After the next release we are going to remove the code completely.
* devel/ftoption.h, include/freetype/config/ftoption.h
(FT_CONFIG_OPTION_OLD_INTERNALS): Comment out.
* docs/CHANGES: Document it.
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.
I. IMPORTANT BUG FIXES
- Various integer overflows have been fixed.
- PFB fonts with MacOS resource fork weren't handled correctly on
non-MacOS platforms.
- The PCF font loarder has been seriously hardened against malformed
font files.
II. IMPORTANT CHANGES
- the unpatented hinter is now part of the default build of the
library, and we added code to automatically support "tricky"
fonts that need it.
what this means is that FreeType should "just work" with certain
Asian fonts, like MingLiu, which cannot properly load without a
bytecode interpreter, but fortunately do not use any of the
patented bytecode opcodes.
Note that the API didn't change, so you can still force
unpatented hinting with a special parameter to FT_Open_Face
as well.
if you're an embedded systems developer, you might want to
*disable* the feature to save code space by undefining
TT_CONFIG_OPTION_UNPATENTED_HINTING in ftoption.h.
- LCD-optimized rendering is now disabled in all default builds
of the library, mainly due to patent reasons. For more information
see:
http://lists.gnu.org/archive/html/freetype/2006-09/msg00064.html
a new configuration macro FT_CONFIG_OPTION_SUBPIXEL_RENDERING has
been introduced in ftoption.h; manually define it in this file
if you want to re-enable the feature.
the change only affects the implementation, not the FreeType API.
This means that clients don't need to be modified, because the
library still generates LCD decimated bitmaps, but with the added
constraint that R=G=B on each triplet.
- Some computation bugs in the TrueType bytecode interpreter were found,
which allow us to get rid of very subtle and rare differences we had
with the Windows renderer.
III. MISCELLANEOUS
- TrueType glyph loading is now about 25% faster.
- the anti-aliased rasterizer has been optimized and is now 15% to 25%
percent faster than the previous one, depending on content
- the Type 1 loader has been improved; as an example, it now skips
over top-level dictionaries properly
======================================================================
Werner Lemberg
Infinality
Chris Morgan
Joel Klinghed
Ralph Giles
David Turner