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[Jfkthame <344814@xxxxxxxxxxxxxxxxxx>]

(In reply to comment #19)
> cairo-ft-font uses FT_GlyphSlot_Embolden to do synthetic bold.
> Bug 490475 comment 5 makes me suspect that the emboldened glyph outlines are
> not embedded.
> 
> There are two fonts embedded, one for each of regular and bold weights
> 
> /f-0-0 1 Tf
> [<0102>-1<030304050406>-1<0307>]TJ
> /f-1-0 1 Tf
> 0 -1.694444 Td
> [<01>-83<02>-84<03>-84<03>-83<04>-83<05>-84<06>-84<04>-83<07>-84<03>-84<08>]TJ
> 
> but AFAIK the two fonts might be the same.

Yes, they are identical in the PostScript output. This suggests that the
expectation is that emboldening is meant to be achieved via a painting
effect rather than by actually modifying the glyph outlines. (That makes
sense.)

> I don't know whether there is any
> way to tell the PS/PDF interpreter to embolden one of these by any particular
> amount suitable to match the metrics from FT_GlyphSlot_Embolden.

One way to create "synthetic bold" is to paint the glyphs with both
stroke (of some appropriate thickness) and fill. This looks similar to
the effect we're seeing on-screen in the browser on Linux (and is better
than simply painting the filled glyphs twice with a slight offset).
However, PostScript type42 fonts don't offer a PaintType value to
directly implement this; it's either 0 (fill) or 2 (stroke), but not
both together. So this approach would mean generating the text twice,
using two versions of the font with different PaintType values.

And I don't know what metrics FT_GlyphSlot_Embolden is using; the glyph
spacing we're seeing on the "bold" line seems rather excessive to me.

-- 
Synthetic emboldening/italic/italic-bold fails for single-styled fonts
https://bugs.launchpad.net/bugs/344814
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