This is the large, famous `Infinality' patch to support ClearType
bytecode which has been available from
http://www.infinality.net/blog/ for some time, and which has been
refined over the last years. While still experimental, it is now
mature enough to be included directly into FreeType.
Most of the code is based on the ClearType whitepaper written by
Greg Hitchcock
http://www.microsoft.com/typography/cleartype/truetypecleartype.aspx
which gives a detailed overview of the necessary changes to the
Microsoft rasterizer so that older fonts are supported. However, a
lot of details are still missing, and this patches provides a
framework to easily handle rendering issues down to the glyph level
of certain fonts.
Note that ClearType support is not completely implemented! In
particular, full support for the options `compatible_widths',
`symmetrical_smoothing, and `bgr' (via the GETINFO bytecode
instruction) is missing.
* src/truetype/ttsubpix.c: New file, providing code to handle
`tweaks', this is, rules for certain glyphs in certain fonts
(including wildcards) which need a special treatment.
* src/truetype/ttsubpix.h: New file, holding the tweaking rules.
* include/freetype/config/ftoption.h, src/devel/ftoption.h
(TT_CONFIG_OPTION_SUBPIXEL_HINTING): New macro.
* include/freetype/internal/ftobjs.h (FT_PIX_FLOOR_GRID,
FT_PIX_ROUND_GRID, FT_PIX_CEIL_GRID): New macros.
* src/truetype/truetype.c [TT_USE_BYTECODE_INTERPRETER]: Include
`ttsubpix.c'.
* src/truetype/ttgload.c: Include `ttsubpix.h'.
[All changes below are guarded by TT_CONFIG_OPTION_SUBPIXEL_HINTING.]
(tt_get_metrics): Set tweak flags.
(TT_Hint_Glyph): Call `FT_Outline_EmboldenXY' if necessary.
(TT_Process_Simple_Glyph): Compensate emboldening if necessary.
(compute_glyph_metrics): Handle `compatible widths' option.
(tt_loader_init): Handle ClearType GETINFO information bits.
* src/truetype/rules.mk (TT_DRC_SRC): Updated.
* src/truetype/ttinterp.c: Include `ttsubpix.h'.
[Where necessary, changes below are guarded by
TT_CONFIG_OPTION_SUBPIXEL_HINTING.]
(Direct_Move, Direct_Move_X): Extended.
(Round_None, Round_To_Grid, Round_To_Half_Grid, Round_Down_To_Grid,
Round_Up_To_Grid, Round_To_Double_Grid, Round_Super, Round_Super_45,
SetSuperRound): Add parameter to handle the number of grid lines per
pixel.
(SET_SuperRound, ROUND_None, CUR_Func_round): Updated.
(DO_SROUND, DOS45ROUND, DO_ODD, DO_EVEN): Updated.
(DO_ROUND, DO_NROUND): Updated.
(DO_RS): Take care of `Typeman' bytecode patterns.
(Ins_FDEF): Add some debugging code. Commented out.
(Ins_ENDF): Restore state.
(Ins_CALL, Ins_LOOPCALL): Handle inline delta functions.
(Ins_MD): Handle `Vacuform' rounds.
(Move_Zp2_Point, Ins_SHPIX, Ins_MSIRP, Ins_MDAP, Ins_MIAP,
Ins_MDRP, Ins_MIRP): Handle tweaks.
(Ins_ALIGNRP): Add tweak guard.
(Ins_IUP, Ins_DELTAP): Handle tweaks.
(Ins_GETINFO): Handle new ClearType bits.
(TT_RunIns): Handle tweaks.
* src/truetype/ttinterp.h: Updated.
(SPH_TweakRule, SPH_ScaleRule): New structures for tweaks.
(TT_ExecContextRec): Add members for subpixel hinting support.
* src/truetype/ttobjs.h (TT_DefRecord): Add `inline_delta' member.
==========================
Tag sources with `VER-2-4-10'.
* docs/VERSION.DLL: Update documentation and bump version number to
2.4.10.
* README, Jamfile (RefDoc),
builds/win32/vc2005/freetype.vcproj, builds/win32/vc2005/index.html,
builds/win32/vc2008/freetype.vcproj, builds/win32/vc2008/index.html,
builds/win32/vc2010/freetype.vcxproj, builds/win32/vc2010/index.html,
builds/win32/visualc/freetype.dsp,
builds/win32/visualc/freetype.vcproj,
builds/win32/visualc/index.html, builds/win32/visualce/freetype.dsp,
builds/win32/visualce/freetype.vcproj,
builds/win32/visualce/index.html,
builds/wince/vc2005-ce/freetype.vcproj,
builds/wince/vc2005-ce/index.html,
builds/wince/vc2008-ce/freetype.vcproj,
builds/wince/vc2008-ce/index.html: s/2.4.9/2.4.10/, s/249/2410/.
* include/freetype/freetype.h (FREETYPE_PATCH): Set to 10.
* builds/unix/configure.raw (version_info): Set to 15:0:9.
to pass special compiler/linker flags under cross development.
Suggested by Savannah bug #36367.
ChangeLog on 2010-07-15 saying as they were removed was wrong
for the official trunk of FreeType2. This commit is the first
introduction of them.
NEC FA family dated in 1996 have different checksum.
Reported by Johnson Y. Yan <yinsen_yan@foxitsoftware.com>; see
http://lists.gnu.org/archive/html/freetype-devel/2012-06/msg00023.html
* src/truetype/ttobjs.c (tt_check_trickyness_sfnt_ids): 4 sets
of fpgm & prep table checksums for FA-Gothic, FA-Minchou,
FA-RoundedGothicM, FA-RoundedGothicB are added. The family
names in sample PDF are truncated, thus the list of the
family names in tt_check_trickyness_family() is not updated yet.
* include/freetype/ftoutln.h (FT_Outline_EmboldenXY): Define it.
* src/base/ftoutln.c (FT_Outline_EmboldenXY): Implement it, using a
simplified embolding algorithm.
(FT_Outline_Embolden): Make it a special case of
`FT_Outline_EmboldenXY'
Without this patch, only the dummy and cjk autohinter modules get
them (since they copy the whole scaler object).
* src/autofit/aflatin.c (af_latin_metrics_scale),
src/autofit/aflatin2.c (af_latin2_metrics_scale): Implement it.
* builds/unix/configure.raw: Check `-ansi' flag works even if gcc
is used. Bionic libc headers for Android lose the consistency
when they are parsed with __STDC_VERSION__ older than 199901L or
__STRICT_ANSI__.
Based on the patch given in the bug report.
* src/type1/t1load.c (IS_INCREMENTAL): New macro.
(read_binary_data): Add parameter `incremental'.
Update all callers using `IS_INCREMENTAL'.
This was quite a subtle bug which accidentally showed up with glyph
`afii10023' of arial.ttf (version 2.76). This glyph is a composite;
the first component, `E', has an advance width of 1366 font units,
while the advance width of the composite itself (which looks like
uppercase `E' with dieresis) is 1367 font units. I think this is
actually a bug in the font itself, because there is no reason that
this glyph has not the same width as uppercase `E' without the
dieresis. Anyway, it helped identify this problem.
Using the TrueType hinter, the correct value (1367) of `afii10023'
was returned, but the autohinter mysteriously returned 1366.
Digging in the code showed that the autohinter recursively calls
FT_Load_Glyph to load the glyph, adding the FT_LOAD_NO_SCALE load
flag. However, the `linearHoriAdvance' field is still returned as a
scaled value. To avoid scaling twice, the old code in autofit reset
`linearHoriAdvance', using the `horiAdvance' field. This seemed to
work since FT_LOAD_NO_SCALE was in use, but it failed actually,
because `horiAdvance' is defined as the distance of the first
subglyph's phantom points, which in turn are initialized using the
advance width of the first subglyph. And as the given example
shows, these widths can differ.
* src/autofit/afloader.c (af_loader_load_g): Temporarily set
FT_LOAD_LINEAR_DESIGN while calling FT_Load_Glyph to get unscaled
values for the linear advance widths.
* src/truetype/ttinterp.c (DO_SSW): SSW *does* use font units. For
verification, it took some time to find a font which actually uses
this instruction.
For some divisions, we use casts to 32bit entities. Always guard
against division by zero with these casts also.
* src/base/ftcalc.c (ft_div64by32): Remove redundant cast.
(FT_MulDiv, FT_MulDiv_No_Round): Add 32bit cast.
(FT_DivFix): Add 32bit cast (this omission triggered the bug).
* src/psaux/afmparse.c (afm_parse_track_kern): Don't inverse sign
for `min_kern'. It is indeed quite common that track kerning
*increases* spacing for very small sizes.
If in function `skip_spaces' the routine `skip_comment' comes to the
end of buffer, `cur' is still increased by one, so we need to check
for `p >= limit' and not `p == limit'.
* src/psaux/psconv.c (PS_Conv_Strtol, PS_Conv_ToFixed,
PS_Conv_ASCIIHexDecode, PS_Conv_EexecDecode): Fix boundary checking.
* src/truetype/ttinterp.c (Ins_MIRP): Typo, present since ages. The
code is now in sync with the other operators (e.g. MSIRP) which
modify twilight points.
* src/bdf/bdflib.c (_bdf_list_ensure): Bring code in sync with
comment before `_bdf_list_split', this is, really allocate at least
five `field' elements.
Werner Lemberg