[scribus-dev] PDF export dialog for font embed, subset and vectorize

[Jean Ghali]

Le 14/01/2016 10:20, JLuc a écrit :
> In 1.5, the PDF export dialog enables to choose for each used font
> whether it has to be embeded, vectorized or none of each.

In 1.5 the "outline" options was not really named properly and triggered different
behaviors depending on font characteristics:
- font subsetting as Type3 font subset : Adobe Reader list the font as embedded in this case
- font vectorization : Adobe Reader would not list the font in this case

Also with Windows 8 and Windows 10, Microsoft started suppressing some tables in their
TrueType fonts which made the behavior of the options even less predictable. Lots of users
where complaining about not seeing their fonts as embedded anymore because the change made
by Microsoft now triggered font vectorization. So the situation was really getting messy.

In 1.5.1.svn, thanks to advance in font subsetting done by Andreas, the subset options now
does exactly what it says: with most of today fonts a real subset will be produced, the
Type3 subset option being now mostly used by old Postscript Type 1 fonts. Same the outline
mode will do what it says, the font will be really vectorized in order to respond to the
need of print shops which do not want to see any trace of font, even Type 3, in the files
they receive.

> 
> In 1.5.1, the new font PDF management options of the export to PDF dialog
> are different.
> There are 3 modes :
> - outline all fonts (no single font option ability)
> - embed or subset : each font can be either embed or subset
> - do not embed (no single font option).
> 
> Mode 1 and 2 obviously enable to avoid the "undefined font" issue
> that could cripple a 1.5 RIP

Yep.

> but It's not clear to me how this set of mode
> is supposed to provide the features that were in 1.5.

It's not supposed to reproduce the feature found in 1.5. It's clearly a breaking change.

> How can I vectorize some fonts ?

True vectorization can be achieved with the "Outline all fonts" mode. But that will affect
all fonts.

> 
> Or maybe some 1.5 features, like vectorize ability, are lost ?

As mentioned above 1.5 did not provide a true vectorization capability as usually they
were still fonts being used, even it is was Type 3 fonts. At the RIP level, the behavior
is quite different. 1.5.1.svn reintroduce in fact a true vectorization capability which
was lost at some point after the 1.3.3.x series.

> If so, why were these features not worth keeping and developping ?

Type 3 fonts are falling out of flavor at printers. Some PDF standards do not even accept
them anymore. Now we have true subsetting capability for most TrueType based fonts, they
are also less suited for display on screen and some of their aspects make them harder to
handle by RIPs.

> What happens in "dont embed" mode ?

Fonts are not embedded at all in any kind of form. So that's a mode which you should use
only at your own risk. Mostly suited for simple forms. I would not mind completely
removing that mode btw.

> 
> When opening a 1.5 file with 1.5.1, the 1.5 font options in PDF export dialog
> seem to be totally ignored.
> Are they somehow identicaly managed, invisibly in the background ?
> Or are they really ignored and lost ?

They are totally ignored and lost.

Jean