lisp/composite.el

   1 ;;; composite.el --- support character composition
   2
   3 ;; Copyright (C) 1999 Electrotechnical Laboratory, JAPAN.
   4 ;; Licensed to the Free Software Foundation.
   5
   6 ;; Keywords: mule, multilingual, character composition
   7
   8 ;; This file is part of GNU Emacs.
   9
  10 ;; GNU Emacs is free software; you can redistribute it and/or modify
  11 ;; it under the terms of the GNU General Public License as published by
  12 ;; the Free Software Foundation; either version 2, or (at your option)
  13 ;; any later version.
  14
  15 ;; GNU Emacs is distributed in the hope that it will be useful,
  16 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  17 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18 ;; GNU General Public License for more details.
  19
  20 ;; You should have received a copy of the GNU General Public License
  21 ;; along with GNU Emacs; see the file COPYING.  If not, write to the
  22 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  23 ;; Boston, MA 02111-1307, USA.
  24
  25 ;;; Commentary:
  26
  27 ;;; Code:
  28
  29 ;;;###autoload
  30 (defconst reference-point-alist
  31   '((tl . 0) (tc . 1) (tr . 2)
  32     (Bl . 3) (Bc . 4) (Br . 5)
  33     (bl . 6) (bc . 7) (br . 8)
  34     (cl . 9) (cc . 10) (cr . 11)
  35     (top-left . 0) (top-center . 1) (top-right . 2)
  36     (base-left . 3) (base-center . 4) (base-right . 5)
  37     (bottom-left . 6) (bottom-center . 7) (bottom-right . 8)
  38     (center-left . 9) (center-center . 10) (center-right . 11)
  39     ;; For backward compatibility...
  40     (ml . 3) (mc . 10) (mr . 5)
  41     (mid-left . 3) (mid-center . 10) (mid-right . 5))
  42   "Alist of symbols vs integer codes of glyph reference points.
  43 A glyph reference point symbol is to be used to specify a composition
  44 rule in COMPONENTS argument to such functions as `compose-region' and
  45 `make-composition'.
  46
  47 Meanings of glyph reference point codes are as follows:
  48
  49     0----1----2 <---- ascent    0:tl or top-left
  50     |         |                 1:tc or top-center
  51     |         |                 2:tr or top-right
  52     |         |                 3:Bl or base-left     9:cl or center-left
  53     9   10   11 <---- center    4:Bc or base-center  10:cc or center-center
  54     |         |                 5:Br or base-right   11:cr or center-right
  55   --3----4----5-- <-- baseline  6:bl or bottom-left
  56     |         |                 7:bc or bottom-center
  57     6----7----8 <---- descent   8:br or bottom-right
  58
  59 Glyph reference point symbols are to be used to specify composition
  60 rule of the form \(GLOBAL-REF-POINT . NEW-REF-POINT), where
  61 GLOBAL-REF-POINT is a reference point in the overall glyphs already
  62 composed, and NEW-REF-POINT is a reference point in the new glyph to
  63 be added.
  64
  65 For instance, if GLOBAL-REF-POINT is `br' (bottom-right) and
  66 NEW-REF-POINT is `tc' (top-center), the overall glyph is updated as
  67 follows (the point `*' corresponds to both reference points):
  68
  69     +-------+--+ <--- new ascent
  70     |       |  |
  71     | global|  |
  72     | glyph |  |
  73  -- |       |  |-- <--- baseline \(doesn't change)
  74     +----+--*--+
  75     |    | new |
  76     |    |glyph|
  77     +----+-----+ <--- new descent
  78 ")
  79
  80 ;; Encode composition rule RULE into an integer value.  RULE is a cons
  81 ;; of global and new reference point symbols.
  82 ;; This must be compatible with C macro COMPOSITION_ENCODE_RULE
  83 ;; defined in composite.h.
  84
  85 (defun encode-composition-rule (rule)
  86   (if (and (integerp rule) (< rule 144))
  87       ;; Already encoded.
  88       rule
  89     (or (consp rule)
  90         (error "Invalid composition rule: %S" rule))
  91     (let ((gref (car rule))
  92           (nref (cdr rule)))
  93       (or (integerp gref)
  94           (setq gref (cdr (assq gref reference-point-alist))))
  95       (or (integerp nref)
  96           (setq nref (cdr (assq nref reference-point-alist))))
  97       (or (and (>= gref 0) (< gref 12) (>= nref 0) (< nref 12))
  98           (error "Invalid composition rule: %S" rule))
  99       (+ (* gref 12) nref))))
 100
 101 ;; Decode encoded composition rule RULE-CODE.  The value is a cons of
 102 ;; global and new reference point symbols.
 103 ;; This must be compatible with C macro COMPOSITION_DECODE_RULE
 104 ;; defined in composite.h.
 105
 106 (defun decode-composition-rule (rule-code)
 107   (or (and (natnump rule-code) (< rule-code 144))
 108       (error "Invalid encoded composition rule: %S" rule-code))
 109   (let ((gref (car (rassq (/ rule-code 12) reference-point-alist)))
 110         (nref (car (rassq (% rule-code 12) reference-point-alist))))
 111     (or (and gref (symbolp gref) nref (symbolp nref))
 112         (error "Invalid composition rule code: %S" rule-code))
 113     (cons gref nref)))
 114
 115 ;; Encode composition rules in composition components COMPONENTS.  The
 116 ;; value is a copy of COMPONENTS, where composition rules (cons of
 117 ;; global and new glyph reference point symbols) are replaced with
 118 ;; encoded composition rules.  Optional 2nd argument NOCOPY non-nil
 119 ;; means don't make a copy but modify COMPONENTS directly.
 120
 121 (defun encode-composition-components (components &optional nocopy)
 122   (or nocopy
 123       (setq components (copy-sequence components)))
 124   (if (vectorp components)
 125       (let ((len (length components))
 126             (i 1))
 127         (while (< i len)
 128           (aset components i
 129                 (encode-composition-rule (aref components i)))
 130           (setq i (+ i 2))))
 131     (let ((tail (cdr components)))
 132       (while tail
 133         (setcar tail
 134                 (encode-composition-rule (car tail)))
 135         (setq tail (nthcdr 2 tail)))))
 136   components)
 137
 138 ;; Decode composition rule codes in composition components COMPONENTS.
 139 ;; The value is a copy of COMPONENTS, where composition rule codes are
 140 ;; replaced with composition rules (cons of global and new glyph
 141 ;; reference point symbols).  Optional 2nd argument NOCOPY non-nil
 142 ;; means don't make a copy but modify COMPONENTS directly.
 143 ;; It is assumed that COMPONENTS is a vector and is for rule-base
 144 ;; composition, thus (2N+1)th elements are rule codes.
 145
 146 (defun decode-composition-components (components &optional nocopy)
 147   (or nocopy
 148       (setq components (copy-sequence components)))
 149   (let ((len (length components))
 150         (i 1))
 151     (while (< i len)
 152       (aset components i
 153             (decode-composition-rule (aref components i)))
 154       (setq i (+ i 2))))
 155   components)
 156
 157 ;;;###autoload
 158 (defun compose-region (start end &optional components modification-func)
 159   "Compose characters in the current region.
 160
 161 Characters are composed relatively, i.e. composed by overstricking or
 162 stacking depending on ascent, descent and other properties.
 163
 164 When called from a program, expects these four arguments.
 165
 166 First two arguments START and END are positions (integers or markers)
 167 specifying the region.
 168
 169 Optional 3rd argument COMPONENTS, if non-nil, is a character or a
 170 sequence (vector, list, or string) of integers.  In this case,
 171 characters are composed not relatively but according to COMPONENTS.
 172
 173 If it is a character, it is an alternate character to display instead
 174 of the text in the region.
 175
 176 If it is a string, the elements are alternate characters.
 177
 178 If it is a vector or list, it is a sequence of alternate characters and
 179 composition rules, where (2N)th elements are characters and (2N+1)th
 180 elements are composition rules to specify how to compose (2N+2)th
 181 elements with previously composed N glyphs.
 182
 183 A composition rule is a cons of global and new glyph reference point
 184 symbols.  See the documentation of `reference-point-alist' for more
 185 detail.
 186
 187 Optional 4th argument MODIFICATION-FUNC is a function to call to
 188 adjust the composition when it gets invalid because of a change of
 189 text in the composition."
 190   (interactive "r")
 191   (let ((modified-p (buffer-modified-p))
 192         (buffer-read-only nil))
 193     (if (or (vectorp components) (listp components))
 194         (setq components (encode-composition-components components)))
 195     (compose-region-internal start end components modification-func)
 196     (set-buffer-modified-p modified-p)))
 197
 198 ;;;###autoload
 199 (defun decompose-region (start end)
 200   "Decompose text in the current region.
 201
 202 When called from a program, expects two arguments,
 203 positions (integers or markers) specifying the region."
 204   (interactive "r")
 205   (let ((modified-p (buffer-modified-p))
 206         (buffer-read-only nil))
 207     (remove-text-properties start end '(composition nil))
 208     (set-buffer-modified-p modified-p)))
 209
 210 ;;;###autoload
 211 (defun compose-string (string &optional start end components modification-func)
 212   "Compose characters in string STRING.
 213
 214 The return value is STRING where `composition' property is put on all
 215 the characters in it.
 216
 217 Optional 2nd and 3rd arguments START and END specify the range of
 218 STRING to be composed.  They defaults to the beginning and the end of
 219 STRING respectively.
 220
 221 Optional 4th argument COMPONENTS, if non-nil, is a character or a
 222 sequence (vector, list, or string) of integers.  See the function
 223 `compose-region' for more detail.
 224
 225 Optional 5th argument MODIFICATION-FUNC is a function to call to
 226 adjust the composition when it gets invalid because of a change of
 227 text in the composition."
 228   (if (or (vectorp components) (listp components))
 229       (setq components (encode-composition-components components)))
 230   (or start (setq start 0))
 231   (or end (setq end (length string)))
 232   (compose-string-internal string start end components modification-func)
 233   string)
 234
 235 ;;;###autoload
 236 (defun decompose-string (string)
 237   "Return STRING where `composition' property is removed."
 238   (remove-text-properties 0 (length string) '(composition nil) string)
 239   string)
 240
 241 ;;;###autoload
 242 (defun compose-chars (&rest args)
 243   "Return a string from arguments in which all characters are composed.
 244 For relative composition, arguments are characters.
 245 For rule-based composition, Mth \(where M is odd) arguments are
 246 characters, and Nth \(where N is even) arguments are composition rules.
 247 A composition rule is a cons of glyph reference points of the form
 248 \(GLOBAL-REF-POINT . NEW-REF-POINT).  See the documentation of
 249 `reference-point-alist' for more detail."
 250   (let (str components)
 251     (if (consp (car (cdr args)))
 252         ;; Rule-base composition.
 253         (let ((len (length args))
 254               (tail (encode-composition-components args 'nocopy)))
 255
 256           (while tail
 257             (setq str (cons (car tail) str))
 258             (setq tail (nthcdr 2 tail)))
 259           (setq str (concat (nreverse str))
 260                 components args))
 261       ;; Relative composition.
 262       (setq str (concat args)))
 263     (compose-string-internal str 0 (length str) components)))
 264
 265 ;;;###autoload
 266 (defun find-composition (pos &optional limit string detail-p)
 267   "Return information about a composition at or nearest to buffer position POS.
 268
 269 If the character at POS has `composition' property, the value is a list
 270 of FROM, TO, and VALID-P.
 271
 272 FROM and TO specify the range of text that has the same `composition'
 273 property, VALID-P is non-nil if and only if this composition is valid.
 274
 275 If there's no composition at POS, and the optional 2nd argument LIMIT
 276 is non-nil, search for a composition toward LIMIT.
 277
 278 If no composition is found, return nil.
 279
 280 Optional 3rd argument STRING, if non-nil, is a string to look for a
 281 composition in; nil means the current buffer.
 282
 283 If a valid composition is found and the optional 4th argument DETAIL-P
 284 is non-nil, the return value is a list of FROM, TO, COMPONENTS,
 285 RELATIVE-P, MOD-FUNC, and WIDTH.
 286
 287 COMPONENTS is a vector of integers, the meaning depends on RELATIVE-P.
 288
 289 RELATIVE-P is t if the composition method is relative, else nil.
 290
 291 If RELATIVE-P is t, COMPONENTS is a vector of characters to be
 292 composed.  If RELATIVE-P is nil, COMPONENTS is a vector of characters
 293 and composition rules as described in `compose-region'.
 294
 295 MOD-FUNC is a modification function of the composition.
 296
 297 WIDTH is a number of columns the composition occupies on the screen."
 298   (let ((result (find-composition-internal pos limit string detail-p)))
 299     (if (and detail-p result (nth 2 result) (not (nth 3 result)))
 300         ;; This is a valid rule-base composition.
 301         (decode-composition-components (nth 2 result) 'nocopy))
 302     result))
 303
 304 \f
 305 ;;;###autoload
 306 (defun compose-chars-after (pos &optional limit object)
 307   "Compose characters in current buffer after position POS.
 308
 309 It looks up the char-table `composition-function-table' (which see) by
 310 a character after POS.  If non-nil value is found, the format of the
 311 value should be an alist of PATTERNs vs FUNCs, where PATTERNs are
 312 regular expressions and FUNCs are functions.  If the text after POS
 313 matches one of PATTERNs, call the corresponding FUNC with three
 314 arguments POS, TO, and PATTERN, where TO is the end position of text
 315 matching PATTERN, and return what FUNC returns.  Otherwise, return
 316 nil.
 317
 318 FUNC is responsible for composing the text properly.  The return value
 319 is:
 320   nil -- if no characters were composed.
 321   CHARS (integer) -- if CHARS characters were composed.
 322
 323 Optional 2nd arg LIMIT, if non-nil, limits the matching of text.
 324
 325 Optional 3rd arg OBJECT, if non-nil, is a string that contains the
 326 text to compose.  In that case, POS and LIMIT index to the string.
 327
 328 This function is the default value of `compose-chars-after-function'."
 329   (let ((tail (aref composition-function-table (char-after pos)))
 330         pattern func result)
 331     (when tail
 332       (save-match-data
 333         (save-excursion
 334           (while (and tail (not func))
 335             (setq pattern (car (car tail))
 336                   func (cdr (car tail)))
 337             (goto-char pos)
 338             (if (if limit
 339                     (and (re-search-forward pattern limit t)
 340                          (= (match-beginning 0) pos))
 341                   (looking-at pattern))
 342                 (setq result (funcall func pos (match-end 0) pattern nil))
 343               (setq func nil tail (cdr tail)))))))
 344       result))
 345
 346 ;;;###autoload
 347 (defun compose-last-chars (args)
 348   "Compose last characters.
 349 The argument is a parameterized event of the form
 350         \(compose-last-chars N COMPONENTS),
 351 where N is the number of characters before point to compose,
 352 COMPONENTS, if non-nil, is the same as the argument to `compose-region'
 353 \(which see).  If it is nil, `compose-chars-after' is called,
 354 and that function find a proper rule to compose the target characters.
 355 This function is intended to be used from input methods.
 356 The global keymap binds special event `compose-last-chars' to this
 357 function.  Input method may generate an event (compose-last-chars N COMPONENTS)
 358 after a sequence character events."
 359   (interactive "e")
 360   (let ((chars (nth 1 args)))
 361     (if (and (numberp chars)
 362              (>= (- (point) (point-min)) chars))
 363         (if (nth 2 args)
 364             (compose-region (- (point) chars) (point) (nth 2 args))
 365           (compose-chars-after (- (point) chars) (point))))))
 366
 367 ;;;###autoload(global-set-key [compose-last-chars] 'compose-last-chars)
 368
 369 \f
 370 ;;; The following codes are only for backward compatibility with Emacs
 371 ;;; 20.4 and earlier.
 372
 373 ;;;###autoload
 374 (defun decompose-composite-char (char &optional type with-composition-rule)
 375   "Convert CHAR to string.
 376
 377 If optional 2nd arg TYPE is non-nil, it is `string', `list', or
 378 `vector'.  In this case, CHAR is converted to string, list of CHAR, or
 379 vector of CHAR respectively.
 380 Optional 3rd arg WITH-COMPOSITION-RULE is ignored."
 381   (cond ((or (null type) (eq type 'string)) (char-to-string char))
 382         ((eq type 'list) (list char))
 383         (t (vector char))))
 384
 385 ;;;###autoload
 386 (make-obsolete 'decompose-composite-char 'char-to-string "21.1")
 387
 388 \f
 389 ;;; composite.el ends here