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 Characters are composed relatively, i.e. composed by overstricking or
160 stacking depending on ascent, descent and other properties.
162 When called from a program, expects these four arguments.
164 First two arguments START and END are positions (integers or markers)
165 specifying the region.
167 Optional 3rd argument COMPONENTS, if non-nil, is a character or a
168 sequence (vector, list, or string) of integers. In this case,
169 characters are composed not relatively but according to COMPONENTS.
171 If it is a character, it is an alternate character to display instead
172 of the text in the region.
174 If it is a string, the elements are alternate characters.
176 If it is a vector or list, it is a sequence of alternate characters and
177 composition rules, where (2N)th elements are characters and (2N+1)th
178 elements are composition rules to specify how to compose (2N+2)th
179 elements with previously composed N glyphs.
181 A composition rule is a cons of global and new glyph reference point
182 symbols. See the documentation of `reference-point-alist' for more
185 Optional 4th argument MODIFICATION-FUNC is a function to call to
186 adjust the composition when it gets invalid because of a change of
187 text in the composition."
189 (let ((modified-p (buffer-modified-p))
190 (buffer-read-only nil))
191 (if (or (vectorp components) (listp components))
192 (setq components (encode-composition-components components)))
193 (compose-region-internal start end components modification-func)
194 (set-buffer-modified-p modified-p)))
196 (defun decompose-region (start end)
197 "Decompose text in the current region.
199 When called from a program, expects two arguments,
200 positions (integers or markers) specifying the region."
202 (let ((modified-p (buffer-modified-p))
203 (buffer-read-only nil))
204 (remove-text-properties start end '(composition nil))
205 (set-buffer-modified-p modified-p)))
207 (defun compose-string (string &optional start end components modification-func)
208 "Compose characters in string STRING.
210 The return value is STRING with the `composition' property put on all
211 the characters in it.
213 Optional 2nd and 3rd arguments START and END specify the range of
214 STRING to be composed. They default to the beginning and the end of
217 Optional 4th argument COMPONENTS, if non-nil, is a character or a
218 sequence (vector, list, or string) of integers. See the function
219 `compose-region' for more detail.
221 Optional 5th argument MODIFICATION-FUNC is a function to call to
222 adjust the composition when it gets invalid because of a change of
223 text in the composition."
224 (if (or (vectorp components) (listp components))
225 (setq components (encode-composition-components components)))
226 (or start (setq start 0))
227 (or end (setq end (length string)))
228 (compose-string-internal string start end components modification-func)
231 (defun decompose-string (string)
232 "Return STRING where `composition' property is removed."
233 (remove-text-properties 0 (length string) '(composition nil) string)
236 (defun compose-chars (&rest args)
237 "Return a string from arguments in which all characters are composed.
238 For relative composition, arguments are characters.
239 For rule-based composition, Mth \(where M is odd) arguments are
240 characters, and Nth \(where N is even) arguments are composition rules.
241 A composition rule is a cons of glyph reference points of the form
242 \(GLOBAL-REF-POINT . NEW-REF-POINT). See the documentation of
243 `reference-point-alist' for more detail."
244 (let (str components)
245 (if (consp (car (cdr args)))
246 ;; Rule-base composition.
247 (let ((len (length args))
248 (tail (encode-composition-components args 'nocopy)))
251 (setq str (cons (car tail) str))
252 (setq tail (nthcdr 2 tail)))
253 (setq str (concat (nreverse str))
255 ;; Relative composition.
256 (setq str (concat args)))
257 (compose-string-internal str 0 (length str) components)))
259 (defun find-composition (pos &optional limit string detail-p)
260 "Return information about a composition at or nearest to buffer position POS.
262 If the character at POS has `composition' property, the value is a list
263 of FROM, TO, and VALID-P.
265 FROM and TO specify the range of text that has the same `composition'
266 property, VALID-P is non-nil if and only if this composition is valid.
268 If there's no composition at POS, and the optional 2nd argument LIMIT
269 is non-nil, search for a composition toward LIMIT.
271 If no composition is found, return nil.
273 Optional 3rd argument STRING, if non-nil, is a string to look for a
274 composition in; nil means the current buffer.
276 If a valid composition is found and the optional 4th argument DETAIL-P
277 is non-nil, the return value is a list of FROM, TO, COMPONENTS,
278 RELATIVE-P, MOD-FUNC, and WIDTH.
280 COMPONENTS is a vector of integers, the meaning depends on RELATIVE-P.
282 RELATIVE-P is t if the composition method is relative, else nil.
284 If RELATIVE-P is t, COMPONENTS is a vector of characters to be
285 composed. If RELATIVE-P is nil, COMPONENTS is a vector of characters
286 and composition rules as described in `compose-region'.
288 MOD-FUNC is a modification function of the composition.
290 WIDTH is a number of columns the composition occupies on the screen."
291 (let ((result (find-composition-internal pos limit string detail-p)))
292 (if (and detail-p result (nth 2 result) (not (nth 3 result)))
293 ;; This is a valid rule-base composition.
294 (decode-composition-components (nth 2 result) 'nocopy))
298 (defun compose-chars-after (pos &optional limit object)
299 "Compose characters in current buffer after position POS.
301 It looks up the char-table `composition-function-table' (which see) by
302 a character after POS. If non-nil value is found, the format of the
303 value should be an alist of PATTERNs vs FUNCs, where PATTERNs are
304 regular expressions and FUNCs are functions. If the text after POS
305 matches one of PATTERNs, call the corresponding FUNC with three
306 arguments POS, TO, and PATTERN, where TO is the end position of text
307 matching PATTERN, and return what FUNC returns. Otherwise, return
310 FUNC is responsible for composing the text properly. The return value
312 nil -- if no characters were composed.
313 CHARS (integer) -- if CHARS characters were composed.
315 Optional 2nd arg LIMIT, if non-nil, limits the matching of text.
317 Optional 3rd arg OBJECT, if non-nil, is a string that contains the
318 text to compose. In that case, POS and LIMIT index to the string.
320 This function is the default value of `compose-chars-after-function'."
321 (let ((tail (aref composition-function-table (char-after pos)))
326 (while (and tail (not func))
327 (setq pattern (car (car tail))
328 func (cdr (car tail)))
331 (and (re-search-forward pattern limit t)
332 (= (match-beginning 0) pos))
333 (looking-at pattern))
334 (setq result (funcall func pos (match-end 0) pattern nil))
335 (setq func nil tail (cdr tail)))))))
338 (defun compose-last-chars (args)
339 "Compose last characters.
340 The argument is a parameterized event of the form
341 \(compose-last-chars N COMPONENTS),
342 where N is the number of characters before point to compose,
343 COMPONENTS, if non-nil, is the same as the argument to `compose-region'
344 \(which see). If it is nil, `compose-chars-after' is called,
345 and that function find a proper rule to compose the target characters.
346 This function is intended to be used from input methods.
347 The global keymap binds special event `compose-last-chars' to this
348 function. Input method may generate an event (compose-last-chars N COMPONENTS)
349 after a sequence character events."
351 (let ((chars (nth 1 args)))
352 (if (and (numberp chars)
353 (>= (- (point) (point-min)) chars))
355 (compose-region (- (point) chars) (point) (nth 2 args))
356 (compose-chars-after (- (point) chars) (point))))))
358 (global-set-key [compose-last-chars] 'compose-last-chars)
361 ;;; Automatic character composition.
363 (defvar composition-function-table
364 (make-char-table nil)
365 "Char table of functions for automatic character composition.
366 For each character that has to be composed automatically with
367 preceding and/or following characters, this char table contains
368 a function to call to compose that character.
370 Each function is called with two arguments, POS and STRING.
372 If STRING is nil, POS is a position in the current buffer, and the
373 function has to compose a character at POS with surrounding characters
374 in the current buffer.
376 Otherwise, STRING is a string, and POS is an index to the string. In
377 this case, the function has to compose a character at POS with
378 surrounding characters in the string.
380 See also the command `toggle-auto-composition'.")
382 ;; Copied from font-lock.el.
385 ;; We don't do this at the top-level as we only use non-autoloaded macros.
388 ;; Borrowed from lazy-lock.el.
389 ;; We use this to preserve or protect things when modifying text properties.
390 (defmacro save-buffer-state (varlist &rest body)
391 "Bind variables according to VARLIST and eval BODY restoring buffer state."
392 `(let* ,(append varlist
393 '((modified (buffer-modified-p)) (buffer-undo-list t)
394 (inhibit-read-only t) (inhibit-point-motion-hooks t)
395 (inhibit-modification-hooks t)
396 deactivate-mark buffer-file-name buffer-file-truename))
399 (restore-buffer-modified-p nil))))
400 (put 'save-buffer-state 'lisp-indent-function 1)
401 ;; Fixme: This makes bootstrapping fails by this error.
402 ;; Symbol's function definition is void: eval-defun
403 ;;(def-edebug-spec save-buffer-state let)
406 (defvar auto-composition-chunk-size 500
407 "*Automatic composition chunks of this many characters, or smaller.")
409 (defun auto-compose-chars (pos string)
410 "Compose characters after the buffer position POS.
411 If STRING is non-nil, it is a string, and POS is an index to the string.
412 In that case, compose characters in the string.
414 This function is the default value of `auto-composition-function' (which see)."
415 (save-buffer-state nil
420 (end (if string (length string) (point-max)))
421 (limit (next-single-property-change pos 'auto-composed string
425 (if (> (- limit start) auto-composition-chunk-size)
426 (setq limit (+ start auto-composition-chunk-size)))
427 (while (and (< pos end)
428 (setq ch (if string (aref string pos)
432 (setq func (aref composition-function-table ch))
434 (setq newpos (funcall func pos string)
435 pos (if (and (integerp newpos) (> newpos pos))
438 (setq pos (1+ pos))))
441 (put-text-property start pos 'auto-composed t string)))))))
443 (setq auto-composition-function 'auto-compose-chars)
445 (defun toggle-auto-composition (&optional arg)
446 "Change whether automatic character composition is enabled in this buffer.
447 With arg, enable it iff arg is positive."
449 (let ((enable (if (null arg) (not auto-composition-function)
450 (> (prefix-numeric-value arg) 0))))
452 (kill-local-variable 'auto-composition-function)
453 (make-local-variable 'auto-composition-function)
454 (setq auto-composition-function nil)
455 (save-buffer-state nil
458 (decompose-region (point-min) (point-max)))))
460 (save-buffer-state nil
463 (put-text-property (point-min) (point-max) 'auto-composed nil)))))
465 ;;; The following codes are only for backward compatibility with Emacs
466 ;;; 20.4 and earlier.
468 (defun decompose-composite-char (char &optional type with-composition-rule)
469 "Convert CHAR to string.
471 If optional 2nd arg TYPE is non-nil, it is `string', `list', or
472 `vector'. In this case, CHAR is converted to string, list of CHAR, or
473 vector of CHAR respectively.
474 Optional 3rd arg WITH-COMPOSITION-RULE is ignored."
475 (cond ((or (null type) (eq type 'string)) (char-to-string char))
476 ((eq type 'list) (list char))
479 (make-obsolete 'decompose-composite-char 'char-to-string "21.1")
482 ;;; composite.el ends here