Re: [Freetype] Fonttootf: first cut of a BDF->TTF converter available

[Vadim Plessky]

Hello Juliusz!

On Wednesday 21 August 2002 9:30 pm, Juliusz Chroboczek wrote:
|  Hello,
|
|  The first cut of fonttootf, a BDF to snft (TTF or OTF) converter for
|  bitmap fonts is available from
|
|    http://www.pps.jussieu.fr/~jch/software/files/fonttootf-20020821.tar.gz
|
|  This is an early beta, please do not redistribute this version.
|
|  A few caveats.  First, you need a version of FreeType that contains
|  the bug fix of August 19; this means current CVS.  Second, due to
|  another bug, you will not be able to use this code on BDF fonts
|  (you'll need to convert to PCF first).
|
|  Second, the Microsoft TrueType, Apple TrueType and OpenType specs
|  differ on what tables are compulsory.  Microsoft TrueType makes all
|  tables compulsory.  OpenType makes loca and glyf optional (but hmtx
|  compulsory), while Apple TrueType makes all tables optional.  Thus,
|  fonttootf can generate different variants of fonts with the -m and -g
|  flags.  Please see the man page for details.
|
|  In short, though, FreeType works with -g at least 2 and -m at least 1.
|  Pfaedit requires -g 3.  The cases -g 2 and -m 0 violate the OpenType
|  spec; all other cases are legal.
|
|  Here's a summary of font sizes:
|                                              (1)      (2)         (3)
|                           .pcf    .pcf.gz  pfaedit  fonttootf  fonttotf -c
|  8x13-L1.pcf              19572     4579     6908     4012        4032
|  8x13.pcf                410660    57158             54044       52244
|  helvR14.pcf              71804    13901             15780       15796
|  9x18.pcf + 18x18ja.pcf        77976 + 580901       796464      917620
|

Results are indeed very good!
We should really consider TTF?OTF format with embedded bitmaps as replacement 
for PCF/BDF.

Do you have ani ideas why PfaEdit produces slightly better results than your 
conversion tool?
Any chance to cooperate with PfaEdit and to have *unified* conversion 
algorithm?

|  All sizes are in bytes.  Column (1) is the size of the TTF generated
|  by pfaedit; I didn't try to tune pfaedit's options -- this is not
|  meant as a fair comparison, but rather as a baseline.  Colum (2) is
|  the size of the TTF generated by fonttootf by default; column (3) is
|  the size of the TTF generated by fonttootf with glyph cropping
|  disabled.
|
|  The first font is a small (196 glyphs) small (8x13) charcell font.
|  The second is a large (almost 4000 glyphs) small (8x13) charcell font.
|  The third is a small (196 glyphs) small (14 ppem) variable width font.
|  The fourth is a large large bi-width font generated from two charcell
|  fonts (yep, fonttootf can do that).
|
|  As you'll notice, cropping doesn't buy you much.  In the case of the
|  variable font, this is expected, as the font is already cropped
|  (except that spaces are represented as 1x1 bitmaps, cropping
|  eliminates the bitmaps altogether).  In the case of the charcell and
|  bi-width fonts, cropping does reduce the bitmap data quite a bit;
|  however, the glyphs then have variable metrics, which prevents
|  fonttootf from optimising the metrics table by encoding metrics only
|  once.  Thus, the gain in bitmap data is mostly offset by the larger
|  metadata.  Only in the case of the 18-pixel font, where the bitmap
|  data dominates the font size, is cropping worthwile.
|
|  Here's a selection of table sizes for the three TTFs generated from
|  8x13-L1.pcf.
|
|  EBDT (bitmap data): (1) 2468, (2) 2272, (3) 2903.
|
|  In case (2), we gain some w.r.t. pfaedit by writing metric-less
|  bitmaps whenever possible.  In case (3), the bitmap data is much
|  larger, but all bitmaps are metric-less (as they are all equal) which
|  makes the EBDT only slightly larger.
|
|  EBLC (bitmap index): (1) 968 , (2) 698, (3) 84.
|
|  As above.  In case (2), some EBDT subtables have been replaced by
|  metric-less tables.  In case (3), there is a single metric-less table,
|  and the EBLC is tiny.
|
|  cmap (character to index mapping): (1) 698, (2) 52, (3) 52.
|
|  Here we simply order all glyphs so that the cmap table is trivial.
|  Pfaedit orders the glyph in what appears to be a random order, and
|  therefore has to output a complex cmap.
|
|  Regards,
|                                          Juliusz
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Vadim Plessky
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