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  • Hash : 79e36bae
    Author : Infinality
    Date : 2012-06-18T10:36:06

    [truetype] Support subpixel hinting. 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.

  • README

  •   FreeType 2.4.10
      ===============
    
      Please   read   the  docs/CHANGES   file,   it  contains   IMPORTANT
      INFORMATION.
    
      Read the files `docs/INSTALL' for installation instructions.
    
      See the  file `docs/LICENSE.TXT'  for the available licenses.   Note
      that we use ranges (`2008-2010') for copyright years also instead of
      listing individual years (`2008, 2009, 2010').
    
      The FreeType 2 API reference is located in `docs/reference'; use the
      file   `ft2-doc.html'   as   the   top  entry   point.    Additional
      documentation is available as a separate package from our sites.  Go
      to
    
        http://download.savannah.gnu.org/releases/freetype/
    
      and download one of the following files.
    
        freetype-doc-2.4.10.tar.bz2
        freetype-doc-2.4.10.tar.gz
        ftdoc2410.zip
    
    
      Bugs
      ====
    
      Please report bugs  by e-mail to `freetype-devel@nongnu.org'.  Don't
      forget to  send a  detailed explanation of  the problem --  there is
      nothing  worse than  receiving a  terse message  that only  says `it
      doesn't work'.
    
      Alternatively, you may submit a bug report at
    
        https://savannah.nongnu.org/bugs/?group=freetype
    
    
      Enjoy!
    
    
        The FreeType Team
    
    ----------------------------------------------------------------------
    
    Copyright 2006-2011 by
    David Turner, Robert Wilhelm, and Werner Lemberg.
    
    This  file is  part of  the FreeType  project, and  may only  be used,
    modified,  and distributed  under the  terms of  the  FreeType project
    license,  LICENSE.TXT.  By  continuing to  use, modify,  or distribute
    this file you  indicate that you have read  the license and understand
    and accept it fully.
    
    
    --- end of README ---