Re: Imprecise font scaling
>> However, 2 * 3.86523438 = 7.73046876 != 7.73242188. > I'm quite sure this is because of > > int pango_size = static_cast ( > std::lround (static_cast (requested_size) * PANGO_SCALE)); > > > in lily/font-select.cc, which we cannot really do anything about, > because the Pango API > > https://docs.gtk.org/Pango/method.FontDescription.set_size.html > > expects an integer size scaled by PANGO_SCALE, which is 1024. That > is, we are limited to a precision of 1/1024 points on the font size. Shall we document this somehow? Werner
Re: Imprecise font scaling
> Shall we document this somehow? Not everything is necessarily worth documenting. signature.asc Description: This is a digitally signed message part
Re: Imprecise font scaling
I'm running the following code
\version "2.25.12"
\markup { LOL }
\markup { \magnify #2.0 LOL }
and the results are not really precise. When producing --eps, the relevant
output lines are
/C059-Roman 3.86523438 output-scale div selectfont
/C059-Roman 7.73242188 output-scale div selectfont
However, 2 * 3.86523438 = 7.73046876 != 7.73242188. Basically the same
behaviour can be observed when using Cairo (both for EPS and SVG).
> (Producing SVG without Cairo is pretty disastrous in this regard, but
> that doesn't bother me too much at the moment.)
I'm quite sure this is because of
int pango_size = static_cast (
std::lround (static_cast (requested_size) * PANGO_SCALE));
in lily/font-select.cc, which we cannot really do anything about, because
the Pango API
https://docs.gtk.org/Pango/method.FontDescription.set_size.html
expects an integer size scaled by PANGO_SCALE, which is 1024. That is, we are
limited to a precision of 1/1024 points on the font size.
signature.asc
Description: This is a digitally signed message part
Re: Imprecise font scaling
Sorry, my mail client changed the formatting in a way I didn't expect.
Resending.
> I'm running the following code
>
> \version "2.25.12"
> \markup { LOL }
> \markup { \magnify #2.0 LOL }
>
> and the results are not really precise. When producing --eps, the relevant
> output lines are
>
> /C059-Roman 3.86523438 output-scale div selectfont
> /C059-Roman 7.73242188 output-scale div selectfont
>
> However, 2 * 3.86523438 = 7.73046876 != 7.73242188. Basically the same
> behaviour
> can be observed when using Cairo (both for EPS and SVG).
> (Producing SVG without Cairo is pretty disastrous in this regard, but
> that doesn't bother me too much at the moment.)
I'm quite sure this is because of
int pango_size = static_cast (
std::lround (static_cast (requested_size) * PANGO_SCALE));
in lily/font-select.cc, which we cannot really do anything about, because
the Pango API
https://docs.gtk.org/Pango/method.FontDescription.set_size.html
expects an integer size scaled by PANGO_SCALE, which is 1024. That is, we are
limited to a precision of 1/1024 points on the font size.
signature.asc
Description: This is a digitally signed message part
Re: Imprecise font scaling
" …expects an integer size scaled by PANGO_SCALE, which is 1024. That is, we are limited to a precision of 1/1024 points on the font size. " An "evidence" for this might be that the difference 7.73242188 - 7.73046876 is pretty close to 2/1024. AS
