[Fontconfig] How to prevent Chromium from scaling bitmapped fonts?

[Raimund Steger]

On Mon, 7 Mar 2016 23:15:13 -0500
Kynn Jones <kynnjo at gmail.com> wrote:
> I can't keep Chromium from scaling the bitmapped font Terminus.
> 
> I have disabled (i.e. removed)
> 
>     /etc/fonts/conf.d/10-scale-bitmap-fonts.conf
>     /etc/fonts/conf.d/70-no-bitmaps.conf

Removing 10-scale-bitmap-fonts.conf should not be needed, it won't scale anything when the requested pixelsize is reasonably exact.

However I believe that Chromium does some scaling on its own, independent of fontconfig version. My desktop font (from XSETTINGS) is Lucida (luRS10-ISO8859-1.pcf) and it looks horribly scaled in many places in the user interface; elsewhere the spacing is off.

FC_DEBUG tells me that Chromium first looks up Terminus with FcFontSort. Afterwards, the pixel size from the CSS is looked up with FcFontMatch but the result isn't used; what's used is the upscaled 12px version. That's really weird. I think I need some more time to figure out what's going on here.

> [...]
> (BTW, the lack of difference between 12px regular and 12px bold is to
> be expected, since there's no 12px bold in this font.  On the other
> hand, there *should* be a difference between sizes 14px and 16px, and
> between 18px and 20px, since my system has separate font specification
> files for all those sizes.  So maybe Iceweasel's rendering is not
> perfect either.  Nevertheless, I'd be delighted if I could get Chrome
> to work as well as Iceweasel does here.)

I think Iceweasel renders OK here. Glyph height of 18/20px is 1px apart; you can tell in your image (e. g. open it in Gimp and use the measuring tool) and it's what I also see when I open ter-u18n.bdf and ter-u20n.bdf in fontforge. 14/16px have identical images even in the source, I can also confirm that in fontforge in ter-u14n.bdf and ter-u16n.bdf.

Raimund

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