Re: Suggest installing more fonts?

[Gregory Heytings]

> But the "bitmap" in this case is a font glyph.  So to get at that glyph, 
> we would need to have the code that is already in the library we use for 
> accessing fonts, is that what you have in mind?  So we'd need to have 
> the code which understands how font files are structured, and how to 
> find in them the glyph(s) for a certain character given that character's 
> codepoint, and how to know whether the font has a glyph for that 
> character to begin with?
>
> For example, look at xftfont_open, which is one implementation of how to 
> open a font.  Count the number of functions and variables whose names 
> begin with "Fc" -- those are references to the Fontconfig library. 
> Under your proposal, we'd need to implement all that in our own code, is 
> that right?

I don't understand why you think we would need something complex.  We 
don't need it.  Unifont has the simplest format you can imagine: a 
sequence of bitmaps.

> > With the proposal, there is no need to find the font, it is already 
> > included, and only used as a fallback when no appropriate font has been 
> > found.  Unifont is just a long sequence of small bitmaps, Emacs only 
> > has to pick the bitmap corresponding to a given character in that list 
> > and to draw it.  For example, the character "A" in Unifont is the 8x16 
> > bitmap "0000000018242442427E424242420000" which occupies only 16 bytes.
>
> So we will code a special font "backend" that is tailored to what 
> Unifont has in its files now, and on top of that support this only for a 
> single size of the default font, i.e. no support for "C-x +", no support 
> for specifying a different size in default-frame-alist, etc.? And then 
> we will have to maintain this code when Unifont changes something in its 
> files?  I'm sorry, but this makes very little sense to me, especially 
> with an ugly font such as Unifont.

The format of Unifont hasn't changed since it was created, about 25 years 
ago, and it will not change in the future (because this format is part of 
its design principles).

But you are so reluctant to this idea that I don't think it is useful to 
continue this discussion.  I only tried to propose something to improve 
Emacs, so that it would behave in a more user-friendly way when it is 
asked to display a character for which it has no fonts.