Jeremias Maerki wrote:
Hi Jeremias,
thanks for the detailed reply. Comments inline.
To a certain degree, it is already possible using the Intermediate
Format. You'd generate the IF file using the font metrics for the PDF
output but render the IF file to AFP output. The tricky thing is to
synchronize the font setups for PDF and AFP (especially the font names)
so there won't be any font selection problems when generating the AFP.
However, the devil is in the detail: for performance reasons we don't
store the position of each individual glyph. This is what would be
necessary to achieve a maximum of "equalness". Otherwise, little
differences in the native font metrics can accumulate to a visible
difference in the final output if you have long strings or use things
like letter-/word-spacing. So much for what is possible today...
So basically it's not really possible because both Area Tree XML and IF
XML use letter/word spacing instead of absolute positioning each glyph.
It is thinkable that a special subclass of AFPPainter would be written
that has a special drawText() method which could use an additional
FontInfo object set up for a PDF renderer to calculate individual glyph
positions but then paint the glyphs using normal AFP infrastructure.
Just so there are no illusions: that comes with a performance penalty. I
can also not guarantee that the result is much better than the above.
Depends on the documents.
That is one possibility I can mention to the client. Any idea on how
much effort it would be to implement these changes in the AFP
Renderer/Painter?
Technically correct is what works and doesn't have a negative impact on
the overall system. ;-) At any rate, it's possible.
So I guess that lists the downsides also. Let's also look at other
possible solutions:
Normal AFP outline fonts are nothing other than Type1 PFB fonts embedded
in a FOCA resource. Type1 fonts are cheap. One could experiment by
writing a program that can turn a Type1 font into a FOCA outline font by
generating the necessary data structures (general and glyph metrics)
from the original font files. However, there's a certain risk that font
generated like this may not have optimal values everywhere so some
differences could result from this. However, I consider the risk here
relatively small as we're speaking about a scalable font. But you also
have to take into account the cost involved writing such a converter.
No need to write such a converter. IBM supplies such a program as part
of the software that ships with Info Print. I guess I need to track down
the CD and try it out. Thanks for the idea!
Another approach would be to generate bitmap fonts from Type 1 or
TrueType fonts. Creating bitmap images of single glyphs is easy. However,
bitmap fonts are usually manually optimized for the various sizes and
target resolutions which an automated program probably couldn't do that
well. The same risk as for the converted Type 1 font applies, only the
risk of suboptimal output is definitely higher.
Going further: modern AFP/IPDS environments allow to directly use
TrueType fonts as data object resources. FOP could be taught to use
TrueType fonts which would make it possible to use the same font for PDF
and AFP. Of course, if it's no option to uprade an old AFP/IPDS
environment...
Finally, there are various tools on the market (ex. Compart's DocBridge
Mill) which can convert AFP to PDF. That would entirely bypass the
problem. However, PDFs generated that way may not offer the same
feature-set that FOP can offer and the generated files might be bigger
than FOP-generated PDFs.
Thanks for your help,
Chris
HTH
On 04.03.2009 09:47:11 Chris Bowditch wrote:
Hi All,
one of my clients is using the PDF and AFP Renderers to produce the same
document via different outputs. PDF is for archiving and AFP for
Printing. However, currently the output between the 2 is different. The
AFP output line breaks differently to the PDF version, with the text
appearing larger and bolder despite the font size being the same between
the output channels. After some investigation I realised that the cause
of the problem was the use of raster AFP Fonts. When I tested PDF and
AFP output using TTF in PDF and an equivalent outline Font in AFP the
output looks identical. So I thought great and told the client to switch
to Outline Fonts in AFP.
However, my client doesn't want to do that. Apparently there would be
some large costs to purchase all the outline fonts necessary for their
large collection of existing documents. My client has asked if it is
possible to enhance FOP to use metrics from TTF or Type1 Fonts when
working with AFP raster Fonts, and just use the glyphs from the raster
font. This would ensure output between PDF and AFP looks identical. I
know XEP does something similar. Is this enhancement feasible? Is it
technically correct to use metrics from one font type and use the glyphs
from other. Is there any downside?
Comments would be appreciated.
Thanks,
Chris
Jeremias Maerki
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
