Ubuntu – LibreOffice – Calibri font availible when opening a doc but not in dropdown

I think it is decided not by Ubuntu but by the program (LibreOffice, OpenOffice etc.). I could not see anything related to LibreOffice per se but OpenOffice has a nice wiki with some details on how this "Font Fallback" works. It might be applicable to LibreOffice also, in general.

I am reproducing some sections from the wiki below for clarify. It is hard to explain better than what is in the wiki, so better to read it from there:

What is Font Fallback in OpenOffice.org 2?

Font-Fallback kicks in whenever a font is requested that is not installed on the system. (Not installed means: not available to OOo). OOo then tries to use a different font from the ones that OOo knows about that matches the requested one as close as possible.

How does Font Fallback work?

For font-fallback to produce satisfying results, OOo somehow has to know about similarities of fonts. OOo must know that it can for example substitute Helvetica in place of Arial, but not Comic Sans. This task is not as easy as it sounds, since many fonts exist and OOo cannot know about all of them.

OOo uses several ways to find a suitable replacement:

• Font alias information provided by the system (e.g., from a fonts.dir file)
• Hard-coded list of fallback-fonts, from VCL.xcu (tried first)
• Alternative font name spellings
• Font-attributes (e.g., does it have CJK-characters, is it a Symbol-font) or style (serif/non-serif, proportional/non-proportional)

if all that fails as well:

• use a default font

Not directly related but this TLDP document is a good read.

Multiple issues are described in the question and comments. This answer summarizes them and points toward resources that may be helpful.

1. Possible reasons for 'wrong' fonts being displayed include:

   • Forgetting to update the font cache with fc-cache -f after installing the font.

   • Not having actually installed the font. For instance, by copying files to a wrong location.

2. Metric-Compatible Fonts are fonts that may used in place of each other without changing layout and pagination.

   • The font displayed in Ubuntu is Carlito, which is a substitute for Calibri. It is part of Google's Chrome OS Extra Fonts (Crosextra). The other font in the collection is Caladea, which replaces Cambria.

   • Google has another collection of fonts, Chrome OS Core Fonts (Croscore), which contains Tinos (for Times New Roman), Arimo (for Arial), and Cousine (for Courier New).

   • Some other Google-sponsored substitutes are available, such as Gelasio (for Georgia).

3. Combinations of letters (particularly f, i, t) that are merged together when rendered are known as ligatures. In print, ligatures are considered desirable. However, people are not used to seeing ligatures because their primary exposure to text is now via web browsers, which don't even bother to attempt to follow any of the typographic conventions that have developed over centuries.

   The following pages may be helpful toward finding an acceptable way to avoid ligatures:

   • Is it possible to disable ligatures?

   • How to disable typographic ligature when using font hinting in xfce

   • How can I fix TTF fonts' ligatures (tt, ti, fi, ff, etc) in Firefox?

4. In one of the images, antialiasing appears to have been turned off. Antialiasing improves the appearance of shapes drawn on an imperfectly matched grid. If turning on antialiasing in system settings does not fix the problem, then the problem may be associated with the use of embedded bitmap fonts.