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From Chris Bowditch <bowditch_ch...@hotmail.com>
Subject Re: AFP Font Question
Date Wed, 04 Mar 2009 15:31:34 GMT
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
> 
> 
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