Quote:
Originally Posted by Peter Sorotokin
Xenophon,
Can you provide the details? In most cases character spacing is burned into the PDF file at creation time, so it may not be possible to fix that in PDF viewer, but showing wrong glyph is bad. Are you saying that Apple's Preview works correctly and Acrobat does not? Also, did you try Digital Editions?
Handling ligatures for EPUB is not at the top of our list, but we plan to do it. (Actually, it is not possible to support some languages, e.g. Arabic or Hindi, without doing ligatures properly, so we'll have to get to it).
Peter
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The reference from your typography guy will take a few days to come up with*. The
issue, on the other hand is easy to demonstrate. Here are the steps:
- Take any OS X Mac (with OS 10.4 or newer), and use an application like TextEdit or Pages.
- Pick a font that has ligature support built in. Fi and Fl are good choices to work with.
- Type a string that uses those character sequences. A fine choice would be: "Orville and Wilbur Wright finally managed flight."
- Print this to pdf using Apple's tools (not Acrobat).
- You will see that Apple has automatically used the fi and fl ligatures in the correct places.
- Send the pdf file to a PC, and view it in Acrobat. You'll see the fi and fl ligatures, but the distance from the left-hand edge of the fi to the left-hand edge of the n in "finally" will be the larger distance that would be appropriate if no ligature was used. THIS IS WRONG! Same problem with the fl in flight. And with the 'll's if the font has that ligature too.
More specifically, it'll look approximately like fi-ligature followed by about half-a-space followed by "nally". More or less. Really ugly; worse than skipping the ligatures, in fact.
If you send the pdf file to a postscript printer from a Mac everything will look just right. If you send the same file to a postscript printer from a PC it will print with the same bug. Again, this is wrong.
Lastly, if you send the PDF file to a Sony Reader, you won't see the ligature
AT ALL. Instead, you'll see either blank space or you'll see some random character that isn't the correct ligature. This latter failure look an awful lot like what happened in the days before OpenType fonts that include all the ligatures in one font file. Back when you had to use the "Foo Professional" or "Foo Extended" font to get the ligatures for the Foo font, you'd see odd characters if you forgot to load the professional/extended fonts along with the base font. I believe that those odd characters were the over-loaded code for the ligature. This also happened with built-in fractions, and other extended-font characters.
In these modern days of OpenType fonts with all the fractions and ligatures and stuff built in to a single font, I would surely hope that no such effect would ever show up ever again. And even with the older fonts that had the ligatures and fractions and swash caps and stuff split out into other fonts, it
still ought to work correctly from a PDF which does, after all, include the bloody fonts as needed!
*I think that the book I saw it in had a title like "Computer Typography" or some such. Recent (within the last few years) fat book on "more than you ever wanted to know about typography and computers" by an author described on the cover as "one of Adobe's leading font/typography gurus" (or words to that effect). It's in my office at school, so I won't lay hands on it before Monday at the soonest. And I'm ten days from my Thesis defense, so I may not get to it until after that. I should note that he also pointed out plenty of things that Apple does wrong too! This just happened to be one of the things that they got right.
Xenophon
P.S. If you want to see a really wild version of this effect, use the font Zapfino in a larger type size -- 24-point or so. Zapfino includes a glyph that is a fancy version of the name of the font. So, type "Zapfino is wonderful" in Pages, and watch as the word Zapfino transforms itself into the fancy glyph. Then move the resulting pdf file around, and watch the spacing be screwed up as above. Experimenting quickly, I see that the word "Zapfino" at 24-point is 1.5 inches wide with ligatures forced to OFF (plus an scoosh for the overhanging tail of the trailing o). With ligatures ON, the Zapfino glyph is a bit less than 2 inches wide, plus a little bit for an overhanging tail from the o and the swash underneath. That should really mess up the spacing!