directly if needed)]

https://hg.mozilla.org/mozilla-central/rev/b2cbd8ef4c84