Discussion
Papyrix uses its own font format they call "EPD". So today I'm studying the support library for handling such EPD fonts.
This includes a method for retrieving glyphs from the font (with fallbacks) to denote some text whilst summing the advance-X & grabbing the bounding-box. This is wrapped in a method for computing the width/height.
It uses a cached binary-search to locate which interval a desired glyph is in. There's a support class to aid this hashmap-caching.
1/3?
There's some structs defining what might be found in an EPD font including glyph positioning & where its bitmap can be found in the file, a charset-interval & where that data can be found, & some font metadata.
A class tracking all the fonts in a font-family has a method for returning the desired font variant, alongside some more getters.
There's a FontLoader class which reads & validates a font from the SD card across a handful of methods.
2/3?
Finally there's a StreamingEPDFont class for when the font's too large to fit in RAM, with an added layer of caching. Though it does keep the intervals in RAM, glyph bitmaps are not.
Otherwise it works much like in-memory fonts only with extra file-reads.
Talking of which... There's several data-headers storing a selection of converted fonts, notably including Reader.
I will note that these are raster fonts, so saves some processing at runtime...
3/3 Fin for today!
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