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[ttfautohint.git] / lib / tablue.dat

//  tablue.dat
//
//    Auto-fitter data for blue strings.
//
// Copyright (C) 2013-2014 by Werner Lemberg.
//
// This file is part of the ttfautohint library, and may only be used,
// modified, and distributed under the terms given in `COPYING'.  By
// continuing to use, modify, or distribute this file you indicate that you
// have read `COPYING' and understand and accept it fully.
//
// The file `COPYING' mentioned in the previous paragraph is distributed
// with the ttfautohint library.

// originally file `afblue.dat' (2013-Sep-22) from FreeType */


// This file contains data specific to blue zones.  It gets processed by
// a script to simulate `jagged arrays', with enumeration values holding
// offsets into the arrays.
//
// The format of the file is rather simple:  A section starts with three
// labels separated by whitespace and followed by a colon (everything in a
// single line); the first label gives the name of the enumeration template,
// the second the name of the array template, and the third the name of the
// `maximum' template, holding the size of the largest array element.  The
// script then fills the corresponding templates (indicated by `@'
// characters around the name).
//
// A section contains one or more data records.  Each data record consists
// of two or more lines.  The first line holds the enumeration name, and the
// remaining lines the corresponding array data.
//
// There are two possible representations for array data.
//
// - A string of characters in UTF-8 encoding enclosed in double quotes,
//   using C syntax.  There can be only one string per line, thus the
//   starting and ending double quote must be the first and last character
//   in the line, respectively, ignoring whitespace before and after the
//   string.  Space characters within the string are ignored too.  If there
//   are multiple strings (in multiple lines), they are concatenated to a
//   single string.  In the output, a string gets represented as a series of
//   singles bytes, followed by a zero byte.  The enumeration values simply
//   hold byte offsets to the start of the corresponding strings.
//
// - Data blocks enclosed in balanced braces, which get copied verbatim and
//   which can span multiple lines.  The opening brace of a block must be
//   the first character of a line (ignoring whitespace), and the closing
//   brace the last (ignoring whitespace also).  The script appends a comma
//   character after each block and counts the number of blocks to set the
//   enumeration values.
//
// A section can contain either strings only or data blocks only.
//
// A comment line starts with `//'; it gets removed.  A preprocessor
// directive line (using the standard syntax of `cpp') starts with `#' and
// gets copied verbatim to both the enumeration and the array.  Whitespace
// outside of a string is insignificant.
//
// Preprocessor directives are ignored while the script computes maximum
// values; this essentially means that the maximum values can easily be too
// large.  Given that the purpose of those values is to create local
// fixed-size arrays at compile time for further processing of the blue zone
// data, this isn't a problem.  Note the the final zero byte of a string is
// not counted.  Note also that the count holds the number of UTF-8 encoded
// characters, not bytes.


// The blue zone string data, to be used in the blue stringsets below.

TA_BLUE_STRING_ENUM TA_BLUE_STRINGS_ARRAY TA_BLUE_STRING_MAX_LEN:

  TA_BLUE_STRING_CYRILLIC_CAPITAL_TOP
    "БВЕПЗОСЭ"
  TA_BLUE_STRING_CYRILLIC_CAPITAL_BOTTOM
    "БВЕШЗОСЭ"
  TA_BLUE_STRING_CYRILLIC_SMALL
    "хпншезос"
  TA_BLUE_STRING_CYRILLIC_SMALL_DESCENDER
    "руф"

  // we separate the letters with spaces to avoid ligatures;
  // this is just for convenience to simplify reading
  TA_BLUE_STRING_DEVANAGARI_BASE
    "क न म उ छ ट ठ ड"
  TA_BLUE_STRING_DEVANAGARI_TOP
    "ई ऐ ओ औ ि ी ो ौ"
  // note that some fonts have extreme variation in the height of the
  // round head elements; for this reason we also define the `base'
  // blue zone, which must be always present
  TA_BLUE_STRING_DEVANAGARI_HEAD
    "क म अ आ थ ध भ श"
  TA_BLUE_STRING_DEVANAGARI_BOTTOM
    "ु ृ"

  TA_BLUE_STRING_GREEK_CAPITAL_TOP
    "ΓΒΕΖΘΟΩ"
  TA_BLUE_STRING_GREEK_CAPITAL_BOTTOM
    "ΒΔΖΞΘΟ"
  TA_BLUE_STRING_GREEK_SMALL_BETA_TOP
    "βθδζλξ"
  TA_BLUE_STRING_GREEK_SMALL
    "αειοπστω"
  TA_BLUE_STRING_GREEK_SMALL_DESCENDER
    "βγημρφχψ"

  TA_BLUE_STRING_HEBREW_TOP
    "בדהחךכםס"
  TA_BLUE_STRING_HEBREW_BOTTOM
    "בטכםסצ"
  TA_BLUE_STRING_HEBREW_DESCENDER
    "קךןףץ"

  TA_BLUE_STRING_LATIN_CAPITAL_TOP
    "THEZOCQS"
  TA_BLUE_STRING_LATIN_CAPITAL_BOTTOM
    "HEZLOCUS"
  TA_BLUE_STRING_LATIN_SMALL_F_TOP
    "fijkdbh"
  TA_BLUE_STRING_LATIN_SMALL
    "xzroesc"
  TA_BLUE_STRING_LATIN_SMALL_DESCENDER
    "pqgjy"

  // we separate the letters with spaces to avoid ligatures;
  // this is just for convenience to simplify reading
  TA_BLUE_STRING_TELUGU_TOP
    "ఇ ఌ ఙ ఞ ణ ఱ ౯"

  TA_BLUE_STRING_TELUGU_BOTTOM
    "అ క చ ర ఽ ౨ ౬"

// The blue zone stringsets, as used in the script styles, cf. `tastyles.h'.
//
// The TA_BLUE_PROPERTY_XXX flags are defined in `tablue.h'; here some
// explanations.
//
// A blue zone in general is defined by a reference and an overshoot line.
// During the hinting process, all coordinate values between those two lines
// are set equal to the reference value, provided that the blue zone is not
// wider than 0.75 pixels (otherwise the blue zone gets ignored).  All
// entries must have `TA_BLUE_STRING_MAX' as the final line.
//
// During the glyph analysis, edges are sorted from bottom to top, and then
// sequentially checked, edge by edge, against the blue zones in the order
// given below.
//
//
// latin auto-hinter
// -----------------
//
// Characters in a blue string are automatically classified as having a flat
// (reference) or a round (overshoot) extremum.  The blue zone is then set
// up by the mean values of all flat extrema and all round extrema,
// respectively.  Only horizontal blue zones (i.e., adjusting vertical
// coordinate values) are supported.
//
// For the latin auto-hinter, the overshoot should be larger than the
// reference for top zones, and vice versa for bottom zones.
//
//   LATIN_TOP
//     Take the maximum flat and round coordinate values of the blue string
//     characters for computing the blue zone's reference and overshoot
//     values.
//
//     If not set, take the minimum values.
//
//   LATIN_NEUTRAL
//     Ignore round extrema and define the blue zone with flat values only.
//     Both top and bottom of contours can match.  This is useful for
//     scripts like Devanagari where vowel signs attach to the base
//     character and are implemented as components of composite glyphs.
//
//     If not set, both round and flat extrema are taken into account.
//     Additionally, only the top or the bottom of a contour can match,
//     depending on the LATIN_TOP flag.
//
//     Neutral blue zones should always follow non-neutral blue zones.
//
//   LATIN_X_HEIGHT
//     Scale all glyphs vertically from the corresponding script to make the
//     reference line of this blue zone align on the grid.  The scaling
//     takes place before all other blue zones get aligned to the grid.
//     Only one blue character string of a script style can have this flag.
//
//   LATIN_LONG
//     Apply an additional constraint for blue zone values: Don't
//     necessarily use the extremum as-is but a segment of the topmost (or
//     bottommost) contour that is longer than a heuristic threshold, and
//     which is not too far away vertically from the real extremum.  This
//     ensures that small bumps in the outline are ignored (for example, the
//     `vertical serifs' found in many Hebrew glyph designs).
//
//     The segment must be at least EM/25 font units long, and the distance
//     to the extremum must be smaller than EM/4.


TA_BLUE_STRINGSET_ENUM TA_BLUE_STRINGSETS_ARRAY TA_BLUE_STRINGSET_MAX_LEN:

  TA_BLUE_STRINGSET_CYRL
    { TA_BLUE_STRING_CYRILLIC_CAPITAL_TOP,     TA_BLUE_PROPERTY_LATIN_TOP        }
    { TA_BLUE_STRING_CYRILLIC_CAPITAL_BOTTOM,  0                                 }
    { TA_BLUE_STRING_CYRILLIC_SMALL,           TA_BLUE_PROPERTY_LATIN_TOP      |
                                               TA_BLUE_PROPERTY_LATIN_X_HEIGHT   }
    { TA_BLUE_STRING_CYRILLIC_SMALL,           0                                 }
    { TA_BLUE_STRING_CYRILLIC_SMALL_DESCENDER, 0                                 }
    { TA_BLUE_STRING_MAX,                      0                                 }

  TA_BLUE_STRINGSET_DEVA
    { TA_BLUE_STRING_DEVANAGARI_TOP,    TA_BLUE_PROPERTY_LATIN_TOP        }
    { TA_BLUE_STRING_DEVANAGARI_HEAD,   TA_BLUE_PROPERTY_LATIN_TOP        }
    { TA_BLUE_STRING_DEVANAGARI_BASE,   TA_BLUE_PROPERTY_LATIN_TOP      |
                                        TA_BLUE_PROPERTY_LATIN_NEUTRAL  |
                                        TA_BLUE_PROPERTY_LATIN_X_HEIGHT   }
    { TA_BLUE_STRING_DEVANAGARI_BASE,   0                                 }
    { TA_BLUE_STRING_DEVANAGARI_BOTTOM, 0                                 }
    { TA_BLUE_STRING_MAX,               0                                 }

  TA_BLUE_STRINGSET_GREK
    { TA_BLUE_STRING_GREEK_CAPITAL_TOP,     TA_BLUE_PROPERTY_LATIN_TOP        }
    { TA_BLUE_STRING_GREEK_CAPITAL_BOTTOM,  0                                 }
    { TA_BLUE_STRING_GREEK_SMALL_BETA_TOP,  TA_BLUE_PROPERTY_LATIN_TOP        }
    { TA_BLUE_STRING_GREEK_SMALL,           TA_BLUE_PROPERTY_LATIN_TOP      |
                                            TA_BLUE_PROPERTY_LATIN_X_HEIGHT   }
    { TA_BLUE_STRING_GREEK_SMALL,           0                                 }
    { TA_BLUE_STRING_GREEK_SMALL_DESCENDER, 0                                 }
    { TA_BLUE_STRING_MAX,                   0                                 }

  TA_BLUE_STRINGSET_HEBR
    { TA_BLUE_STRING_HEBREW_TOP,       TA_BLUE_PROPERTY_LATIN_TOP  |
                                       TA_BLUE_PROPERTY_LATIN_LONG   }
    { TA_BLUE_STRING_HEBREW_BOTTOM,    0                             }
    { TA_BLUE_STRING_HEBREW_DESCENDER, 0                             }
    { TA_BLUE_STRING_MAX,              0                             }

  TA_BLUE_STRINGSET_LATN
    { TA_BLUE_STRING_LATIN_CAPITAL_TOP,     TA_BLUE_PROPERTY_LATIN_TOP        }
    { TA_BLUE_STRING_LATIN_CAPITAL_BOTTOM,  0                                 }
    { TA_BLUE_STRING_LATIN_SMALL_F_TOP,     TA_BLUE_PROPERTY_LATIN_TOP        }
    { TA_BLUE_STRING_LATIN_SMALL,           TA_BLUE_PROPERTY_LATIN_TOP      |
                                            TA_BLUE_PROPERTY_LATIN_X_HEIGHT   }
    { TA_BLUE_STRING_LATIN_SMALL,           0                                 }
    { TA_BLUE_STRING_LATIN_SMALL_DESCENDER, 0                                 }
    { TA_BLUE_STRING_MAX,                   0                                 }

  TA_BLUE_STRINGSET_TELU
    { TA_BLUE_STRING_TELUGU_TOP,    TA_BLUE_PROPERTY_LATIN_TOP }
    { TA_BLUE_STRING_TELUGU_BOTTOM, 0                          }
    { TA_BLUE_STRING_MAX,           0                          }

// END