Hi Karen

Well, I don't call myself a font expert, yet, though I'm working hard to
get to Tore's level. I haven't had much contact with TrueType fonts, so
I'm probably not the right person to answer your proposal but I think if
it works it's ok.

On 19.11.2002 23:38:21 Karen Lease wrote:
> Hi all (and especially Jeremias or other font experts),
> 
> This bug seems to be due to the way we generate the 'loca' table in the 
> embedded font subsets (CID fonts). In fact, it has offsets to the 
> correct glyph descriptions, but the offsets are not in ascending order. 
> Since it seems that the length of the glyph description is found by 
> subtracting the offset to the glyph from the offset for the next glyph 
> in the loca table, this does not work. For Acrobat, as long as there 
> actually _is_ a glyph description, it seems to work anyway. However for 
> space characters, there is no glyph. Acrobat thinks there is because of 
> the offset, so it draws the glyph that _is_ stored at the offset.
> 
> This only shows up with SVG text because it has embedded spaces. The 
> spaces in normal text are generally turned into explicit offsets and not 
> drawn as such.
> 
> The attached diff fixes the bug; though there are perhaps more elegant 
> ways to do it. Does anyone see anything wrong with this idea?
> If not, I'll commit asap.

Please do. We can always change again if it doesn't work out.

The only other idea that's coming to my mind is to enhance the
TextPainter so it doesn't paint spaces but also just advanced the
current position. But that only complicates the code there and I don't
know if it's worth it.

> In fact, using this fix, xpdf now also works with embedded fonts, 
> whereas before it produced garbage.

I'd like to point out that IMO it's important to separate TrueType and
Type 1 support where embedded fonts are concerned. I'm pretty sure I
have identified a problem with embedded Type 1 fonts that leads to
errors on certain PDF and PostScript RIP engines. I don't know about
xpdf. I intend to fix that very soon now.

> Regards,
> Karen Lease
> 
> (Lately very overworked) Senior Software Developer
> SPX Valley Forge
> Paris/Munich

Have you already signed up for the germany-based committers meeting? :-)


Jeremias Maerki


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