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From Apache Wiki <wikidi...@apache.org>
Subject [Xmlgraphics-fop Wiki] Update of "TrueTypeInPostScript" by cbowditch
Date Tue, 11 May 2010 09:41:28 GMT
Dear Wiki user,

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The "TrueTypeInPostScript" page has been changed by cbowditch.
http://wiki.apache.org/xmlgraphics-fop/TrueTypeInPostScript?action=diff&rev1=1&rev2=2

--------------------------------------------------

  
  == Introduction ==
  
- I (JeremiasMaerki) was asked to compile some pointers and hints concerning the addition
of TrueType/OpenType support for PostScript output. At the moment (Mai 2010), we only support
Type 1 fonts in PostScript output.
+ I (JeremiasMaerki) was asked to compile some pointers and hints concerning the addition
of TrueType/OpenType support for PostScript output. At the moment (May 2010), we only support
Type 1 fonts in PostScript output.
  
  == Requirements ==
  
   * The PostScript renderer/painter shall learn to support Asian fonts including Chinese,
Japanese and Thai fonts. (This does not necessarily mean the inclusion of non-LR-TB writing
modes!)
+  * All the CJK Fonts that we have found from open source and commercial providers have been
either TTF CID-keyed or OTF with CFF glyphs. So FOP must support both CID-keyed and OTF with
CFF glyphs.
+  * All the CJK Fonts that we have found appear to be very large, i.e. > 5 Mb, so the
Postscript Renderer needs to be able to support sub-setting to keep the output size down to
reasonable levels.
  
  == Gathered hints and thoughts ==
  
@@ -17, +19 @@

  
  TrueType support was introduced during the transition from PS level 2 to
  3. Some late level 2 interpreters (version >= 2010) have support for Type 42 (TrueType)
- fonts. Of the level 3 interpreters, all do. We should probably limit support for TrueType
to level 3 PostScript so we can reduce support issues.
+ fonts. Of the level 3 interpreters, all do. We should limit support for TrueType to level
3 PostScript so we can reduce support issues and the complexity of having to deal with Type
42 fonts.
  
  There are several approaches to handling TrueType fonts, like in PDF.
  One is to create multiple single-byte encodings like we do for Type 1
  fonts (encoding-mode="single-byte" in FOP's configuration). The other
  is CID-keyed fonts which are a bit more complex (default mode with PDF
- output when using TTF fonts). In both cases it should be possible to
- work with TTF subsets.
+ output when using TTF fonts). All the CJK fonts that we've found appear 
+ to be CID-keyed fonts, so we need to support the extra complexity of CID-keyed.
  
  It seems to be possible to incrementally define a TTF
  font in PS (keyword: GlyphDirectory). However, that could interfere with
@@ -35, +37 @@

  font embedding and then use the GID from the TTF file to access the
  glyphs.
  
- Like we do with PDF output, we should only implement TTF subsetting if we
- take the CID-keyed font route. Due to the learning curve, it is suggested to
- implement full embedding and multiple single-byte encodings
- (encoding-mode="single-byte") first and subsetting later (if necessary at all).
  Keep in mind that full font embedding may offer the possibility to
  pre-install a font on the printer and just reference it in PostScript.
  However, I've never worked with TrueType fonts on PostScript so I can't
@@ -71, +69 @@

   * PSPainter
   * PSTextPainter (for SVG text)
  
- In case OpenType fonts with CFF glyphs shall be used, it may actually make sense to add
CFF
+ For OpenType fonts with CFF glyphs, it may actually make sense to add CFF
  support to our TrueType/OpenType loading code and try to use the CFF glyphs in
  PostScript since PS supports CFF fonts (Type 2 fonts). However, I don't
  know if there are any insurmountable differences between PS CFF support

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