dcpomatic/src/lib/font_id_allocator.cc, branch make-centre

Fix handling of empty font IDs and default DCP fonts (#2721) (part of #2722).

2024-01-15T09:21:59Z

Previously we used an empty font ID as the default for when a subtitle has no Font, but in #2721 we saw a DCP with an empty font ID which raised an assertion (because we'd already added our default font with the empty ID). Here we try to fix this (and also make the default font correctly be that from the first ).

Don't try to add fonts from an asset that we don't have.

2024-01-04T22:35:44Z

Always add a font with an empty ID (#2649).

2023-11-16T23:24:35Z

It's not just subtitle files with no that can have subtitles without a specified font. In particular, DoM makes a single space subtitle with no font spec when it creates filler subtitles in multi-reel DCPs.

Fix DCP content font ID allocation to cope with DCPs that have multiple fonts

2023-10-15T07:10:18Z

with the same name in the same reel (#2600). Previously we had this id_for_font_in_reel() which would give an ID of N_font-ID. This means we got duplicate font IDs. Here we replace that method with FontAllocator, which gives an ID of N_font-ID for the first font and M_font-ID, where M is a number higher than the highest reel index. The idea is to support the required new IDs without breaking exisiting projects. There is some documentation of how it works in doc/design/fonts