1 /* 2 * Copyright © 2013 Ran Benita 3 * 4 * Permission is hereby granted, free of charge, to any person obtaining a 5 * copy of this software and associated documentation files (the "Software"), 6 * to deal in the Software without restriction, including without limitation 7 * the rights to use, copy, modify, merge, publish, distribute, sublicense, 8 * and/or sell copies of the Software, and to permit persons to whom the 9 * Software is furnished to do so, subject to the following conditions: 10 * 11 * The above copyright notice and this permission notice (including the next 12 * paragraph) shall be included in all copies or substantial portions of the 13 * Software. 14 * 15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 18 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 20 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 21 * DEALINGS IN THE SOFTWARE. 22 */ 23 24 #ifndef _XKBCOMMON_COMPOSE_H 25 #define _XKBCOMMON_COMPOSE_H 26 27 #include <xkbcommon/xkbcommon.h> 28 29 #ifdef __cplusplus 30 extern "C" { 31 #endif 32 33 /** 34 * @file 35 * libxkbcommon Compose API - support for Compose and dead-keys. 36 */ 37 38 /** 39 * @defgroup compose Compose and dead-keys support 40 * Support for Compose and dead-keys. 41 * @since 0.5.0 42 * 43 * @{ 44 */ 45 46 /** 47 * @page compose-overview Overview 48 * @parblock 49 * 50 * Compose and dead-keys are a common feature of many keyboard input 51 * systems. They extend the range of the keysysm that can be produced 52 * directly from a keyboard by using a sequence of key strokes, instead 53 * of just one. 54 * 55 * Here are some example sequences, in the libX11 Compose file format: 56 * 57 * <dead_acute> <a> : "á" aacute # LATIN SMALL LETTER A WITH ACUTE 58 * <Multi_key> <A> <T> : "@" at # COMMERCIAL AT 59 * 60 * When the user presses a key which produces the `<dead_acute>` keysym, 61 * nothing initially happens (thus the key is dubbed a "dead-key"). But 62 * when the user enters `<a>`, "á" is "composed", in place of "a". If 63 * instead the user had entered a keysym which does not follow 64 * `<dead_acute>` in any compose sequence, the sequence is said to be 65 * "cancelled". 66 * 67 * Compose files define many such sequences. For a description of the 68 * common file format for Compose files, see the Compose(5) man page. 69 * 70 * A successfuly-composed sequence has two results: a keysym and a UTF-8 71 * string. At least one of the two is defined for each sequence. If only 72 * a keysym is given, the keysym's string representation is used for the 73 * result string (using xkb_keysym_to_utf8()). 74 * 75 * This library provides low-level support for Compose file parsing and 76 * processing. Higher-level APIs (such as libX11's `Xutf8LookupString`(3)) 77 * may be built upon it, or it can be used directly. 78 * 79 * @endparblock 80 */ 81 82 /** 83 * @page compose-conflicting Conflicting Sequences 84 * @parblock 85 * 86 * To avoid ambiguity, a sequence is not allowed to be a prefix of another. 87 * In such a case, the conflict is resolved thus: 88 * 89 * 1. A longer sequence overrides a shorter one. 90 * 2. An equal sequence overrides an existing one. 91 * 3. A shorter sequence does not override a longer one. 92 * 93 * Sequences of length 1 are allowed. 94 * 95 * @endparblock 96 */ 97 98 /** 99 * @page compose-cancellation Cancellation Behavior 100 * @parblock 101 * 102 * What should happen when a sequence is cancelled? For example, consider 103 * there are only the above sequences, and the input keysyms are 104 * `<dead_acute> <b>`. There are a few approaches: 105 * 106 * 1. Swallow the cancelling keysym; that is, no keysym is produced. 107 * This is the approach taken by libX11. 108 * 2. Let the cancelling keysym through; that is, `<b>` is produced. 109 * 3. Replay the entire sequence; that is, `<dead_acute> <b>` is produced. 110 * This is the approach taken by Microsoft Windows (approximately; 111 * instead of `<dead_acute>`, the underlying key is used. This is 112 * difficult to simulate with XKB keymaps). 113 * 114 * You can program whichever approach best fits users' expectations. 115 * 116 * @endparblock 117 */ 118 119 /** 120 * @struct xkb_compose_table 121 * Opaque Compose table object. 122 * 123 * The compose table holds the definitions of the Compose sequences, as 124 * gathered from Compose files. It is immutable. 125 */ 126 struct xkb_compose_table; 127 128 /** 129 * @struct xkb_compose_state 130 * Opaque Compose state object. 131 * 132 * The compose state maintains state for compose sequence matching, such 133 * as which possible sequences are being matched, and the position within 134 * these sequences. It acts as a simple state machine wherein keysyms are 135 * the input, and composed keysyms and strings are the output. 136 * 137 * The compose state is usually associated with a keyboard device. 138 */ 139 struct xkb_compose_state; 140 141 /** Flags affecting Compose file compilation. */ 142 enum xkb_compose_compile_flags { 143 /** Do not apply any flags. */ 144 XKB_COMPOSE_COMPILE_NO_FLAGS = 0 145 }; 146 147 /** The recognized Compose file formats. */ 148 enum xkb_compose_format { 149 /** The classic libX11 Compose text format, described in Compose(5). */ 150 XKB_COMPOSE_FORMAT_TEXT_V1 = 1 151 }; 152 153 /** 154 * @page compose-locale Compose Locale 155 * @parblock 156 * 157 * Compose files are locale dependent: 158 * - Compose files are written for a locale, and the locale is used when 159 * searching for the appropriate file to use. 160 * - Compose files may reference the locale internally, with directives 161 * such as \%L. 162 * 163 * As such, functions like xkb_compose_table_new_from_locale() require 164 * a `locale` parameter. This will usually be the current locale (see 165 * locale(7) for more details). You may also want to allow the user to 166 * explicitly configure it, so he can use the Compose file of a given 167 * locale, but not use that locale for other things. 168 * 169 * You may query the current locale as follows: 170 * @code 171 * const char *locale; 172 * locale = setlocale(LC_CTYPE, NULL); 173 * @endcode 174 * 175 * This will only give useful results if the program had previously set 176 * the current locale using setlocale(3), with `LC_CTYPE` or `LC_ALL` 177 * and a non-NULL argument. 178 * 179 * If you prefer not to use the locale system of the C runtime library, 180 * you may nevertheless obtain the user's locale directly using 181 * environment variables, as described in locale(7). For example, 182 * @code 183 * const char *locale; 184 * locale = getenv("LC_ALL"); 185 * if (!locale || !*locale) 186 * locale = getenv("LC_CTYPE"); 187 * if (!locale || !*locale) 188 * locale = getenv("LANG"); 189 * if (!locale || !*locale) 190 * locale = "C"; 191 * @endcode 192 * 193 * Note that some locales supported by the C standard library may not 194 * have a Compose file assigned. 195 * 196 * @endparblock 197 */ 198 199 /** 200 * Create a compose table for a given locale. 201 * 202 * The locale is used for searching the file-system for an appropriate 203 * Compose file. The search order is described in Compose(5). It is 204 * affected by the following environment variables: 205 * 206 * 1. `XCOMPOSEFILE` - see Compose(5). 207 * 2. `XDG_CONFIG_HOME` - before `$HOME/.XCompose` is checked, 208 * `$XDG_CONFIG_HOME/XCompose` is checked (with a fall back to 209 * `$HOME/.config/XCompose` if `XDG_CONFIG_HOME` is not defined). 210 * This is a libxkbcommon extension to the search procedure in 211 * Compose(5) (since libxkbcommon 1.0.0). Note that other 212 * implementations, such as libX11, might not find a Compose file in 213 * this path. 214 * 3. `HOME` - see Compose(5). 215 * 4. `XLOCALEDIR` - if set, used as the base directory for the system's 216 * X locale files, e.g. `/usr/share/X11/locale`, instead of the 217 * preconfigured directory. 218 * 219 * @param context 220 * The library context in which to create the compose table. 221 * @param locale 222 * The current locale. See @ref compose-locale. 223 * \n 224 * The value is copied, so it is safe to pass the result of getenv(3) 225 * (or similar) without fear of it being invalidated by a subsequent 226 * setenv(3) (or similar). 227 * @param flags 228 * Optional flags for the compose table, or 0. 229 * 230 * @returns A compose table for the given locale, or NULL if the 231 * compilation failed or a Compose file was not found. 232 * 233 * @memberof xkb_compose_table 234 */ 235 struct xkb_compose_table * 236 xkb_compose_table_new_from_locale(struct xkb_context *context, 237 const char *locale, 238 enum xkb_compose_compile_flags flags); 239 240 /** 241 * Create a new compose table from a Compose file. 242 * 243 * @param context 244 * The library context in which to create the compose table. 245 * @param file 246 * The Compose file to compile. 247 * @param locale 248 * The current locale. See @ref compose-locale. 249 * @param format 250 * The text format of the Compose file to compile. 251 * @param flags 252 * Optional flags for the compose table, or 0. 253 * 254 * @returns A compose table compiled from the given file, or NULL if 255 * the compilation failed. 256 * 257 * @memberof xkb_compose_table 258 */ 259 struct xkb_compose_table * 260 xkb_compose_table_new_from_file(struct xkb_context *context, 261 FILE *file, 262 const char *locale, 263 enum xkb_compose_format format, 264 enum xkb_compose_compile_flags flags); 265 266 /** 267 * Create a new compose table from a memory buffer. 268 * 269 * This is just like xkb_compose_table_new_from_file(), but instead of 270 * a file, gets the table as one enormous string. 271 * 272 * @see xkb_compose_table_new_from_file() 273 * @memberof xkb_compose_table 274 */ 275 struct xkb_compose_table * 276 xkb_compose_table_new_from_buffer(struct xkb_context *context, 277 const char *buffer, size_t length, 278 const char *locale, 279 enum xkb_compose_format format, 280 enum xkb_compose_compile_flags flags); 281 282 /** 283 * Take a new reference on a compose table. 284 * 285 * @returns The passed in object. 286 * 287 * @memberof xkb_compose_table 288 */ 289 struct xkb_compose_table * 290 xkb_compose_table_ref(struct xkb_compose_table *table); 291 292 /** 293 * Release a reference on a compose table, and possibly free it. 294 * 295 * @param table The object. If it is NULL, this function does nothing. 296 * 297 * @memberof xkb_compose_table 298 */ 299 void 300 xkb_compose_table_unref(struct xkb_compose_table *table); 301 302 /** Flags for compose state creation. */ 303 enum xkb_compose_state_flags { 304 /** Do not apply any flags. */ 305 XKB_COMPOSE_STATE_NO_FLAGS = 0 306 }; 307 308 /** 309 * Create a new compose state object. 310 * 311 * @param table 312 * The compose table the state will use. 313 * @param flags 314 * Optional flags for the compose state, or 0. 315 * 316 * @returns A new compose state, or NULL on failure. 317 * 318 * @memberof xkb_compose_state 319 */ 320 struct xkb_compose_state * 321 xkb_compose_state_new(struct xkb_compose_table *table, 322 enum xkb_compose_state_flags flags); 323 324 /** 325 * Take a new reference on a compose state object. 326 * 327 * @returns The passed in object. 328 * 329 * @memberof xkb_compose_state 330 */ 331 struct xkb_compose_state * 332 xkb_compose_state_ref(struct xkb_compose_state *state); 333 334 /** 335 * Release a reference on a compose state object, and possibly free it. 336 * 337 * @param state The object. If NULL, do nothing. 338 * 339 * @memberof xkb_compose_state 340 */ 341 void 342 xkb_compose_state_unref(struct xkb_compose_state *state); 343 344 /** 345 * Get the compose table which a compose state object is using. 346 * 347 * @returns The compose table which was passed to xkb_compose_state_new() 348 * when creating this state object. 349 * 350 * This function does not take a new reference on the compose table; you 351 * must explicitly reference it yourself if you plan to use it beyond the 352 * lifetime of the state. 353 * 354 * @memberof xkb_compose_state 355 */ 356 struct xkb_compose_table * 357 xkb_compose_state_get_compose_table(struct xkb_compose_state *state); 358 359 /** Status of the Compose sequence state machine. */ 360 enum xkb_compose_status { 361 /** The initial state; no sequence has started yet. */ 362 XKB_COMPOSE_NOTHING, 363 /** In the middle of a sequence. */ 364 XKB_COMPOSE_COMPOSING, 365 /** A complete sequence has been matched. */ 366 XKB_COMPOSE_COMPOSED, 367 /** The last sequence was cancelled due to an unmatched keysym. */ 368 XKB_COMPOSE_CANCELLED 369 }; 370 371 /** The effect of a keysym fed to xkb_compose_state_feed(). */ 372 enum xkb_compose_feed_result { 373 /** The keysym had no effect - it did not affect the status. */ 374 XKB_COMPOSE_FEED_IGNORED, 375 /** The keysym started, advanced or cancelled a sequence. */ 376 XKB_COMPOSE_FEED_ACCEPTED 377 }; 378 379 /** 380 * Feed one keysym to the Compose sequence state machine. 381 * 382 * This function can advance into a compose sequence, cancel a sequence, 383 * start a new sequence, or do nothing in particular. The resulting 384 * status may be observed with xkb_compose_state_get_status(). 385 * 386 * Some keysyms, such as keysyms for modifier keys, are ignored - they 387 * have no effect on the status or otherwise. 388 * 389 * The following is a description of the possible status transitions, in 390 * the format CURRENT STATUS => NEXT STATUS, given a non-ignored input 391 * keysym `keysym`: 392 * 393 @verbatim 394 NOTHING or CANCELLED or COMPOSED => 395 NOTHING if keysym does not start a sequence. 396 COMPOSING if keysym starts a sequence. 397 COMPOSED if keysym starts and terminates a single-keysym sequence. 398 399 COMPOSING => 400 COMPOSING if keysym advances any of the currently possible 401 sequences but does not terminate any of them. 402 COMPOSED if keysym terminates one of the currently possible 403 sequences. 404 CANCELLED if keysym does not advance any of the currently 405 possible sequences. 406 @endverbatim 407 * 408 * The current Compose formats do not support multiple-keysyms. 409 * Therefore, if you are using a function such as xkb_state_key_get_syms() 410 * and it returns more than one keysym, consider feeding XKB_KEY_NoSymbol 411 * instead. 412 * 413 * @param state 414 * The compose state object. 415 * @param keysym 416 * A keysym, usually obtained after a key-press event, with a 417 * function such as xkb_state_key_get_one_sym(). 418 * 419 * @returns Whether the keysym was ignored. This is useful, for example, 420 * if you want to keep a record of the sequence matched thus far. 421 * 422 * @memberof xkb_compose_state 423 */ 424 enum xkb_compose_feed_result 425 xkb_compose_state_feed(struct xkb_compose_state *state, 426 xkb_keysym_t keysym); 427 428 /** 429 * Reset the Compose sequence state machine. 430 * 431 * The status is set to XKB_COMPOSE_NOTHING, and the current sequence 432 * is discarded. 433 * 434 * @memberof xkb_compose_state 435 */ 436 void 437 xkb_compose_state_reset(struct xkb_compose_state *state); 438 439 /** 440 * Get the current status of the compose state machine. 441 * 442 * @see xkb_compose_status 443 * @memberof xkb_compose_state 444 **/ 445 enum xkb_compose_status 446 xkb_compose_state_get_status(struct xkb_compose_state *state); 447 448 /** 449 * Get the result Unicode/UTF-8 string for a composed sequence. 450 * 451 * See @ref compose-overview for more details. This function is only 452 * useful when the status is XKB_COMPOSE_COMPOSED. 453 * 454 * @param[in] state 455 * The compose state. 456 * @param[out] buffer 457 * A buffer to write the string into. 458 * @param[in] size 459 * Size of the buffer. 460 * 461 * @warning If the buffer passed is too small, the string is truncated 462 * (though still NUL-terminated). 463 * 464 * @returns 465 * The number of bytes required for the string, excluding the NUL byte. 466 * If the sequence is not complete, or does not have a viable result 467 * string, returns 0, and sets `buffer` to the empty string (if possible). 468 * @returns 469 * You may check if truncation has occurred by comparing the return value 470 * with the size of `buffer`, similarly to the `snprintf`(3) function. 471 * You may safely pass NULL and 0 to `buffer` and `size` to find the 472 * required size (without the NUL-byte). 473 * 474 * @memberof xkb_compose_state 475 **/ 476 int 477 xkb_compose_state_get_utf8(struct xkb_compose_state *state, 478 char *buffer, size_t size); 479 480 /** 481 * Get the result keysym for a composed sequence. 482 * 483 * See @ref compose-overview for more details. This function is only 484 * useful when the status is XKB_COMPOSE_COMPOSED. 485 * 486 * @returns The result keysym. If the sequence is not complete, or does 487 * not specify a result keysym, returns XKB_KEY_NoSymbol. 488 * 489 * @memberof xkb_compose_state 490 **/ 491 xkb_keysym_t 492 xkb_compose_state_get_one_sym(struct xkb_compose_state *state); 493 494 /** @} */ 495 496 #ifdef __cplusplus 497 } /* extern "C" */ 498 #endif 499 500 #endif /* _XKBCOMMON_COMPOSE_H */ 501