1 ;;; composite.el --- support character composition
3 ;; Copyright (C) 1999 Electrotechnical Laboratory, JAPAN.
4 ;; Licensed to the Free Software Foundation.
6 ;; Keywords: mule, multilingual, character composition
8 ;; This file is part of GNU Emacs.
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)
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.
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.
29 (defconst reference-point-alist
30 '((tl . 0) (tc . 1) (tr . 2)
31 (Bl . 3) (Bc . 4) (Br . 5)
32 (bl . 6) (bc . 7) (br . 8)
33 (cl . 9) (cc . 10) (cr . 11)
34 (top-left . 0) (top-center . 1) (top-right . 2)
35 (base-left . 3) (base-center . 4) (base-right . 5)
36 (bottom-left . 6) (bottom-center . 7) (bottom-right . 8)
37 (center-left . 9) (center-center . 10) (center-right . 11)
38 ;; For backward compatibility...
39 (ml . 3) (mc . 10) (mr . 5)
40 (mid-left . 3) (mid-center . 10) (mid-right . 5))
41 "Alist of symbols vs integer codes of glyph reference points.
42 A glyph reference point symbol is to be used to specify a composition
43 rule in COMPONENTS argument to such functions as `compose-region' and
46 Meanings of glyph reference point codes are as follows:
48 0----1----2 <---- ascent 0:tl or top-left
49 | | 1:tc or top-center
51 | | 3:Bl or base-left 9:cl or center-left
52 9 10 11 <---- center 4:Bc or base-center 10:cc or center-center
53 | | 5:Br or base-right 11:cr or center-right
54 --3----4----5-- <-- baseline 6:bl or bottom-left
55 | | 7:bc or bottom-center
56 6----7----8 <---- descent 8:br or bottom-right
58 Glyph reference point symbols are to be used to specify composition
59 rule of the form \(GLOBAL-REF-POINT . NEW-REF-POINT), where
60 GLOBAL-REF-POINT is a reference point in the overall glyphs already
61 composed, and NEW-REF-POINT is a reference point in the new glyph to
64 For instance, if GLOBAL-REF-POINT is `br' (bottom-right) and
65 NEW-REF-POINT is `tc' (top-center), the overall glyph is updated as
66 follows (the point `*' corresponds to both reference points):
68 +-------+--+ <--- new ascent
72 -- | | |-- <--- baseline \(doesn't change)
76 +----+-----+ <--- new descent
79 ;; Encode composition rule RULE into an integer value. RULE is a cons
80 ;; of global and new reference point symbols.
81 ;; This must be compatible with C macro COMPOSITION_ENCODE_RULE
82 ;; defined in composite.h.
84 (defun encode-composition-rule (rule)
85 (if (and (integerp rule) (< rule 144))
89 (error "Invalid composition rule: %S" rule))
90 (let ((gref (car rule))
93 (setq gref (cdr (assq gref reference-point-alist))))
95 (setq nref (cdr (assq nref reference-point-alist))))
96 (or (and (>= gref 0) (< gref 12) (>= nref 0) (< nref 12))
97 (error "Invalid composition rule: %S" rule))
98 (+ (* gref 12) nref))))
100 ;; Decode encoded composition rule RULE-CODE. The value is a cons of
101 ;; global and new reference point symbols.
102 ;; This must be compatible with C macro COMPOSITION_DECODE_RULE
103 ;; defined in composite.h.
105 (defun decode-composition-rule (rule-code)
106 (or (and (natnump rule-code) (< rule-code 144))
107 (error "Invalid encoded composition rule: %S" rule-code))
108 (let ((gref (car (rassq (/ rule-code 12) reference-point-alist)))
109 (nref (car (rassq (% rule-code 12) reference-point-alist))))
110 (or (and gref (symbolp gref) nref (symbolp nref))
111 (error "Invalid composition rule code: %S" rule-code))
114 ;; Encode composition rules in composition components COMPONENTS. The
115 ;; value is a copy of COMPONENTS, where composition rules (cons of
116 ;; global and new glyph reference point symbols) are replaced with
117 ;; encoded composition rules. Optional 2nd argument NOCOPY non-nil
118 ;; means don't make a copy but modify COMPONENTS directly.
120 (defun encode-composition-components (components &optional nocopy)
122 (setq components (copy-sequence components)))
123 (if (vectorp components)
124 (let ((len (length components))
128 (encode-composition-rule (aref components i)))
130 (let ((tail (cdr components)))
133 (encode-composition-rule (car tail)))
134 (setq tail (nthcdr 2 tail)))))
137 ;; Decode composition rule codes in composition components COMPONENTS.
138 ;; The value is a copy of COMPONENTS, where composition rule codes are
139 ;; replaced with composition rules (cons of global and new glyph
140 ;; reference point symbols). Optional 2nd argument NOCOPY non-nil
141 ;; means don't make a copy but modify COMPONENTS directly.
142 ;; It is assumed that COMPONENTS is a vector and is for rule-base
143 ;; composition, thus (2N+1)th elements are rule codes.
145 (defun decode-composition-components (components &optional nocopy)
147 (setq components (copy-sequence components)))
148 (let ((len (length components))
152 (decode-composition-rule (aref components i)))
156 (defun compose-region (start end &optional components modification-func)
157 "Compose characters in the current region.
159 When called from a program, expects these four arguments.
161 First two arguments START and END are positions (integers or markers)
162 specifying the region.
164 Optional 3rd argument COMPONENTS, if non-nil, is a character or a
165 sequence (vector, list, or string) of integers.
167 If it is a character, it is an alternate character to display instead
168 of the text in the region.
170 If it is a string, the elements are alternate characters.
172 If it is a vector or list, it is a sequence of alternate characters and
173 composition rules, where (2N)th elements are characters and (2N+1)th
174 elements are composition rules to specify how to compose (2N+2)th
175 elements with previously composed N glyphs.
177 A composition rule is a cons of global and new glyph reference point
178 symbols. See the documentation of `reference-point-alist' for more
181 Optional 4th argument MODIFICATION-FUNC is a function to call to
182 adjust the composition when it gets invalid because of a change of
183 text in the composition."
185 (let ((modified-p (buffer-modified-p))
186 (buffer-read-only nil))
187 (if (or (vectorp components) (listp components))
188 (setq components (encode-composition-components components)))
189 (compose-region-internal start end components modification-func)
190 (set-buffer-modified-p modified-p)))
192 (defun decompose-region (start end)
193 "Decompose text in the current region.
195 When called from a program, expects two arguments,
196 positions (integers or markers) specifying the region."
198 (let ((modified-p (buffer-modified-p))
199 (buffer-read-only nil))
200 (remove-text-properties start end '(composition nil))
201 (set-buffer-modified-p modified-p)))
203 (defun compose-string (string &optional start end components modification-func)
204 "Compose characters in string STRING.
206 The return value is STRING with the `composition' property put on all
207 the characters in it.
209 Optional 2nd and 3rd arguments START and END specify the range of
210 STRING to be composed. They default to the beginning and the end of
213 Optional 4th argument COMPONENTS, if non-nil, is a character or a
214 sequence (vector, list, or string) of integers. See the function
215 `compose-region' for more detail.
217 Optional 5th argument MODIFICATION-FUNC is a function to call to
218 adjust the composition when it gets invalid because of a change of
219 text in the composition."
220 (if (or (vectorp components) (listp components))
221 (setq components (encode-composition-components components)))
222 (or start (setq start 0))
223 (or end (setq end (length string)))
224 (compose-string-internal string start end components modification-func)
227 (defun decompose-string (string)
228 "Return STRING where `composition' property is removed."
229 (remove-text-properties 0 (length string) '(composition nil) string)
232 (defun compose-chars (&rest args)
233 "Return a string from arguments in which all characters are composed.
234 For relative composition, arguments are characters.
235 For rule-based composition, Mth \(where M is odd) arguments are
236 characters, and Nth \(where N is even) arguments are composition rules.
237 A composition rule is a cons of glyph reference points of the form
238 \(GLOBAL-REF-POINT . NEW-REF-POINT). See the documentation of
239 `reference-point-alist' for more detail."
240 (let (str components)
241 (if (consp (car (cdr args)))
242 ;; Rule-base composition.
243 (let ((len (length args))
244 (tail (encode-composition-components args 'nocopy)))
247 (setq str (cons (car tail) str))
248 (setq tail (nthcdr 2 tail)))
249 (setq str (concat (nreverse str))
251 ;; Relative composition.
252 (setq str (concat args)))
253 (compose-string-internal str 0 (length str) components)))
255 (defun find-composition (pos &optional limit string detail-p)
256 "Return information about a composition at or nearest to buffer position POS.
258 If the character at POS has `composition' property, the value is a list
259 of FROM, TO, and VALID-P.
261 FROM and TO specify the range of text that has the same `composition'
262 property, VALID-P is non-nil if and only if this composition is valid.
264 If there's no composition at POS, and the optional 2nd argument LIMIT
265 is non-nil, search for a composition toward LIMIT.
267 If no composition is found, return nil.
269 Optional 3rd argument STRING, if non-nil, is a string to look for a
270 composition in; nil means the current buffer.
272 If a valid composition is found and the optional 4th argument DETAIL-P
273 is non-nil, the return value is a list of FROM, TO, COMPONENTS,
274 RELATIVE-P, MOD-FUNC, and WIDTH.
276 COMPONENTS is a vector of integers, the meaning depends on RELATIVE-P.
278 RELATIVE-P is t if the composition method is relative, else nil.
280 If RELATIVE-P is t, COMPONENTS is a vector of characters to be
281 composed. If RELATIVE-P is nil, COMPONENTS is a vector of characters
282 and composition rules as described in `compose-region'.
284 MOD-FUNC is a modification function of the composition.
286 WIDTH is a number of columns the composition occupies on the screen."
287 (let ((result (find-composition-internal pos limit string detail-p)))
288 (if (and detail-p result (nth 2 result) (not (nth 3 result)))
289 ;; This is a valid rule-base composition.
290 (decode-composition-components (nth 2 result) 'nocopy))
294 (defun compose-chars-after (pos &optional limit object)
295 "Compose characters in current buffer after position POS.
297 It looks up the char-table `composition-function-table' (which see) by
298 a character after POS. If non-nil value is found, the format of the
299 value should be an alist of PATTERNs vs FUNCs, where PATTERNs are
300 regular expressions and FUNCs are functions. If the text after POS
301 matches one of PATTERNs, call the corresponding FUNC with three
302 arguments POS, TO, and PATTERN, where TO is the end position of text
303 matching PATTERN, and return what FUNC returns. Otherwise, return
306 FUNC is responsible for composing the text properly. The return value
308 nil -- if no characters were composed.
309 CHARS (integer) -- if CHARS characters were composed.
311 Optional 2nd arg LIMIT, if non-nil, limits the matching of text.
313 Optional 3rd arg OBJECT, if non-nil, is a string that contains the
314 text to compose. In that case, POS and LIMIT index to the string.
316 This function is the default value of `compose-chars-after-function'."
317 (let ((tail (aref composition-function-table (char-after pos)))
322 (while (and tail (not func))
323 (setq pattern (car (car tail))
324 func (cdr (car tail)))
327 (and (re-search-forward pattern limit t)
328 (= (match-beginning 0) pos))
329 (looking-at pattern))
330 (setq result (funcall func pos (match-end 0) pattern nil))
331 (setq func nil tail (cdr tail)))))))
334 (defun compose-last-chars (args)
335 "Compose last characters.
336 The argument is a parameterized event of the form
337 \(compose-last-chars N COMPONENTS),
338 where N is the number of characters before point to compose,
339 COMPONENTS, if non-nil, is the same as the argument to `compose-region'
340 \(which see). If it is nil, `compose-chars-after' is called,
341 and that function find a proper rule to compose the target characters.
342 This function is intended to be used from input methods.
343 The global keymap binds special event `compose-last-chars' to this
344 function. Input method may generate an event (compose-last-chars N COMPONENTS)
345 after a sequence character events."
347 (let ((chars (nth 1 args)))
348 (if (and (numberp chars)
349 (>= (- (point) (point-min)) chars))
351 (compose-region (- (point) chars) (point) (nth 2 args))
352 (compose-chars-after (- (point) chars) (point))))))
354 (global-set-key [compose-last-chars] 'compose-last-chars)
357 ;;; Automatic character composition.
359 (defvar composition-function-table
360 (make-char-table nil)
361 "Char table of functions for automatic character composition.
362 For each character that has to be composed automatically with
363 preceding and/or following characters, this char table contains
364 a function to call to compose that character.
366 Each function is called with two arguments, POS and STRING.
368 If STRING is nil, POS is a position in the current buffer, and the
369 function has to compose a character at POS with surrounding characters
370 in the current buffer.
372 Otherwise, STRING is a string, and POS is an index to the string. In
373 this case, the function has to compose a character at POS with
374 surrounding characters in the string.
376 See also the command `toggle-auto-composition'.")
378 ;; Copied from font-lock.el.
381 ;; We don't do this at the top-level as we only use non-autoloaded macros.
384 ;; Borrowed from lazy-lock.el.
385 ;; We use this to preserve or protect things when modifying text properties.
386 (defmacro save-buffer-state (varlist &rest body)
387 "Bind variables according to VARLIST and eval BODY restoring buffer state."
388 `(let* ,(append varlist
389 '((modified (buffer-modified-p)) (buffer-undo-list t)
390 (inhibit-read-only t) (inhibit-point-motion-hooks t)
391 (inhibit-modification-hooks t)
392 deactivate-mark buffer-file-name buffer-file-truename))
395 (restore-buffer-modified-p nil))))
396 (put 'save-buffer-state 'lisp-indent-function 1)
397 ;; Fixme: This makes bootstrapping fails by this error.
398 ;; Symbol's function definition is void: eval-defun
399 ;;(def-edebug-spec save-buffer-state let)
402 (defvar auto-composition-chunk-size 500
403 "*Automatic composition chunks of this many characters, or smaller.")
405 (defun auto-compose-chars (pos string)
406 "Compose characters after the buffer position POS.
407 If STRING is non-nil, it is a string, and POS is an index to the string.
408 In that case, compose characters in the string.
410 This function is the default value of `auto-composition-function' (which see)."
411 (save-buffer-state nil
416 (end (if string (length string) (point-max)))
417 (limit (next-single-property-change pos 'auto-composed string
421 (if (> (- limit start) auto-composition-chunk-size)
422 (setq limit (+ start auto-composition-chunk-size)))
423 (while (and (< pos end)
424 (setq ch (if string (aref string pos)
428 (setq func (aref composition-function-table ch))
430 (setq newpos (funcall func pos string)
431 pos (if (and (integerp newpos) (> newpos pos))
434 (setq pos (1+ pos))))
437 (put-text-property start pos 'auto-composed t string)))))))
439 (setq auto-composition-function 'auto-compose-chars)
441 (defun toggle-auto-composition (&optional arg)
442 "Change whether automatic character composition is enabled in this buffer.
443 With arg, enable it iff arg is positive."
445 (let ((enable (if (null arg) (not auto-composition-function)
446 (> (prefix-numeric-value arg) 0))))
448 (kill-local-variable 'auto-composition-function)
449 (make-local-variable 'auto-composition-function)
450 (setq auto-composition-function nil)
451 (save-buffer-state nil
454 (decompose-region (point-min) (point-max)))))
456 (save-buffer-state nil
459 (put-text-property (point-min) (point-max) 'auto-composed nil)))))
462 ;;; The following codes are only for backward compatibility with Emacs
463 ;;; 20.4 and the earlier.
465 (defun decompose-composite-char (char &optional type with-composition-rule)
466 "Convert CHAR to string.
467 This is only for backward compatibility with Emacs 20.4 and the earlier.
469 If optional 2nd arg TYPE is non-nil, it is `string', `list', or
470 `vector'. In this case, CHAR is converted string, list of CHAR, or
471 vector of CHAR respectively."
472 (cond ((or (null type) (eq type 'string)) (char-to-string char))
473 ((eq type 'list) (list char))
476 (make-obsolete 'decompose-composite-char 'char-to-string "21.1")
479 ;;; composite.el ends here