This reduces redundancy and increases synergy; it also reduces the number of header files. * include/freetype/config/ftheader.h (FT_DRIVER_H): New macro. (FT_AUTOHINTER_H, FT_CFF_DRIVER_H, FT_TRUETYPE_DRIVER_H, FT_PCF_DRIVER_H, FT_TYPE1_DRIVER_H): Make them aliases to FT_DRIVER_H. * include/freetype/ftautoh.h, include/freetype/ftcffdrv.h, include/freetype/ftpcfdrv.h, include/freetype/ftt1drv.h, include/freetype/ftttdrv.h: Replaced with... * include/freetype/ftdriver.h: ...this new file. (FT_CFF_HINTING_ADOBE, FT_T1_HINTING_ADOBE): Renamed to... (FT_HINTING_ADOBE): ... this new macro. (FT_CFF_HINTING_FREETYPE, FT_T1_HINTING_FREETYPE): Renamed to... (FT_HINTING_FREETYPE): ... this new macro. * src/*/*: Updated accordingly.GSoC-2017-kushal
Werner Lemberg
7 years ago
parent
bef8de2a85
commit
98ba0c4a37
29 changed files with 1313 additions and 1473 deletions
@ -1,535 +0,0 @@ |
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/***************************************************************************/ |
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/* */ |
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/* ftautoh.h */ |
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/* */ |
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/* FreeType API for controlling the auto-hinter (specification only). */ |
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/* */ |
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/* Copyright 2012-2017 by */ |
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/* David Turner, Robert Wilhelm, and Werner Lemberg. */ |
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/* */ |
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/* This file is part of the FreeType project, and may only be used, */ |
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/* modified, and distributed under the terms of the FreeType project */ |
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/* license, LICENSE.TXT. By continuing to use, modify, or distribute */ |
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/* this file you indicate that you have read the license and */ |
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/* understand and accept it fully. */ |
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/* */ |
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/***************************************************************************/ |
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|
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|
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#ifndef FTAUTOH_H_ |
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#define FTAUTOH_H_ |
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|
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#include <ft2build.h> |
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#include FT_FREETYPE_H |
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#include FT_PARAMETER_TAGS_H |
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|
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#ifdef FREETYPE_H |
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#error "freetype.h of FreeType 1 has been loaded!" |
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#error "Please fix the directory search order for header files" |
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#error "so that freetype.h of FreeType 2 is found first." |
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#endif |
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FT_BEGIN_HEADER |
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|
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/**************************************************************************
|
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* |
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* @section: |
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* auto_hinter |
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* |
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* @title: |
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* The auto-hinter |
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* |
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* @abstract: |
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* Controlling the auto-hinting module. |
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* |
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* @description: |
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* While FreeType's auto-hinter doesn't expose API functions by itself, |
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* it is possible to control its behaviour with @FT_Property_Set and |
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* @FT_Property_Get. The following lists the available properties |
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* together with the necessary macros and structures. |
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* |
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* Note that the auto-hinter's module name is `autofitter' for |
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* historical reasons. |
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* |
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*/ |
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|
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|
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/**************************************************************************
|
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* |
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* @property: |
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* glyph-to-script-map |
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* |
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* @description: |
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* *Experimental* *only* |
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* |
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* The auto-hinter provides various script modules to hint glyphs. |
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* Examples of supported scripts are Latin or CJK. Before a glyph is |
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* auto-hinted, the Unicode character map of the font gets examined, and |
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* the script is then determined based on Unicode character ranges, see |
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* below. |
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* |
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* OpenType fonts, however, often provide much more glyphs than |
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* character codes (small caps, superscripts, ligatures, swashes, etc.), |
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* to be controlled by so-called `features'. Handling OpenType features |
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* can be quite complicated and thus needs a separate library on top of |
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* FreeType. |
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* |
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* The mapping between glyph indices and scripts (in the auto-hinter |
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* sense, see the @FT_AUTOHINTER_SCRIPT_XXX values) is stored as an |
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* array with `num_glyphs' elements, as found in the font's @FT_Face |
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* structure. The `glyph-to-script-map' property returns a pointer to |
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* this array, which can be modified as needed. Note that the |
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* modification should happen before the first glyph gets processed by |
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* the auto-hinter so that the global analysis of the font shapes |
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* actually uses the modified mapping. |
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* |
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* The following example code demonstrates how to access it (omitting |
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* the error handling). |
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* |
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* { |
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* FT_Library library; |
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* FT_Face face; |
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* FT_Prop_GlyphToScriptMap prop; |
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* |
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* |
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* FT_Init_FreeType( &library ); |
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* FT_New_Face( library, "foo.ttf", 0, &face ); |
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* |
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* prop.face = face; |
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* |
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* FT_Property_Get( library, "autofitter", |
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* "glyph-to-script-map", &prop ); |
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* |
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* // adjust `prop.map' as needed right here
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* |
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* FT_Load_Glyph( face, ..., FT_LOAD_FORCE_AUTOHINT ); |
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* } |
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* |
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* @since: |
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* 2.4.11 |
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* |
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*/ |
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|
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|
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/**************************************************************************
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* |
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* @enum: |
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* FT_AUTOHINTER_SCRIPT_XXX |
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* |
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* @description: |
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* *Experimental* *only* |
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* |
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* A list of constants used for the @glyph-to-script-map property to |
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* specify the script submodule the auto-hinter should use for hinting a |
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* particular glyph. |
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* |
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* @values: |
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* FT_AUTOHINTER_SCRIPT_NONE :: |
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* Don't auto-hint this glyph. |
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* |
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* FT_AUTOHINTER_SCRIPT_LATIN :: |
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* Apply the latin auto-hinter. For the auto-hinter, `latin' is a |
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* very broad term, including Cyrillic and Greek also since characters |
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* from those scripts share the same design constraints. |
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* |
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* By default, characters from the following Unicode ranges are |
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* assigned to this submodule. |
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* |
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* { |
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* U+0020 - U+007F // Basic Latin (no control characters)
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* U+00A0 - U+00FF // Latin-1 Supplement (no control characters)
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* U+0100 - U+017F // Latin Extended-A
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* U+0180 - U+024F // Latin Extended-B
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* U+0250 - U+02AF // IPA Extensions
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* U+02B0 - U+02FF // Spacing Modifier Letters
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* U+0300 - U+036F // Combining Diacritical Marks
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* U+0370 - U+03FF // Greek and Coptic
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* U+0400 - U+04FF // Cyrillic
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* U+0500 - U+052F // Cyrillic Supplement
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* U+1D00 - U+1D7F // Phonetic Extensions
|
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* U+1D80 - U+1DBF // Phonetic Extensions Supplement
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* U+1DC0 - U+1DFF // Combining Diacritical Marks Supplement
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* U+1E00 - U+1EFF // Latin Extended Additional
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* U+1F00 - U+1FFF // Greek Extended
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* U+2000 - U+206F // General Punctuation
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* U+2070 - U+209F // Superscripts and Subscripts
|
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* U+20A0 - U+20CF // Currency Symbols
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* U+2150 - U+218F // Number Forms
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* U+2460 - U+24FF // Enclosed Alphanumerics
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* U+2C60 - U+2C7F // Latin Extended-C
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* U+2DE0 - U+2DFF // Cyrillic Extended-A
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* U+2E00 - U+2E7F // Supplemental Punctuation
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* U+A640 - U+A69F // Cyrillic Extended-B
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* U+A720 - U+A7FF // Latin Extended-D
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* U+FB00 - U+FB06 // Alphab. Present. Forms (Latin Ligatures)
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* U+1D400 - U+1D7FF // Mathematical Alphanumeric Symbols
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* U+1F100 - U+1F1FF // Enclosed Alphanumeric Supplement
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* } |
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* |
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* FT_AUTOHINTER_SCRIPT_CJK :: |
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* Apply the CJK auto-hinter, covering Chinese, Japanese, Korean, old |
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* Vietnamese, and some other scripts. |
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* |
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* By default, characters from the following Unicode ranges are |
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* assigned to this submodule. |
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* |
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* { |
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* U+1100 - U+11FF // Hangul Jamo
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* U+2E80 - U+2EFF // CJK Radicals Supplement
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* U+2F00 - U+2FDF // Kangxi Radicals
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* U+2FF0 - U+2FFF // Ideographic Description Characters
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* U+3000 - U+303F // CJK Symbols and Punctuation
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* U+3040 - U+309F // Hiragana
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* U+30A0 - U+30FF // Katakana
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* U+3100 - U+312F // Bopomofo
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* U+3130 - U+318F // Hangul Compatibility Jamo
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* U+3190 - U+319F // Kanbun
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* U+31A0 - U+31BF // Bopomofo Extended
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* U+31C0 - U+31EF // CJK Strokes
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* U+31F0 - U+31FF // Katakana Phonetic Extensions
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* U+3200 - U+32FF // Enclosed CJK Letters and Months
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* U+3300 - U+33FF // CJK Compatibility
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* U+3400 - U+4DBF // CJK Unified Ideographs Extension A
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* U+4DC0 - U+4DFF // Yijing Hexagram Symbols
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* U+4E00 - U+9FFF // CJK Unified Ideographs
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* U+A960 - U+A97F // Hangul Jamo Extended-A
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* U+AC00 - U+D7AF // Hangul Syllables
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* U+D7B0 - U+D7FF // Hangul Jamo Extended-B
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* U+F900 - U+FAFF // CJK Compatibility Ideographs
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* U+FE10 - U+FE1F // Vertical forms
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* U+FE30 - U+FE4F // CJK Compatibility Forms
|
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* U+FF00 - U+FFEF // Halfwidth and Fullwidth Forms
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* U+1B000 - U+1B0FF // Kana Supplement
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* U+1D300 - U+1D35F // Tai Xuan Hing Symbols
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* U+1F200 - U+1F2FF // Enclosed Ideographic Supplement
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* U+20000 - U+2A6DF // CJK Unified Ideographs Extension B
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* U+2A700 - U+2B73F // CJK Unified Ideographs Extension C
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* U+2B740 - U+2B81F // CJK Unified Ideographs Extension D
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* U+2F800 - U+2FA1F // CJK Compatibility Ideographs Supplement
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* } |
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* |
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* FT_AUTOHINTER_SCRIPT_INDIC :: |
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* Apply the indic auto-hinter, covering all major scripts from the |
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* Indian sub-continent and some other related scripts like Thai, Lao, |
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* or Tibetan. |
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* |
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* By default, characters from the following Unicode ranges are |
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* assigned to this submodule. |
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* |
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* { |
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* U+0900 - U+0DFF // Indic Range
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* U+0F00 - U+0FFF // Tibetan
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* U+1900 - U+194F // Limbu
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* U+1B80 - U+1BBF // Sundanese
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* U+A800 - U+A82F // Syloti Nagri
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* U+ABC0 - U+ABFF // Meetei Mayek
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* U+11800 - U+118DF // Sharada
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* } |
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* |
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* Note that currently Indic support is rudimentary only, missing blue |
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* zone support. |
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* |
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* @since: |
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* 2.4.11 |
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* |
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*/ |
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#define FT_AUTOHINTER_SCRIPT_NONE 0 |
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#define FT_AUTOHINTER_SCRIPT_LATIN 1 |
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#define FT_AUTOHINTER_SCRIPT_CJK 2 |
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#define FT_AUTOHINTER_SCRIPT_INDIC 3 |
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|
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|
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/**************************************************************************
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* |
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* @struct: |
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* FT_Prop_GlyphToScriptMap |
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* |
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* @description: |
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* *Experimental* *only* |
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* |
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* The data exchange structure for the @glyph-to-script-map property. |
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* |
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* @since: |
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* 2.4.11 |
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* |
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*/ |
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typedef struct FT_Prop_GlyphToScriptMap_ |
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{ |
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FT_Face face; |
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FT_UShort* map; |
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} FT_Prop_GlyphToScriptMap; |
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/**************************************************************************
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* |
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* @property: |
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* fallback-script |
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* |
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* @description: |
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* *Experimental* *only* |
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* |
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* If no auto-hinter script module can be assigned to a glyph, a |
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* fallback script gets assigned to it (see also the |
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* @glyph-to-script-map property). By default, this is |
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* @FT_AUTOHINTER_SCRIPT_CJK. Using the `fallback-script' property, |
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* this fallback value can be changed. |
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* |
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* { |
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* FT_Library library; |
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* FT_UInt fallback_script = FT_AUTOHINTER_SCRIPT_NONE; |
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* |
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* |
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* FT_Init_FreeType( &library ); |
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* |
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* FT_Property_Set( library, "autofitter", |
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* "fallback-script", &fallback_script ); |
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* } |
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* |
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* @note: |
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* This property can be used with @FT_Property_Get also. |
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* |
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* It's important to use the right timing for changing this value: The |
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* creation of the glyph-to-script map that eventually uses the |
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* fallback script value gets triggered either by setting or reading a |
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* face-specific property like @glyph-to-script-map, or by auto-hinting |
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* any glyph from that face. In particular, if you have already created |
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* an @FT_Face structure but not loaded any glyph (using the |
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* auto-hinter), a change of the fallback script will affect this face. |
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* |
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* @since: |
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* 2.4.11 |
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* |
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*/ |
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|
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|
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/**************************************************************************
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* |
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* @property: |
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* default-script |
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* |
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* @description: |
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* *Experimental* *only* |
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* |
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* If FreeType gets compiled with FT_CONFIG_OPTION_USE_HARFBUZZ to make |
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* the HarfBuzz library access OpenType features for getting better |
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* glyph coverages, this property sets the (auto-fitter) script to be |
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* used for the default (OpenType) script data of a font's GSUB table. |
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* Features for the default script are intended for all scripts not |
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* explicitly handled in GSUB; an example is a `dlig' feature, |
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* containing the combination of the characters `T', `E', and `L' to |
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* form a `TEL' ligature. |
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* |
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* By default, this is @FT_AUTOHINTER_SCRIPT_LATIN. Using the |
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* `default-script' property, this default value can be changed. |
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* |
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* { |
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* FT_Library library; |
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* FT_UInt default_script = FT_AUTOHINTER_SCRIPT_NONE; |
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* |
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* |
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* FT_Init_FreeType( &library ); |
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* |
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* FT_Property_Set( library, "autofitter", |
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* "default-script", &default_script ); |
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* } |
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* |
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* @note: |
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* This property can be used with @FT_Property_Get also. |
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* |
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* It's important to use the right timing for changing this value: The |
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* creation of the glyph-to-script map that eventually uses the |
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* default script value gets triggered either by setting or reading a |
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* face-specific property like @glyph-to-script-map, or by auto-hinting |
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* any glyph from that face. In particular, if you have already created |
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* an @FT_Face structure but not loaded any glyph (using the |
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* auto-hinter), a change of the default script will affect this face. |
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* |
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*/ |
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|
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|
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/**************************************************************************
|
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* |
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* @property: |
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* increase-x-height |
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* |
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* @description: |
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* For ppem values in the range 6~<= ppem <= `increase-x-height', round |
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* up the font's x~height much more often than normally. If the value |
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* is set to~0, which is the default, this feature is switched off. Use |
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* this property to improve the legibility of small font sizes if |
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* necessary. |
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* |
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* { |
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* FT_Library library; |
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* FT_Face face; |
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* FT_Prop_IncreaseXHeight prop; |
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* |
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* |
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* FT_Init_FreeType( &library ); |
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* FT_New_Face( library, "foo.ttf", 0, &face ); |
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* FT_Set_Char_Size( face, 10 * 64, 0, 72, 0 ); |
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* |
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* prop.face = face; |
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* prop.limit = 14; |
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* |
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* FT_Property_Set( library, "autofitter", |
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* "increase-x-height", &prop ); |
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* } |
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* |
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* @note: |
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* This property can be used with @FT_Property_Get also. |
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* |
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* Set this value right after calling @FT_Set_Char_Size, but before |
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* loading any glyph (using the auto-hinter). |
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* |
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* @since: |
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* 2.4.11 |
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* |
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*/ |
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|
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|
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/**************************************************************************
|
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* |
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* @struct: |
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* FT_Prop_IncreaseXHeight |
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* |
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* @description: |
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* The data exchange structure for the @increase-x-height property. |
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* |
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*/ |
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typedef struct FT_Prop_IncreaseXHeight_ |
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{ |
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FT_Face face; |
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FT_UInt limit; |
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|
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} FT_Prop_IncreaseXHeight; |
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|
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|
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/**************************************************************************
|
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* |
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* @property: |
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* warping |
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* |
||||
* @description: |
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* *Experimental* *only* |
||||
* |
||||
* If FreeType gets compiled with option AF_CONFIG_OPTION_USE_WARPER to |
||||
* activate the warp hinting code in the auto-hinter, this property |
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* switches warping on and off. |
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* |
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* Warping only works in `normal' auto-hinting mode replacing it. |
||||
* The idea of the code is to slightly scale and shift a glyph along |
||||
* the non-hinted dimension (which is usually the horizontal axis) so |
||||
* that as much of its segments are aligned (more or less) to the grid. |
||||
* To find out a glyph's optimal scaling and shifting value, various |
||||
* parameter combinations are tried and scored. |
||||
* |
||||
* By default, warping is off. The example below shows how to switch on |
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* warping (omitting the error handling). |
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* |
||||
* { |
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* FT_Library library; |
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* FT_Bool warping = 1; |
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* |
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* |
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* FT_Init_FreeType( &library ); |
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* |
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* FT_Property_Set( library, "autofitter", |
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* "warping", &warping ); |
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* } |
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* |
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* @note: |
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* This property can be used with @FT_Property_Get also. |
||||
* |
||||
* This property can be set via the `FREETYPE_PROPERTIES' environment |
||||
* variable (using values 1 and 0 for `on' and `off', respectively). |
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* |
||||
* The warping code can also change advance widths. Have a look at the |
||||
* `lsb_delta' and `rsb_delta' fields in the @FT_GlyphSlotRec structure |
||||
* for details on improving inter-glyph distances while rendering. |
||||
* |
||||
* Since warping is a global property of the auto-hinter it is best to |
||||
* change its value before rendering any face. Otherwise, you should |
||||
* reload all faces that get auto-hinted in `normal' hinting mode. |
||||
* |
||||
*/ |
||||
|
||||
|
||||
/**************************************************************************
|
||||
* |
||||
* @property: |
||||
* no-stem-darkening[autofit] |
||||
* |
||||
* @description: |
||||
* *Experimental* *only*, *requires* *linear* *alpha* *blending* *and* |
||||
* *gamma* *correction* |
||||
* |
||||
* Stem darkening emboldens glyphs at smaller sizes to make them more |
||||
* readable on common low-DPI screens when using linear alpha blending |
||||
* and gamma correction, see @FT_Render_Glyph. When not using linear |
||||
* alpha blending and gamma correction, glyphs will appear heavy and |
||||
* fuzzy! |
||||
* |
||||
* Gamma correction essentially lightens fonts since shades of grey are |
||||
* shifted to higher pixel values (=~higher brightness) to match the |
||||
* original intention to the reality of our screens. The side-effect is |
||||
* that glyphs `thin out'. Mac OS~X and Adobe's proprietary font |
||||
* rendering library implement a counter-measure: stem darkening at |
||||
* smaller sizes where shades of gray dominate. By emboldening a glyph |
||||
* slightly in relation to its pixel size, individual pixels get higher |
||||
* coverage of filled-in outlines and are therefore `blacker'. This |
||||
* counteracts the `thinning out' of glyphs, making text remain readable |
||||
* at smaller sizes. All glyphs that pass through the auto-hinter will |
||||
* be emboldened unless this property is set to TRUE. |
||||
* |
||||
* See the description of the CFF driver for algorithmic details. Total |
||||
* consistency with the CFF driver is currently not achieved because the |
||||
* emboldening method differs and glyphs must be scaled down on the |
||||
* Y-axis to keep outline points inside their precomputed blue zones. |
||||
* The smaller the size (especially 9ppem and down), the higher the loss |
||||
* of emboldening versus the CFF driver. |
||||
* |
||||
* This property can be set via the `FREETYPE_PROPERTIES' environment |
||||
* variable similar to the CFF driver. It can also be set per face |
||||
* using @FT_Face_Properties with @FT_PARAM_TAG_STEM_DARKENING. |
||||
* |
||||
* @since: |
||||
* 2.6.2 |
||||
* |
||||
*/ |
||||
|
||||
|
||||
/**************************************************************************
|
||||
* |
||||
* @property: |
||||
* darkening-parameters[autofit] |
||||
* |
||||
* @description: |
||||
* *Experimental* *only* |
||||
* |
||||
* See the description of the CFF driver for details. This |
||||
* implementation appropriates the |
||||
* CFF_CONFIG_OPTION_DARKENING_PARAMETER_* #defines for consistency. |
||||
* Note the differences described in @no-stem-darkening[autofit]. |
||||
* |
||||
* This property can be set via the `FREETYPE_PROPERTIES' environment |
||||
* variable similar to the CFF driver. |
||||
* |
||||
* @since: |
||||
* 2.6.2 |
||||
* |
||||
*/ |
||||
|
||||
|
||||
/* */ |
||||
|
||||
|
||||
FT_END_HEADER |
||||
|
||||
#endif /* FTAUTOH_H_ */ |
||||
|
||||
|
||||
/* END */ |
||||
@ -1,322 +0,0 @@ |
||||
/***************************************************************************/ |
||||
/* */ |
||||
/* ftcffdrv.h */ |
||||
/* */ |
||||
/* FreeType API for controlling the CFF driver (specification only). */ |
||||
/* */ |
||||
/* Copyright 2013-2017 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. */ |
||||
/* */ |
||||
/***************************************************************************/ |
||||
|
||||
|
||||
#ifndef FTCFFDRV_H_ |
||||
#define FTCFFDRV_H_ |
||||
|
||||
#include <ft2build.h> |
||||
#include FT_FREETYPE_H |
||||
#include FT_PARAMETER_TAGS_H |
||||
|
||||
#ifdef FREETYPE_H |
||||
#error "freetype.h of FreeType 1 has been loaded!" |
||||
#error "Please fix the directory search order for header files" |
||||
#error "so that freetype.h of FreeType 2 is found first." |
||||
#endif |
||||
|
||||
|
||||
FT_BEGIN_HEADER |
||||
|
||||
|
||||
/**************************************************************************
|
||||
* |
||||
* @section: |
||||
* cff_driver |
||||
* |
||||
* @title: |
||||
* The CFF driver |
||||
* |
||||
* @abstract: |
||||
* Controlling the CFF driver module. |
||||
* |
||||
* @description: |
||||
* While FreeType's CFF driver doesn't expose API functions by itself, |
||||
* it is possible to control its behaviour with @FT_Property_Set and |
||||
* @FT_Property_Get. The list below gives the available properties |
||||
* together with the necessary macros and structures. |
||||
* |
||||
* The CFF driver's module name is `cff'. |
||||
* |
||||
* *Hinting* *and* *antialiasing* *principles* *of* *the* *new* *engine* |
||||
* |
||||
* The rasterizer is positioning horizontal features (e.g., ascender |
||||
* height & x-height, or crossbars) on the pixel grid and minimizing the |
||||
* amount of antialiasing applied to them, while placing vertical |
||||
* features (vertical stems) on the pixel grid without hinting, thus |
||||
* representing the stem position and weight accurately. Sometimes the |
||||
* vertical stems may be only partially black. In this context, |
||||
* `antialiasing' means that stems are not positioned exactly on pixel |
||||
* borders, causing a fuzzy appearance. |
||||
* |
||||
* There are two principles behind this approach. |
||||
* |
||||
* 1) No hinting in the horizontal direction: Unlike `superhinted' |
||||
* TrueType, which changes glyph widths to accommodate regular |
||||
* inter-glyph spacing, Adobe's approach is `faithful to the design' in |
||||
* representing both the glyph width and the inter-glyph spacing |
||||
* designed for the font. This makes the screen display as close as it |
||||
* can be to the result one would get with infinite resolution, while |
||||
* preserving what is considered the key characteristics of each glyph. |
||||
* Note that the distances between unhinted and grid-fitted positions at |
||||
* small sizes are comparable to kerning values and thus would be |
||||
* noticeable (and distracting) while reading if hinting were applied. |
||||
* |
||||
* One of the reasons to not hint horizontally is antialiasing for LCD |
||||
* screens: The pixel geometry of modern displays supplies three |
||||
* vertical sub-pixels as the eye moves horizontally across each visible |
||||
* pixel. On devices where we can be certain this characteristic is |
||||
* present a rasterizer can take advantage of the sub-pixels to add |
||||
* increments of weight. In Western writing systems this turns out to |
||||
* be the more critical direction anyway; the weights and spacing of |
||||
* vertical stems (see above) are central to Armenian, Cyrillic, Greek, |
||||
* and Latin type designs. Even when the rasterizer uses greyscale |
||||
* antialiasing instead of color (a necessary compromise when one |
||||
* doesn't know the screen characteristics), the unhinted vertical |
||||
* features preserve the design's weight and spacing much better than |
||||
* aliased type would. |
||||
* |
||||
* 2) Alignment in the vertical direction: Weights and spacing along the |
||||
* y~axis are less critical; what is much more important is the visual |
||||
* alignment of related features (like cap-height and x-height). The |
||||
* sense of alignment for these is enhanced by the sharpness of grid-fit |
||||
* edges, while the cruder vertical resolution (full pixels instead of |
||||
* 1/3 pixels) is less of a problem. |
||||
* |
||||
* On the technical side, horizontal alignment zones for ascender, |
||||
* x-height, and other important height values (traditionally called |
||||
* `blue zones') as defined in the font are positioned independently, |
||||
* each being rounded to the nearest pixel edge, taking care of |
||||
* overshoot suppression at small sizes, stem darkening, and scaling. |
||||
* |
||||
* Hstems (this is, hint values defined in the font to help align |
||||
* horizontal features) that fall within a blue zone are said to be |
||||
* `captured' and are aligned to that zone. Uncaptured stems are moved |
||||
* in one of four ways, top edge up or down, bottom edge up or down. |
||||
* Unless there are conflicting hstems, the smallest movement is taken |
||||
* to minimize distortion. |
||||
* |
||||
* @order: |
||||
* hinting-engine[cff] |
||||
* no-stem-darkening[cff] |
||||
* darkening-parameters[cff] |
||||
* random-seed |
||||
* |
||||
*/ |
||||
|
||||
|
||||
/**************************************************************************
|
||||
* |
||||
* @property: |
||||
* hinting-engine[cff] |
||||
* |
||||
* @description: |
||||
* Thanks to Adobe, which contributed a new hinting (and parsing) |
||||
* engine, an application can select between `freetype' and `adobe' if |
||||
* compiled with CFF_CONFIG_OPTION_OLD_ENGINE. If this configuration |
||||
* macro isn't defined, `hinting-engine' does nothing. |
||||
* |
||||
* The default engine is `freetype' if CFF_CONFIG_OPTION_OLD_ENGINE is |
||||
* defined, and `adobe' otherwise. |
||||
* |
||||
* The following example code demonstrates how to select Adobe's hinting |
||||
* engine (omitting the error handling). |
||||
* |
||||
* { |
||||
* FT_Library library; |
||||
* FT_UInt hinting_engine = FT_CFF_HINTING_ADOBE; |
||||
* |
||||
* |
||||
* FT_Init_FreeType( &library ); |
||||
* |
||||
* FT_Property_Set( library, "cff", |
||||
* "hinting-engine", &hinting_engine ); |
||||
* } |
||||
* |
||||
* @note: |
||||
* This property can be used with @FT_Property_Get also. |
||||
* |
||||
* This property can be set via the `FREETYPE_PROPERTIES' environment |
||||
* variable (using values `adobe' or `freetype'). |
||||
* |
||||
* @since: |
||||
* 2.4.12 |
||||
*/ |
||||
|
||||
|
||||
/**************************************************************************
|
||||
* |
||||
* @enum: |
||||
* FT_CFF_HINTING_XXX |
||||
* |
||||
* @description: |
||||
* A list of constants used for the @hinting-engine[cff] property to |
||||
* select the hinting engine for CFF fonts. |
||||
* |
||||
* @values: |
||||
* FT_CFF_HINTING_FREETYPE :: |
||||
* Use the old FreeType hinting engine. |
||||
* |
||||
* FT_CFF_HINTING_ADOBE :: |
||||
* Use the hinting engine contributed by Adobe. |
||||
* |
||||
* @since: |
||||
* 2.4.12 |
||||
* |
||||
*/ |
||||
#define FT_CFF_HINTING_FREETYPE 0 |
||||
#define FT_CFF_HINTING_ADOBE 1 |
||||
|
||||
|
||||
/**************************************************************************
|
||||
* |
||||
* @property: |
||||
* no-stem-darkening[cff] |
||||
* |
||||
* @description: |
||||
* By default, the Adobe CFF engine darkens stems at smaller sizes, |
||||
* regardless of hinting, to enhance contrast. This feature requires |
||||
* a rendering system with proper gamma correction. Setting this |
||||
* property, stem darkening gets switched off. |
||||
* |
||||
* Note that stem darkening is never applied if @FT_LOAD_NO_SCALE is set. |
||||
* |
||||
* { |
||||
* FT_Library library; |
||||
* FT_Bool no_stem_darkening = TRUE; |
||||
* |
||||
* |
||||
* FT_Init_FreeType( &library ); |
||||
* |
||||
* FT_Property_Set( library, "cff", |
||||
* "no-stem-darkening", &no_stem_darkening ); |
||||
* } |
||||
* |
||||
* @note: |
||||
* This property can be used with @FT_Property_Get also. |
||||
* |
||||
* This property can be set via the `FREETYPE_PROPERTIES' environment |
||||
* variable (using values 1 and 0 for `on' and `off', respectively). |
||||
* It can also be set per face using @FT_Face_Properties with |
||||
* @FT_PARAM_TAG_STEM_DARKENING. |
||||
* |
||||
* @since: |
||||
* 2.4.12 |
||||
* |
||||
*/ |
||||
|
||||
|
||||
/**************************************************************************
|
||||
* |
||||
* @property: |
||||
* darkening-parameters[cff] |
||||
* |
||||
* @description: |
||||
* By default, the Adobe CFF engine darkens stems as follows (if the |
||||
* `no-stem-darkening' property isn't set): |
||||
* |
||||
* { |
||||
* stem width <= 0.5px: darkening amount = 0.4px |
||||
* stem width = 1px: darkening amount = 0.275px |
||||
* stem width = 1.667px: darkening amount = 0.275px |
||||
* stem width >= 2.333px: darkening amount = 0px |
||||
* } |
||||
* |
||||
* and piecewise linear in-between. At configuration time, these four |
||||
* control points can be set with the macro |
||||
* `CFF_CONFIG_OPTION_DARKENING_PARAMETERS'. At runtime, the control |
||||
* points can be changed using the `darkening-parameters' property, as |
||||
* the following example demonstrates. |
||||
* |
||||
* { |
||||
* FT_Library library; |
||||
* FT_Int darken_params[8] = { 500, 300, // x1, y1
|
||||
* 1000, 200, // x2, y2
|
||||
* 1500, 100, // x3, y3
|
||||
* 2000, 0 }; // x4, y4
|
||||
* |
||||
* |
||||
* FT_Init_FreeType( &library ); |
||||
* |
||||
* FT_Property_Set( library, "cff", |
||||
* "darkening-parameters", darken_params ); |
||||
* } |
||||
* |
||||
* The x~values give the stem width, and the y~values the darkening |
||||
* amount. The unit is 1000th of pixels. All coordinate values must be |
||||
* positive; the x~values must be monotonically increasing; the |
||||
* y~values must be monotonically decreasing and smaller than or |
||||
* equal to 500 (corresponding to half a pixel); the slope of each |
||||
* linear piece must be shallower than -1 (e.g., -.4). |
||||
* |
||||
* @note: |
||||
* This property can be used with @FT_Property_Get also. |
||||
* |
||||
* This property can be set via the `FREETYPE_PROPERTIES' environment |
||||
* variable, using eight comma-separated integers without spaces. Here |
||||
* the above example, using `\' to break the line for readability. |
||||
* |
||||
* { |
||||
* FREETYPE_PROPERTIES=\
|
||||
* cff:darkening-parameters=500,300,1000,200,1500,100,2000,0 |
||||
* } |
||||
* |
||||
* @since: |
||||
* 2.5.1 |
||||
* |
||||
*/ |
||||
|
||||
|
||||
/**************************************************************************
|
||||
* |
||||
* @property: |
||||
* random-seed |
||||
* |
||||
* @description: |
||||
* By default, the seed value for the CFF `random' operator is set to a |
||||
* random value. However, mainly for debugging purposes, it is often |
||||
* necessary to use a known value as a seed so that the pseudo-random |
||||
* number sequences generated by `random' are repeatable. |
||||
* |
||||
* The `random-seed' property does that. Its argument is a signed 32bit |
||||
* integer; if the value is zero or negative, the seed given by the |
||||
* `intitialRandomSeed' private DICT operator in a CFF file gets used |
||||
* (or a default value if there is no such operator). If the value is |
||||
* positive, use it instead of `initialRandomSeed', which is |
||||
* consequently ignored. |
||||
* |
||||
* @note: |
||||
* This property can be set via the `FREETYPE_PROPERTIES' environment |
||||
* variable. It can also be set per face using @FT_Face_Properties with |
||||
* @FT_PARAM_TAG_RANDOM_SEED. |
||||
* |
||||
* @since: |
||||
* 2.8 |
||||
* |
||||
*/ |
||||
|
||||
|
||||
/* */ |
||||
|
||||
|
||||
FT_END_HEADER |
||||
|
||||
|
||||
#endif /* FTCFFDRV_H_ */ |
||||
|
||||
|
||||
/* END */ |
||||
File diff suppressed because it is too large
Load Diff
@ -1,107 +0,0 @@ |
||||
/***************************************************************************/ |
||||
/* */ |
||||
/* ftpcfdrv.h */ |
||||
/* */ |
||||
/* FreeType API for controlling the PCF driver (specification only). */ |
||||
/* */ |
||||
/* Copyright 2017 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. */ |
||||
/* */ |
||||
/***************************************************************************/ |
||||
|
||||
|
||||
#ifndef FTPCFDRV_H_ |
||||
#define FTPCFDRV_H_ |
||||
|
||||
#include <ft2build.h> |
||||
#include FT_FREETYPE_H |
||||
|
||||
#ifdef FREETYPE_H |
||||
#error "freetype.h of FreeType 1 has been loaded!" |
||||
#error "Please fix the directory search order for header files" |
||||
#error "so that freetype.h of FreeType 2 is found first." |
||||
#endif |
||||
|
||||
|
||||
FT_BEGIN_HEADER |
||||
|
||||
|
||||
/**************************************************************************
|
||||
* |
||||
* @section: |
||||
* pcf_driver |
||||
* |
||||
* @title: |
||||
* The PCF driver |
||||
* |
||||
* @abstract: |
||||
* Controlling the PCF driver module. |
||||
* |
||||
* @description: |
||||
* While FreeType's PCF driver doesn't expose API functions by itself, |
||||
* it is possible to control its behaviour with @FT_Property_Set and |
||||
* @FT_Property_Get. Right now, there is a single property |
||||
* `no-long-family-names' available if FreeType is compiled with |
||||
* PCF_CONFIG_OPTION_LONG_FAMILY_NAMES. |
||||
* |
||||
* The PCF driver's module name is `pcf'. |
||||
* |
||||
*/ |
||||
|
||||
|
||||
/**************************************************************************
|
||||
* |
||||
* @property: |
||||
* no-long-family-names |
||||
* |
||||
* @description: |
||||
* If PCF_CONFIG_OPTION_LONG_FAMILY_NAMES is active while compiling |
||||
* FreeType, the PCF driver constructs long family names. |
||||
* |
||||
* There are many PCF fonts just called `Fixed' which look completely |
||||
* different, and which have nothing to do with each other. When |
||||
* selecting `Fixed' in KDE or Gnome one gets results that appear rather |
||||
* random, the style changes often if one changes the size and one |
||||
* cannot select some fonts at all. The improve this situation, the PCF |
||||
* module prepends the foundry name (plus a space) to the family name. |
||||
* It also checks whether there are `wide' characters; all put together, |
||||
* family names like `Sony Fixed' or `Misc Fixed Wide' are constructed. |
||||
* |
||||
* If `no-long-family-names' is set, this feature gets switched off. |
||||
* |
||||
* { |
||||
* FT_Library library; |
||||
* FT_Bool no_long_family_names = TRUE; |
||||
* |
||||
* |
||||
* FT_Init_FreeType( &library ); |
||||
* |
||||
* FT_Property_Set( library, "pcf", |
||||
* "no-long-family-names", |
||||
* &no_long_family_names ); |
||||
* } |
||||
* |
||||
* @note: |
||||
* This property can be used with @FT_Property_Get also. |
||||
* |
||||
* This property can be set via the `FREETYPE_PROPERTIES' environment |
||||
* variable (using values 1 and 0 for `on' and `off', respectively). |
||||
* |
||||
* @since: |
||||
* 2.8 |
||||
*/ |
||||
|
||||
|
||||
FT_END_HEADER |
||||
|
||||
|
||||
#endif /* FTPCFDRV_H_ */ |
||||
|
||||
|
||||
/* END */ |
||||
@ -1,109 +0,0 @@ |
||||
/***************************************************************************/ |
||||
/* */ |
||||
/* ftt1drv.h */ |
||||
/* */ |
||||
/* FreeType API for controlling the Type 1 driver (specification only). */ |
||||
/* */ |
||||
/* Copyright 2017 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. */ |
||||
/* */ |
||||
/***************************************************************************/ |
||||
|
||||
|
||||
#ifndef FTT1DRV_H_ |
||||
#define FTT1DRV_H_ |
||||
|
||||
#include <ft2build.h> |
||||
#include FT_FREETYPE_H |
||||
#include FT_PARAMETER_TAGS_H |
||||
|
||||
#ifdef FREETYPE_H |
||||
#error "freetype.h of FreeType 1 has been loaded!" |
||||
#error "Please fix the directory search order for header files" |
||||
#error "so that freetype.h of FreeType 2 is found first." |
||||
#endif |
||||
|
||||
|
||||
FT_BEGIN_HEADER |
||||
|
||||
|
||||
/**************************************************************************
|
||||
* |
||||
* @property: |
||||
* hinting-engine[type1] |
||||
* |
||||
* @description: |
||||
* Thanks to Adobe, which contributed a new hinting (and parsing) |
||||
* engine, an application can select between `freetype' and `adobe' if |
||||
* compiled with T1_CONFIG_OPTION_OLD_ENGINE. If this configuration |
||||
* macro isn't defined, `hinting-engine' does nothing. |
||||
* |
||||
* The default engine is `freetype' if T1_CONFIG_OPTION_OLD_ENGINE is |
||||
* defined, and `adobe' otherwise. |
||||
* |
||||
* The following example code demonstrates how to select Adobe's hinting |
||||
* engine (omitting the error handling). |
||||
* |
||||
* { |
||||
* FT_Library library; |
||||
* FT_UInt hinting_engine = FT_T1_HINTING_ADOBE; |
||||
* |
||||
* |
||||
* FT_Init_FreeType( &library ); |
||||
* |
||||
* FT_Property_Set( library, "type1", |
||||
* "hinting-engine", &hinting_engine ); |
||||
* } |
||||
* |
||||
* @note: |
||||
* This property can be used with @FT_Property_Get also. |
||||
* |
||||
* This property can be set via the `FREETYPE_PROPERTIES' environment |
||||
* variable (using values `adobe' or `freetype'). |
||||
* |
||||
* @since: |
||||
* 2.8.2 |
||||
* |
||||
*/ |
||||
|
||||
|
||||
/**************************************************************************
|
||||
* |
||||
* @enum: |
||||
* FT_T1_HINTING_XXX |
||||
* |
||||
* @description: |
||||
* A list of constants used for the @hinting-engine[type1] property to |
||||
* select the hinting engine for Type 1 fonts. |
||||
* |
||||
* @values: |
||||
* FT_T1_HINTING_FREETYPE :: |
||||
* Use the old FreeType hinting engine. |
||||
* |
||||
* FT_T1_HINTING_ADOBE :: |
||||
* Use the hinting engine contributed by Adobe. |
||||
* |
||||
* @since: |
||||
* 2.8.2 |
||||
* |
||||
*/ |
||||
#define FT_T1_HINTING_FREETYPE 0 |
||||
#define FT_T1_HINTING_ADOBE 1 |
||||
|
||||
|
||||
/* */ |
||||
|
||||
|
||||
FT_END_HEADER |
||||
|
||||
|
||||
#endif /* FTT1DRV_H_ */ |
||||
|
||||
|
||||
/* END */ |
||||
@ -1,331 +0,0 @@ |
||||
/***************************************************************************/ |
||||
/* */ |
||||
/* ftttdrv.h */ |
||||
/* */ |
||||
/* FreeType API for controlling the TrueType driver */ |
||||
/* (specification only). */ |
||||
/* */ |
||||
/* Copyright 2013-2017 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. */ |
||||
/* */ |
||||
/***************************************************************************/ |
||||
|
||||
|
||||
#ifndef FTTTDRV_H_ |
||||
#define FTTTDRV_H_ |
||||
|
||||
#include <ft2build.h> |
||||
#include FT_FREETYPE_H |
||||
|
||||
#ifdef FREETYPE_H |
||||
#error "freetype.h of FreeType 1 has been loaded!" |
||||
#error "Please fix the directory search order for header files" |
||||
#error "so that freetype.h of FreeType 2 is found first." |
||||
#endif |
||||
|
||||
|
||||
FT_BEGIN_HEADER |
||||
|
||||
|
||||
/**************************************************************************
|
||||
* |
||||
* @section: |
||||
* tt_driver |
||||
* |
||||
* @title: |
||||
* The TrueType driver |
||||
* |
||||
* @abstract: |
||||
* Controlling the TrueType driver module. |
||||
* |
||||
* @description: |
||||
* While FreeType's TrueType driver doesn't expose API functions by |
||||
* itself, it is possible to control its behaviour with @FT_Property_Set |
||||
* and @FT_Property_Get. The following lists the available properties |
||||
* together with the necessary macros and structures. |
||||
* |
||||
* The TrueType driver's module name is `truetype'. |
||||
* |
||||
* We start with a list of definitions, kindly provided by Greg |
||||
* Hitchcock. |
||||
* |
||||
* _Bi-Level_ _Rendering_ |
||||
* |
||||
* Monochromatic rendering, exclusively used in the early days of |
||||
* TrueType by both Apple and Microsoft. Microsoft's GDI interface |
||||
* supported hinting of the right-side bearing point, such that the |
||||
* advance width could be non-linear. Most often this was done to |
||||
* achieve some level of glyph symmetry. To enable reasonable |
||||
* performance (e.g., not having to run hinting on all glyphs just to |
||||
* get the widths) there was a bit in the head table indicating if the |
||||
* side bearing was hinted, and additional tables, `hdmx' and `LTSH', to |
||||
* cache hinting widths across multiple sizes and device aspect ratios. |
||||
* |
||||
* _Font_ _Smoothing_ |
||||
* |
||||
* Microsoft's GDI implementation of anti-aliasing. Not traditional |
||||
* anti-aliasing as the outlines were hinted before the sampling. The |
||||
* widths matched the bi-level rendering. |
||||
* |
||||
* _ClearType_ _Rendering_ |
||||
* |
||||
* Technique that uses physical subpixels to improve rendering on LCD |
||||
* (and other) displays. Because of the higher resolution, many methods |
||||
* of improving symmetry in glyphs through hinting the right-side |
||||
* bearing were no longer necessary. This lead to what GDI calls |
||||
* `natural widths' ClearType, see |
||||
* http://www.beatstamm.com/typography/RTRCh4.htm#Sec21. Since hinting
|
||||
* has extra resolution, most non-linearity went away, but it is still |
||||
* possible for hints to change the advance widths in this mode. |
||||
* |
||||
* _ClearType_ _Compatible_ _Widths_ |
||||
* |
||||
* One of the earliest challenges with ClearType was allowing the |
||||
* implementation in GDI to be selected without requiring all UI and |
||||
* documents to reflow. To address this, a compatible method of |
||||
* rendering ClearType was added where the font hints are executed once |
||||
* to determine the width in bi-level rendering, and then re-run in |
||||
* ClearType, with the difference in widths being absorbed in the font |
||||
* hints for ClearType (mostly in the white space of hints); see |
||||
* http://www.beatstamm.com/typography/RTRCh4.htm#Sec20. Somewhat by
|
||||
* definition, compatible width ClearType allows for non-linear widths, |
||||
* but only when the bi-level version has non-linear widths. |
||||
* |
||||
* _ClearType_ _Subpixel_ _Positioning_ |
||||
* |
||||
* One of the nice benefits of ClearType is the ability to more crisply |
||||
* display fractional widths; unfortunately, the GDI model of integer |
||||
* bitmaps did not support this. However, the WPF and Direct Write |
||||
* frameworks do support fractional widths. DWrite calls this `natural |
||||
* mode', not to be confused with GDI's `natural widths'. Subpixel |
||||
* positioning, in the current implementation of Direct Write, |
||||
* unfortunately does not support hinted advance widths, see |
||||
* http://www.beatstamm.com/typography/RTRCh4.htm#Sec22. Note that the
|
||||
* TrueType interpreter fully allows the advance width to be adjusted in |
||||
* this mode, just the DWrite client will ignore those changes. |
||||
* |
||||
* _ClearType_ _Backward_ _Compatibility_ |
||||
* |
||||
* This is a set of exceptions made in the TrueType interpreter to |
||||
* minimize hinting techniques that were problematic with the extra |
||||
* resolution of ClearType; see |
||||
* http://www.beatstamm.com/typography/RTRCh4.htm#Sec1 and
|
||||
* https://www.microsoft.com/typography/cleartype/truetypecleartype.aspx.
|
||||
* This technique is not to be confused with ClearType compatible |
||||
* widths. ClearType backward compatibility has no direct impact on |
||||
* changing advance widths, but there might be an indirect impact on |
||||
* disabling some deltas. This could be worked around in backward |
||||
* compatibility mode. |
||||
* |
||||
* _Native_ _ClearType_ _Mode_ |
||||
* |
||||
* (Not to be confused with `natural widths'.) This mode removes all |
||||
* the exceptions in the TrueType interpreter when running with |
||||
* ClearType. Any issues on widths would still apply, though. |
||||
* |
||||
*/ |
||||
|
||||
|
||||
/**************************************************************************
|
||||
* |
||||
* @property: |
||||
* interpreter-version |
||||
* |
||||
* @description: |
||||
* Currently, three versions are available, two representing the |
||||
* bytecode interpreter with subpixel hinting support (old `Infinality' |
||||
* code and new stripped-down and higher performance `minimal' code) and |
||||
* one without, respectively. The default is subpixel support if |
||||
* TT_CONFIG_OPTION_SUBPIXEL_HINTING is defined, and no subpixel support |
||||
* otherwise (since it isn't available then). |
||||
* |
||||
* If subpixel hinting is on, many TrueType bytecode instructions behave |
||||
* differently compared to B/W or grayscale rendering (except if `native |
||||
* ClearType' is selected by the font). Microsoft's main idea is to |
||||
* render at a much increased horizontal resolution, then sampling down |
||||
* the created output to subpixel precision. However, many older fonts |
||||
* are not suited to this and must be specially taken care of by |
||||
* applying (hardcoded) tweaks in Microsoft's interpreter. |
||||
* |
||||
* Details on subpixel hinting and some of the necessary tweaks can be |
||||
* found in Greg Hitchcock's whitepaper at |
||||
* `https://www.microsoft.com/typography/cleartype/truetypecleartype.aspx'.
|
||||
* Note that FreeType currently doesn't really `subpixel hint' (6x1, 6x2, |
||||
* or 6x5 supersampling) like discussed in the paper. Depending on the |
||||
* chosen interpreter, it simply ignores instructions on vertical stems |
||||
* to arrive at very similar results. |
||||
* |
||||
* The following example code demonstrates how to deactivate subpixel |
||||
* hinting (omitting the error handling). |
||||
* |
||||
* { |
||||
* FT_Library library; |
||||
* FT_Face face; |
||||
* FT_UInt interpreter_version = TT_INTERPRETER_VERSION_35; |
||||
* |
||||
* |
||||
* FT_Init_FreeType( &library ); |
||||
* |
||||
* FT_Property_Set( library, "truetype", |
||||
* "interpreter-version", |
||||
* &interpreter_version ); |
||||
* } |
||||
* |
||||
* @note: |
||||
* This property can be used with @FT_Property_Get also. |
||||
* |
||||
* This property can be set via the `FREETYPE_PROPERTIES' environment |
||||
* variable (using values `35', `38', or `40'). |
||||
* |
||||
* @since: |
||||
* 2.5 |
||||
*/ |
||||
|
||||
|
||||
/**************************************************************************
|
||||
* |
||||
* @enum: |
||||
* TT_INTERPRETER_VERSION_XXX |
||||
* |
||||
* @description: |
||||
* A list of constants used for the @interpreter-version property to |
||||
* select the hinting engine for Truetype fonts. |
||||
* |
||||
* The numeric value in the constant names represents the version |
||||
* number as returned by the `GETINFO' bytecode instruction. |
||||
* |
||||
* @values: |
||||
* TT_INTERPRETER_VERSION_35 :: |
||||
* Version~35 corresponds to MS rasterizer v.1.7 as used e.g. in |
||||
* Windows~98; only grayscale and B/W rasterizing is supported. |
||||
* |
||||
* TT_INTERPRETER_VERSION_38 :: |
||||
* Version~38 corresponds to MS rasterizer v.1.9; it is roughly |
||||
* equivalent to the hinting provided by DirectWrite ClearType (as can |
||||
* be found, for example, in the Internet Explorer~9 running on |
||||
* Windows~7). It is used in FreeType to select the `Infinality' |
||||
* subpixel hinting code. The code may be removed in a future |
||||
* version. |
||||
* |
||||
* TT_INTERPRETER_VERSION_40 :: |
||||
* Version~40 corresponds to MS rasterizer v.2.1; it is roughly |
||||
* equivalent to the hinting provided by DirectWrite ClearType (as can |
||||
* be found, for example, in Microsoft's Edge Browser on Windows~10). |
||||
* It is used in FreeType to select the `minimal' subpixel hinting |
||||
* code, a stripped-down and higher performance version of the |
||||
* `Infinality' code. |
||||
* |
||||
* @note: |
||||
* This property controls the behaviour of the bytecode interpreter |
||||
* and thus how outlines get hinted. It does *not* control how glyph |
||||
* get rasterized! In particular, it does not control subpixel color |
||||
* filtering. |
||||
* |
||||
* If FreeType has not been compiled with the configuration option |
||||
* TT_CONFIG_OPTION_SUBPIXEL_HINTING, selecting version~38 or~40 causes |
||||
* an `FT_Err_Unimplemented_Feature' error. |
||||
* |
||||
* Depending on the graphics framework, Microsoft uses different |
||||
* bytecode and rendering engines. As a consequence, the version |
||||
* numbers returned by a call to the `GETINFO' bytecode instruction are |
||||
* more convoluted than desired. |
||||
* |
||||
* Here are two tables that try to shed some light on the possible |
||||
* values for the MS rasterizer engine, together with the additional |
||||
* features introduced by it. |
||||
* |
||||
* { |
||||
* GETINFO framework version feature |
||||
* ------------------------------------------------------------------- |
||||
* 3 GDI (Win 3.1), v1.0 16-bit, first version |
||||
* TrueImage |
||||
* 33 GDI (Win NT 3.1), v1.5 32-bit |
||||
* HP Laserjet |
||||
* 34 GDI (Win 95) v1.6 font smoothing, |
||||
* new SCANTYPE opcode |
||||
* 35 GDI (Win 98/2000) v1.7 (UN)SCALED_COMPONENT_OFFSET |
||||
* bits in composite glyphs |
||||
* 36 MGDI (Win CE 2) v1.6+ classic ClearType |
||||
* 37 GDI (XP and later), v1.8 ClearType |
||||
* GDI+ old (before Vista) |
||||
* 38 GDI+ old (Vista, Win 7), v1.9 subpixel ClearType, |
||||
* WPF Y-direction ClearType, |
||||
* additional error checking |
||||
* 39 DWrite (before Win 8) v2.0 subpixel ClearType flags |
||||
* in GETINFO opcode, |
||||
* bug fixes |
||||
* 40 GDI+ (after Win 7), v2.1 Y-direction ClearType flag |
||||
* DWrite (Win 8) in GETINFO opcode, |
||||
* Gray ClearType |
||||
* } |
||||
* |
||||
* The `version' field gives a rough orientation only, since some |
||||
* applications provided certain features much earlier (as an example, |
||||
* Microsoft Reader used subpixel and Y-direction ClearType already in |
||||
* Windows 2000). Similarly, updates to a given framework might include |
||||
* improved hinting support. |
||||
* |
||||
* { |
||||
* version sampling rendering comment |
||||
* x y x y |
||||
* -------------------------------------------------------------- |
||||
* v1.0 normal normal B/W B/W bi-level |
||||
* v1.6 high high gray gray grayscale |
||||
* v1.8 high normal color-filter B/W (GDI) ClearType |
||||
* v1.9 high high color-filter gray Color ClearType |
||||
* v2.1 high normal gray B/W Gray ClearType |
||||
* v2.1 high high gray gray Gray ClearType |
||||
* } |
||||
* |
||||
* Color and Gray ClearType are the two available variants of |
||||
* `Y-direction ClearType', meaning grayscale rasterization along the |
||||
* Y-direction; the name used in the TrueType specification for this |
||||
* feature is `symmetric smoothing'. `Classic ClearType' is the |
||||
* original algorithm used before introducing a modified version in |
||||
* Win~XP. Another name for v1.6's grayscale rendering is `font |
||||
* smoothing', and `Color ClearType' is sometimes also called `DWrite |
||||
* ClearType'. To differentiate between today's Color ClearType and the |
||||
* earlier ClearType variant with B/W rendering along the vertical axis, |
||||
* the latter is sometimes called `GDI ClearType'. |
||||
* |
||||
* `Normal' and `high' sampling describe the (virtual) resolution to |
||||
* access the rasterized outline after the hinting process. `Normal' |
||||
* means 1 sample per grid line (i.e., B/W). In the current Microsoft |
||||
* implementation, `high' means an extra virtual resolution of 16x16 (or |
||||
* 16x1) grid lines per pixel for bytecode instructions like `MIRP'. |
||||
* After hinting, these 16 grid lines are mapped to 6x5 (or 6x1) grid |
||||
* lines for color filtering if Color ClearType is activated. |
||||
* |
||||
* Note that `Gray ClearType' is essentially the same as v1.6's |
||||
* grayscale rendering. However, the GETINFO instruction handles it |
||||
* differently: v1.6 returns bit~12 (hinting for grayscale), while v2.1 |
||||
* returns bits~13 (hinting for ClearType), 18 (symmetrical smoothing), |
||||
* and~19 (Gray ClearType). Also, this mode respects bits 2 and~3 for |
||||
* the version~1 gasp table exclusively (like Color ClearType), while |
||||
* v1.6 only respects the values of version~0 (bits 0 and~1). |
||||
* |
||||
* Keep in mind that the features of the above interpreter versions |
||||
* might not map exactly to FreeType features or behavior because it is |
||||
* a fundamentally different library with different internals. |
||||
* |
||||
*/ |
||||
#define TT_INTERPRETER_VERSION_35 35 |
||||
#define TT_INTERPRETER_VERSION_38 38 |
||||
#define TT_INTERPRETER_VERSION_40 40 |
||||
|
||||
/* */ |
||||
|
||||
|
||||
FT_END_HEADER |
||||
|
||||
|
||||
#endif /* FTTTDRV_H_ */ |
||||
|
||||
|
||||
/* END */ |
||||
Loading…
Reference in new issue