What has responsibility for beautiful terminal render utf 8 glyphs?

Ask Fedora
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1

Hello. I use gnome terminal and in Fedora could output some utf-8 glyphs.
Снимок экрана от 2024-01-30 10-26-46
Who duty for render?
I’ve come across a distribution where have problem - render only some glyphs (not at all). I assumed:

  1. Problem in terminal. Install kitty and konsole - same result.
  2. Updated locale on all language in system and updated locale (the most populate answers) - same result.
  3. Loaded fonts. Used the nerd fonts (have all glyphs) and cantarell (fedora used by default) - same result.

None of these points were affected. I assuming for this behaviour the provided by on level OS or kernel.

2

From Project Discussion to Ask Fedora

3

Added emojis, gnome-terminal, unicode and removed coreos-wg, engineering

4

No this is provided by the terminal application and the GUI tool kit it uses.
Nothing to do with the kernel.

The terminal needs to be configured with a font that includes the unicode characters you wish to use.

In my case I see the a folder icon with macOS iterm2 and KDE Konsole in Fedora.
Konsole defaults to the “Noto Sans Mono” font.

5

I disagree. Font not resolved this problem. Chec this out on “3270 Nerd Font”. This font include very very more glyphs
Gnome-terminal:
Снимок экрана от 2024-02-08 13-21-15
Konsole:
Снимок экрана от 2024-02-08 13-14-59
Konsole (other distr):
Снимок экрана от 2024-02-08 14-54-13

Font same everywhere, but renders in difference.
Why this behaviour?

6

It is common, I understand, for a “font” to be actually be a set of fonts merged to cover all glyphs. Its worthy checkout what font config thinks is available in each font.

I think it will be font config that is used every where now.

7

I found the culpirt. If i remove font google-noto-emoji-color-fonts then not avaliabled beautiful renders.
Снимок экрана от 2024-02-09 11-32-44
But i have new question. Where placed hardcode for this fonts?
I don’t see anything config(fontconfig) in /etc/fonts/conf.d/ for with associated glyphs or emoji.

8

I see google-noto-color-emoji-fonts was installed as a dependency of default-fonts-core-emoji.
Which was installed when I did a fresh install of f39 kde.

9

Yes. This fonts “out of box”. I’m intrested how fontconfig found google-noto-color-emoji-fonts for render glyphs. I guess i can set 3270 Nerd Font for render glyphs but how?

10

Its usually a setting in your terminal program to set the font to use.

11

No. I showed above. In terminal used some font, but glyphs linked to google-noto-emoji-color-fonts

12

What I think you are seeing is some feature of fontconfig filling in missing glyphs when a font is selected. I think by merging in other font files.
Suggest you read up on fontconfig.

13

Thanks @barryascott for the tip fontconfig. I continued my investigetion and found two configs:
/etc/fonts/conf.d/45-generic.conf
/etc/fonts/conf.d/60-generic.conf
45-generic.conf describe family emoji for font
60-generic.conf describe prefed used font fot font family emoji

Now i decided write own config for set prefer font for family emoji

~/.config/fontconfig/fonts.conf 
<?xml version="1.0"?>
<!DOCTYPE fontconfig SYSTEM "urn:fontconfig:fonts.dtd">
<fontconfig>

        <alias binding="same">
               <family>3270 Nerd Font,3270 Nerd Font Cond</family>
               <default><family>emoji</family></default>
        </alias>

        <alias binding="same">
               <family>DejaVu Sans Mono</family>
               <default><family>emoji</family></default>
        </alias>

        <alias binding="same">
               <family>monospace</family>
               <prefer>
                        <family>3270 Nerd Font,3270 Nerd Font Cond</family>
                        <family>DejaVu Sans Mono</family>
                        <family>emoji</family>
               </prefer>
        </alias>
        <alias binding="same">
               <family>sans-serif</family>
               <prefer>
                        <family>3270 Nerd Font,3270 Nerd Font Cond</family>
                        <family>DejaVu Sans Mono</family>
                        <family>emoji</family>
               </prefer>
        </alias>
        <alias binding="same">
               <family>serif</family>
               <prefer>
                        <family>3270 Nerd Font,3270 Nerd Font Cond</family>
                        <family>DejaVu Sans Mono</family>
                        <family>emoji</family>
               </prefer>
        </alias>

        <alias binding="same">
            <family>emoji</family>
            <prefer>
                        <family>3270 Nerd Font,3270 Nerd Font Cond</family>
                        <family>DejaVu Sans Mono</family>
                        <family>Segoe UI Emoji</family> <!-- Microsoft -->
            </prefer>
        </alias>

</fontconfig>

I used three font for emoji, but working only Segoe UI Emoji. I set prefer for family monospace, serif, sans-serif used Nerd Font and second emoji. I set for Nerd Font and DejaVu family emoji. Nothing has change.
I also added Nerd Font in 45-generic and 60-generic config - nothing has change.
If remove buiding="same" the Segoe UI Emoji it will stop working.

I not understand how can set priority for own font for emoji family.