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8cf51b2c | 1 | @c This is part of the Emacs manual. |
ba318903 | 2 | @c Copyright (C) 1997, 1999-2014 Free Software Foundation, Inc. |
8cf51b2c | 3 | @c See file emacs.texi for copying conditions. |
abb9615e | 4 | @node International |
8cf51b2c | 5 | @chapter International Character Set Support |
59eda47f RS |
6 | @c This node is referenced in the tutorial. When renaming or deleting |
7 | @c it, the tutorial needs to be adjusted. (TUTORIAL.de) | |
8cf51b2c GM |
8 | @cindex international scripts |
9 | @cindex multibyte characters | |
10 | @cindex encoding of characters | |
11 | ||
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12 | @cindex Arabic |
13 | @cindex Bengali | |
8cf51b2c GM |
14 | @cindex Chinese |
15 | @cindex Cyrillic | |
acc112c7 | 16 | @cindex Han |
8cf51b2c | 17 | @cindex Hindi |
8cf51b2c | 18 | @cindex Ethiopic |
acc112c7 | 19 | @cindex Georgian |
8cf51b2c | 20 | @cindex Greek |
acc112c7 | 21 | @cindex Hangul |
8cf51b2c | 22 | @cindex Hebrew |
acc112c7 | 23 | @cindex Hindi |
8cf51b2c GM |
24 | @cindex IPA |
25 | @cindex Japanese | |
26 | @cindex Korean | |
8cf51b2c | 27 | @cindex Latin |
8cf51b2c | 28 | @cindex Thai |
8cf51b2c | 29 | @cindex Vietnamese |
8cf51b2c GM |
30 | Emacs supports a wide variety of international character sets, |
31 | including European and Vietnamese variants of the Latin alphabet, as | |
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32 | well as Arabic scripts, Brahmic scripts (for languages such as |
33 | Bengali, Hindi, and Thai), Cyrillic, Ethiopic, Georgian, Greek, Han | |
34 | (for Chinese and Japanese), Hangul (for Korean), Hebrew and IPA@. | |
8edb942b | 35 | Emacs also supports various encodings of these characters that are used by |
8cf51b2c GM |
36 | other internationalized software, such as word processors and mailers. |
37 | ||
38 | Emacs allows editing text with international characters by supporting | |
39 | all the related activities: | |
40 | ||
41 | @itemize @bullet | |
42 | @item | |
43 | You can visit files with non-@acronym{ASCII} characters, save non-@acronym{ASCII} text, and | |
44 | pass non-@acronym{ASCII} text between Emacs and programs it invokes (such as | |
45 | compilers, spell-checkers, and mailers). Setting your language | |
46 | environment (@pxref{Language Environments}) takes care of setting up the | |
47 | coding systems and other options for a specific language or culture. | |
48 | Alternatively, you can specify how Emacs should encode or decode text | |
49 | for each command; see @ref{Text Coding}. | |
50 | ||
51 | @item | |
52 | You can display non-@acronym{ASCII} characters encoded by the various | |
53 | scripts. This works by using appropriate fonts on graphics displays | |
0be641c0 | 54 | (@pxref{Defining Fontsets}), and by sending special codes to text |
8cf51b2c GM |
55 | displays (@pxref{Terminal Coding}). If some characters are displayed |
56 | incorrectly, refer to @ref{Undisplayable Characters}, which describes | |
57 | possible problems and explains how to solve them. | |
58 | ||
f4b6ba46 EZ |
59 | @item |
60 | Characters from scripts whose natural ordering of text is from right | |
61 | to left are reordered for display (@pxref{Bidirectional Editing}). | |
62 | These scripts include Arabic, Hebrew, Syriac, Thaana, and a few | |
63 | others. | |
64 | ||
8cf51b2c GM |
65 | @item |
66 | You can insert non-@acronym{ASCII} characters or search for them. To do that, | |
67 | you can specify an input method (@pxref{Select Input Method}) suitable | |
8edb942b | 68 | for your language, or use the default input method set up when you chose |
8cf51b2c GM |
69 | your language environment. If |
70 | your keyboard can produce non-@acronym{ASCII} characters, you can select an | |
71 | appropriate keyboard coding system (@pxref{Terminal Coding}), and Emacs | |
72 | will accept those characters. Latin-1 characters can also be input by | |
73 | using the @kbd{C-x 8} prefix, see @ref{Unibyte Mode}. | |
74 | ||
8edb942b | 75 | With the X Window System, your locale should be set to an appropriate |
50b063c3 | 76 | value to make sure Emacs interprets keyboard input correctly; see |
8cf51b2c GM |
77 | @ref{Language Environments, locales}. |
78 | @end itemize | |
79 | ||
80 | The rest of this chapter describes these issues in detail. | |
81 | ||
82 | @menu | |
83 | * International Chars:: Basic concepts of multibyte characters. | |
8cf51b2c GM |
84 | * Language Environments:: Setting things up for the language you use. |
85 | * Input Methods:: Entering text characters not on your keyboard. | |
86 | * Select Input Method:: Specifying your choice of input methods. | |
8cf51b2c GM |
87 | * Coding Systems:: Character set conversion when you read and |
88 | write files, and so on. | |
89 | * Recognize Coding:: How Emacs figures out which conversion to use. | |
90 | * Specify Coding:: Specifying a file's coding system explicitly. | |
91 | * Output Coding:: Choosing coding systems for output. | |
92 | * Text Coding:: Choosing conversion to use for file text. | |
93 | * Communication Coding:: Coding systems for interprocess communication. | |
94 | * File Name Coding:: Coding systems for file @emph{names}. | |
95 | * Terminal Coding:: Specifying coding systems for converting | |
96 | terminal input and output. | |
97 | * Fontsets:: Fontsets are collections of fonts | |
98 | that cover the whole spectrum of characters. | |
99 | * Defining Fontsets:: Defining a new fontset. | |
70bb6cac | 100 | * Modifying Fontsets:: Modifying an existing fontset. |
8cf51b2c GM |
101 | * Undisplayable Characters:: When characters don't display. |
102 | * Unibyte Mode:: You can pick one European character set | |
103 | to use without multibyte characters. | |
104 | * Charsets:: How Emacs groups its internal character codes. | |
f4b6ba46 | 105 | * Bidirectional Editing:: Support for right-to-left scripts. |
8cf51b2c GM |
106 | @end menu |
107 | ||
108 | @node International Chars | |
109 | @section Introduction to International Character Sets | |
110 | ||
111 | The users of international character sets and scripts have | |
112 | established many more-or-less standard coding systems for storing | |
ad36c422 CY |
113 | files. These coding systems are typically @dfn{multibyte}, meaning |
114 | that sequences of two or more bytes are used to represent individual | |
115 | non-@acronym{ASCII} characters. | |
116 | ||
117 | @cindex Unicode | |
118 | Internally, Emacs uses its own multibyte character encoding, which | |
119 | is a superset of the @dfn{Unicode} standard. This internal encoding | |
120 | allows characters from almost every known script to be intermixed in a | |
121 | single buffer or string. Emacs translates between the multibyte | |
122 | character encoding and various other coding systems when reading and | |
123 | writing files, and when exchanging data with subprocesses. | |
8cf51b2c GM |
124 | |
125 | @kindex C-h h | |
126 | @findex view-hello-file | |
127 | @cindex undisplayable characters | |
128 | @cindex @samp{?} in display | |
129 | The command @kbd{C-h h} (@code{view-hello-file}) displays the file | |
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130 | @file{etc/HELLO}, which illustrates various scripts by showing |
131 | how to say ``hello'' in many languages. If some characters can't be | |
8cf51b2c GM |
132 | displayed on your terminal, they appear as @samp{?} or as hollow boxes |
133 | (@pxref{Undisplayable Characters}). | |
134 | ||
ad36c422 CY |
135 | Keyboards, even in the countries where these character sets are |
136 | used, generally don't have keys for all the characters in them. You | |
137 | can insert characters that your keyboard does not support, using | |
138 | @kbd{C-q} (@code{quoted-insert}) or @kbd{C-x 8 @key{RET}} | |
9ea10cc3 | 139 | (@code{insert-char}). @xref{Inserting Text}. Emacs also supports |
ad36c422 CY |
140 | various @dfn{input methods}, typically one for each script or |
141 | language, which make it easier to type characters in the script. | |
142 | @xref{Input Methods}. | |
8cf51b2c GM |
143 | |
144 | @kindex C-x RET | |
145 | The prefix key @kbd{C-x @key{RET}} is used for commands that pertain | |
146 | to multibyte characters, coding systems, and input methods. | |
147 | ||
8087d399 CY |
148 | @kindex C-x = |
149 | @findex what-cursor-position | |
150 | The command @kbd{C-x =} (@code{what-cursor-position}) shows | |
151 | information about the character at point. In addition to the | |
152 | character position, which was described in @ref{Position Info}, this | |
153 | command displays how the character is encoded. For instance, it | |
154 | displays the following line in the echo area for the character | |
155 | @samp{c}: | |
156 | ||
157 | @smallexample | |
158 | Char: c (99, #o143, #x63) point=28062 of 36168 (78%) column=53 | |
159 | @end smallexample | |
160 | ||
161 | The four values after @samp{Char:} describe the character that | |
162 | follows point, first by showing it and then by giving its character | |
163 | code in decimal, octal and hex. For a non-@acronym{ASCII} multibyte | |
164 | character, these are followed by @samp{file} and the character's | |
165 | representation, in hex, in the buffer's coding system, if that coding | |
166 | system encodes the character safely and with a single byte | |
167 | (@pxref{Coding Systems}). If the character's encoding is longer than | |
168 | one byte, Emacs shows @samp{file ...}. | |
169 | ||
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170 | As a special case, if the character lies in the range 128 (0200 |
171 | octal) through 159 (0237 octal), it stands for a ``raw'' byte that | |
172 | does not correspond to any specific displayable character. Such a | |
173 | ``character'' lies within the @code{eight-bit-control} character set, | |
174 | and is displayed as an escaped octal character code. In this case, | |
175 | @kbd{C-x =} shows @samp{part of display ...} instead of @samp{file}. | |
8087d399 CY |
176 | |
177 | @cindex character set of character at point | |
178 | @cindex font of character at point | |
179 | @cindex text properties at point | |
180 | @cindex face at point | |
181 | With a prefix argument (@kbd{C-u C-x =}), this command displays a | |
182 | detailed description of the character in a window: | |
183 | ||
184 | @itemize @bullet | |
185 | @item | |
186 | The character set name, and the codes that identify the character | |
187 | within that character set; @acronym{ASCII} characters are identified | |
188 | as belonging to the @code{ascii} character set. | |
189 | ||
190 | @item | |
7195b841 | 191 | The character's script, syntax and categories. |
8087d399 CY |
192 | |
193 | @item | |
194 | What keys to type to input the character in the current input method | |
195 | (if it supports the character). | |
196 | ||
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197 | @item |
198 | The character's encodings, both internally in the buffer, and externally | |
199 | if you were to save the file. | |
200 | ||
8087d399 CY |
201 | @item |
202 | If you are running Emacs on a graphical display, the font name and | |
0be641c0 | 203 | glyph code for the character. If you are running Emacs on a text |
8087d399 CY |
204 | terminal, the code(s) sent to the terminal. |
205 | ||
206 | @item | |
207 | The character's text properties (@pxref{Text Properties,,, | |
208 | elisp, the Emacs Lisp Reference Manual}), including any non-default | |
209 | faces used to display the character, and any overlays containing it | |
210 | (@pxref{Overlays,,, elisp, the same manual}). | |
211 | @end itemize | |
212 | ||
7195b841 | 213 | Here's an example, with some lines folded to fit into this manual: |
8087d399 CY |
214 | |
215 | @smallexample | |
8edb942b | 216 | position: 1 of 1 (0%), column: 0 |
7195b841 | 217 | character: @^e (displayed as @^e) (codepoint 234, #o352, #xea) |
8edb942b | 218 | preferred charset: unicode (Unicode (ISO10646)) |
7195b841 PE |
219 | code point in charset: 0xEA |
220 | script: latin | |
221 | syntax: w which means: word | |
222 | category: .:Base, L:Left-to-right (strong), c:Chinese, | |
8edb942b | 223 | j:Japanese, l:Latin, v:Viet |
7195b841 PE |
224 | to input: type "C-x 8 RET HEX-CODEPOINT" or "C-x 8 RET NAME" |
225 | buffer code: #xC3 #xAA | |
226 | file code: #xC3 #xAA (encoded by coding system utf-8-unix) | |
8edb942b | 227 | display: by this font (glyph code) |
ae742cb5 | 228 | xft:-unknown-DejaVu Sans Mono-normal-normal- |
7195b841 | 229 | normal-*-15-*-*-*-m-0-iso10646-1 (#xAC) |
8087d399 CY |
230 | |
231 | Character code properties: customize what to show | |
7195b841 PE |
232 | name: LATIN SMALL LETTER E WITH CIRCUMFLEX |
233 | old-name: LATIN SMALL LETTER E CIRCUMFLEX | |
234 | general-category: Ll (Letter, Lowercase) | |
235 | decomposition: (101 770) ('e' '^') | |
8087d399 CY |
236 | @end smallexample |
237 | ||
8cf51b2c GM |
238 | @node Language Environments |
239 | @section Language Environments | |
240 | @cindex language environments | |
241 | ||
242 | All supported character sets are supported in Emacs buffers whenever | |
243 | multibyte characters are enabled; there is no need to select a | |
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244 | particular language in order to display its characters. |
245 | However, it is important to select a @dfn{language | |
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246 | environment} in order to set various defaults. Roughly speaking, the |
247 | language environment represents a choice of preferred script rather | |
248 | than a choice of language. | |
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249 | |
250 | The language environment controls which coding systems to recognize | |
251 | when reading text (@pxref{Recognize Coding}). This applies to files, | |
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252 | incoming mail, and any other text you read into Emacs. It may also |
253 | specify the default coding system to use when you create a file. Each | |
254 | language environment also specifies a default input method. | |
8cf51b2c GM |
255 | |
256 | @findex set-language-environment | |
257 | @vindex current-language-environment | |
ae742cb5 | 258 | To select a language environment, customize |
8cf51b2c GM |
259 | @code{current-language-environment} or use the command @kbd{M-x |
260 | set-language-environment}. It makes no difference which buffer is | |
ad36c422 | 261 | current when you use this command, because the effects apply globally |
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262 | to the Emacs session. See the variable @code{language-info-alist} for |
263 | the list of supported language environments, and use the command | |
264 | @kbd{C-h L @var{lang-env} @key{RET}} (@code{describe-language-environment}) | |
265 | for more information about the language environment @var{lang-env}. | |
266 | Supported language environments include: | |
8cf51b2c | 267 | |
8cf51b2c | 268 | @quotation |
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269 | @cindex ASCII |
270 | ASCII, | |
271 | @cindex Arabic | |
272 | Arabic, | |
273 | @cindex Belarusian | |
274 | Belarusian, | |
275 | @cindex Bengali | |
276 | Bengali, | |
277 | @cindex Brazilian Portuguese | |
278 | Brazilian Portuguese, | |
279 | @cindex Bulgarian | |
280 | Bulgarian, | |
281 | @cindex Burmese | |
282 | Burmese, | |
283 | @cindex Cham | |
284 | Cham, | |
285 | @cindex Chinese | |
286 | Chinese-BIG5, Chinese-CNS, Chinese-EUC-TW, Chinese-GB, | |
287 | Chinese-GB18030, Chinese-GBK, | |
288 | @cindex Croatian | |
289 | Croatian, | |
290 | @cindex Cyrillic | |
291 | Cyrillic-ALT, Cyrillic-ISO, Cyrillic-KOI8, | |
292 | @cindex Czech | |
293 | Czech, | |
294 | @cindex Devanagari | |
295 | Devanagari, | |
296 | @cindex Dutch | |
297 | Dutch, | |
298 | @cindex English | |
299 | English, | |
300 | @cindex Esperanto | |
301 | Esperanto, | |
302 | @cindex Ethiopic | |
303 | Ethiopic, | |
304 | @cindex French | |
305 | French, | |
306 | @cindex Georgian | |
307 | Georgian, | |
308 | @cindex German | |
309 | German, | |
310 | @cindex Greek | |
311 | Greek, | |
312 | @cindex Gujarati | |
313 | Gujarati, | |
314 | @cindex Hebrew | |
315 | Hebrew, | |
316 | @cindex IPA | |
317 | IPA, | |
318 | @cindex Italian | |
319 | Italian, | |
320 | @cindex Japanese | |
321 | Japanese, | |
322 | @cindex Kannada | |
323 | Kannada, | |
324 | @cindex Khmer | |
325 | Khmer, | |
326 | @cindex Korean | |
327 | Korean, | |
328 | @cindex Lao | |
329 | Lao, | |
330 | @cindex Latin | |
331 | Latin-1, Latin-2, Latin-3, Latin-4, Latin-5, Latin-6, Latin-7, | |
332 | Latin-8, Latin-9, | |
333 | @cindex Latvian | |
334 | Latvian, | |
335 | @cindex Lithuanian | |
336 | Lithuanian, | |
337 | @cindex Malayalam | |
338 | Malayalam, | |
339 | @cindex Oriya | |
340 | Oriya, | |
341 | @cindex Persian | |
342 | Persian, | |
343 | @cindex Polish | |
344 | Polish, | |
345 | @cindex Punjabi | |
346 | Punjabi, | |
347 | @cindex Romanian | |
348 | Romanian, | |
349 | @cindex Russian | |
350 | Russian, | |
351 | @cindex Sinhala | |
352 | Sinhala, | |
353 | @cindex Slovak | |
354 | Slovak, | |
355 | @cindex Slovenian | |
356 | Slovenian, | |
357 | @cindex Spanish | |
358 | Spanish, | |
359 | @cindex Swedish | |
360 | Swedish, | |
361 | @cindex TaiViet | |
362 | TaiViet, | |
363 | @cindex Tajik | |
364 | Tajik, | |
365 | @cindex Tamil | |
366 | Tamil, | |
367 | @cindex Telugu | |
368 | Telugu, | |
369 | @cindex Thai | |
370 | Thai, | |
371 | @cindex Tibetan | |
372 | Tibetan, | |
373 | @cindex Turkish | |
374 | Turkish, | |
375 | @cindex UTF-8 | |
376 | UTF-8, | |
377 | @cindex Ukrainian | |
378 | Ukrainian, | |
379 | @cindex Vietnamese | |
380 | Vietnamese, | |
381 | @cindex Welsh | |
382 | Welsh, and | |
383 | @cindex Windows-1255 | |
384 | Windows-1255. | |
8cf51b2c GM |
385 | @end quotation |
386 | ||
8cf51b2c | 387 | To display the script(s) used by your language environment on a |
05806f43 | 388 | graphical display, you need to have suitable fonts. |
8cf51b2c GM |
389 | @xref{Fontsets}, for more details about setting up your fonts. |
390 | ||
391 | @findex set-locale-environment | |
392 | @vindex locale-language-names | |
393 | @vindex locale-charset-language-names | |
394 | @cindex locales | |
395 | Some operating systems let you specify the character-set locale you | |
396 | are using by setting the locale environment variables @env{LC_ALL}, | |
e0550cae | 397 | @env{LC_CTYPE}, or @env{LANG}. (If more than one of these is |
8cf51b2c | 398 | set, the first one that is nonempty specifies your locale for this |
e0550cae | 399 | purpose.) During startup, Emacs looks up your character-set locale's |
8cf51b2c GM |
400 | name in the system locale alias table, matches its canonical name |
401 | against entries in the value of the variables | |
e0550cae GM |
402 | @code{locale-charset-language-names} and @code{locale-language-names} |
403 | (the former overrides the latter), | |
8cf51b2c | 404 | and selects the corresponding language environment if a match is found. |
e0550cae | 405 | It also adjusts the display |
8cf51b2c GM |
406 | table and terminal coding system, the locale coding system, the |
407 | preferred coding system as needed for the locale, and---last but not | |
408 | least---the way Emacs decodes non-@acronym{ASCII} characters sent by your keyboard. | |
409 | ||
e0550cae | 410 | @c This seems unlikely, doesn't it? |
8cf51b2c | 411 | If you modify the @env{LC_ALL}, @env{LC_CTYPE}, or @env{LANG} |
e0550cae GM |
412 | environment variables while running Emacs (by using @kbd{M-x setenv}), |
413 | you may want to invoke the @code{set-locale-environment} | |
414 | function afterwards to readjust the language environment from the new | |
415 | locale. | |
8cf51b2c GM |
416 | |
417 | @vindex locale-preferred-coding-systems | |
418 | The @code{set-locale-environment} function normally uses the preferred | |
419 | coding system established by the language environment to decode system | |
420 | messages. But if your locale matches an entry in the variable | |
421 | @code{locale-preferred-coding-systems}, Emacs uses the corresponding | |
422 | coding system instead. For example, if the locale @samp{ja_JP.PCK} | |
423 | matches @code{japanese-shift-jis} in | |
424 | @code{locale-preferred-coding-systems}, Emacs uses that encoding even | |
425 | though it might normally use @code{japanese-iso-8bit}. | |
426 | ||
427 | You can override the language environment chosen at startup with | |
428 | explicit use of the command @code{set-language-environment}, or with | |
429 | customization of @code{current-language-environment} in your init | |
430 | file. | |
431 | ||
432 | @kindex C-h L | |
433 | @findex describe-language-environment | |
434 | To display information about the effects of a certain language | |
435 | environment @var{lang-env}, use the command @kbd{C-h L @var{lang-env} | |
436 | @key{RET}} (@code{describe-language-environment}). This tells you | |
437 | which languages this language environment is useful for, and lists the | |
438 | character sets, coding systems, and input methods that go with it. It | |
439 | also shows some sample text to illustrate scripts used in this | |
440 | language environment. If you give an empty input for @var{lang-env}, | |
441 | this command describes the chosen language environment. | |
442 | ||
443 | @vindex set-language-environment-hook | |
444 | You can customize any language environment with the normal hook | |
445 | @code{set-language-environment-hook}. The command | |
446 | @code{set-language-environment} runs that hook after setting up the new | |
447 | language environment. The hook functions can test for a specific | |
448 | language environment by checking the variable | |
449 | @code{current-language-environment}. This hook is where you should | |
e0550cae | 450 | put non-default settings for specific language environments, such as |
8cf51b2c GM |
451 | coding systems for keyboard input and terminal output, the default |
452 | input method, etc. | |
453 | ||
454 | @vindex exit-language-environment-hook | |
455 | Before it starts to set up the new language environment, | |
456 | @code{set-language-environment} first runs the hook | |
457 | @code{exit-language-environment-hook}. This hook is useful for undoing | |
458 | customizations that were made with @code{set-language-environment-hook}. | |
459 | For instance, if you set up a special key binding in a specific language | |
460 | environment using @code{set-language-environment-hook}, you should set | |
461 | up @code{exit-language-environment-hook} to restore the normal binding | |
462 | for that key. | |
463 | ||
464 | @node Input Methods | |
465 | @section Input Methods | |
466 | ||
467 | @cindex input methods | |
468 | An @dfn{input method} is a kind of character conversion designed | |
469 | specifically for interactive input. In Emacs, typically each language | |
893585f4 | 470 | has its own input method; sometimes several languages that use the same |
8cf51b2c GM |
471 | characters can share one input method. A few languages support several |
472 | input methods. | |
473 | ||
474 | The simplest kind of input method works by mapping @acronym{ASCII} letters | |
475 | into another alphabet; this allows you to use one other alphabet | |
476 | instead of @acronym{ASCII}. The Greek and Russian input methods | |
477 | work this way. | |
478 | ||
479 | A more powerful technique is composition: converting sequences of | |
480 | characters into one letter. Many European input methods use composition | |
481 | to produce a single non-@acronym{ASCII} letter from a sequence that consists of a | |
482 | letter followed by accent characters (or vice versa). For example, some | |
893585f4 | 483 | methods convert the sequence @kbd{o ^} into a single accented letter. |
8cf51b2c GM |
484 | These input methods have no special commands of their own; all they do |
485 | is compose sequences of printing characters. | |
486 | ||
487 | The input methods for syllabic scripts typically use mapping followed | |
488 | by composition. The input methods for Thai and Korean work this way. | |
489 | First, letters are mapped into symbols for particular sounds or tone | |
893585f4 | 490 | marks; then, sequences of these that make up a whole syllable are |
8cf51b2c GM |
491 | mapped into one syllable sign. |
492 | ||
493 | Chinese and Japanese require more complex methods. In Chinese input | |
494 | methods, first you enter the phonetic spelling of a Chinese word (in | |
495 | input method @code{chinese-py}, among others), or a sequence of | |
496 | portions of the character (input methods @code{chinese-4corner} and | |
497 | @code{chinese-sw}, and others). One input sequence typically | |
498 | corresponds to many possible Chinese characters. You select the one | |
499 | you mean using keys such as @kbd{C-f}, @kbd{C-b}, @kbd{C-n}, | |
893585f4 GM |
500 | @kbd{C-p} (or the arrow keys), and digits, which have special meanings |
501 | in this situation. | |
8cf51b2c GM |
502 | |
503 | The possible characters are conceptually arranged in several rows, | |
504 | with each row holding up to 10 alternatives. Normally, Emacs displays | |
505 | just one row at a time, in the echo area; @code{(@var{i}/@var{j})} | |
506 | appears at the beginning, to indicate that this is the @var{i}th row | |
507 | out of a total of @var{j} rows. Type @kbd{C-n} or @kbd{C-p} to | |
508 | display the next row or the previous row. | |
509 | ||
510 | Type @kbd{C-f} and @kbd{C-b} to move forward and backward among | |
511 | the alternatives in the current row. As you do this, Emacs highlights | |
512 | the current alternative with a special color; type @code{C-@key{SPC}} | |
513 | to select the current alternative and use it as input. The | |
514 | alternatives in the row are also numbered; the number appears before | |
893585f4 GM |
515 | the alternative. Typing a number selects the associated alternative |
516 | of the current row and uses it as input. | |
8cf51b2c GM |
517 | |
518 | @key{TAB} in these Chinese input methods displays a buffer showing | |
519 | all the possible characters at once; then clicking @kbd{Mouse-2} on | |
520 | one of them selects that alternative. The keys @kbd{C-f}, @kbd{C-b}, | |
521 | @kbd{C-n}, @kbd{C-p}, and digits continue to work as usual, but they | |
522 | do the highlighting in the buffer showing the possible characters, | |
523 | rather than in the echo area. | |
524 | ||
525 | In Japanese input methods, first you input a whole word using | |
526 | phonetic spelling; then, after the word is in the buffer, Emacs | |
527 | converts it into one or more characters using a large dictionary. One | |
528 | phonetic spelling corresponds to a number of different Japanese words; | |
529 | to select one of them, use @kbd{C-n} and @kbd{C-p} to cycle through | |
530 | the alternatives. | |
531 | ||
532 | Sometimes it is useful to cut off input method processing so that the | |
533 | characters you have just entered will not combine with subsequent | |
534 | characters. For example, in input method @code{latin-1-postfix}, the | |
893585f4 | 535 | sequence @kbd{o ^} combines to form an @samp{o} with an accent. What if |
8cf51b2c GM |
536 | you want to enter them as separate characters? |
537 | ||
538 | One way is to type the accent twice; this is a special feature for | |
893585f4 GM |
539 | entering the separate letter and accent. For example, @kbd{o ^ ^} gives |
540 | you the two characters @samp{o^}. Another way is to type another letter | |
541 | after the @kbd{o}---something that won't combine with that---and | |
542 | immediately delete it. For example, you could type @kbd{o o @key{DEL} | |
543 | ^} to get separate @samp{o} and @samp{^}. | |
8cf51b2c GM |
544 | |
545 | Another method, more general but not quite as easy to type, is to use | |
546 | @kbd{C-\ C-\} between two characters to stop them from combining. This | |
547 | is the command @kbd{C-\} (@code{toggle-input-method}) used twice. | |
548 | @ifnottex | |
549 | @xref{Select Input Method}. | |
550 | @end ifnottex | |
551 | ||
552 | @cindex incremental search, input method interference | |
553 | @kbd{C-\ C-\} is especially useful inside an incremental search, | |
554 | because it stops waiting for more characters to combine, and starts | |
555 | searching for what you have already entered. | |
556 | ||
557 | To find out how to input the character after point using the current | |
558 | input method, type @kbd{C-u C-x =}. @xref{Position Info}. | |
559 | ||
560 | @vindex input-method-verbose-flag | |
561 | @vindex input-method-highlight-flag | |
562 | The variables @code{input-method-highlight-flag} and | |
563 | @code{input-method-verbose-flag} control how input methods explain | |
564 | what is happening. If @code{input-method-highlight-flag} is | |
565 | non-@code{nil}, the partial sequence is highlighted in the buffer (for | |
566 | most input methods---some disable this feature). If | |
567 | @code{input-method-verbose-flag} is non-@code{nil}, the list of | |
568 | possible characters to type next is displayed in the echo area (but | |
569 | not when you are in the minibuffer). | |
570 | ||
ce79424f | 571 | Another facility for typing characters not on your keyboard is by |
9ea10cc3 | 572 | using @kbd{C-x 8 @key{RET}} (@code{insert-char}) to insert a single |
ce79424f EZ |
573 | character based on its Unicode name or code-point; see @ref{Inserting |
574 | Text}. | |
575 | ||
8cf51b2c GM |
576 | @node Select Input Method |
577 | @section Selecting an Input Method | |
578 | ||
579 | @table @kbd | |
580 | @item C-\ | |
71cd7772 | 581 | Enable or disable use of the selected input method (@code{toggle-input-method}). |
8cf51b2c GM |
582 | |
583 | @item C-x @key{RET} C-\ @var{method} @key{RET} | |
71cd7772 | 584 | Select a new input method for the current buffer (@code{set-input-method}). |
8cf51b2c GM |
585 | |
586 | @item C-h I @var{method} @key{RET} | |
587 | @itemx C-h C-\ @var{method} @key{RET} | |
588 | @findex describe-input-method | |
589 | @kindex C-h I | |
590 | @kindex C-h C-\ | |
591 | Describe the input method @var{method} (@code{describe-input-method}). | |
592 | By default, it describes the current input method (if any). This | |
593 | description should give you the full details of how to use any | |
594 | particular input method. | |
595 | ||
596 | @item M-x list-input-methods | |
597 | Display a list of all the supported input methods. | |
598 | @end table | |
599 | ||
600 | @findex set-input-method | |
601 | @vindex current-input-method | |
602 | @kindex C-x RET C-\ | |
603 | To choose an input method for the current buffer, use @kbd{C-x | |
604 | @key{RET} C-\} (@code{set-input-method}). This command reads the | |
605 | input method name from the minibuffer; the name normally starts with the | |
606 | language environment that it is meant to be used with. The variable | |
607 | @code{current-input-method} records which input method is selected. | |
608 | ||
609 | @findex toggle-input-method | |
610 | @kindex C-\ | |
611 | Input methods use various sequences of @acronym{ASCII} characters to | |
612 | stand for non-@acronym{ASCII} characters. Sometimes it is useful to | |
613 | turn off the input method temporarily. To do this, type @kbd{C-\} | |
614 | (@code{toggle-input-method}). To reenable the input method, type | |
615 | @kbd{C-\} again. | |
616 | ||
617 | If you type @kbd{C-\} and you have not yet selected an input method, | |
05f7d0d3 | 618 | it prompts you to specify one. This has the same effect as using |
8cf51b2c GM |
619 | @kbd{C-x @key{RET} C-\} to specify an input method. |
620 | ||
621 | When invoked with a numeric argument, as in @kbd{C-u C-\}, | |
622 | @code{toggle-input-method} always prompts you for an input method, | |
623 | suggesting the most recently selected one as the default. | |
624 | ||
625 | @vindex default-input-method | |
626 | Selecting a language environment specifies a default input method for | |
627 | use in various buffers. When you have a default input method, you can | |
628 | select it in the current buffer by typing @kbd{C-\}. The variable | |
629 | @code{default-input-method} specifies the default input method | |
630 | (@code{nil} means there is none). | |
631 | ||
632 | In some language environments, which support several different input | |
633 | methods, you might want to use an input method different from the | |
634 | default chosen by @code{set-language-environment}. You can instruct | |
635 | Emacs to select a different default input method for a certain | |
636 | language environment, if you wish, by using | |
637 | @code{set-language-environment-hook} (@pxref{Language Environments, | |
638 | set-language-environment-hook}). For example: | |
639 | ||
640 | @lisp | |
641 | (defun my-chinese-setup () | |
642 | "Set up my private Chinese environment." | |
643 | (if (equal current-language-environment "Chinese-GB") | |
644 | (setq default-input-method "chinese-tonepy"))) | |
645 | (add-hook 'set-language-environment-hook 'my-chinese-setup) | |
646 | @end lisp | |
647 | ||
648 | @noindent | |
649 | This sets the default input method to be @code{chinese-tonepy} | |
650 | whenever you choose a Chinese-GB language environment. | |
651 | ||
0cf8a906 KH |
652 | You can instruct Emacs to activate a certain input method |
653 | automatically. For example: | |
654 | ||
655 | @lisp | |
656 | (add-hook 'text-mode-hook | |
657 | (lambda () (set-input-method "german-prefix"))) | |
658 | @end lisp | |
659 | ||
660 | @noindent | |
05f7d0d3 | 661 | This automatically activates the input method ``german-prefix'' in |
0cf8a906 KH |
662 | Text mode. |
663 | ||
8cf51b2c GM |
664 | @findex quail-set-keyboard-layout |
665 | Some input methods for alphabetic scripts work by (in effect) | |
666 | remapping the keyboard to emulate various keyboard layouts commonly used | |
667 | for those scripts. How to do this remapping properly depends on your | |
668 | actual keyboard layout. To specify which layout your keyboard has, use | |
669 | the command @kbd{M-x quail-set-keyboard-layout}. | |
670 | ||
671 | @findex quail-show-key | |
672 | You can use the command @kbd{M-x quail-show-key} to show what key (or | |
673 | key sequence) to type in order to input the character following point, | |
674 | using the selected keyboard layout. The command @kbd{C-u C-x =} also | |
05f7d0d3 | 675 | shows that information, in addition to other information about the |
8cf51b2c GM |
676 | character. |
677 | ||
678 | @findex list-input-methods | |
ae742cb5 CY |
679 | @kbd{M-x list-input-methods} displays a list of all the supported |
680 | input methods. The list gives information about each input method, | |
681 | including the string that stands for it in the mode line. | |
8cf51b2c | 682 | |
8cf51b2c GM |
683 | @node Coding Systems |
684 | @section Coding Systems | |
685 | @cindex coding systems | |
686 | ||
687 | Users of various languages have established many more-or-less standard | |
688 | coding systems for representing them. Emacs does not use these coding | |
689 | systems internally; instead, it converts from various coding systems to | |
690 | its own system when reading data, and converts the internal coding | |
691 | system to other coding systems when writing data. Conversion is | |
692 | possible in reading or writing files, in sending or receiving from the | |
693 | terminal, and in exchanging data with subprocesses. | |
694 | ||
695 | Emacs assigns a name to each coding system. Most coding systems are | |
ad36c422 CY |
696 | used for one language, and the name of the coding system starts with |
697 | the language name. Some coding systems are used for several | |
698 | languages; their names usually start with @samp{iso}. There are also | |
699 | special coding systems, such as @code{no-conversion}, @code{raw-text}, | |
700 | and @code{emacs-internal}. | |
8cf51b2c GM |
701 | |
702 | @cindex international files from DOS/Windows systems | |
703 | A special class of coding systems, collectively known as | |
704 | @dfn{codepages}, is designed to support text encoded by MS-Windows and | |
705 | MS-DOS software. The names of these coding systems are | |
706 | @code{cp@var{nnnn}}, where @var{nnnn} is a 3- or 4-digit number of the | |
707 | codepage. You can use these encodings just like any other coding | |
708 | system; for example, to visit a file encoded in codepage 850, type | |
709 | @kbd{C-x @key{RET} c cp850 @key{RET} C-x C-f @var{filename} | |
f68eb991 | 710 | @key{RET}}. |
8cf51b2c GM |
711 | |
712 | In addition to converting various representations of non-@acronym{ASCII} | |
713 | characters, a coding system can perform end-of-line conversion. Emacs | |
714 | handles three different conventions for how to separate lines in a file: | |
05f7d0d3 GM |
715 | newline (``unix''), carriage-return linefeed (``dos''), and just |
716 | carriage-return (``mac''). | |
8cf51b2c GM |
717 | |
718 | @table @kbd | |
719 | @item C-h C @var{coding} @key{RET} | |
71cd7772 | 720 | Describe coding system @var{coding} (@code{describe-coding-system}). |
8cf51b2c GM |
721 | |
722 | @item C-h C @key{RET} | |
723 | Describe the coding systems currently in use. | |
724 | ||
725 | @item M-x list-coding-systems | |
726 | Display a list of all the supported coding systems. | |
727 | @end table | |
728 | ||
729 | @kindex C-h C | |
730 | @findex describe-coding-system | |
731 | The command @kbd{C-h C} (@code{describe-coding-system}) displays | |
732 | information about particular coding systems, including the end-of-line | |
733 | conversion specified by those coding systems. You can specify a coding | |
734 | system name as the argument; alternatively, with an empty argument, it | |
735 | describes the coding systems currently selected for various purposes, | |
736 | both in the current buffer and as the defaults, and the priority list | |
737 | for recognizing coding systems (@pxref{Recognize Coding}). | |
738 | ||
739 | @findex list-coding-systems | |
740 | To display a list of all the supported coding systems, type @kbd{M-x | |
741 | list-coding-systems}. The list gives information about each coding | |
742 | system, including the letter that stands for it in the mode line | |
743 | (@pxref{Mode Line}). | |
744 | ||
745 | @cindex end-of-line conversion | |
746 | @cindex line endings | |
747 | @cindex MS-DOS end-of-line conversion | |
748 | @cindex Macintosh end-of-line conversion | |
749 | Each of the coding systems that appear in this list---except for | |
750 | @code{no-conversion}, which means no conversion of any kind---specifies | |
751 | how and whether to convert printing characters, but leaves the choice of | |
752 | end-of-line conversion to be decided based on the contents of each file. | |
753 | For example, if the file appears to use the sequence carriage-return | |
754 | linefeed to separate lines, DOS end-of-line conversion will be used. | |
755 | ||
05f7d0d3 | 756 | Each of the listed coding systems has three variants, which specify |
8cf51b2c GM |
757 | exactly what to do for end-of-line conversion: |
758 | ||
759 | @table @code | |
760 | @item @dots{}-unix | |
761 | Don't do any end-of-line conversion; assume the file uses | |
762 | newline to separate lines. (This is the convention normally used | |
05f7d0d3 | 763 | on Unix and GNU systems, and Mac OS X.) |
8cf51b2c GM |
764 | |
765 | @item @dots{}-dos | |
766 | Assume the file uses carriage-return linefeed to separate lines, and do | |
767 | the appropriate conversion. (This is the convention normally used on | |
768 | Microsoft systems.@footnote{It is also specified for MIME @samp{text/*} | |
769 | bodies and in other network transport contexts. It is different | |
05f7d0d3 | 770 | from the SGML reference syntax record-start/record-end format, which |
8cf51b2c GM |
771 | Emacs doesn't support directly.}) |
772 | ||
773 | @item @dots{}-mac | |
774 | Assume the file uses carriage-return to separate lines, and do the | |
05f7d0d3 GM |
775 | appropriate conversion. (This was the convention used on the |
776 | Macintosh system prior to OS X.) | |
8cf51b2c GM |
777 | @end table |
778 | ||
779 | These variant coding systems are omitted from the | |
780 | @code{list-coding-systems} display for brevity, since they are entirely | |
781 | predictable. For example, the coding system @code{iso-latin-1} has | |
782 | variants @code{iso-latin-1-unix}, @code{iso-latin-1-dos} and | |
783 | @code{iso-latin-1-mac}. | |
784 | ||
785 | @cindex @code{undecided}, coding system | |
786 | The coding systems @code{unix}, @code{dos}, and @code{mac} are | |
787 | aliases for @code{undecided-unix}, @code{undecided-dos}, and | |
788 | @code{undecided-mac}, respectively. These coding systems specify only | |
789 | the end-of-line conversion, and leave the character code conversion to | |
790 | be deduced from the text itself. | |
791 | ||
978ff6c5 | 792 | @cindex @code{raw-text}, coding system |
8cf51b2c | 793 | The coding system @code{raw-text} is good for a file which is mainly |
05f7d0d3 | 794 | @acronym{ASCII} text, but may contain byte values above 127 that are |
8cf51b2c GM |
795 | not meant to encode non-@acronym{ASCII} characters. With |
796 | @code{raw-text}, Emacs copies those byte values unchanged, and sets | |
797 | @code{enable-multibyte-characters} to @code{nil} in the current buffer | |
798 | so that they will be interpreted properly. @code{raw-text} handles | |
799 | end-of-line conversion in the usual way, based on the data | |
800 | encountered, and has the usual three variants to specify the kind of | |
801 | end-of-line conversion to use. | |
802 | ||
978ff6c5 | 803 | @cindex @code{no-conversion}, coding system |
8cf51b2c GM |
804 | In contrast, the coding system @code{no-conversion} specifies no |
805 | character code conversion at all---none for non-@acronym{ASCII} byte values and | |
806 | none for end of line. This is useful for reading or writing binary | |
807 | files, tar files, and other files that must be examined verbatim. It, | |
808 | too, sets @code{enable-multibyte-characters} to @code{nil}. | |
809 | ||
810 | The easiest way to edit a file with no conversion of any kind is with | |
811 | the @kbd{M-x find-file-literally} command. This uses | |
812 | @code{no-conversion}, and also suppresses other Emacs features that | |
813 | might convert the file contents before you see them. @xref{Visiting}. | |
814 | ||
978ff6c5 | 815 | @cindex @code{emacs-internal}, coding system |
ad36c422 CY |
816 | The coding system @code{emacs-internal} (or @code{utf-8-emacs}, |
817 | which is equivalent) means that the file contains non-@acronym{ASCII} | |
818 | characters stored with the internal Emacs encoding. This coding | |
819 | system handles end-of-line conversion based on the data encountered, | |
820 | and has the usual three variants to specify the kind of end-of-line | |
821 | conversion. | |
8cf51b2c GM |
822 | |
823 | @node Recognize Coding | |
824 | @section Recognizing Coding Systems | |
825 | ||
ad36c422 CY |
826 | Whenever Emacs reads a given piece of text, it tries to recognize |
827 | which coding system to use. This applies to files being read, output | |
828 | from subprocesses, text from X selections, etc. Emacs can select the | |
829 | right coding system automatically most of the time---once you have | |
830 | specified your preferences. | |
8cf51b2c GM |
831 | |
832 | Some coding systems can be recognized or distinguished by which byte | |
833 | sequences appear in the data. However, there are coding systems that | |
834 | cannot be distinguished, not even potentially. For example, there is no | |
835 | way to distinguish between Latin-1 and Latin-2; they use the same byte | |
836 | values with different meanings. | |
837 | ||
838 | Emacs handles this situation by means of a priority list of coding | |
839 | systems. Whenever Emacs reads a file, if you do not specify the coding | |
840 | system to use, Emacs checks the data against each coding system, | |
841 | starting with the first in priority and working down the list, until it | |
842 | finds a coding system that fits the data. Then it converts the file | |
843 | contents assuming that they are represented in this coding system. | |
844 | ||
845 | The priority list of coding systems depends on the selected language | |
846 | environment (@pxref{Language Environments}). For example, if you use | |
847 | French, you probably want Emacs to prefer Latin-1 to Latin-2; if you use | |
848 | Czech, you probably want Latin-2 to be preferred. This is one of the | |
849 | reasons to specify a language environment. | |
850 | ||
851 | @findex prefer-coding-system | |
852 | However, you can alter the coding system priority list in detail | |
853 | with the command @kbd{M-x prefer-coding-system}. This command reads | |
854 | the name of a coding system from the minibuffer, and adds it to the | |
855 | front of the priority list, so that it is preferred to all others. If | |
856 | you use this command several times, each use adds one element to the | |
857 | front of the priority list. | |
858 | ||
859 | If you use a coding system that specifies the end-of-line conversion | |
860 | type, such as @code{iso-8859-1-dos}, what this means is that Emacs | |
861 | should attempt to recognize @code{iso-8859-1} with priority, and should | |
862 | use DOS end-of-line conversion when it does recognize @code{iso-8859-1}. | |
863 | ||
864 | @vindex file-coding-system-alist | |
865 | Sometimes a file name indicates which coding system to use for the | |
866 | file. The variable @code{file-coding-system-alist} specifies this | |
867 | correspondence. There is a special function | |
868 | @code{modify-coding-system-alist} for adding elements to this list. For | |
869 | example, to read and write all @samp{.txt} files using the coding system | |
870 | @code{chinese-iso-8bit}, you can execute this Lisp expression: | |
871 | ||
872 | @smallexample | |
873 | (modify-coding-system-alist 'file "\\.txt\\'" 'chinese-iso-8bit) | |
874 | @end smallexample | |
875 | ||
876 | @noindent | |
877 | The first argument should be @code{file}, the second argument should be | |
878 | a regular expression that determines which files this applies to, and | |
879 | the third argument says which coding system to use for these files. | |
880 | ||
881 | @vindex inhibit-eol-conversion | |
882 | @cindex DOS-style end-of-line display | |
883 | Emacs recognizes which kind of end-of-line conversion to use based on | |
884 | the contents of the file: if it sees only carriage-returns, or only | |
885 | carriage-return linefeed sequences, then it chooses the end-of-line | |
886 | conversion accordingly. You can inhibit the automatic use of | |
887 | end-of-line conversion by setting the variable @code{inhibit-eol-conversion} | |
888 | to non-@code{nil}. If you do that, DOS-style files will be displayed | |
889 | with the @samp{^M} characters visible in the buffer; some people | |
890 | prefer this to the more subtle @samp{(DOS)} end-of-line type | |
891 | indication near the left edge of the mode line (@pxref{Mode Line, | |
892 | eol-mnemonic}). | |
893 | ||
894 | @vindex inhibit-iso-escape-detection | |
895 | @cindex escape sequences in files | |
896 | By default, the automatic detection of coding system is sensitive to | |
897 | escape sequences. If Emacs sees a sequence of characters that begin | |
898 | with an escape character, and the sequence is valid as an ISO-2022 | |
899 | code, that tells Emacs to use one of the ISO-2022 encodings to decode | |
900 | the file. | |
901 | ||
902 | However, there may be cases that you want to read escape sequences | |
903 | in a file as is. In such a case, you can set the variable | |
904 | @code{inhibit-iso-escape-detection} to non-@code{nil}. Then the code | |
905 | detection ignores any escape sequences, and never uses an ISO-2022 | |
906 | encoding. The result is that all escape sequences become visible in | |
907 | the buffer. | |
908 | ||
909 | The default value of @code{inhibit-iso-escape-detection} is | |
910 | @code{nil}. We recommend that you not change it permanently, only for | |
05f7d0d3 | 911 | one specific operation. That's because some Emacs Lisp source files |
8cf51b2c GM |
912 | in the Emacs distribution contain non-@acronym{ASCII} characters encoded in the |
913 | coding system @code{iso-2022-7bit}, and they won't be | |
914 | decoded correctly when you visit those files if you suppress the | |
915 | escape sequence detection. | |
05f7d0d3 | 916 | @c I count a grand total of 3 such files, so is the above really true? |
8cf51b2c GM |
917 | |
918 | @vindex auto-coding-alist | |
919 | @vindex auto-coding-regexp-alist | |
05f7d0d3 GM |
920 | The variables @code{auto-coding-alist} and |
921 | @code{auto-coding-regexp-alist} are | |
8cf51b2c | 922 | the strongest way to specify the coding system for certain patterns of |
05f7d0d3 GM |
923 | file names, or for files containing certain patterns, respectively. |
924 | These variables even override @samp{-*-coding:-*-} tags in the file | |
71cd7772 | 925 | itself (@pxref{Specify Coding}). For example, Emacs |
8cf51b2c GM |
926 | uses @code{auto-coding-alist} for tar and archive files, to prevent it |
927 | from being confused by a @samp{-*-coding:-*-} tag in a member of the | |
928 | archive and thinking it applies to the archive file as a whole. | |
05f7d0d3 GM |
929 | @ignore |
930 | @c This describes old-style BABYL files, which are no longer relevant. | |
8cf51b2c GM |
931 | Likewise, Emacs uses @code{auto-coding-regexp-alist} to ensure that |
932 | RMAIL files, whose names in general don't match any particular | |
05f7d0d3 GM |
933 | pattern, are decoded correctly. |
934 | @end ignore | |
935 | ||
936 | @vindex auto-coding-functions | |
937 | Another way to specify a coding system is with the variable | |
938 | @code{auto-coding-functions}. For example, one of the builtin | |
8cf51b2c | 939 | @code{auto-coding-functions} detects the encoding for XML files. |
05f7d0d3 GM |
940 | Unlike the previous two, this variable does not override any |
941 | @samp{-*-coding:-*-} tag. | |
8cf51b2c | 942 | |
8cf51b2c GM |
943 | @node Specify Coding |
944 | @section Specifying a File's Coding System | |
945 | ||
946 | If Emacs recognizes the encoding of a file incorrectly, you can | |
313f790e CY |
947 | reread the file using the correct coding system with @kbd{C-x |
948 | @key{RET} r} (@code{revert-buffer-with-coding-system}). This command | |
949 | prompts for the coding system to use. To see what coding system Emacs | |
950 | actually used to decode the file, look at the coding system mnemonic | |
951 | letter near the left edge of the mode line (@pxref{Mode Line}), or | |
952 | type @kbd{C-h C} (@code{describe-coding-system}). | |
8cf51b2c GM |
953 | |
954 | @vindex coding | |
955 | You can specify the coding system for a particular file in the file | |
956 | itself, using the @w{@samp{-*-@dots{}-*-}} construct at the beginning, | |
957 | or a local variables list at the end (@pxref{File Variables}). You do | |
958 | this by defining a value for the ``variable'' named @code{coding}. | |
959 | Emacs does not really have a variable @code{coding}; instead of | |
960 | setting a variable, this uses the specified coding system for the | |
961 | file. For example, @samp{-*-mode: C; coding: latin-1;-*-} specifies | |
962 | use of the Latin-1 coding system, as well as C mode. When you specify | |
963 | the coding explicitly in the file, that overrides | |
964 | @code{file-coding-system-alist}. | |
965 | ||
8cf51b2c GM |
966 | @node Output Coding |
967 | @section Choosing Coding Systems for Output | |
968 | ||
969 | @vindex buffer-file-coding-system | |
970 | Once Emacs has chosen a coding system for a buffer, it stores that | |
971 | coding system in @code{buffer-file-coding-system}. That makes it the | |
972 | default for operations that write from this buffer into a file, such | |
973 | as @code{save-buffer} and @code{write-region}. You can specify a | |
974 | different coding system for further file output from the buffer using | |
975 | @code{set-buffer-file-coding-system} (@pxref{Text Coding}). | |
976 | ||
977 | You can insert any character Emacs supports into any Emacs buffer, | |
978 | but most coding systems can only handle a subset of these characters. | |
ad36c422 CY |
979 | Therefore, it's possible that the characters you insert cannot be |
980 | encoded with the coding system that will be used to save the buffer. | |
981 | For example, you could visit a text file in Polish, encoded in | |
982 | @code{iso-8859-2}, and add some Russian words to it. When you save | |
8cf51b2c GM |
983 | that buffer, Emacs cannot use the current value of |
984 | @code{buffer-file-coding-system}, because the characters you added | |
985 | cannot be encoded by that coding system. | |
986 | ||
987 | When that happens, Emacs tries the most-preferred coding system (set | |
988 | by @kbd{M-x prefer-coding-system} or @kbd{M-x | |
ad36c422 CY |
989 | set-language-environment}). If that coding system can safely encode |
990 | all of the characters in the buffer, Emacs uses it, and stores its | |
991 | value in @code{buffer-file-coding-system}. Otherwise, Emacs displays | |
992 | a list of coding systems suitable for encoding the buffer's contents, | |
993 | and asks you to choose one of those coding systems. | |
8cf51b2c GM |
994 | |
995 | If you insert the unsuitable characters in a mail message, Emacs | |
996 | behaves a bit differently. It additionally checks whether the | |
71cd7772 | 997 | @c What determines this? |
8cf51b2c | 998 | most-preferred coding system is recommended for use in MIME messages; |
eceeb5fc CY |
999 | if not, it informs you of this fact and prompts you for another coding |
1000 | system. This is so you won't inadvertently send a message encoded in | |
1001 | a way that your recipient's mail software will have difficulty | |
1002 | decoding. (You can still use an unsuitable coding system if you enter | |
1003 | its name at the prompt.) | |
8cf51b2c | 1004 | |
71cd7772 | 1005 | @c It seems that select-message-coding-system does this. |
1df7defd | 1006 | @c Both sendmail.el and smptmail.el call it; i.e., smtpmail.el still |
71cd7772 | 1007 | @c obeys sendmail-coding-system. |
8cf51b2c | 1008 | @vindex sendmail-coding-system |
71cd7772 | 1009 | When you send a mail message (@pxref{Sending Mail}), |
e73c2434 CY |
1010 | Emacs has four different ways to determine the coding system to use |
1011 | for encoding the message text. It tries the buffer's own value of | |
1012 | @code{buffer-file-coding-system}, if that is non-@code{nil}. | |
1013 | Otherwise, it uses the value of @code{sendmail-coding-system}, if that | |
1014 | is non-@code{nil}. The third way is to use the default coding system | |
1015 | for new files, which is controlled by your choice of language | |
71cd7772 | 1016 | @c i.e., default-sendmail-coding-system |
e73c2434 CY |
1017 | environment, if that is non-@code{nil}. If all of these three values |
1018 | are @code{nil}, Emacs encodes outgoing mail using the Latin-1 coding | |
1019 | system. | |
71cd7772 | 1020 | @c FIXME? Where does the Latin-1 default come in? |
8cf51b2c GM |
1021 | |
1022 | @node Text Coding | |
1023 | @section Specifying a Coding System for File Text | |
1024 | ||
1025 | In cases where Emacs does not automatically choose the right coding | |
1026 | system for a file's contents, you can use these commands to specify | |
1027 | one: | |
1028 | ||
1029 | @table @kbd | |
1030 | @item C-x @key{RET} f @var{coding} @key{RET} | |
71cd7772 GM |
1031 | Use coding system @var{coding} to save or revisit the file in |
1032 | the current buffer (@code{set-buffer-file-coding-system}). | |
8cf51b2c GM |
1033 | |
1034 | @item C-x @key{RET} c @var{coding} @key{RET} | |
1035 | Specify coding system @var{coding} for the immediately following | |
313f790e | 1036 | command (@code{universal-coding-system-argument}). |
8cf51b2c GM |
1037 | |
1038 | @item C-x @key{RET} r @var{coding} @key{RET} | |
313f790e CY |
1039 | Revisit the current file using the coding system @var{coding} |
1040 | (@code{revert-buffer-with-coding-system}). | |
8cf51b2c GM |
1041 | |
1042 | @item M-x recode-region @key{RET} @var{right} @key{RET} @var{wrong} @key{RET} | |
1043 | Convert a region that was decoded using coding system @var{wrong}, | |
1044 | decoding it using coding system @var{right} instead. | |
1045 | @end table | |
1046 | ||
1047 | @kindex C-x RET f | |
1048 | @findex set-buffer-file-coding-system | |
1049 | The command @kbd{C-x @key{RET} f} | |
1050 | (@code{set-buffer-file-coding-system}) sets the file coding system for | |
1df7defd | 1051 | the current buffer (i.e., the coding system to use when saving or |
cd996018 CY |
1052 | reverting the file). You specify which coding system using the |
1053 | minibuffer. You can also invoke this command by clicking with | |
1054 | @kbd{Mouse-3} on the coding system indicator in the mode line | |
1055 | (@pxref{Mode Line}). | |
1056 | ||
1057 | If you specify a coding system that cannot handle all the characters | |
1058 | in the buffer, Emacs will warn you about the troublesome characters, | |
1059 | and ask you to choose another coding system, when you try to save the | |
1060 | buffer (@pxref{Output Coding}). | |
8cf51b2c GM |
1061 | |
1062 | @cindex specify end-of-line conversion | |
1063 | You can also use this command to specify the end-of-line conversion | |
1064 | (@pxref{Coding Systems, end-of-line conversion}) for encoding the | |
1065 | current buffer. For example, @kbd{C-x @key{RET} f dos @key{RET}} will | |
71cd7772 GM |
1066 | cause Emacs to save the current buffer's text with DOS-style |
1067 | carriage-return linefeed line endings. | |
8cf51b2c GM |
1068 | |
1069 | @kindex C-x RET c | |
1070 | @findex universal-coding-system-argument | |
1071 | Another way to specify the coding system for a file is when you visit | |
1072 | the file. First use the command @kbd{C-x @key{RET} c} | |
1073 | (@code{universal-coding-system-argument}); this command uses the | |
1074 | minibuffer to read a coding system name. After you exit the minibuffer, | |
1075 | the specified coding system is used for @emph{the immediately following | |
1076 | command}. | |
1077 | ||
1078 | So if the immediately following command is @kbd{C-x C-f}, for example, | |
1079 | it reads the file using that coding system (and records the coding | |
1080 | system for when you later save the file). Or if the immediately following | |
1081 | command is @kbd{C-x C-w}, it writes the file using that coding system. | |
1082 | When you specify the coding system for saving in this way, instead | |
1083 | of with @kbd{C-x @key{RET} f}, there is no warning if the buffer | |
1084 | contains characters that the coding system cannot handle. | |
1085 | ||
1086 | Other file commands affected by a specified coding system include | |
1087 | @kbd{C-x i} and @kbd{C-x C-v}, as well as the other-window variants | |
1088 | of @kbd{C-x C-f}. @kbd{C-x @key{RET} c} also affects commands that | |
1089 | start subprocesses, including @kbd{M-x shell} (@pxref{Shell}). If the | |
1090 | immediately following command does not use the coding system, then | |
1091 | @kbd{C-x @key{RET} c} ultimately has no effect. | |
1092 | ||
1093 | An easy way to visit a file with no conversion is with the @kbd{M-x | |
1094 | find-file-literally} command. @xref{Visiting}. | |
1095 | ||
4e3b4528 SM |
1096 | The default value of the variable @code{buffer-file-coding-system} |
1097 | specifies the choice of coding system to use when you create a new file. | |
1098 | It applies when you find a new file, and when you create a buffer and | |
1099 | then save it in a file. Selecting a language environment typically sets | |
1100 | this variable to a good choice of default coding system for that language | |
8cf51b2c GM |
1101 | environment. |
1102 | ||
1103 | @kindex C-x RET r | |
1104 | @findex revert-buffer-with-coding-system | |
1105 | If you visit a file with a wrong coding system, you can correct this | |
1106 | with @kbd{C-x @key{RET} r} (@code{revert-buffer-with-coding-system}). | |
1107 | This visits the current file again, using a coding system you specify. | |
1108 | ||
1109 | @findex recode-region | |
1110 | If a piece of text has already been inserted into a buffer using the | |
1111 | wrong coding system, you can redo the decoding of it using @kbd{M-x | |
1112 | recode-region}. This prompts you for the proper coding system, then | |
1113 | for the wrong coding system that was actually used, and does the | |
1114 | conversion. It first encodes the region using the wrong coding system, | |
1115 | then decodes it again using the proper coding system. | |
1116 | ||
1117 | @node Communication Coding | |
1118 | @section Coding Systems for Interprocess Communication | |
1119 | ||
1120 | This section explains how to specify coding systems for use | |
1121 | in communication with other processes. | |
1122 | ||
1123 | @table @kbd | |
1124 | @item C-x @key{RET} x @var{coding} @key{RET} | |
1125 | Use coding system @var{coding} for transferring selections to and from | |
166bc0c8 | 1126 | other graphical applications (@code{set-selection-coding-system}). |
8cf51b2c GM |
1127 | |
1128 | @item C-x @key{RET} X @var{coding} @key{RET} | |
1129 | Use coding system @var{coding} for transferring @emph{one} | |
166bc0c8 | 1130 | selection---the next one---to or from another graphical application |
313f790e | 1131 | (@code{set-next-selection-coding-system}). |
8cf51b2c GM |
1132 | |
1133 | @item C-x @key{RET} p @var{input-coding} @key{RET} @var{output-coding} @key{RET} | |
1134 | Use coding systems @var{input-coding} and @var{output-coding} for | |
313f790e CY |
1135 | subprocess input and output in the current buffer |
1136 | (@code{set-buffer-process-coding-system}). | |
8cf51b2c GM |
1137 | @end table |
1138 | ||
1139 | @kindex C-x RET x | |
1140 | @kindex C-x RET X | |
1141 | @findex set-selection-coding-system | |
1142 | @findex set-next-selection-coding-system | |
1143 | The command @kbd{C-x @key{RET} x} (@code{set-selection-coding-system}) | |
1144 | specifies the coding system for sending selected text to other windowing | |
1145 | applications, and for receiving the text of selections made in other | |
1146 | applications. This command applies to all subsequent selections, until | |
1147 | you override it by using the command again. The command @kbd{C-x | |
1148 | @key{RET} X} (@code{set-next-selection-coding-system}) specifies the | |
1149 | coding system for the next selection made in Emacs or read by Emacs. | |
1150 | ||
53b7759e | 1151 | @vindex x-select-request-type |
221bb7f6 EZ |
1152 | The variable @code{x-select-request-type} specifies the data type to |
1153 | request from the X Window System for receiving text selections from | |
1154 | other applications. If the value is @code{nil} (the default), Emacs | |
71cd7772 | 1155 | tries @code{UTF8_STRING} and @code{COMPOUND_TEXT}, in this order, and |
221bb7f6 EZ |
1156 | uses various heuristics to choose the more appropriate of the two |
1157 | results; if none of these succeed, Emacs falls back on @code{STRING}. | |
1158 | If the value of @code{x-select-request-type} is one of the symbols | |
1159 | @code{COMPOUND_TEXT}, @code{UTF8_STRING}, @code{STRING}, or | |
1160 | @code{TEXT}, Emacs uses only that request type. If the value is a | |
1161 | list of some of these symbols, Emacs tries only the request types in | |
1162 | the list, in order, until one of them succeeds, or until the list is | |
1163 | exhausted. | |
53b7759e | 1164 | |
8cf51b2c GM |
1165 | @kindex C-x RET p |
1166 | @findex set-buffer-process-coding-system | |
1167 | The command @kbd{C-x @key{RET} p} (@code{set-buffer-process-coding-system}) | |
1168 | specifies the coding system for input and output to a subprocess. This | |
1169 | command applies to the current buffer; normally, each subprocess has its | |
1170 | own buffer, and thus you can use this command to specify translation to | |
1171 | and from a particular subprocess by giving the command in the | |
1172 | corresponding buffer. | |
1173 | ||
313f790e CY |
1174 | You can also use @kbd{C-x @key{RET} c} |
1175 | (@code{universal-coding-system-argument}) just before the command that | |
1176 | runs or starts a subprocess, to specify the coding system for | |
1177 | communicating with that subprocess. @xref{Text Coding}. | |
8cf51b2c GM |
1178 | |
1179 | The default for translation of process input and output depends on the | |
1180 | current language environment. | |
1181 | ||
1182 | @vindex locale-coding-system | |
1183 | @cindex decoding non-@acronym{ASCII} keyboard input on X | |
1184 | The variable @code{locale-coding-system} specifies a coding system | |
1185 | to use when encoding and decoding system strings such as system error | |
1186 | messages and @code{format-time-string} formats and time stamps. That | |
71cd7772 GM |
1187 | coding system is also used for decoding non-@acronym{ASCII} keyboard |
1188 | input on the X Window System. You should choose a coding system that is compatible | |
8cf51b2c GM |
1189 | with the underlying system's text representation, which is normally |
1190 | specified by one of the environment variables @env{LC_ALL}, | |
1191 | @env{LC_CTYPE}, and @env{LANG}. (The first one, in the order | |
1192 | specified above, whose value is nonempty is the one that determines | |
1193 | the text representation.) | |
1194 | ||
1195 | @node File Name Coding | |
1196 | @section Coding Systems for File Names | |
1197 | ||
1198 | @table @kbd | |
1199 | @item C-x @key{RET} F @var{coding} @key{RET} | |
1200 | Use coding system @var{coding} for encoding and decoding file | |
71cd7772 | 1201 | names (@code{set-file-name-coding-system}). |
8cf51b2c GM |
1202 | @end table |
1203 | ||
8cf51b2c GM |
1204 | @findex set-file-name-coding-system |
1205 | @kindex C-x @key{RET} F | |
71cd7772 GM |
1206 | @cindex file names with non-@acronym{ASCII} characters |
1207 | The command @kbd{C-x @key{RET} F} (@code{set-file-name-coding-system}) | |
1208 | specifies a coding system to use for encoding file @emph{names}. It | |
1209 | has no effect on reading and writing the @emph{contents} of files. | |
1210 | ||
1211 | @vindex file-name-coding-system | |
1212 | In fact, all this command does is set the value of the variable | |
1213 | @code{file-name-coding-system}. If you set the variable to a coding | |
1214 | system name (as a Lisp symbol or a string), Emacs encodes file names | |
1215 | using that coding system for all file operations. This makes it | |
1216 | possible to use non-@acronym{ASCII} characters in file names---or, at | |
1217 | least, those non-@acronym{ASCII} characters that the specified coding | |
1218 | system can encode. | |
8cf51b2c GM |
1219 | |
1220 | If @code{file-name-coding-system} is @code{nil}, Emacs uses a | |
71cd7772 GM |
1221 | default coding system determined by the selected language environment, |
1222 | and stored in the @code{default-file-name-coding-system} variable. | |
1223 | @c FIXME? Is this correct? What is the "default language environment"? | |
ad36c422 CY |
1224 | In the default language environment, non-@acronym{ASCII} characters in |
1225 | file names are not encoded specially; they appear in the file system | |
1226 | using the internal Emacs representation. | |
8cf51b2c | 1227 | |
7df14908 EZ |
1228 | @cindex file-name encoding, MS-Windows |
1229 | @vindex w32-unicode-filenames | |
1230 | When Emacs runs on MS-Windows versions that are descendants of the | |
1231 | NT family (Windows 2000, XP, Vista, Windows 7, and Windows 8), the | |
1232 | value of @code{file-name-coding-system} is largely ignored, as Emacs | |
1233 | by default uses APIs that allow to pass Unicode file names directly. | |
1234 | By contrast, on Windows 9X, file names are encoded using | |
1235 | @code{file-name-coding-system}, which should be set to the codepage | |
1236 | (@pxref{Coding Systems, codepage}) pertinent for the current system | |
1237 | locale. The value of the variable @code{w32-unicode-filenames} | |
1238 | controls whether Emacs uses the Unicode APIs when it calls OS | |
1239 | functions that accept file names. This variable is set by the startup | |
1240 | code to @code{nil} on Windows 9X, and to @code{t} on newer versions of | |
1241 | MS-Windows. | |
1242 | ||
8cf51b2c GM |
1243 | @strong{Warning:} if you change @code{file-name-coding-system} (or the |
1244 | language environment) in the middle of an Emacs session, problems can | |
1245 | result if you have already visited files whose names were encoded using | |
1246 | the earlier coding system and cannot be encoded (or are encoded | |
1247 | differently) under the new coding system. If you try to save one of | |
1248 | these buffers under the visited file name, saving may use the wrong file | |
71cd7772 | 1249 | name, or it may encounter an error. If such a problem happens, use @kbd{C-x |
8cf51b2c GM |
1250 | C-w} to specify a new file name for that buffer. |
1251 | ||
1252 | @findex recode-file-name | |
1253 | If a mistake occurs when encoding a file name, use the command | |
1254 | @kbd{M-x recode-file-name} to change the file name's coding | |
1255 | system. This prompts for an existing file name, its old coding | |
1256 | system, and the coding system to which you wish to convert. | |
1257 | ||
1258 | @node Terminal Coding | |
1259 | @section Coding Systems for Terminal I/O | |
1260 | ||
1261 | @table @kbd | |
8cf51b2c | 1262 | @item C-x @key{RET} t @var{coding} @key{RET} |
313f790e CY |
1263 | Use coding system @var{coding} for terminal output |
1264 | (@code{set-terminal-coding-system}). | |
71cd7772 GM |
1265 | |
1266 | @item C-x @key{RET} k @var{coding} @key{RET} | |
1267 | Use coding system @var{coding} for keyboard input | |
1268 | (@code{set-keyboard-coding-system}). | |
8cf51b2c GM |
1269 | @end table |
1270 | ||
1271 | @kindex C-x RET t | |
1272 | @findex set-terminal-coding-system | |
1273 | The command @kbd{C-x @key{RET} t} (@code{set-terminal-coding-system}) | |
1274 | specifies the coding system for terminal output. If you specify a | |
1275 | character code for terminal output, all characters output to the | |
1276 | terminal are translated into that coding system. | |
1277 | ||
1278 | This feature is useful for certain character-only terminals built to | |
1279 | support specific languages or character sets---for example, European | |
1280 | terminals that support one of the ISO Latin character sets. You need to | |
1281 | specify the terminal coding system when using multibyte text, so that | |
1282 | Emacs knows which characters the terminal can actually handle. | |
1283 | ||
1284 | By default, output to the terminal is not translated at all, unless | |
1285 | Emacs can deduce the proper coding system from your terminal type or | |
1286 | your locale specification (@pxref{Language Environments}). | |
1287 | ||
1288 | @kindex C-x RET k | |
1289 | @findex set-keyboard-coding-system | |
1290 | @vindex keyboard-coding-system | |
71cd7772 GM |
1291 | The command @kbd{C-x @key{RET} k} (@code{set-keyboard-coding-system}), |
1292 | or the variable @code{keyboard-coding-system}, specifies the coding | |
8cf51b2c GM |
1293 | system for keyboard input. Character-code translation of keyboard |
1294 | input is useful for terminals with keys that send non-@acronym{ASCII} | |
1295 | graphic characters---for example, some terminals designed for ISO | |
1296 | Latin-1 or subsets of it. | |
1297 | ||
1298 | By default, keyboard input is translated based on your system locale | |
1299 | setting. If your terminal does not really support the encoding | |
1300 | implied by your locale (for example, if you find it inserts a | |
1301 | non-@acronym{ASCII} character if you type @kbd{M-i}), you will need to set | |
1302 | @code{keyboard-coding-system} to @code{nil} to turn off encoding. | |
1303 | You can do this by putting | |
1304 | ||
1305 | @lisp | |
1306 | (set-keyboard-coding-system nil) | |
1307 | @end lisp | |
1308 | ||
1309 | @noindent | |
ad36c422 | 1310 | in your init file. |
8cf51b2c GM |
1311 | |
1312 | There is a similarity between using a coding system translation for | |
1313 | keyboard input, and using an input method: both define sequences of | |
1314 | keyboard input that translate into single characters. However, input | |
1315 | methods are designed to be convenient for interactive use by humans, and | |
1316 | the sequences that are translated are typically sequences of @acronym{ASCII} | |
1317 | printing characters. Coding systems typically translate sequences of | |
1318 | non-graphic characters. | |
1319 | ||
1320 | @node Fontsets | |
1321 | @section Fontsets | |
1322 | @cindex fontsets | |
1323 | ||
1324 | A font typically defines shapes for a single alphabet or script. | |
1325 | Therefore, displaying the entire range of scripts that Emacs supports | |
1326 | requires a collection of many fonts. In Emacs, such a collection is | |
05806f43 | 1327 | called a @dfn{fontset}. A fontset is defined by a list of font specifications, |
b545ff9c | 1328 | each assigned to handle a range of character codes, and may fall back |
05806f43 | 1329 | on another fontset for characters that are not covered by the fonts |
b545ff9c | 1330 | it specifies. |
8cf51b2c | 1331 | |
05806f43 GM |
1332 | @cindex fonts for various scripts |
1333 | @cindex Intlfonts package, installation | |
8cf51b2c GM |
1334 | Each fontset has a name, like a font. However, while fonts are |
1335 | stored in the system and the available font names are defined by the | |
1336 | system, fontsets are defined within Emacs itself. Once you have | |
1337 | defined a fontset, you can use it within Emacs by specifying its name, | |
1338 | anywhere that you could use a single font. Of course, Emacs fontsets | |
05806f43 GM |
1339 | can use only the fonts that the system supports. If some characters |
1340 | appear on the screen as empty boxes or hex codes, this means that the | |
1341 | fontset in use for them has no font for those characters. In this | |
1342 | case, or if the characters are shown, but not as well as you would | |
1343 | like, you may need to install extra fonts. Your operating system may | |
1344 | have optional fonts that you can install; or you can install the GNU | |
1345 | Intlfonts package, which includes fonts for most supported | |
1346 | scripts.@footnote{If you run Emacs on X, you may need to inform the X | |
1347 | server about the location of the newly installed fonts with commands | |
1348 | such as: | |
1349 | @c FIXME? I feel like this may be out of date. | |
1df7defd | 1350 | @c E.g., the intlfonts tarfile is ~ 10 years old. |
05806f43 GM |
1351 | |
1352 | @example | |
1353 | xset fp+ /usr/local/share/emacs/fonts | |
1354 | xset fp rehash | |
1355 | @end example | |
1356 | } | |
8cf51b2c | 1357 | |
b545ff9c JR |
1358 | Emacs creates three fontsets automatically: the @dfn{standard |
1359 | fontset}, the @dfn{startup fontset} and the @dfn{default fontset}. | |
05806f43 GM |
1360 | @c FIXME? The doc of *standard*-fontset-spec says: |
1361 | @c "You have the biggest chance to display international characters | |
1362 | @c with correct glyphs by using the *standard* fontset." (my emphasis) | |
de649682 | 1363 | @c See http://lists.gnu.org/archive/html/emacs-devel/2012-04/msg00430.html |
b545ff9c | 1364 | The default fontset is most likely to have fonts for a wide variety of |
05806f43 | 1365 | non-@acronym{ASCII} characters, and is the default fallback for the |
b545ff9c | 1366 | other two fontsets, and if you set a default font rather than fontset. |
05806f43 | 1367 | However, it does not specify font family names, so results can be |
a4bead12 | 1368 | somewhat random if you use it directly. You can specify use of a |
05806f43 GM |
1369 | particular fontset by starting Emacs with the @samp{-fn} option. |
1370 | For example, | |
8cf51b2c GM |
1371 | |
1372 | @example | |
1373 | emacs -fn fontset-standard | |
1374 | @end example | |
1375 | ||
1376 | @noindent | |
1377 | You can also specify a fontset with the @samp{Font} resource (@pxref{X | |
1378 | Resources}). | |
1379 | ||
a4bead12 JR |
1380 | If no fontset is specified for use, then Emacs uses an |
1381 | @acronym{ASCII} font, with @samp{fontset-default} as a fallback for | |
1382 | characters the font does not cover. The standard fontset is only used if | |
1383 | explicitly requested, despite its name. | |
1384 | ||
8cf51b2c | 1385 | A fontset does not necessarily specify a font for every character |
0eb025fb EZ |
1386 | code. If a fontset specifies no font for a certain character, or if |
1387 | it specifies a font that does not exist on your system, then it cannot | |
1388 | display that character properly. It will display that character as a | |
0088729a | 1389 | hex code or thin space or an empty box instead. (@xref{Text Display, , |
0eb025fb | 1390 | glyphless characters}, for details.) |
8cf51b2c GM |
1391 | |
1392 | @node Defining Fontsets | |
1393 | @section Defining fontsets | |
1394 | ||
1395 | @vindex standard-fontset-spec | |
b545ff9c JR |
1396 | @vindex w32-standard-fontset-spec |
1397 | @vindex ns-standard-fontset-spec | |
8cf51b2c | 1398 | @cindex standard fontset |
b545ff9c | 1399 | When running on X, Emacs creates a standard fontset automatically according to the value |
8cf51b2c GM |
1400 | of @code{standard-fontset-spec}. This fontset's name is |
1401 | ||
1402 | @example | |
1403 | -*-fixed-medium-r-normal-*-16-*-*-*-*-*-fontset-standard | |
1404 | @end example | |
1405 | ||
1406 | @noindent | |
1407 | or just @samp{fontset-standard} for short. | |
1408 | ||
05806f43 GM |
1409 | On GNUstep and Mac OS X, the standard fontset is created using the value of |
1410 | @code{ns-standard-fontset-spec}, and on MS Windows it is | |
b545ff9c JR |
1411 | created using the value of @code{w32-standard-fontset-spec}. |
1412 | ||
05806f43 GM |
1413 | @c FIXME? How does one access these, or do anything with them? |
1414 | @c Does it matter? | |
8cf51b2c GM |
1415 | Bold, italic, and bold-italic variants of the standard fontset are |
1416 | created automatically. Their names have @samp{bold} instead of | |
1417 | @samp{medium}, or @samp{i} instead of @samp{r}, or both. | |
1418 | ||
1419 | @cindex startup fontset | |
b545ff9c JR |
1420 | Emacs generates a fontset automatically, based on any default |
1421 | @acronym{ASCII} font that you specify with the @samp{Font} resource or | |
1422 | the @samp{-fn} argument, or the default font that Emacs found when it | |
1423 | started. This is the @dfn{startup fontset} and its name is | |
1424 | @code{fontset-startup}. It does this by replacing the | |
1425 | @var{charset_registry} field with @samp{fontset}, and replacing | |
1426 | @var{charset_encoding} field with @samp{startup}, then using the | |
1427 | resulting string to specify a fontset. | |
8cf51b2c | 1428 | |
05806f43 | 1429 | For instance, if you start Emacs with a font of this form, |
8cf51b2c | 1430 | |
05806f43 GM |
1431 | @c FIXME? I think this is a little misleading, because you cannot (?) |
1432 | @c actually specify a font with wildcards, it has to be a complete spec. | |
1433 | @c Also, an X font specification of this form hasn't (?) been | |
1434 | @c mentioned before now, and is somewhat obsolete these days. | |
1435 | @c People are more likely to use a form like | |
1436 | @c emacs -fn "DejaVu Sans Mono-12" | |
1437 | @c How does any of this apply in that case? | |
8cf51b2c GM |
1438 | @example |
1439 | emacs -fn "*courier-medium-r-normal--14-140-*-iso8859-1" | |
1440 | @end example | |
1441 | ||
1442 | @noindent | |
1443 | Emacs generates the following fontset and uses it for the initial X | |
1444 | window frame: | |
1445 | ||
1446 | @example | |
b545ff9c | 1447 | -*-courier-medium-r-normal-*-14-140-*-*-*-*-fontset-startup |
8cf51b2c GM |
1448 | @end example |
1449 | ||
05806f43 GM |
1450 | The startup fontset will use the font that you specify, or a variant |
1451 | with a different registry and encoding, for all the characters that | |
b545ff9c JR |
1452 | are supported by that font, and fallback on @samp{fontset-default} for |
1453 | other characters. | |
1454 | ||
8cf51b2c GM |
1455 | With the X resource @samp{Emacs.Font}, you can specify a fontset name |
1456 | just like an actual font name. But be careful not to specify a fontset | |
1457 | name in a wildcard resource like @samp{Emacs*Font}---that wildcard | |
1458 | specification matches various other resources, such as for menus, and | |
05806f43 GM |
1459 | @c FIXME is this still true? |
1460 | menus cannot handle fontsets. @xref{X Resources}. | |
8cf51b2c GM |
1461 | |
1462 | You can specify additional fontsets using X resources named | |
1463 | @samp{Fontset-@var{n}}, where @var{n} is an integer starting from 0. | |
1464 | The resource value should have this form: | |
1465 | ||
1466 | @smallexample | |
1467 | @var{fontpattern}, @r{[}@var{charset}:@var{font}@r{]@dots{}} | |
1468 | @end smallexample | |
1469 | ||
1470 | @noindent | |
05806f43 GM |
1471 | @var{fontpattern} should have the form of a standard X font name (see |
1472 | the previous fontset-startup example), except | |
8cf51b2c GM |
1473 | for the last two fields. They should have the form |
1474 | @samp{fontset-@var{alias}}. | |
1475 | ||
1476 | The fontset has two names, one long and one short. The long name is | |
1477 | @var{fontpattern}. The short name is @samp{fontset-@var{alias}}. You | |
1478 | can refer to the fontset by either name. | |
1479 | ||
1480 | The construct @samp{@var{charset}:@var{font}} specifies which font to | |
1481 | use (in this fontset) for one particular character set. Here, | |
1482 | @var{charset} is the name of a character set, and @var{font} is the | |
1483 | font to use for that character set. You can use this construct any | |
1484 | number of times in defining one fontset. | |
1485 | ||
1486 | For the other character sets, Emacs chooses a font based on | |
1487 | @var{fontpattern}. It replaces @samp{fontset-@var{alias}} with values | |
1488 | that describe the character set. For the @acronym{ASCII} character font, | |
1489 | @samp{fontset-@var{alias}} is replaced with @samp{ISO8859-1}. | |
1490 | ||
1491 | In addition, when several consecutive fields are wildcards, Emacs | |
1492 | collapses them into a single wildcard. This is to prevent use of | |
1493 | auto-scaled fonts. Fonts made by scaling larger fonts are not usable | |
05806f43 | 1494 | for editing, and scaling a smaller font is not also useful, because it is |
8cf51b2c GM |
1495 | better to use the smaller font in its own size, which is what Emacs |
1496 | does. | |
1497 | ||
1498 | Thus if @var{fontpattern} is this, | |
1499 | ||
1500 | @example | |
1501 | -*-fixed-medium-r-normal-*-24-*-*-*-*-*-fontset-24 | |
1502 | @end example | |
1503 | ||
1504 | @noindent | |
1505 | the font specification for @acronym{ASCII} characters would be this: | |
1506 | ||
1507 | @example | |
1508 | -*-fixed-medium-r-normal-*-24-*-ISO8859-1 | |
1509 | @end example | |
1510 | ||
1511 | @noindent | |
1512 | and the font specification for Chinese GB2312 characters would be this: | |
1513 | ||
1514 | @example | |
1515 | -*-fixed-medium-r-normal-*-24-*-gb2312*-* | |
1516 | @end example | |
1517 | ||
1518 | You may not have any Chinese font matching the above font | |
1519 | specification. Most X distributions include only Chinese fonts that | |
05806f43 GM |
1520 | have @samp{song ti} or @samp{fangsong ti} in the @var{family} field. In |
1521 | such a case, @samp{Fontset-@var{n}} can be specified as: | |
8cf51b2c GM |
1522 | |
1523 | @smallexample | |
1524 | Emacs.Fontset-0: -*-fixed-medium-r-normal-*-24-*-*-*-*-*-fontset-24,\ | |
1525 | chinese-gb2312:-*-*-medium-r-normal-*-24-*-gb2312*-* | |
1526 | @end smallexample | |
1527 | ||
1528 | @noindent | |
1529 | Then, the font specifications for all but Chinese GB2312 characters have | |
1530 | @samp{fixed} in the @var{family} field, and the font specification for | |
1531 | Chinese GB2312 characters has a wild card @samp{*} in the @var{family} | |
1532 | field. | |
1533 | ||
1534 | @findex create-fontset-from-fontset-spec | |
1535 | The function that processes the fontset resource value to create the | |
1536 | fontset is called @code{create-fontset-from-fontset-spec}. You can also | |
1537 | call this function explicitly to create a fontset. | |
1538 | ||
d68eb23c | 1539 | @xref{Fonts}, for more information about font naming. |
8cf51b2c | 1540 | |
b545ff9c JR |
1541 | @node Modifying Fontsets |
1542 | @section Modifying Fontsets | |
1543 | @cindex fontsets, modifying | |
1544 | @findex set-fontset-font | |
1545 | ||
1546 | Fontsets do not always have to be created from scratch. If only | |
1547 | minor changes are required it may be easier to modify an existing | |
1548 | fontset. Modifying @samp{fontset-default} will also affect other | |
1549 | fontsets that use it as a fallback, so can be an effective way of | |
1550 | fixing problems with the fonts that Emacs chooses for a particular | |
1551 | script. | |
1552 | ||
1553 | Fontsets can be modified using the function @code{set-fontset-font}, | |
1554 | specifying a character, a charset, a script, or a range of characters | |
05806f43 GM |
1555 | to modify the font for, and a font specification for the font to be |
1556 | used. Some examples are: | |
b545ff9c JR |
1557 | |
1558 | @example | |
1559 | ;; Use Liberation Mono for latin-3 charset. | |
ae742cb5 CY |
1560 | (set-fontset-font "fontset-default" 'iso-8859-3 |
1561 | "Liberation Mono") | |
b545ff9c JR |
1562 | |
1563 | ;; Prefer a big5 font for han characters | |
ae742cb5 CY |
1564 | (set-fontset-font "fontset-default" |
1565 | 'han (font-spec :registry "big5") | |
b545ff9c JR |
1566 | nil 'prepend) |
1567 | ||
ae742cb5 CY |
1568 | ;; Use DejaVu Sans Mono as a fallback in fontset-startup |
1569 | ;; before resorting to fontset-default. | |
1570 | (set-fontset-font "fontset-startup" nil "DejaVu Sans Mono" | |
1571 | nil 'append) | |
b545ff9c JR |
1572 | |
1573 | ;; Use MyPrivateFont for the Unicode private use area. | |
ae742cb5 CY |
1574 | (set-fontset-font "fontset-default" '(#xe000 . #xf8ff) |
1575 | "MyPrivateFont") | |
b545ff9c JR |
1576 | |
1577 | @end example | |
1578 | ||
1579 | ||
8cf51b2c GM |
1580 | @node Undisplayable Characters |
1581 | @section Undisplayable Characters | |
1582 | ||
05806f43 | 1583 | There may be some non-@acronym{ASCII} characters that your |
0be641c0 CY |
1584 | terminal cannot display. Most text terminals support just a single |
1585 | character set (use the variable @code{default-terminal-coding-system} | |
05806f43 | 1586 | to tell Emacs which one, @ref{Terminal Coding}); characters that |
8cf51b2c GM |
1587 | can't be encoded in that coding system are displayed as @samp{?} by |
1588 | default. | |
1589 | ||
1590 | Graphical displays can display a broader range of characters, but | |
1591 | you may not have fonts installed for all of them; characters that have | |
1592 | no font appear as a hollow box. | |
1593 | ||
1594 | If you use Latin-1 characters but your terminal can't display | |
1595 | Latin-1, you can arrange to display mnemonic @acronym{ASCII} sequences | |
1df7defd | 1596 | instead, e.g., @samp{"o} for o-umlaut. Load the library |
8cf51b2c GM |
1597 | @file{iso-ascii} to do this. |
1598 | ||
1599 | @vindex latin1-display | |
1600 | If your terminal can display Latin-1, you can display characters | |
1601 | from other European character sets using a mixture of equivalent | |
1602 | Latin-1 characters and @acronym{ASCII} mnemonics. Customize the variable | |
1603 | @code{latin1-display} to enable this. The mnemonic @acronym{ASCII} | |
1604 | sequences mostly correspond to those of the prefix input methods. | |
1605 | ||
1606 | @node Unibyte Mode | |
1607 | @section Unibyte Editing Mode | |
1608 | ||
1609 | @cindex European character sets | |
1610 | @cindex accented characters | |
1611 | @cindex ISO Latin character sets | |
1612 | @cindex Unibyte operation | |
1613 | The ISO 8859 Latin-@var{n} character sets define character codes in | |
1614 | the range 0240 to 0377 octal (160 to 255 decimal) to handle the | |
1615 | accented letters and punctuation needed by various European languages | |
43b3b4d1 EZ |
1616 | (and some non-European ones). Note that Emacs considers bytes with |
1617 | codes in this range as raw bytes, not as characters, even in a unibyte | |
64a695bd XF |
1618 | buffer, i.e., if you disable multibyte characters. However, Emacs can |
1619 | still handle these character codes as if they belonged to @emph{one} | |
1620 | of the single-byte character sets at a time. To specify @emph{which} | |
1621 | of these codes to use, invoke @kbd{M-x set-language-environment} and | |
1622 | specify a suitable language environment such as @samp{Latin-@var{n}}. | |
1623 | @xref{Disabling Multibyte, , Disabling Multibyte Characters, elisp, | |
1624 | GNU Emacs Lisp Reference Manual}. | |
8cf51b2c GM |
1625 | |
1626 | @vindex unibyte-display-via-language-environment | |
43b3b4d1 EZ |
1627 | Emacs can also display bytes in the range 160 to 255 as readable |
1628 | characters, provided the terminal or font in use supports them. This | |
1629 | works automatically. On a graphical display, Emacs can also display | |
1630 | single-byte characters through fontsets, in effect by displaying the | |
1631 | equivalent multibyte characters according to the current language | |
1632 | environment. To request this, set the variable | |
1633 | @code{unibyte-display-via-language-environment} to a non-@code{nil} | |
1634 | value. Note that setting this only affects how these bytes are | |
1635 | displayed, but does not change the fundamental fact that Emacs treats | |
1636 | them as raw bytes, not as characters. | |
8cf51b2c GM |
1637 | |
1638 | @cindex @code{iso-ascii} library | |
1639 | If your terminal does not support display of the Latin-1 character | |
1640 | set, Emacs can display these characters as @acronym{ASCII} sequences which at | |
1641 | least give you a clear idea of what the characters are. To do this, | |
1642 | load the library @code{iso-ascii}. Similar libraries for other | |
05806f43 GM |
1643 | Latin-@var{n} character sets could be implemented, but have not been |
1644 | so far. | |
8cf51b2c GM |
1645 | |
1646 | @findex standard-display-8bit | |
1647 | @cindex 8-bit display | |
1648 | Normally non-ISO-8859 characters (decimal codes between 128 and 159 | |
1649 | inclusive) are displayed as octal escapes. You can change this for | |
1650 | non-standard ``extended'' versions of ISO-8859 character sets by using the | |
1651 | function @code{standard-display-8bit} in the @code{disp-table} library. | |
1652 | ||
1653 | There are two ways to input single-byte non-@acronym{ASCII} | |
1654 | characters: | |
1655 | ||
1656 | @itemize @bullet | |
1657 | @cindex 8-bit input | |
1658 | @item | |
1659 | You can use an input method for the selected language environment. | |
1660 | @xref{Input Methods}. When you use an input method in a unibyte buffer, | |
1661 | the non-@acronym{ASCII} character you specify with it is converted to unibyte. | |
1662 | ||
1663 | @item | |
1664 | If your keyboard can generate character codes 128 (decimal) and up, | |
1665 | representing non-@acronym{ASCII} characters, you can type those character codes | |
1666 | directly. | |
1667 | ||
0be641c0 CY |
1668 | On a graphical display, you should not need to do anything special to |
1669 | use these keys; they should simply work. On a text terminal, you | |
05806f43 | 1670 | should use the command @code{M-x set-keyboard-coding-system} or customize the |
8cf51b2c GM |
1671 | variable @code{keyboard-coding-system} to specify which coding system |
1672 | your keyboard uses (@pxref{Terminal Coding}). Enabling this feature | |
d7e9a7f8 | 1673 | will probably require you to use @key{ESC} to type Meta characters; |
8cf51b2c | 1674 | however, on a console terminal or in @code{xterm}, you can arrange for |
d7e9a7f8 EZ |
1675 | Meta to be converted to @key{ESC} and still be able type 8-bit |
1676 | characters present directly on the keyboard or using @key{Compose} or | |
1677 | @key{AltGr} keys. @xref{User Input}. | |
8cf51b2c GM |
1678 | |
1679 | @kindex C-x 8 | |
1680 | @cindex @code{iso-transl} library | |
1681 | @cindex compose character | |
1682 | @cindex dead character | |
1683 | @item | |
1684 | For Latin-1 only, you can use the key @kbd{C-x 8} as a ``compose | |
1685 | character'' prefix for entry of non-@acronym{ASCII} Latin-1 printing | |
1686 | characters. @kbd{C-x 8} is good for insertion (in the minibuffer as | |
1687 | well as other buffers), for searching, and in any other context where | |
1688 | a key sequence is allowed. | |
1689 | ||
1690 | @kbd{C-x 8} works by loading the @code{iso-transl} library. Once that | |
d7e9a7f8 EZ |
1691 | library is loaded, the @key{Alt} modifier key, if the keyboard has |
1692 | one, serves the same purpose as @kbd{C-x 8}: use @key{Alt} together | |
8cf51b2c | 1693 | with an accent character to modify the following letter. In addition, |
8edb942b | 1694 | if the keyboard has keys for the Latin-1 ``dead accent characters'', |
8cf51b2c GM |
1695 | they too are defined to compose with the following character, once |
1696 | @code{iso-transl} is loaded. | |
1697 | ||
1698 | Use @kbd{C-x 8 C-h} to list all the available @kbd{C-x 8} translations. | |
1699 | @end itemize | |
1700 | ||
1701 | @node Charsets | |
1702 | @section Charsets | |
1703 | @cindex charsets | |
1704 | ||
18430066 CY |
1705 | In Emacs, @dfn{charset} is short for ``character set''. Emacs |
1706 | supports most popular charsets (such as @code{ascii}, | |
1707 | @code{iso-8859-1}, @code{cp1250}, @code{big5}, and @code{unicode}), in | |
1708 | addition to some charsets of its own (such as @code{emacs}, | |
1709 | @code{unicode-bmp}, and @code{eight-bit}). All supported characters | |
1710 | belong to one or more charsets. | |
1711 | ||
1712 | Emacs normally ``does the right thing'' with respect to charsets, so | |
1713 | that you don't have to worry about them. However, it is sometimes | |
1714 | helpful to know some of the underlying details about charsets. | |
1715 | ||
d68eb23c | 1716 | One example is font selection (@pxref{Fonts}). Each language |
18430066 CY |
1717 | environment (@pxref{Language Environments}) defines a ``priority |
1718 | list'' for the various charsets. When searching for a font, Emacs | |
1719 | initially attempts to find one that can display the highest-priority | |
1720 | charsets. For instance, in the Japanese language environment, the | |
1721 | charset @code{japanese-jisx0208} has the highest priority, so Emacs | |
1722 | tries to use a font whose @code{registry} property is | |
1723 | @samp{JISX0208.1983-0}. | |
8cf51b2c GM |
1724 | |
1725 | @findex list-charset-chars | |
1726 | @cindex characters in a certain charset | |
1727 | @findex describe-character-set | |
18430066 | 1728 | There are two commands that can be used to obtain information about |
3af970a0 KH |
1729 | charsets. The command @kbd{M-x list-charset-chars} prompts for a |
1730 | charset name, and displays all the characters in that character set. | |
1731 | The command @kbd{M-x describe-character-set} prompts for a charset | |
18430066 | 1732 | name, and displays information about that charset, including its |
3af970a0 KH |
1733 | internal representation within Emacs. |
1734 | ||
1735 | @findex list-character-sets | |
ae742cb5 CY |
1736 | @kbd{M-x list-character-sets} displays a list of all supported |
1737 | charsets. The list gives the names of charsets and additional | |
05806f43 GM |
1738 | information to identity each charset; see the |
1739 | @url{http://www.itscj.ipsj.or.jp/ISO-IR/, International Register of | |
1740 | Coded Character Sets} for more details. In this list, | |
18430066 CY |
1741 | charsets are divided into two categories: @dfn{normal charsets} are |
1742 | listed first, followed by @dfn{supplementary charsets}. A | |
1743 | supplementary charset is one that is used to define another charset | |
1744 | (as a parent or a subset), or to provide backward-compatibility for | |
1745 | older Emacs versions. | |
1746 | ||
1747 | To find out which charset a character in the buffer belongs to, put | |
1748 | point before it and type @kbd{C-u C-x =} (@pxref{International | |
1749 | Chars}). | |
8cf51b2c | 1750 | |
f4b6ba46 EZ |
1751 | @node Bidirectional Editing |
1752 | @section Bidirectional Editing | |
1753 | @cindex bidirectional editing | |
1754 | @cindex right-to-left text | |
1755 | ||
1756 | Emacs supports editing text written in scripts, such as Arabic and | |
1757 | Hebrew, whose natural ordering of horizontal text for display is from | |
1758 | right to left. However, digits and Latin text embedded in these | |
1759 | scripts are still displayed left to right. It is also not uncommon to | |
05806f43 GM |
1760 | have small portions of text in Arabic or Hebrew embedded in an otherwise |
1761 | Latin document; e.g., as comments and strings in a program source | |
f4b6ba46 EZ |
1762 | file. For these reasons, text that uses these scripts is actually |
1763 | @dfn{bidirectional}: a mixture of runs of left-to-right and | |
1764 | right-to-left characters. | |
1765 | ||
1766 | This section describes the facilities and options provided by Emacs | |
1767 | for editing bidirectional text. | |
1768 | ||
1769 | @cindex logical order | |
1770 | @cindex visual order | |
1771 | Emacs stores right-to-left and bidirectional text in the so-called | |
1772 | @dfn{logical} (or @dfn{reading}) order: the buffer or string position | |
1773 | of the first character you read precedes that of the next character. | |
1774 | Reordering of bidirectional text into the @dfn{visual} order happens | |
1775 | at display time. As result, character positions no longer increase | |
1776 | monotonically with their positions on display. Emacs implements the | |
1777 | Unicode Bidirectional Algorithm described in the Unicode Standard | |
1778 | Annex #9, for reordering of bidirectional text for display. | |
1779 | ||
1780 | @vindex bidi-display-reordering | |
1781 | The buffer-local variable @code{bidi-display-reordering} controls | |
1782 | whether text in the buffer is reordered for display. If its value is | |
1783 | non-@code{nil}, Emacs reorders characters that have right-to-left | |
1784 | directionality when they are displayed. The default value is | |
4cc60b9b | 1785 | @code{t}. |
f4b6ba46 | 1786 | |
84412f2c EZ |
1787 | @cindex base direction of paragraphs |
1788 | @cindex paragraph, base direction | |
f4b6ba46 EZ |
1789 | Each paragraph of bidirectional text can have its own @dfn{base |
1790 | direction}, either right-to-left or left-to-right. (Paragraph | |
05806f43 | 1791 | @c paragraph-separate etc have no influence on this? |
1df7defd | 1792 | boundaries are empty lines, i.e., lines consisting entirely of |
84412f2c EZ |
1793 | whitespace characters.) Text in left-to-right paragraphs begins on |
1794 | the screen at the left margin of the window and is truncated or | |
1795 | continued when it reaches the right margin. By contrast, text in | |
1796 | right-to-left paragraphs is displayed starting at the right margin and | |
1797 | is continued or truncated at the left margin. | |
f4b6ba46 EZ |
1798 | |
1799 | @vindex bidi-paragraph-direction | |
1800 | Emacs determines the base direction of each paragraph dynamically, | |
1801 | based on the text at the beginning of the paragraph. However, | |
1802 | sometimes a buffer may need to force a certain base direction for its | |
1803 | paragraphs. The variable @code{bidi-paragraph-direction}, if | |
1804 | non-@code{nil}, disables the dynamic determination of the base | |
1805 | direction, and instead forces all paragraphs in the buffer to have the | |
1806 | direction specified by its buffer-local value. The value can be either | |
1807 | @code{right-to-left} or @code{left-to-right}. Any other value is | |
1808 | interpreted as @code{nil}. | |
1809 | ||
1810 | @cindex LRM | |
1811 | @cindex RLM | |
1812 | Alternatively, you can control the base direction of a paragraph by | |
1813 | inserting special formatting characters in front of the paragraph. | |
1814 | The special character @code{RIGHT-TO-LEFT MARK}, or @sc{rlm}, forces | |
1815 | the right-to-left direction on the following paragraph, while | |
1816 | @code{LEFT-TO-RIGHT MARK}, or @sc{lrm} forces the left-to-right | |
d7e9a7f8 | 1817 | direction. (You can use @kbd{C-x 8 @key{RET}} to insert these characters.) |
2d3fe5d7 EZ |
1818 | In a GUI session, the @sc{lrm} and @sc{rlm} characters display as very |
1819 | thin blank characters; on text terminals they display as blanks. | |
f4b6ba46 EZ |
1820 | |
1821 | Because characters are reordered for display, Emacs commands that | |
1822 | operate in the logical order or on stretches of buffer positions may | |
1823 | produce unusual effects. For example, @kbd{C-f} and @kbd{C-b} | |
1824 | commands move point in the logical order, so the cursor will sometimes | |
1825 | jump when point traverses reordered bidirectional text. Similarly, a | |
1826 | highlighted region covering a contiguous range of character positions | |
1827 | may look discontinuous if the region spans reordered text. This is | |
05806f43 | 1828 | normal and similar to the behavior of other programs that support |
4c672a0f EZ |
1829 | bidirectional text. If you set @code{visual-order-cursor-movement} to |
1830 | a non-@code{nil} value, cursor motion by the arrow keys follows the | |
1831 | visual order on screen (@pxref{Moving Point, visual-order movement}). |