lisp/language/hebrew.el

   1 ;;; hebrew.el --- support for Hebrew -*- coding: utf-8 -*-
   2
   3 ;; Copyright (C) 2001-2011  Free Software Foundation, Inc.
   4 ;; Copyright (C) 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004,
   5 ;;   2005, 2006, 2007, 2008, 2009, 2010, 2011
   6 ;;   National Institute of Advanced Industrial Science and Technology (AIST)
   7 ;;   Registration Number H14PRO021
   8
   9 ;; Copyright (C) 2003
  10 ;;   National Institute of Advanced Industrial Science and Technology (AIST)
  11 ;;   Registration Number H13PRO009
  12
  13 ;; Keywords: multilingual, Hebrew
  14
  15 ;; This file is part of GNU Emacs.
  16
  17 ;; GNU Emacs is free software: you can redistribute it and/or modify
  18 ;; it under the terms of the GNU General Public License as published by
  19 ;; the Free Software Foundation, either version 3 of the License, or
  20 ;; (at your option) any later version.
  21
  22 ;; GNU Emacs is distributed in the hope that it will be useful,
  23 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  24 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  25 ;; GNU General Public License for more details.
  26
  27 ;; You should have received a copy of the GNU General Public License
  28 ;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
  29
  30 ;;; Commentary:
  31
  32 ;; For Hebrew, the character set ISO8859-8 is supported.
  33 ;; See http://www.ecma.ch/ecma1/STAND/ECMA-121.HTM.
  34 ;; Windows-1255 is also supported.
  35
  36 ;;; Code:
  37
  38 (define-coding-system 'hebrew-iso-8bit
  39   "ISO 2022 based 8-bit encoding for Hebrew (MIME:ISO-8859-8)."
  40   :coding-type 'charset
  41   :mnemonic ?8
  42   :charset-list '(iso-8859-8)
  43   :mime-charset 'iso-8859-8)
  44
  45 (define-coding-system-alias 'iso-8859-8 'hebrew-iso-8bit)
  46
  47 ;; These are for Explicit and Implicit directionality information, as
  48 ;; defined in RFC 1556.
  49 (define-coding-system-alias 'iso-8859-8-e 'hebrew-iso-8bit)
  50 (define-coding-system-alias 'iso-8859-8-i 'hebrew-iso-8bit)
  51
  52 (set-language-info-alist
  53  "Hebrew" '((tutorial . "TUTORIAL.he")
  54             (charset iso-8859-8)
  55             (coding-priority hebrew-iso-8bit)
  56             (coding-system hebrew-iso-8bit windows-1255 cp862)
  57             (nonascii-translation . iso-8859-8)
  58             (input-method . "hebrew")
  59             (unibyte-display . hebrew-iso-8bit)
  60             (sample-text . "Hebrew      שלום")
  61             (documentation . "Bidirectional editing is supported.")))
  62
  63 (set-language-info-alist
  64  "Windows-1255" '((coding-priority windows-1255)
  65                   (coding-system windows-1255)
  66                   (documentation . "\
  67 Support for Windows-1255 encoding, e.g. for Yiddish.
  68 Bidirectional editing is supported.")))
  69
  70 (define-coding-system 'windows-1255
  71   "windows-1255 (Hebrew) encoding (MIME: WINDOWS-1255)"
  72   :coding-type 'charset
  73   :mnemonic ?h
  74   :charset-list '(windows-1255)
  75   :mime-charset 'windows-1255)
  76 (define-coding-system-alias 'cp1255 'windows-1255)
  77
  78 (define-coding-system 'cp862
  79   "DOS codepage 862 (Hebrew)"
  80   :coding-type 'charset
  81   :mnemonic ?D
  82   :charset-list '(cp862)
  83   :mime-charset 'cp862)
  84 (define-coding-system-alias 'ibm862 'cp862)
  85
  86 ;; Return a nested alist of Hebrew character sequences vs the
  87 ;; corresponding glyph of FONT-OBJECT.
  88 (defun hebrew-font-get-precomposed (font-object)
  89   (let ((precomposed (font-get font-object 'hebrew-precomposed))
  90         ;; Vector of Hebrew precomposed characters.
  91         (chars [#xFB2A #xFB2B #xFB2C #xFB2D #xFB2E #xFB2F #xFB30 #xFB31
  92                 #xFB32 #xFB33 #xFB34 #xFB35 #xFB36 #xFB38 #xFB39 #xFB3A
  93                 #xFB3B #xFB3C #xFB3E #xFB40 #xFB41 #xFB43 #xFB44 #xFB46
  94                 #xFB47 #xFB48 #xFB49 #xFB4A #xFB4B #xFB4C #xFB4D #xFB4E])
  95         ;; Vector of decomposition character sequences corresponding
  96         ;; to the above vector.
  97         (decomposed
  98          [[#x05E9 #x05C1]
  99           [#x05E9 #x05C2]
 100           [#x05E9 #x05BC #x05C1]
 101           [#x05E9 #x05BC #x05C2]
 102           [#x05D0 #x05B7]
 103           [#x05D0 #x05B8]
 104           [#x05D0 #x05BC]
 105           [#x05D1 #x05BC]
 106           [#x05D2 #x05BC]
 107           [#x05D3 #x05BC]
 108           [#x05D4 #x05BC]
 109           [#x05D5 #x05BC]
 110           [#x05D6 #x05BC]
 111           [#x05D8 #x05BC]
 112           [#x05D9 #x05BC]
 113           [#x05DA #x05BC]
 114           [#x05DB #x05BC]
 115           [#x05DC #x05BC]
 116           [#x05DE #x05BC]
 117           [#x05E0 #x05BC]
 118           [#x05E1 #x05BC]
 119           [#x05E3 #x05BC]
 120           [#x05E4 #x05BC]
 121           [#x05E6 #x05BC]
 122           [#x05E7 #x05BC]
 123           [#x05E8 #x05BC]
 124           [#x05E9 #x05BC]
 125           [#x05EA #x05BC]
 126           [#x05D5 #x05B9]
 127           [#x05D1 #x05BF]
 128           [#x05DB #x05BF]
 129           [#x05E4 #x05BF]]))
 130     (unless precomposed
 131       (setq precomposed (list t))
 132       (let ((gvec (font-get-glyphs font-object 0 (length chars) chars)))
 133         (dotimes (i (length chars))
 134           (if (aref gvec i)
 135               (set-nested-alist (aref decomposed i) (aref gvec i)
 136                                 precomposed))))
 137       ;; Cache the result in FONT-OBJECT's property.
 138       (font-put font-object 'hebrew-precomposed precomposed))
 139     precomposed))
 140
 141 ;; Composition function for hebrew.  GSTRING is made of a Hebrew base
 142 ;; character followed by Hebrew diacritical marks, or is made of
 143 ;; single Hebrew diacritical mark.  Adjust GSTRING to display that
 144 ;; sequence properly.  The basic strategy is:
 145 ;;
 146 ;; (1) If there's single diacritical, add padding space to the left
 147 ;; and right of the glyph.
 148 ;;
 149 ;; (2) If the font has OpenType features for Hebrew, ask the OTF
 150 ;; driver the whole work.
 151 ;;
 152 ;; (3) If the font has precomposed glyphs, use them as far as
 153 ;; possible.  Adjust the remaining glyphs artificially.
 154
 155 (defun hebrew-shape-gstring (gstring)
 156   (let* ((font (lgstring-font gstring))
 157          (otf (font-get font :otf))
 158          (nchars (lgstring-char-len gstring))
 159          header nglyphs base-width glyph precomposed val idx)
 160     (cond
 161      ((= nchars 1)
 162       ;; Independent diacritical mark.  Add padding space to left or
 163       ;; right so that the glyph doesn't overlap with the surrounding
 164       ;; chars.
 165       (setq glyph (lgstring-glyph gstring 0))
 166       (let ((width (lglyph-width glyph))
 167             bearing)
 168         (if (< (setq bearing (lglyph-lbearing glyph)) 0)
 169             (lglyph-set-adjustment glyph bearing 0 (- width bearing)))
 170         (if (> (setq bearing (lglyph-rbearing glyph)) width)
 171             (lglyph-set-adjustment glyph 0 0 bearing))))
 172
 173      ((or (assq 'hebr (car otf)) (assq 'hebr (cdr otf)))
 174       ;; FONT has OpenType features for Hebrew.
 175       (font-shape-gstring gstring))
 176
 177      (t
 178       ;; FONT doesn't have OpenType features for Hebrew.
 179       ;; Try a precomposed glyph.
 180       ;; Now GSTRING is in this form:
 181       ;;   [[FONT CHAR1 CHAR2 ... CHARn] nil GLYPH1 GLYPH2 ... GLYPHn nil ...]
 182       (setq precomposed (hebrew-font-get-precomposed font)
 183             header (lgstring-header gstring)
 184             val (lookup-nested-alist header precomposed nil 1))
 185       (if (and (consp val) (vectorp (car val)))
 186           ;; All characters can be displayed by a single precomposed glyph.
 187           ;; Reform GSTRING to [HEADER nil PRECOMPOSED-GLYPH nil ...]
 188           (let ((glyph (copy-sequence (car val))))
 189             (lglyph-set-from-to glyph 0 (1- nchars))
 190             (lgstring-set-glyph gstring 0 glyph)
 191             (lgstring-set-glyph gstring 1 nil))
 192         (if (and (integerp val) (> val 2)
 193                  (setq glyph (lookup-nested-alist header precomposed val 1))
 194                  (consp glyph) (vectorp (car glyph)))
 195             ;; The first (1- VAL) characters can be displayed by a
 196             ;; precomposed glyph.  Provided that VAL is 3, the first
 197             ;; two glyphs should be replaced by the precomposed glyph.
 198             ;; In that case, reform GSTRING to:
 199             ;;   [HEADER nil PRECOMPOSED-GLYPH GLYPH3 ... GLYPHn nil ...]
 200             (let* ((ncmp (1- val))      ; number of composed glyphs
 201                    (diff (1- ncmp)))    ; number of reduced glyphs
 202               (setq glyph (copy-sequence (car glyph)))
 203               (lglyph-set-from-to glyph 0 (1- nchars))
 204               (lgstring-set-glyph gstring 0 glyph)
 205               (setq idx ncmp)
 206               (while (< idx nchars)
 207                 (setq glyph (lgstring-glyph gstring idx))
 208                 (lglyph-set-from-to glyph 0 (1- nchars))
 209                 (lgstring-set-glyph gstring (- idx diff) glyph)
 210                 (setq idx (1+ idx)))
 211               (lgstring-set-glyph gstring (- idx diff) nil)
 212               (setq idx (- ncmp diff)
 213                     nglyphs (- nchars diff)))
 214           (setq glyph (lgstring-glyph gstring 0))
 215           (lglyph-set-from-to glyph 0 (1- nchars))
 216           (setq idx 1 nglyphs nchars))
 217         ;; Now IDX is an index to the first non-precomposed glyph.
 218         ;; Adjust positions of the remaining glyphs artificially.
 219         (setq base-width (lglyph-width (lgstring-glyph gstring 0)))
 220         (while (< idx nglyphs)
 221           (setq glyph (lgstring-glyph gstring idx))
 222           (lglyph-set-from-to glyph 0 (1- nchars))
 223           (if (>= (lglyph-lbearing glyph) (lglyph-width glyph))
 224               ;; It seems that this glyph is designed to be rendered
 225               ;; before the base glyph.
 226               (lglyph-set-adjustment glyph (- base-width) 0 0)
 227             (if (>= (lglyph-lbearing glyph) 0)
 228                 ;; Align the horizontal center of this glyph to the
 229                 ;; horizontal center of the base glyph.
 230                 (let ((width (- (lglyph-rbearing glyph)
 231                                 (lglyph-lbearing glyph))))
 232                   (lglyph-set-adjustment glyph
 233                                          (- (/ (- base-width width) 2)
 234                                             (lglyph-lbearing glyph)
 235                                             base-width) 0 0))))
 236           (setq idx (1+ idx))))))
 237     gstring))
 238
 239 (let* ((base "[\u05D0-\u05F2]")
 240        (combining "[\u0591-\u05BD\u05BF\u05C1-\u05C2\u05C4-\u05C5\u05C7]+")
 241        (pattern1 (concat base combining))
 242        (pattern2 (concat base "\u200D" combining)))
 243   (set-char-table-range
 244    composition-function-table '(#x591 . #x5C7)
 245    (list (vector pattern2 3 'hebrew-shape-gstring)
 246          (vector pattern2 2 'hebrew-shape-gstring)
 247          (vector pattern1 1 'hebrew-shape-gstring)
 248          [nil 0 hebrew-shape-gstring]))
 249   ;; Exclude non-combining characters.
 250   (set-char-table-range
 251    composition-function-table #x5BE nil)
 252   (set-char-table-range
 253    composition-function-table #x5C0 nil)
 254   (set-char-table-range
 255    composition-function-table #x5C3 nil)
 256   (set-char-table-range
 257    composition-function-table #x5C6 nil))
 258
 259 (provide 'hebrew)
 260
 261 ;;; hebrew.el ends here