summaryrefslogtreecommitdiff
path: root/lisp/composite.el
blob: ce7ea95800b9cc039f6d8ca51ba110efee135239 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
;;; composite.el --- support character composition

;; Copyright (C) 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007,
;;   2008, 2009
;;   National Institute of Advanced Industrial Science and Technology (AIST)
;;   Registration Number H14PRO021

;; Author: Kenichi HANDA <handa@etl.go.jp>
;; (according to ack.texi)
;; Keywords: mule, multilingual, character composition

;; This file is part of GNU Emacs.

;; GNU Emacs is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.

;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.

;;; Commentary:

;;; Code:

(defconst reference-point-alist
  '((tl . 0) (tc . 1) (tr . 2)
    (Bl . 3) (Bc . 4) (Br . 5)
    (bl . 6) (bc . 7) (br . 8)
    (cl . 9) (cc . 10) (cr . 11)
    (top-left . 0) (top-center . 1) (top-right . 2)
    (base-left . 3) (base-center . 4) (base-right . 5)
    (bottom-left . 6) (bottom-center . 7) (bottom-right . 8)
    (center-left . 9) (center-center . 10) (center-right . 11)
    ;; For backward compatibility...
    (ml . 3) (mc . 10) (mr . 5)
    (mid-left . 3) (mid-center . 10) (mid-right . 5))
  "Alist of symbols vs integer codes of glyph reference points.
A glyph reference point symbol is to be used to specify a composition
rule in COMPONENTS argument to such functions as `compose-region'.

Meanings of glyph reference point codes are as follows:

    0----1----2 <---- ascent	0:tl or top-left
    |         |			1:tc or top-center
    |         |			2:tr or top-right
    |         |			3:Bl or base-left     9:cl or center-left
    9   10   11 <---- center	4:Bc or base-center  10:cc or center-center
    |         |			5:Br or base-right   11:cr or center-right
  --3----4----5-- <-- baseline	6:bl or bottom-left
    |         |			7:bc or bottom-center
    6----7----8 <---- descent	8:br or bottom-right

Glyph reference point symbols are to be used to specify composition
rule of the form \(GLOBAL-REF-POINT . NEW-REF-POINT), where
GLOBAL-REF-POINT is a reference point in the overall glyphs already
composed, and NEW-REF-POINT is a reference point in the new glyph to
be added.

For instance, if GLOBAL-REF-POINT is `br' (bottom-right) and
NEW-REF-POINT is `tc' (top-center), the overall glyph is updated as
follows (the point `*' corresponds to both reference points):

    +-------+--+ <--- new ascent
    |       |  |
    | global|  |
    | glyph |  |
 -- |       |  |-- <--- baseline \(doesn't change)
    +----+--*--+
    |    | new |
    |    |glyph|
    +----+-----+ <--- new descent

A composition rule may have the form \(GLOBAL-REF-POINT
NEW-REF-POINT XOFF YOFF), where XOFF and YOFF specifies how much
to shift NEW-REF-POINT from GLOBAL-REF-POINT.  In this case, XOFF
and YOFF are integers in the range -100..100 representing the
shifting percentage against the font size.")


;;;###autoload
(defun encode-composition-rule (rule)
  "Encode composition rule RULE into an integer value.
RULE is a cons of global and new reference point symbols
\(see `reference-point-alist')."

  ;; This must be compatible with C macro COMPOSITION_ENCODE_RULE
  ;; defined in composite.h.

  (if (and (integerp rule) (< rule 144))
      ;; Already encoded.
      rule
    (if (consp rule)
	(let ((gref (car rule))
	      (nref (cdr rule))
	      xoff yoff)
	  (if (consp nref)		; (GREF NREF XOFF YOFF)
	      (progn
		(setq xoff (nth 1 nref)
		      yoff (nth 2 nref)
		      nref (car nref))
		(or (and (>= xoff -100) (<= xoff 100)
			 (>= yoff -100) (<= yoff 100))
		    (error "Invalid composition rule: %s" rule))
		(setq xoff (+ xoff 128) yoff (+ yoff 128)))
	    ;; (GREF . NREF)
	    (setq xoff 0 yoff 0))
	  (or (integerp gref)
	      (setq gref (cdr (assq gref reference-point-alist))))
	  (or (integerp nref)
	      (setq nref (cdr (assq nref reference-point-alist))))
	  (or (and (>= gref 0) (< gref 12) (>= nref 0) (< nref 12))
	      (error "Invalid composition rule: %S" rule))
	  (logior (lsh xoff 16) (lsh yoff 8) (+ (* gref 12) nref)))
      (error "Invalid composition rule: %S" rule))))

;; Decode encoded composition rule RULE-CODE.  The value is a cons of
;; global and new reference point symbols.
;; This must be compatible with C macro COMPOSITION_DECODE_RULE
;; defined in composite.h.

(defun decode-composition-rule (rule-code)
  (or (and (natnump rule-code) (< rule-code #x1000000))
      (error "Invalid encoded composition rule: %S" rule-code))
  (let ((xoff (lsh rule-code -16))
	(yoff (logand (lsh rule-code -8) #xFF))
	gref nref)
    (setq rule-code (logand rule-code #xFF)
	  gref (car (rassq (/ rule-code 12) reference-point-alist))
	  nref (car (rassq (% rule-code 12) reference-point-alist)))
    (or (and gref (symbolp gref) nref (symbolp nref))
	(error "Invalid composition rule code: %S" rule-code))
    (if (and (= xoff 0) (= yoff 0))
	(cons gref nref)
      (setq xoff (- xoff 128) yoff (- yoff 128))
      (list gref xoff yoff nref))))

;; Encode composition rules in composition components COMPONENTS.  The
;; value is a copy of COMPONENTS, where composition rules (cons of
;; global and new glyph reference point symbols) are replaced with
;; encoded composition rules.  Optional 2nd argument NOCOPY non-nil
;; means don't make a copy but modify COMPONENTS directly.

(defun encode-composition-components (components &optional nocopy)
  (or nocopy
      (setq components (copy-sequence components)))
  (if (vectorp components)
      (let ((len (length components))
	    (i 1))
	(while (< i len)
	  (aset components i
		(encode-composition-rule (aref components i)))
	  (setq i (+ i 2))))
    (let ((tail (cdr components)))
      (while tail
	(setcar tail
		(encode-composition-rule (car tail)))
	(setq tail (nthcdr 2 tail)))))
  components)

;; Decode composition rule codes in composition components COMPONENTS.
;; The value is a copy of COMPONENTS, where composition rule codes are
;; replaced with composition rules (cons of global and new glyph
;; reference point symbols).  Optional 2nd argument NOCOPY non-nil
;; means don't make a copy but modify COMPONENTS directly.
;; It is assumed that COMPONENTS is a vector and is for rule-base
;; composition, thus (2N+1)th elements are rule codes.

(defun decode-composition-components (components &optional nocopy)
  (or nocopy
      (setq components (copy-sequence components)))
  (let ((len (length components))
	(i 1))
    (while (< i len)
      (aset components i
	    (decode-composition-rule (aref components i)))
      (setq i (+ i 2))))
  components)

(defun compose-region (start end &optional components modification-func)
  "Compose characters in the current region.

Characters are composed relatively, i.e. composed by overstriking
or stacking depending on ascent, descent and other metrics of
glyphs.

For instance, if the region has three characters \"XYZ\", X is
regarded as BASE glyph, and Y is displayed:
  (1) above BASE if Y's descent value is not positive
  (2) below BASE if Y's ascent value is not positive
  (3) on BASE (i.e. at the BASE position) otherwise
and Z is displayed with the same rule while regarding the whole
XY glyphs as BASE.

When called from a program, expects these four arguments.

First two arguments START and END are positions (integers or markers)
specifying the region.

Optional 3rd argument COMPONENTS, if non-nil, is a character, a string
or a vector or list of integers and rules.

If it is a character, it is an alternate character to display instead
of the text in the region.

If it is a string, the elements are alternate characters.  In
this case, TAB element has a special meaning.  If the first
characer is TAB, the glyphs are displayed with left padding space
so that no pixel overlaps with the previous column.  If the last
character is TAB, the glyphs are displayed with rigth padding
space so that no pixel overlaps with the following column.

If it is a vector or list, it is a sequence of alternate characters and
composition rules, where (2N)th elements are characters and (2N+1)th
elements are composition rules to specify how to compose (2N+2)th
elements with previously composed N glyphs.

A composition rule is a cons of global and new glyph reference point
symbols.  See the documentation of `reference-point-alist' for more
detail.

Optional 4th argument MODIFICATION-FUNC is a function to call to
adjust the composition when it gets invalid because of a change of
text in the composition."
  (interactive "r")
  (let ((modified-p (buffer-modified-p))
	(inhibit-read-only t))
    (if (or (vectorp components) (listp components))
	(setq components (encode-composition-components components)))
    (compose-region-internal start end components modification-func)
    (restore-buffer-modified-p modified-p)))

(defun decompose-region (start end)
  "Decompose text in the current region.

When called from a program, expects two arguments,
positions (integers or markers) specifying the region."
  (interactive "r")
  (let ((modified-p (buffer-modified-p))
	(inhibit-read-only t))
    (remove-text-properties start end '(composition nil))
    (restore-buffer-modified-p modified-p)))

(defun compose-string (string &optional start end components modification-func)
  "Compose characters in string STRING.

The return value is STRING with the `composition' property put on all
the characters in it.

Optional 2nd and 3rd arguments START and END specify the range of
STRING to be composed.  They default to the beginning and the end of
STRING respectively.

Optional 4th argument COMPONENTS, if non-nil, is a character or a
sequence (vector, list, or string) of integers.  See the function
`compose-region' for more detail.

Optional 5th argument MODIFICATION-FUNC is a function to call to
adjust the composition when it gets invalid because of a change of
text in the composition."
  (if (or (vectorp components) (listp components))
      (setq components (encode-composition-components components)))
  (or start (setq start 0))
  (or end (setq end (length string)))
  (compose-string-internal string start end components modification-func)
  string)

(defun decompose-string (string)
  "Return STRING where `composition' property is removed."
  (remove-text-properties 0 (length string) '(composition nil) string)
  string)

(defun compose-chars (&rest args)
  "Return a string from arguments in which all characters are composed.
For relative composition, arguments are characters.
For rule-based composition, Mth \(where M is odd) arguments are
characters, and Nth \(where N is even) arguments are composition rules.
A composition rule is a cons of glyph reference points of the form
\(GLOBAL-REF-POINT . NEW-REF-POINT).  See the documentation of
`reference-point-alist' for more detail."
  (let (str components)
    (if (consp (car (cdr args)))
	;; Rule-base composition.
	(let ((len (length args))
	      (tail (encode-composition-components args 'nocopy)))

	  (while tail
	    (setq str (cons (car tail) str))
	    (setq tail (nthcdr 2 tail)))
	  (setq str (concat (nreverse str))
		components args))
      ;; Relative composition.
      (setq str (concat args)))
    (compose-string-internal str 0 (length str) components)))

(defun find-composition (pos &optional limit string detail-p)
  "Return information about a composition at or nearest to buffer position POS.

If the character at POS has `composition' property, the value is a list
of FROM, TO, and VALID-P.

FROM and TO specify the range of text that has the same `composition'
property, VALID-P is t if this composition is valid, and nil if not.

If there's no composition at POS, and the optional 2nd argument LIMIT
is non-nil, search for a composition toward LIMIT.

If no composition is found, return nil.

Optional 3rd argument STRING, if non-nil, is a string to look for a
composition in; nil means the current buffer.

If a valid composition is found and the optional 4th argument DETAIL-P
is non-nil, the return value is a list of FROM, TO, COMPONENTS,
RELATIVE-P, MOD-FUNC, and WIDTH.

COMPONENTS is a vector of integers, the meaning depends on RELATIVE-P.

RELATIVE-P is t if the composition method is relative, else nil.

If RELATIVE-P is t, COMPONENTS is a vector of characters to be
composed.  If RELATIVE-P is nil, COMPONENTS is a vector of characters
and composition rules as described in `compose-region'.

MOD-FUNC is a modification function of the composition.

WIDTH is a number of columns the composition occupies on the screen.

When Automatic Compostion mode is on, this function also finds a
chunk of text that is automatically composed.  If such a chunk is
found closer to POS than the position that has `composition'
property, the value is a list of FROM, TO, and a glyph gstring
the specify how the chunk is composed.  See the function
`composition-get-gstring' for the format of the glyph string."
  (let ((result (find-composition-internal pos limit string detail-p)))
    (if (and detail-p (> (length result) 3) (nth 2 result) (not (nth 3 result)))
	;; This is a valid rule-base composition.
	(decode-composition-components (nth 2 result) 'nocopy))
    result))


(defun compose-chars-after (pos &optional limit object)
  "Compose characters in current buffer after position POS.

It looks up the char-table `composition-function-table' (which
see) by a character at POS, and compose characters after POS
according to the contents of `composition-function-table'.

Optional 2nd arg LIMIT, if non-nil, limits characters to compose.

Optional 3rd arg OBJECT, if non-nil, is a string that contains the
text to compose.  In that case, POS and LIMIT index into the string.

This function is the default value of `compose-chars-after-function'."
  (let ((tail (aref composition-function-table (char-after pos)))
	(font-obj (and (display-multi-font-p)
		       (and (not (stringp object))
			    (font-at pos (selected-window)))))
	pattern func result)
    (or limit
	(setq limit (if (stringp object) (length object) (point-max))))
    (when (and font-obj tail)
      (save-match-data
	(save-excursion
	  (while tail
	    (if (functionp (car tail))
		(setq pattern nil func (car tail))
	      (setq pattern (car (car tail))
		    func (cdr (car tail))))
	    (goto-char pos)
	    (if pattern
		(if (and (if (stringp object)
			     (eq (string-match pattern object) 0)
			   (looking-at pattern))
			 (<= (match-end 0) limit))
		    (setq result
			  (funcall func pos (match-end 0) font-obj object)))
	      (setq result (funcall func pos limit font-obj  object)))
	    (if result (setq tail nil))))))
    result))

(defun compose-last-chars (args)
  "Compose last characters.
The argument is a parameterized event of the form
	\(compose-last-chars N COMPONENTS),
where N is the number of characters before point to compose,
COMPONENTS, if non-nil, is the same as the argument to `compose-region'
\(which see).  If it is nil, `compose-chars-after' is called,
and that function finds a proper rule to compose the target characters.
This function is intended to be used from input methods.
The global keymap binds special event `compose-last-chars' to this
function.  Input method may generate an event (compose-last-chars N COMPONENTS)
after a sequence of character events."
  (interactive "e")
  (let ((chars (nth 1 args)))
    (if (and (numberp chars)
	     (>= (- (point) (point-min)) chars))
	(if (nth 2 args)
	    (compose-region (- (point) chars) (point) (nth 2 args))
	  (compose-chars-after (- (point) chars) (point))))))

(global-set-key [compose-last-chars] 'compose-last-chars)


;;; Automatic character composition.

;; Copied from font-lock.el.
(eval-when-compile
  ;; Borrowed from lazy-lock.el.
  ;; We use this to preserve or protect things when modifying text properties.
  (defmacro save-buffer-state (varlist &rest body)
    "Bind variables according to VARLIST and eval BODY restoring buffer state."
    `(let* ,(append varlist
		    '((modified (buffer-modified-p)) (buffer-undo-list t)
		      (inhibit-read-only t) (inhibit-point-motion-hooks t)
		      (inhibit-modification-hooks t)
		      deactivate-mark buffer-file-name buffer-file-truename))
       ,@body
       (unless modified
	 (restore-buffer-modified-p nil))))
  ;; Fixme: This makes bootstrapping fail with this error.
  ;;   Symbol's function definition is void: eval-defun
  ;;(def-edebug-spec save-buffer-state let)
  )

(put 'save-buffer-state 'lisp-indent-function 1)

;; These macros must match with C macros LGSTRING_XXX and LGLYPH_XXX in font.h
(defsubst lgstring-header (gstring) (aref gstring 0))
(defsubst lgstring-set-header (gstring header) (aset gstring 0 header))
(defsubst lgstring-font (gstring) (aref (lgstring-header gstring) 0))
(defsubst lgstring-char (gstring i) (aref (lgstring-header gstring) (1+ i)))
(defsubst lgstring-char-len (gstring) (1- (length (lgstring-header gstring))))
(defsubst lgstring-shaped-p (gstring) (aref gstring 1))
(defsubst lgstring-set-id (gstring id) (aset gstring 1 id))
(defsubst lgstring-glyph (gstring i) (aref gstring (+ i 2)))
(defsubst lgstring-glyph-len (gstring) (- (length gstring) 2))
(defsubst lgstring-set-glyph (gstring i glyph) (aset gstring (+ i 2) glyph))

(defsubst lglyph-from (glyph) (aref glyph 0))
(defsubst lglyph-to (glyph) (aref glyph 1))
(defsubst lglyph-char (glyph) (aref glyph 2))
(defsubst lglyph-code (glyph) (aref glyph 3))
(defsubst lglyph-width (glyph) (aref glyph 4))
(defsubst lglyph-lbearing (glyph) (aref glyph 5))
(defsubst lglyph-rbearing (glyph) (aref glyph 6))
(defsubst lglyph-ascent (glyph) (aref glyph 7))
(defsubst lglyph-descent (glyph) (aref glyph 8))
(defsubst lglyph-adjustment (glyph) (aref glyph 9))

(defsubst lglyph-set-from-to (glyph from to)
  (progn (aset glyph 0 from) (aset glyph 1 to)))
(defsubst lglyph-set-char (glyph char) (aset glyph 2 char))
(defsubst lglyph-set-code (glyph code) (aset glyph 3 code))
(defsubst lglyph-set-width (glyph width) (aset glyph 4 width))
(defsubst lglyph-set-adjustment (glyph &optional xoff yoff wadjust)
  (aset glyph 9 (vector (or xoff 0) (or yoff 0) (or wadjust 0))))

(defsubst lglyph-copy (glyph) (copy-sequence glyph))

(defun lgstring-insert-glyph (gstring idx glyph)
  (let ((nglyphs (lgstring-glyph-len gstring))
	(i idx) g)
    (while (and (< i nglyphs) (setq g (lgstring-glyph gstring i)))
      (setq i (1+ i)))
    (if (= i nglyphs)
	(setq gstring (vconcat gstring (vector glyph)))
      (if (< (1+ i) nglyphs)
	  (lgstring-set-glyph gstring (1+ i) nil)))
    (while (> i idx)
      (lgstring-set-glyph gstring i (lgstring-glyph gstring (1- i)))
      (setq i (1- i)))
    (lgstring-set-glyph gstring i glyph)
    gstring))

(defun compose-glyph-string (gstring from to)
  (let ((glyph (lgstring-glyph gstring from))
	from-pos to-pos
	ascent descent lbearing rbearing)
    (setq from-pos (lglyph-from glyph)
	  to-pos (lglyph-to (lgstring-glyph gstring (1- to))))
    (lglyph-set-from-to glyph from-pos to-pos)
    (setq from (1+ from))
    (while (and (< from to)
		(setq glyph (lgstring-glyph gstring from)))
      (lglyph-set-from-to glyph from-pos to-pos)
      (let ((xoff (if (<= (lglyph-rbearing glyph) 0) 0
		    (- (lglyph-width glyph)))))
	(lglyph-set-adjustment glyph xoff 0 0))
      (setq from (1+ from)))
    gstring))

(defun compose-glyph-string-relative (gstring from to &optional gap)
  (let ((font-object (lgstring-font gstring))
	(glyph (lgstring-glyph gstring from))
	from-pos to-pos
	ascent descent lbearing rbearing)
    (if gap
	(setq gap (floor (* (font-get font-object :size) gap)))
      (setq gap 0))
    (setq from-pos (lglyph-from glyph)
	  to-pos (lglyph-to (lgstring-glyph gstring (1- to)))
	  ascent (lglyph-ascent glyph)
	  descent (lglyph-descent glyph))
    (lglyph-set-from-to glyph from-pos to-pos)
    (setq from (1+ from))
    (while (< from to)
      (setq glyph (lgstring-glyph gstring from))
      (lglyph-set-from-to glyph from-pos to-pos)
      (let ((this-ascent (lglyph-ascent glyph))
	    (this-descent (lglyph-descent glyph))
	    xoff yoff wadjust)
	(setq xoff (if (<= (lglyph-rbearing glyph) 0) 0
		     (- (lglyph-width glyph))))
	(if (> this-ascent 0)
	    (if (< this-descent 0)
		(setq yoff (- 0 ascent gap this-descent)
		      ascent (+ ascent gap this-ascent this-descent))
	      (setq yoff 0))
	  (setq yoff (+ descent gap this-ascent)
		descent (+ descent gap this-ascent this-descent)))
	(if (or (/= xoff 0) (/= yoff 0))
	    (lglyph-set-adjustment glyph xoff yoff 0)))
      (setq from (1+ from)))
    gstring))

(defun compose-gstring-for-graphic (gstring)
  "Compose glyph-string GSTRING for graphic display.
Non-spacing characters are composed with the preceding base
character.  If the preceding character is not a base character,
each non-spacing character is composed as a spacing character by
a padding space before and/or after the character.

All non-spacing characters has this function in
`composition-function-table' unless overwritten."
  (let* ((header (lgstring-header gstring))
	 (nchars (lgstring-char-len gstring))
	 (nglyphs (lgstring-glyph-len gstring))
	 (glyph (lgstring-glyph gstring 0)))
    (cond
     ;; A non-spacing character not following a proper base character.
     ((= nchars 1)
      (let ((lbearing (lglyph-lbearing glyph))
	    (rbearing (lglyph-rbearing glyph))
	    (width (lglyph-width glyph))
	    xoff wadjust)
	(if (< lbearing 0)
	    (setq xoff (- lbearing))
	  (setq xoff 0 lbearing 0))
	(if (< rbearing width)
	    (setq rbearing width))
	(lglyph-set-adjustment glyph xoff 0 (- rbearing lbearing))
	gstring))

     ;; This sequence doesn't start with a proper base character.
     ((memq (get-char-code-property (lgstring-char gstring 0)
				    'general-category)
	    '(Mn Mc Me Zs Zl Zp Cc Cf Cs))
      nil)

     ;; A base character and the following non-spacing characters.
     (t
      (let ((gstr (font-shape-gstring gstring)))
	(if (and gstr
		 (> (lglyph-to (lgstring-glyph gstr 0)) 0))
	    gstr
	  ;; The shaper of the font couldn't shape the gstring.
	  ;; Shape them according to canonical-combining-class.
	  (lgstring-set-id gstring nil)
	  (let* ((width (lglyph-width glyph))
		 (ascent (lglyph-ascent glyph))
		 (descent (lglyph-descent glyph))
		 (rbearing (lglyph-rbearing glyph))
		 (lbearing (lglyph-lbearing glyph))
		 (center (/ (+ lbearing rbearing) 2))
		 (gap (round (* (font-get (lgstring-font gstring) :size) 0.1)))
		 xoff yoff)
	    (dotimes (i nchars)
	      (setq glyph (lgstring-glyph gstring i))
	      (when (> i 0)
		(let* ((class (get-char-code-property
			       (lglyph-char glyph) 'canonical-combining-class))
		       (lb (lglyph-lbearing glyph))
		       (rb (lglyph-rbearing glyph))
		       (as (lglyph-ascent glyph))
		       (de (lglyph-descent glyph))
		       (ce (/ (+ lb rb) 2))
		       xoff yoff)
		  (when (and class (>= class 200) (<= class 240))
		    (setq xoff 0 yoff 0)
		    (cond
		     ((= class 200)
		      (setq xoff (- lbearing ce)
			    yoff (if (> as 0) 0 (+ descent as))))
		     ((= class 202)
		      (if (> as 0) (setq as 0))
		      (setq xoff (- center ce)
			    yoff (if (> as 0) 0 (+ descent as))))
		     ((= class 204)
		      (if (> as 0) (setq as 0))
		      (setq xoff (- rbearing ce)
			    yoff (if (> as 0) 0 (+ descent as))))
		     ((= class 208)
		      (setq xoff (- lbearing rb)))
		     ((= class 210)
		      (setq xoff (- rbearing lb)))
		     ((= class 212)
		      (setq xoff (- lbearing ce)
			    yoff (if (>= de 0) 0 (- (- ascent) de))))
		     ((= class 214)
		      (setq xoff (- center ce)
			    yoff (if (>= de 0) 0 (- (- ascent) de))))
		     ((= class 216)
		      (setq xoff (- rbearing ce)
			    yoff (if (>= de 0) 0 (- (- ascent) de))))
		     ((= class 218)
		      (setq xoff (- lbearing ce)
			    yoff (if (> as 0) 0 (+ descent as gap))))
		     ((= class 220)
		      (setq xoff (- center ce)
			    yoff (if (> as 0) 0 (+ descent as gap))))
		     ((= class 222)
		      (setq xoff (- rbearing ce)
			    yoff (if (> as 0) 0 (+ descent as gap))))
		     ((= class 224)
		      (setq xoff (- lbearing rb)))
		     ((= class 226)
		      (setq xoff (- rbearing lb)))
		     ((= class 228)
		      (setq xoff (- lbearing ce)
			    yoff (if (>= de 0) 0 (- (- ascent) de gap))))
		     ((= class 230)
		      (setq xoff (- center ce)
			    yoff (if (>= de 0) 0 (- (- ascent) de gap))))
		     ((= class 232)
		      (setq xoff (- rbearing ce)
			    yoff (if (>= de 0) 0 (- (+ ascent de) gap)))))
		    (lglyph-set-adjustment glyph (- xoff width) yoff)
		    (setq lb (+ lb xoff)
			  rb (+ lb xoff)
			  as (- as yoff)
			  de (+ de yoff)))
		  (if (< ascent as)
		      (setq ascent as))
		  (if (< descent de)
		      (setq descent de))))))
	  (let ((i 0))
	    (while (and (< i nglyphs) (setq glyph (lgstring-glyph gstring i)))
	      (lglyph-set-from-to glyph 0 (1- nchars))
	      (setq i (1+ i))))
	  gstring))))))

(let ((elt `([,(purecopy "\\c.\\c^+") 1 compose-gstring-for-graphic]
	     [nil 0 compose-gstring-for-graphic])))
  (map-char-table
   #'(lambda (key val)
       (if (= val 0)
	   (set-char-table-range composition-function-table key elt)))
   char-width-table))

(defun compose-gstring-for-terminal (gstring)
  "Compose glyph string GSTRING for terminal display.
Non-spacing characters are composed with the preceding base
character.  If the preceding character is not a base character,
each non-spacing character is composed as a spacing character by
a prepending a space before it."
  (let* ((header (lgstring-header gstring))
	 (nchars (lgstring-char-len gstring))
	 (nglyphs (lgstring-glyph-len gstring))
	 (i 0)
	 (coding (lgstring-font gstring))
	 glyph)
    (while (and (< i nglyphs)
		(setq glyph (lgstring-glyph gstring i)))
      (if (not (char-charset (lglyph-char glyph) coding))
	  (progn
	    ;; As the terminal doesn't support this glyph, return a
	    ;; gstring in which each glyph is its own graphme-cluster
	    ;; of width 1..
	    (setq i 0)
	    (while (and (< i nglyphs)
			(setq glyph (lgstring-glyph gstring i)))
	      (if (< (lglyph-width glyph) 1)
		  (lglyph-set-width glyph 1))
	      (lglyph-set-from-to glyph i i)
	      (setq i (1+ i))))
	(if (= (lglyph-width glyph) 0)
	    (if (eq (get-char-code-property (lglyph-char glyph)
					    'general-category)
		    'Cf)
		(progn
		  ;; Compose by replacing with a space.
		  (lglyph-set-char glyph 32)
		  (lglyph-set-width glyph 1)
		  (setq i (1+ i)))
	      ;; Compose by prepending a space.
	      (setq gstring (lgstring-insert-glyph gstring i
						   (lglyph-copy glyph))
		    nglyphs (lgstring-glyph-len gstring))
	      (setq glyph (lgstring-glyph gstring i))
	      (lglyph-set-char glyph 32)
	      (lglyph-set-width glyph 1)
	      (setq i (+ 2)))
	  (let ((from (lglyph-from glyph))
		(to (lglyph-to glyph))
		(j (1+ i)))
	    (while (and (< j nglyphs)
			(setq glyph (lgstring-glyph gstring j))
			(char-charset (lglyph-char glyph) coding)
			(= (lglyph-width glyph) 0))
	      (setq to (lglyph-to glyph)
		    j (1+ j)))
	    (while (< i j)
	      (setq glyph (lgstring-glyph gstring i))
	      (lglyph-set-from-to glyph from to)
	      (setq i (1+ i)))))))
    gstring))


(defun auto-compose-chars (func from to font-object string)
  "Compose the characters at FROM by FUNC.
FUNC is called with one argument GSTRING which is built for characters
in the region FROM (inclusive) and TO (exclusive).

If the character are composed on a graphic display, FONT-OBJECT
is a font to use.  Otherwise, FONT-OBJECT is nil, and the function
`compose-gstring-for-terminal' is used instead of FUNC.

If STRING is non-nil, it is a string, and FROM and TO are indices
into the string.  In that case, compose characters in the string.

The value is a gstring containing information for shaping the characters.

This function is the default value of `auto-composition-function' (which see)."
  (let ((gstring (composition-get-gstring from to font-object string)))
    (if (lgstring-shaped-p gstring)
	gstring
      (or (fontp font-object 'font-object)
	  (setq func 'compose-gstring-for-terminal))
      (funcall func gstring))))

(make-variable-buffer-local 'auto-composition-function)

;;;###autoload
(define-minor-mode auto-composition-mode
  "Toggle Auto Composition mode.
With ARG, turn Auto Composition mode off if and only if ARG is a non-positive
number; if ARG is nil, toggle Auto Composition mode; anything else turns Auto
Composition on.

When Auto Composition is enabled, text characters are automatically composed
by functions registered in `composition-function-table' (which see).

You can use `global-auto-composition-mode' to turn on
Auto Composition mode in all buffers (this is the default)."
  nil nil nil
  (if noninteractive
      (setq auto-composition-mode nil))
  (cond (auto-composition-mode
	 (setq auto-composition-function 'auto-compose-chars))
	(t
	 (setq auto-composition-function nil))))

(defun turn-on-auto-composition-if-enabled ()
  (if enable-multibyte-characters
      (auto-composition-mode 1)))

;;;###autoload
(define-global-minor-mode global-auto-composition-mode
  auto-composition-mode turn-on-auto-composition-if-enabled
  ;; This :extra-args' appears to be the result of a naive copy&paste
  ;; from global-font-lock-mode.
  ;; :extra-args (dummy)
  :initialize 'custom-initialize-delay
  :init-value (not noninteractive)
  :group 'auto-composition
  :version "23.1")

(defalias 'toggle-auto-composition 'auto-composition-mode)


;; The following codes are only for backward compatibility with Emacs
;; 20.4 and earlier.

(defun decompose-composite-char (char &optional type with-composition-rule)
  "Convert CHAR to string.

If optional 2nd arg TYPE is non-nil, it is `string', `list', or
`vector'.  In this case, CHAR is converted to string, list of CHAR, or
vector of CHAR respectively.
Optional 3rd arg WITH-COMPOSITION-RULE is ignored."
  (cond ((or (null type) (eq type 'string)) (char-to-string char))
	((eq type 'list) (list char))
	(t (vector char))))

(make-obsolete 'decompose-composite-char 'char-to-string "21.1")



;; arch-tag: ee703d77-1723-45d4-a31f-e9f0f867aa33
;;; composite.el ends here