bug#5503: Font choice in Emacs 23 does not match weight/traits

[Andrew Hyatt <ahyatt@gmail.com>]

David Reitter <david.reitter@gmail.com> writes:

> The fonts chosen for non-latin (here: Asian) characters are not very similar to the face font.
>
> For example, if "Lucida Grande" is selected as the frame's default font, the following:
>
> DOUBLETはあなたと->世 界をつなげる翻訳会社です。
>
> is displayed using a much to lightweight (skinny) font for all the non-Latin glyphs.  The Hiragana portion at the beginning is set in PMingLiU, while the Kanji (Han script) is displayed in LiSung.
>
> These fonts appear very thin compared to the Latin text.
> This is despite there being the "Osaka" font present on my system, which is a medium-weight, very suitable font.
>
> -apple-PMingLiU-medium-normal-normal-*-13-*-*-*-p-0-iso10646-1 (#x303)
> -apple-Apple_LiSung-medium-normal-normal-*-13-*-*-*-p-0-iso10646-1 (#x7CD)
>
> This is under NS, whereas I am not positive that this is actually due to NS.
>
> This worked great on Emacs 22 - Osaka is chosen there [well, I have tried with Aquamacs].
> I have received concrete complaints from users who say that they're not using Emacs 23 because of that.  
> The user also said that matching the font according to further traits (serif/sans) would be desirable/expected.
>
> I advised the user of setting Osaka directly (which works), and of fontsets (which appear inappropriate for such simple use-cases in 2010).
>
> For what it's worth, I have been trying to fix this myself.
> So far I know that Osaka has 95% "han" script coverage and is returned among the list of (many) fonts in the font driver's "list" function.
>
> It seems that exact weight and more specific traits are not being made available to Emacs by the NS font driver (e.g., nsfont.m:532, call to ns_descriptor_to_entity, last argument is NULL).  Font weight should go into "ADSTYLE", which is one matching criterion in font_find_for_lface.  font_select_entity() presumably doesn't have enough weight information.
>
> ns_descriptor_to_entity() sets weight, but only to Qbold and Qmedium.  If I comment some code in:
>    FONT_SET_STYLE (font_entity, FONT_WEIGHT_INDEX,
> 		    make_number (100 + 100
> 			* ns_attribute_fvalue (desc, NSFontWeightTrait)));
> .. then the "han" portion in the above examples is rendered with a matching font (LiGothic), but not any of the Hiragana text (still in PMingLiU).
>
> FWIW, the AppKit port of 23 shows the same behavior as NS.
> Again, Emacs 22 got it right - unfortunately I haven't managed to figure out how the Emacs 22 code works.

I actually responded to this bug several weeks ago, but for some reason
didn't reply-all, so it didn't get captured on this bug.  Here's what I wrote:

I can't reproduce this in Emacs 25 on a Mac w / El Capitan. I get a nice
font for the Japanese - Hiragino Sans. Do you still see a problem when
you try?

I'll leave this bug open for a few more weeks to see if it gets any
response, but if no one can reproduce it I'll close it as
unreproducible.