I can't be sure - without inspecting the font and debugging the code - but this looks like in the first case you get the ID=16 typographic font family ("JetBrains Mono") and
in the other case you get the ID=1 font family ("JetBrains Mono Medium").
Without debugging I can't explain why there's this apparent inconsistency.

ID=1 is the traditional 4 member font family with regular/bold/italic/bold italic

The typographic (some times called extended) family supports weight and sometimes width and these days they may even be combined into a single font via font variations.

There may be a bug here (can't be sure without investigating) and there also may be a need
for API which works with the typographic family.


>Besides these issues, I also get tired of the subtle differences in behavior between different platforms. >Can we bridge the differences in how JavaFX handles font family names on different platforms?

Some of it may come from the platform APIs being different.
Can you give me additional examples ?

-phil.

On 7/15/25 7:21 AM, Glavo wrote:
Hi Philip,

Thanks for your reply.

> (1) fixing this for DW wouldn't help Linux or Mac so there'd need to be separate implementations if they also don't do it automatically

I also tested on Linux and macOS. I think this problem does not exist on these two platforms. JavaFX uses the English font family names everywhere on both platforms, rather than the localized names, so this problem does not occur.

However, I encountered another annoying behavior on macOS:

    jshell> Font.getFamilies().stream().filter(it ->
    it.contains("JetBrains Mono")).toList()
    $2 ==> [JetBrains Mono, JetBrains Mono NL]

    jshell> Font.font("JetBrains Mono")
    $3 ==> Font[name=JetBrains Mono Medium, family=JetBrains Mono
    Medium, style=Regular, size=13.0]

    jshell> $3.getFamily()
    $4 ==> "JetBrains Mono Medium"

    jshell> Font.font("JetBrains Mono Medium")
    $5 ==> Font[name=System Regular, family=System, style=Regular,
    size=13.0]


As you can see, multiple weights of a font on macOS are unified into the same font family. We can find a Font by this font family name, but the family name returned by Font:getFamily() includes the weight,
and we cannot find the font based on the returned name.
This problem does not occur on Linux and Windows, because those platforms do not unify fonts into a single family.

Besides these issues, I also get tired of the subtle differences in behavior between different platforms. Can we bridge the differences in how JavaFX handles font family names on different platforms?

Glavo

On Tue, Jul 15, 2025 at 3:50 AM Philip Race <philip.r...@oracle.com> wrote:

    Font.font will, on Windows, use
    IDWriteFontCollection::FindFamilyName(..)
    The docs for that appear to be silent on whether the matching
    process will check all localized names,
    but it sounds like it must not.  I don't see an alternative look
    up API, such as one that accepts a locale arg.

    
https://learn.microsoft.com/en-us/windows/win32/api/dwrite/nn-dwrite-idwritefontcollection


    It seems like the app (which in this case means the FX
    implementation) will have to do this itself which is going to be
    tedious.

    We would need to compare with every localized name of every font
    on the system looking for a match.

    And one annoying aspect of this is that until you've done that
    exhaustive search you don't
    know if the name the application supplied is present at all on the
    system.

    How would you know that someone mis-spelled Arial as Ariel and not
    that Ariel is the German localized name for Arial ?

    So failed lookups will be slow.

    In Java 2D we already do this but I'd have hoped DW used by FX was
    better than this than GDI used by 2D.

    Also note that
    (1) fixing this for DW wouldn't help Linux or Mac so there'd need
    to be separate implementations if they also don't do it automatically
    (2) There isn't any FX API which lets you enumerate or access
    localized names, so as you note, that also is an issue.
    Although I'm actually a little surprised FX finds 幼圆 but reports
    YouYuan. I would have thought it would be consistent.

    I'm also a little surprised that it has taken this long for anyone
    to even implicitly ask for FX to support localized font names.
    Java2D has had this support for a very long time.

    -phil.

    On 7/12/25 4:18 AM, Glavo wrote:
    Hi,

    We recently noticed a problem: For fonts with localized names,
    Font.font(String) can only find the font based on the localized
    name in the current locale.

    For example, the Chinese version of Windows comes with a font
    called "YouYuan", and its Chinese name is "幼圆".
    When the system language is Chinese, JavaFX has the following
    behaviors:

        jshell> Font.font("YouYuan")
        $2 ==> Font[name=System Regular, family=System,
        style=Regular, size=13.333333015441895]

        jshell> Font.font("幼圆")
        $3 ==> Font[name=YouYuan, family=YouYuan, style=Regular,
        size=13.333333015441895]

        jshell> $3.getFamily()
        $4 ==> "YouYuan"


    As you can see, we cannot find the font based on the English
    name, we can only use the Chinese name.
    But Font::getName() returns the English name, so we can't get the
    Chinese name from the Font.
    This makes it impossible to generate a style sheet based on a
    Font object, because

        "-fx-font-family: \"%s\";".formatted(font.getFamily())

    will not work with these fonts.

    The only workaround I can think of is to generate a mapping table
    from English names to Chinese names like this:


        Font.getFamilies().stream().collect(Collectors.toMap(it ->
        Font.font(it).getFamily(), Function.identity()))


    But this seems like a lot of overhead :(

    So, I want JavaFX to provide the following features:

     1. Regardless of the current system language, Font.font(String)
        should be able to find the font by its English name;
     2. Provide a new method Font::getLocalizedFamily() to get the
        localized name of the font.

    Glavo

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