Spacing with Font Roboto
rdtennent at gmail.com
Tue Dec 10 23:09:28 CET 2019
>|On Tue, Dec 10, 2019 at 03:05:11PM -0500, Bob Tennent wrote:
>|> I've tried to re-construct the roboto package using the TTF
>|> set and it certainly seems that otftotfm has problems with
>|> those fonts, which is presumably why I had converted to OTF.
>|> But the TTF Roboto fonts also have em size 2048. Why do they
>|> work better with luatex than the converted OTF fonts?
>|The usual rule is that TrueType based fonts have a power of two,
>|normally 1024 or 2048 because this is sometimes faster for TTF
>|renderers. In contrast, OpenType/CCF (aka .otf) fonts are based on Type 1
>|fonts which traditionally use em size 1000. I don't know exactly where
>|it is coming from but even the Type 1 font specification said that it is
>|"typical of a Type 1 font program and is highly recommended". Given that
>|OpenType just combined existing formats, this is one of many places
>|where slightly different behaviour is expected for CFF and TTF fonts.
>|Given that Type 1 based fonts with other em size are quite unusual and
>|sometimes not supported, LuaTeX just sets the value to 1000 and then
>|manually fixes the appearance if a Type 1 based font with non-standard
>|em size is found. This doesn't happen for TrueType fonts because there,
>|2048 isn't unusual in any way. (Also I think for TTF fonts it is more
>|common to have non-standard em sizes, so renderers are usually more
>|For reference, this "feature" of LuaTeX is the "fix" for
>|Anyway, would it be an option to keep the OTF fonts but "rescale" them
>|to 1000 em size. I think that's the usual approach here. In fontforge,
>|that can be done by just changing the em size. Then fontforge takes care
>|to rescale everything so that no difference can be seen.
I can do that for a single font but for all 32 of the
fonts in the family, I'd need a script. I've asked on the
fontforge-users mail list:
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