1 /* 2 Internal file viewer for the Midnight Commander 3 Function for plain view 4 5 Copyright (C) 1994-2025 6 Free Software Foundation, Inc. 7 8 Written by: 9 Miguel de Icaza, 1994, 1995, 1998 10 Janne Kukonlehto, 1994, 1995 11 Jakub Jelinek, 1995 12 Joseph M. Hinkle, 1996 13 Norbert Warmuth, 1997 14 Pavel Machek, 1998 15 Roland Illig <roland.illig@gmx.de>, 2004, 2005 16 Slava Zanko <slavazanko@google.com>, 2009 17 Andrew Borodin <aborodin@vmail.ru>, 2009-2022 18 Ilia Maslakov <il.smind@gmail.com>, 2009 19 Rewritten almost from scratch by: 20 Egmont Koblinger <egmont@gmail.com>, 2014 21 22 This file is part of the Midnight Commander. 23 24 The Midnight Commander is free software: you can redistribute it 25 and/or modify it under the terms of the GNU General Public License as 26 published by the Free Software Foundation, either version 3 of the License, 27 or (at your option) any later version. 28 29 The Midnight Commander is distributed in the hope that it will be useful, 30 but WITHOUT ANY WARRANTY; without even the implied warranty of 31 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 32 GNU General Public License for more details. 33 34 You should have received a copy of the GNU General Public License 35 along with this program. If not, see <https://www.gnu.org/licenses/>. 36 37 ------------------------------------------------------------------------------------------------ 38 39 The viewer is implemented along the following design principles: 40 41 Goals: Always display simple scripts, double wide (CJK), combining accents and spacing marks 42 (often used e.g. in Devanagari) perfectly. Make the arrow keys always work correctly. 43 44 Absolutely non-goal: RTL. 45 46 Terminology: 47 48 - A "paragraph" is the text between two adjacent newline characters. A "line" or "row" is a 49 visual row on the screen. In wrap mode, the viewer formats a paragraph into one or more lines. 50 51 - The Unicode glossary <https://www.unicode.org/glossary/> doesn't seem to have a notion of "base 52 character followed by zero or more combining characters". The closest matches are "Combining 53 Character Sequence" meaning a base character followed by one or more combining characters, or 54 "Grapheme" which seems to exclude non-printable characters such as newline. In this file, 55 "combining character sequence" (or any obvious abbreviation thereof) means a base character 56 followed by zero or more (up to a current limit of 4) combining characters. 57 58 ------------------------------------------------------------------------------------------------ 59 60 The parser-formatter is designed to be stateless across paragraphs. This is so that we can walk 61 backwards without having to reparse the whole file (although we still need to reparse and 62 reformat the whole paragraph, but it's a lot better). This principle needs to be changed if we 63 ever get to address tickets 1849/2977, but then we can still store (for efficiency) the parser 64 state at the beginning of the paragraph, and safely walk backwards if we don't cross an escape 65 character. 66 67 The parser-formatter, however, definitely needs to carry a state across lines. Currently this 68 state contains: 69 70 - The logical column (as if we didn't wrap). This is used for handling TAB characters after a 71 wordwrap consistently with less. 72 73 - Whether the last nroff character was bold or underlined. This is used for displaying the 74 ambiguous _\b_ sequence consistently with less. 75 76 - Whether the desired way of displaying a lonely combining accent or spacing mark is to place it 77 over a dotted circle (we do this at the beginning of the paragraph of after a TAB), or to ignore 78 the combining char and show replacement char for the spacing mark (we do this if e.g. too many 79 of these were encountered and hence we don't glue them with their base character). 80 81 - (This state needs to be expanded if e.g. we decide to print verbose replacement characters 82 (e.g. "<U+0080>") and allow these to wrap around lines.) 83 84 The state also contains the file offset, as it doesn't make sense to ever know the state without 85 knowing the corresponding offset. 86 87 The state depends on various settings (viewer width, encoding, nroff mode, charwrap or wordwrap 88 mode (if we'll have that one day) etc.), needs to be recomputed if any of these changes. 89 90 Walking forwards is usually relatively easy both in the file and on the screen. Walking 91 backwards within a paragraph would only be possible in some special cases and even then it would 92 be painful, so we always walk back to the beginning of the paragraph and reparse-reformat from 93 there. 94 95 (Walking back within a line in the file would have at least the following difficulties: handling 96 the parser state; processing invalid UTF-8; processing invalid nroff (e.g. what is "_\bA\bA"?). 97 Walking back on the display: we wouldn't know where to display the last line of a paragraph, or 98 where to display a line if its following line starts with a wide (CJK or Tab) character. Long 99 story short: just forget this approach.) 100 101 Most important variables: 102 103 - dpy_start: Both in unwrap and wrap modes this points to the beginning of the topmost displayed 104 paragraph. 105 106 - dpy_text_column: Only in unwrap mode, an additional horizontal scroll. 107 108 - dpy_paragraph_skip_lines: Only in wrap mode, an additional vertical scroll (the number of 109 lines that are scrolled off at the top from the topmost paragraph). 110 111 - dpy_state_top: Only in wrap mode, the offset and parser-formatter state at the line where 112 displaying the file begins is cached here. 113 114 - dpy_wrap_dirty: If some parameter has changed that makes it necessary to reparse-redisplay the 115 topmost paragraph. 116 117 In wrap mode, the three variables "dpy_start", "dpy_paragraph_skip_lines" and "dpy_state_top" 118 are kept consistent. Think of the first two as the ones describing the position, and the third 119 as a cached value for better performance so that we don't need to wrap the invisible beginning 120 of the topmost paragraph over and over again. The third value needs to be recomputed each time a 121 parameter that influences parsing or displaying the file (e.g. width of screen, encoding, nroff 122 mode) changes, this is signaled by "dpy_wrap_dirty" to force recomputing "dpy_state_top" (and 123 clamp "dpy_paragraph_skip_lines" if necessary). 124 125 ------------------------------------------------------------------------------------------------ 126 127 Help integration 128 129 I'm planning to port the help viewer to this codebase. 130 131 Splitting at sections would still happen in the help viewer. It would either copy a section, or 132 set force_max and a similar force_min to limit displaying to one section only. 133 134 Parsing the help format would go next to the nroff parser. The colors, alternate character set, 135 and emitting the version number would go to the "state". (The version number would be 136 implemented by emitting remaining characters of a buffer in the "state" one by one, without 137 advancing in the file position.) 138 139 The active link would be drawn similarly to the search highlight. Other than that, the viewer 140 wouldn't care about links (except for their color). help.c would keep track of which one is 141 highlighted, how to advance to the next/prev on an arrow, how the scroll offset needs to be 142 adjusted when moving, etc. 143 144 Add wrapping at word boundaries to where wrapping at char boundaries happens now. 145 */ 146 147 #include <config.h> 148 149 #include "lib/global.h" 150 #include "lib/tty/tty.h" 151 #include "lib/skin.h" 152 #include "lib/util.h" // is_printable() 153 #ifdef HAVE_CHARSET 154 # include "lib/charsets.h" 155 #endif 156 157 #include "src/setup.h" // option_tab_spacing 158 159 #include "internal.h" 160 161 /*** global variables ****************************************************************************/ 162 163 /*** file scope macro definitions ****************************************************************/ 164 165 /* The Unicode standard recommends that lonely combining characters are printed over a dotted 166 * circle. If the terminal is not UTF-8, this will be replaced by a dot anyway. */ 167 #define BASE_CHARACTER_FOR_LONELY_COMBINING 0x25CC // dotted circle 168 #define MAX_COMBINING_CHARS 4 // both slang and ncurses support exactly 4 169 170 /* I think anything other than space (e.g. arrows) just introduce visual clutter without actually 171 * adding value. */ 172 #define PARTIAL_CJK_AT_LEFT_MARGIN ' ' 173 #define PARTIAL_CJK_AT_RIGHT_MARGIN ' ' 174 175 /* 176 * Wrap mode: This is for safety so that jumping to the end of file (which already includes 177 * scrolling back by a page) and then walking backwards is reasonably fast, even if the file is 178 * extremely large and consists of maybe full zeros or something like that. If there's no newline 179 * found within this limit, just start displaying from there and see what happens. We might get 180 * some displaying parameters (most importantly the columns) incorrect, but at least will show the 181 * file without spinning the CPU for ages. When scrolling back to that point, the user might see a 182 * garbled first line (even starting with an invalid partial UTF-8), but then walking back by yet 183 * another line should fix it. 184 * 185 * Unwrap mode: This is not used, we wouldn't be able to do anything reasonable without walking 186 * back a whole paragraph (well, view->data_area.height paragraphs actually). 187 */ 188 #define MAX_BACKWARDS_WALK_IN_PARAGRAPH (100 * 1000) 189 190 /*** file scope type declarations ****************************************************************/ 191 192 /*** forward declarations (file scope functions) *************************************************/ 193 194 /*** file scope variables ************************************************************************/ 195 196 /* --------------------------------------------------------------------------------------------- */ 197 /*** file scope functions ************************************************************************/ 198 /* --------------------------------------------------------------------------------------------- */ 199 200 /* TODO: These methods shouldn't be necessary, see ticket 3257 */ 201 202 static int 203 mcview_wcwidth (const WView *view, int c) /**/ 204 { 205 #ifdef HAVE_CHARSET 206 if (view->utf8) 207 { 208 if (g_unichar_iswide (c)) 209 return 2; 210 if (g_unichar_iszerowidth (c)) 211 return 0; 212 } 213 #else 214 (void) view; 215 (void) c; 216 #endif 217 return 1; 218 } 219 220 /* --------------------------------------------------------------------------------------------- */ 221 222 static gboolean 223 mcview_ismark (const WView *view, int c) /*
*/ 224 { 225 #ifdef HAVE_CHARSET 226 if (view->utf8) 227 return g_unichar_ismark (c); 228 #else 229 (void) view; 230 (void) c; 231 #endif 232 return FALSE; 233 } 234 235 /* --------------------------------------------------------------------------------------------- */ 236 237 /* actually is_non_spacing_mark_or_enclosing_mark */ 238 static gboolean 239 mcview_is_non_spacing_mark (const WView *view, int c) /*
*/ 240 { 241 #ifdef HAVE_CHARSET 242 if (view->utf8) 243 { 244 GUnicodeType type; 245 246 type = g_unichar_type (c); 247 248 return type == G_UNICODE_NON_SPACING_MARK || type == G_UNICODE_ENCLOSING_MARK; 249 } 250 #else 251 (void) view; 252 (void) c; 253 #endif 254 return FALSE; 255 } 256 257 /* --------------------------------------------------------------------------------------------- */ 258 259 #if 0 260 static gboolean 261 mcview_is_spacing_mark (const WView *view, int c) /*
*/ 262 { 263 # ifdef HAVE_CHARSET 264 if (view->utf8) 265 return g_unichar_type (c) == G_UNICODE_SPACING_MARK; 266 # else 267 (void) view; 268 (void) c; 269 # endif 270 return FALSE; 271 } 272 #endif 273 274 /* --------------------------------------------------------------------------------------------- */ 275 276 static gboolean 277 mcview_isprint (const WView *view, int c) /*
*/ 278 { 279 #ifdef HAVE_CHARSET 280 if (!view->utf8) 281 c = convert_from_8bit_to_utf_c ((unsigned char) c, view->converter); 282 return g_unichar_isprint (c); 283 #else 284 (void) view; 285 // TODO this is very-very buggy by design: ticket 3257 comments 0-1 286 return is_printable (c); 287 #endif 288 } 289 290 /* --------------------------------------------------------------------------------------------- */ 291 292 static int 293 mcview_char_display (const WView *view, int c, char *s) /*
*/ 294 { 295 #ifdef HAVE_CHARSET 296 if (mc_global.utf8_display) 297 { 298 if (!view->utf8) 299 c = convert_from_8bit_to_utf_c ((unsigned char) c, view->converter); 300 if (!g_unichar_isprint (c)) 301 c = '.'; 302 return g_unichar_to_utf8 (c, s); 303 } 304 if (view->utf8) 305 { 306 if (g_unichar_iswide (c)) 307 { 308 s[0] = s[1] = '.'; 309 return 2; 310 } 311 if (g_unichar_iszerowidth (c)) 312 return 0; 313 // TODO the is_printable check below will be broken for this 314 c = convert_from_utf_to_current_c (c, view->converter); 315 } 316 else 317 { 318 // TODO the is_printable check below will be broken for this 319 c = convert_to_display_c (c); 320 } 321 #else 322 (void) view; 323 #endif 324 // TODO this is very-very buggy by design: ticket 3257 comments 0-1 325 if (!is_printable (c)) 326 c = '.'; 327 *s = c; 328 return 1; 329 } 330 331 /* --------------------------------------------------------------------------------------------- */ 332 333 /** 334 * Just for convenience, a common interface in front of mcview_get_utf and mcview_get_byte, so that 335 * the caller doesn't have to care about utf8 vs 8-bit modes. 336 * 337 * Normally: stores c, updates state, returns TRUE. 338 * At EOF: state is unchanged, c is undefined, returns FALSE. 339 * 340 * Just as with mcview_get_utf(), invalid UTF-8 is reported using negative integers. 341 * 342 * Also, temporary hack: handle force_max here. 343 * TODO: move it to lower layers (datasource.c)? 344 */ 345 static gboolean 346 mcview_get_next_char (WView *view, mcview_state_machine_t *state, int *c) /*
*/ 347 { 348 // Pretend EOF if we reached force_max 349 if (view->force_max >= 0 && state->offset >= view->force_max) 350 return FALSE; 351 352 #ifdef HAVE_CHARSET 353 if (view->utf8) 354 { 355 int char_length = 0; 356 357 if (!mcview_get_utf (view, state->offset, c, &char_length)) 358 return FALSE; 359 // Pretend EOF if we crossed force_max 360 if (view->force_max >= 0 && state->offset + char_length > view->force_max) 361 return FALSE; 362 363 state->offset += char_length; 364 return TRUE; 365 } 366 #endif 367 if (!mcview_get_byte (view, state->offset, c)) 368 return FALSE; 369 state->offset++; 370 return TRUE; 371 } 372 373 /* --------------------------------------------------------------------------------------------- */ 374 /** 375 * This function parses the next nroff character and gives it to you along with its desired color, 376 * so you never have to care about nroff again. 377 * 378 * The nroff mode does the backspace trick for every single character (Unicode codepoint). At least 379 * that's what the GNU groff 1.22 package produces, and that's what less 458 expects. For 380 * double-wide characters (CJK), still only a single backspace is emitted. For combining accents 381 * and such, the print-backspace-print step is repeated for the base character and then for each 382 * accent separately. 383 * 384 * So, the right place for this layer is after the bytes are interpreted in UTF-8, but before 385 * joining a base character with its combining accents. 386 * 387 * Normally: stores c and color, updates state, returns TRUE. 388 * At EOF: state is unchanged, c and color are undefined, returns FALSE. 389 * 390 * color can be null if the caller doesn't care. 391 */ 392 static gboolean 393 mcview_get_next_maybe_nroff_char (WView *view, mcview_state_machine_t *state, int *c, int *color) /*
*/ 394 { 395 mcview_state_machine_t state_after_nroff; 396 int c2, c3; 397 398 if (color != NULL) 399 *color = VIEW_NORMAL_COLOR; 400 401 if (!view->mode_flags.nroff) 402 return mcview_get_next_char (view, state, c); 403 404 if (!mcview_get_next_char (view, state, c)) 405 return FALSE; 406 // Don't allow nroff formatting around CR, LF, TAB or other special chars 407 if (!mcview_isprint (view, *c)) 408 return TRUE; 409 410 state_after_nroff = *state; 411 412 if (!mcview_get_next_char (view, &state_after_nroff, &c2)) 413 return TRUE; 414 if (c2 != '\b') 415 return TRUE; 416 417 if (!mcview_get_next_char (view, &state_after_nroff, &c3)) 418 return TRUE; 419 if (!mcview_isprint (view, c3)) 420 return TRUE; 421 422 if (*c == '_' && c3 == '_') 423 { 424 *state = state_after_nroff; 425 if (color != NULL) 426 *color = 427 state->nroff_underscore_is_underlined ? VIEW_UNDERLINED_COLOR : VIEW_BOLD_COLOR; 428 } 429 else if (*c == c3) 430 { 431 *state = state_after_nroff; 432 state->nroff_underscore_is_underlined = FALSE; 433 if (color != NULL) 434 *color = VIEW_BOLD_COLOR; 435 } 436 else if (*c == '_') 437 { 438 *c = c3; 439 *state = state_after_nroff; 440 state->nroff_underscore_is_underlined = TRUE; 441 if (color != NULL) 442 *color = VIEW_UNDERLINED_COLOR; 443 } 444 445 return TRUE; 446 } 447 448 /* --------------------------------------------------------------------------------------------- */ 449 /** 450 * Get one base character, along with its combining or spacing mark characters. 451 * 452 * (A spacing mark is a character that extends the base character's width 1 into a combined 453 * character of width 2, yet these two character cells should not be separated. E.g. Devanagari 454 * <U+0939><U+094B>.) 455 * 456 * This method exists mainly for two reasons. One is to be able to tell if we fit on the current 457 * line or need to wrap to the next one. The other is that both slang and ncurses seem to require 458 * that the character and its combining marks are printed in a single call (or is it just a 459 * limitation of mc's wrapper to them?). 460 * 461 * For convenience, this method takes care of converting CR or CR+LF into LF. 462 * TODO this should probably happen later, when displaying the file? 463 * 464 * Normally: stores cs and color, updates state, returns >= 1 (entries in cs). 465 * At EOF: state is unchanged, cs and color are undefined, returns 0. 466 * 467 * @param view ... 468 * @param state the parser-formatter state machine's state, updated 469 * @param cs store the characters here 470 * @param clen the room available in cs (that is, at most clen-1 combining marks are allowed), must 471 * be at least 2 472 * @param color if non-NULL, store the color here, taken from the first codepoint's color 473 * @return the number of entries placed in cs, or 0 on EOF 474 */ 475 static int 476 mcview_next_combining_char_sequence (WView *view, mcview_state_machine_t *state, int *cs, int clen, /*
*/ 477 int *color) 478 { 479 int i = 1; 480 481 if (!mcview_get_next_maybe_nroff_char (view, state, cs, color)) 482 return 0; 483 484 // Process \r and \r\n newlines. 485 if (cs[0] == '\r') 486 { 487 int cnext; 488 489 mcview_state_machine_t state_after_crlf = *state; 490 if (mcview_get_next_maybe_nroff_char (view, &state_after_crlf, &cnext, NULL) 491 && cnext == '\n') 492 *state = state_after_crlf; 493 cs[0] = '\n'; 494 return 1; 495 } 496 497 // We don't want combining over non-printable characters. This includes '\n' and '\t' too. 498 if (!mcview_isprint (view, cs[0])) 499 return 1; 500 501 if (mcview_ismark (view, cs[0])) 502 { 503 if (!state->print_lonely_combining) 504 { 505 // First character is combining. Either just return it, ... 506 return 1; 507 } 508 else 509 { 510 // or place this (and subsequent combining ones) over a dotted circle. 511 cs[1] = cs[0]; 512 cs[0] = BASE_CHARACTER_FOR_LONELY_COMBINING; 513 i = 2; 514 } 515 } 516 517 if (mcview_wcwidth (view, cs[0]) == 2) 518 { 519 // Don't allow combining or spacing mark for wide characters, is this okay? 520 return 1; 521 } 522 523 /* Look for more combining chars. Either at most clen-1 zero-width combining chars, 524 * or at most 1 spacing mark. Is this logic correct? */ 525 for (; i < clen; i++) 526 { 527 mcview_state_machine_t state_after_combining; 528 529 state_after_combining = *state; 530 if (!mcview_get_next_maybe_nroff_char (view, &state_after_combining, &cs[i], NULL)) 531 return i; 532 if (!mcview_ismark (view, cs[i]) || !mcview_isprint (view, cs[i])) 533 return i; 534 if (g_unichar_type (cs[i]) == G_UNICODE_SPACING_MARK) 535 { 536 // Only allow as the first combining char. Stop processing in either case. 537 if (i == 1) 538 { 539 *state = state_after_combining; 540 i++; 541 } 542 return i; 543 } 544 *state = state_after_combining; 545 } 546 return i; 547 } 548 549 /* --------------------------------------------------------------------------------------------- */ 550 /** 551 * Parse, format and possibly display one visual line of text. 552 * 553 * Formatting starts at the given "state" (which encodes the file offset and parser and formatter's 554 * internal state). In unwrap mode, this should point to the beginning of the paragraph with the 555 * default state, the additional horizontal scrolling is added here. In wrap mode, this should 556 * point to the beginning of the line, with the proper state at that point. 557 * 558 * In wrap mode, if a line ends in a newline, it is consumed, even if it's exactly at the right 559 * edge. In unwrap mode, the whole remaining line, including the newline is consumed. Displaying 560 * the next line should start at "state"'s new value, or if we displayed the bottom line then 561 * state->offset tells the file offset to be shown in the top bar. 562 * 563 * If "row" is offscreen, don't actually display the line but still update "state" and return the 564 * proper value. This is used by mcview_wrap_move_down to advance in the file. 565 * 566 * @param view ... 567 * @param state the parser-formatter state machine's state, updated 568 * @param row print to this row 569 * @param paragraph_ended store TRUE if paragraph ended by newline or EOF, FALSE if wraps to next 570 * line 571 * @param linewidth store the width of the line here 572 * @return the number of rows, that is, 0 if we were already at EOF, otherwise 1 573 */ 574 static int 575 mcview_display_line (WView *view, mcview_state_machine_t *state, int row, gboolean *paragraph_ended, /*
*/ 576 off_t *linewidth) 577 { 578 const WRect *r = &view->data_area; 579 off_t dpy_text_column = view->mode_flags.wrap ? 0 : view->dpy_text_column; 580 int col = 0; 581 int cs[1 + MAX_COMBINING_CHARS]; 582 char str[(1 + MAX_COMBINING_CHARS) * UTF8_CHAR_LEN + 1]; 583 int i, j; 584 585 if (paragraph_ended != NULL) 586 *paragraph_ended = TRUE; 587 588 if (!view->mode_flags.wrap && (row < 0 || row >= r->lines) && linewidth == NULL) 589 { 590 /* Optimization: Fast forward to the end of the line, rather than carefully 591 * parsing and then not actually displaying it. */ 592 off_t eol; 593 int retval; 594 595 eol = mcview_eol (view, state->offset); 596 retval = (eol > state->offset) ? 1 : 0; 597 598 mcview_state_machine_init (state, eol); 599 return retval; 600 } 601 602 while (TRUE) 603 { 604 int charwidth = 0; 605 mcview_state_machine_t state_saved; 606 int n; 607 int color; 608 609 state_saved = *state; 610 n = mcview_next_combining_char_sequence (view, state, cs, 1 + MAX_COMBINING_CHARS, &color); 611 if (n == 0) 612 { 613 if (linewidth != NULL) 614 *linewidth = col; 615 return (col > 0) ? 1 : 0; 616 } 617 618 if (view->search_start <= state->offset && state->offset < view->search_end) 619 color = VIEW_SELECTED_COLOR; 620 621 if (cs[0] == '\n') 622 { 623 // New line: reset all formatting state for the next paragraph. 624 mcview_state_machine_init (state, state->offset); 625 if (linewidth != NULL) 626 *linewidth = col; 627 return 1; 628 } 629 630 if (mcview_is_non_spacing_mark (view, cs[0])) 631 { 632 // Lonely combining character. Probably leftover after too many combining chars. Just 633 // ignore. 634 continue; 635 } 636 637 // Nonprintable, or lonely spacing mark 638 if ((!mcview_isprint (view, cs[0]) || mcview_ismark (view, cs[0])) && cs[0] != '\t') 639 cs[0] = '.'; 640 641 for (i = 0; i < n; i++) 642 charwidth += mcview_wcwidth (view, cs[i]); 643 644 /* Adjust the width for TAB. It's handled below along with the normal characters, 645 * so that it's wrapped consistently with them, and is painted with the proper 646 * attributes (although currently it can't have a special color). */ 647 if (cs[0] == '\t') 648 { 649 charwidth = option_tab_spacing - state->unwrapped_column % option_tab_spacing; 650 state->print_lonely_combining = TRUE; 651 } 652 else 653 state->print_lonely_combining = FALSE; 654 655 /* In wrap mode only: We're done with this row if the character sequence wouldn't fit. 656 * Except if at the first column, because then it wouldn't fit in the next row either. 657 * In this extreme case let the unwrapped code below do its best to display it. */ 658 if (view->mode_flags.wrap && (off_t) col + charwidth > dpy_text_column + (off_t) r->cols 659 && col > 0) 660 { 661 *state = state_saved; 662 if (paragraph_ended != NULL) 663 *paragraph_ended = FALSE; 664 if (linewidth != NULL) 665 *linewidth = col; 666 return 1; 667 } 668 669 // Display, unless outside of the viewport. 670 if (row >= 0 && row < r->lines) 671 { 672 if ((off_t) col >= dpy_text_column 673 && (off_t) col + charwidth <= dpy_text_column + (off_t) r->cols) 674 { 675 // The combining character sequence fits entirely in the viewport. Print it. 676 tty_setcolor (color); 677 widget_gotoyx (view, r->y + row, r->x + ((off_t) col - dpy_text_column)); 678 if (cs[0] == '\t') 679 { 680 for (i = 0; i < charwidth; i++) 681 tty_print_char (' '); 682 } 683 else 684 { 685 j = 0; 686 for (i = 0; i < n; i++) 687 j += mcview_char_display (view, cs[i], str + j); 688 str[j] = '\0'; 689 /* This is probably a bug in our tty layer, but tty_print_string 690 * normalizes the string, whereas tty_printf doesn't. Don't normalize, 691 * since we handle combining characters ourselves correctly, it's 692 * better if they are copy-pasted correctly. Ticket 3255. */ 693 tty_printf ("%s", str); 694 } 695 } 696 else if ((off_t) col < dpy_text_column && (off_t) col + charwidth > dpy_text_column) 697 { 698 /* The combining character sequence would cross the left edge of the viewport. 699 * This cannot happen with wrap mode. Print replacement character(s), 700 * or spaces with the correct attributes for partial Tabs. */ 701 tty_setcolor (color); 702 for (i = dpy_text_column; 703 i < (off_t) col + charwidth && i < dpy_text_column + (off_t) r->cols; i++) 704 { 705 widget_gotoyx (view, r->y + row, r->x + (i - dpy_text_column)); 706 tty_print_anychar ((cs[0] == '\t') ? ' ' : PARTIAL_CJK_AT_LEFT_MARGIN); 707 } 708 } 709 else if ((off_t) col < dpy_text_column + (off_t) r->cols 710 && (off_t) col + charwidth > dpy_text_column + (off_t) r->cols) 711 { 712 /* The combining character sequence would cross the right edge of the viewport 713 * and we're not wrapping. Print replacement character(s), 714 * or spaces with the correct attributes for partial Tabs. */ 715 tty_setcolor (color); 716 for (i = col; i < dpy_text_column + (off_t) r->cols; i++) 717 { 718 widget_gotoyx (view, r->y + row, r->x + (i - dpy_text_column)); 719 tty_print_anychar ((cs[0] == '\t') ? ' ' : PARTIAL_CJK_AT_RIGHT_MARGIN); 720 } 721 } 722 } 723 724 col += charwidth; 725 state->unwrapped_column += charwidth; 726 727 if (!view->mode_flags.wrap && (off_t) col >= dpy_text_column + (off_t) r->cols 728 && linewidth == NULL) 729 { 730 /* Optimization: Fast forward to the end of the line, rather than carefully 731 * parsing and then not actually displaying it. */ 732 off_t eol; 733 734 eol = mcview_eol (view, state->offset); 735 mcview_state_machine_init (state, eol); 736 return 1; 737 } 738 } 739 } 740 741 /* --------------------------------------------------------------------------------------------- */ 742 /** 743 * Parse, format and possibly display one paragraph (perhaps not from the beginning). 744 * 745 * Formatting starts at the given "state" (which encodes the file offset and parser and formatter's 746 * internal state). In unwrap mode, this should point to the beginning of the paragraph with the 747 * default state, the additional horizontal scrolling is added here. In wrap mode, this may point 748 * to the beginning of the line within a paragraph (to display the partial paragraph at the top), 749 * with the proper state at that point. 750 * 751 * Displaying the next paragraph should start at "state"'s new value, or if we displayed the bottom 752 * line then state->offset tells the file offset to be shown in the top bar. 753 * 754 * If "row" is negative, don't display the first abs(row) lines and display the rest from the top. 755 * This was a nice idea but it's now unused :) 756 * 757 * If "row" is too large, don't display the paragraph at all but still return the number of lines. 758 * This is used when moving upwards. 759 * 760 * @param view ... 761 * @param state the parser-formatter state machine's state, updated 762 * @param row print starting at this row 763 * @return the number of rows the paragraphs is wrapped to, that is, 0 if we were already at EOF, 764 * otherwise 1 in unwrap mode, >= 1 in wrap mode. We stop when reaching the bottom of the 765 * viewport, it's not counted how many more lines the paragraph would occupy 766 */ 767 static int 768 mcview_display_paragraph (WView *view, mcview_state_machine_t *state, int row) /*
*/ 769 { 770 int lines = 0; 771 772 while (TRUE) 773 { 774 gboolean paragraph_ended; 775 776 lines += mcview_display_line (view, state, row, ¶graph_ended, NULL); 777 if (paragraph_ended) 778 return lines; 779 780 if (row < view->data_area.lines) 781 { 782 row++; 783 // stop if bottom of screen reached 784 if (row >= view->data_area.lines) 785 return lines; 786 } 787 } 788 } 789 790 /* --------------------------------------------------------------------------------------------- */ 791 /** 792 * Recompute dpy_state_top from dpy_start and dpy_paragraph_skip_lines. Clamp 793 * dpy_paragraph_skip_lines if necessary. 794 * 795 * This method should be called in wrap mode after changing one of the parsing or formatting 796 * properties (e.g. window width, encoding, nroff), or when switching to wrap mode from unwrap or 797 * hex. 798 * 799 * If we stayed within the same paragraph then try to keep the vertical offset within that 800 * paragraph as well. It might happen though that the paragraph became shorter than our desired 801 * vertical position, in that case move to its last row. 802 */ 803 static void 804 mcview_wrap_fixup (WView *view) /*
*/ 805 { 806 int lines = view->dpy_paragraph_skip_lines; 807 808 if (!view->dpy_wrap_dirty) 809 return; 810 view->dpy_wrap_dirty = FALSE; 811 812 view->dpy_paragraph_skip_lines = 0; 813 mcview_state_machine_init (&view->dpy_state_top, view->dpy_start); 814 815 while (lines-- != 0) 816 { 817 mcview_state_machine_t state_prev; 818 gboolean paragraph_ended; 819 820 state_prev = view->dpy_state_top; 821 if (mcview_display_line (view, &view->dpy_state_top, -1, ¶graph_ended, NULL) == 0) 822 break; 823 if (paragraph_ended) 824 { 825 view->dpy_state_top = state_prev; 826 break; 827 } 828 view->dpy_paragraph_skip_lines++; 829 } 830 } 831 832 /* --------------------------------------------------------------------------------------------- */ 833 /*** public functions ****************************************************************************/ 834 /* --------------------------------------------------------------------------------------------- */ 835 836 /** 837 * In both wrap and unwrap modes, dpy_start points to the beginning of the paragraph. 838 * 839 * In unwrap mode, start displaying from this position, probably applying an additional horizontal 840 * scroll. 841 * 842 * In wrap mode, an additional dpy_paragraph_skip_lines lines are skipped from the top of this 843 * paragraph. dpy_state_top contains the position and parser-formatter state corresponding to the 844 * top left corner so we can just start rendering from here. Unless dpy_wrap_dirty is set in which 845 * case dpy_state_top is invalid and we need to recompute first. 846 */ 847 void 848 mcview_display_text (WView *view) /*
*/ 849 { 850 const WRect *r = &view->data_area; 851 int row; 852 mcview_state_machine_t state; 853 gboolean again; 854 855 do 856 { 857 int n; 858 859 again = FALSE; 860 861 mcview_display_clean (view); 862 mcview_display_ruler (view); 863 864 if (!view->mode_flags.wrap) 865 mcview_state_machine_init (&state, view->dpy_start); 866 else 867 { 868 mcview_wrap_fixup (view); 869 state = view->dpy_state_top; 870 } 871 872 for (row = 0; row < r->lines; row += n) 873 { 874 n = mcview_display_paragraph (view, &state, row); 875 if (n == 0) 876 { 877 /* In the rare case that displaying didn't start at the beginning 878 * of the file, yet there are some empty lines at the bottom, 879 * scroll the file and display again. This happens when e.g. the 880 * window is made bigger, or the file becomes shorter due to 881 * charset change or enabling nroff. */ 882 if ((view->mode_flags.wrap ? view->dpy_state_top.offset : view->dpy_start) > 0) 883 { 884 mcview_ascii_move_up (view, r->lines - row); 885 again = TRUE; 886 } 887 break; 888 } 889 } 890 } 891 while (again); 892 893 view->dpy_end = state.offset; 894 view->dpy_state_bottom = state; 895 896 tty_setcolor (VIEW_NORMAL_COLOR); 897 if (mcview_show_eof != NULL && mcview_show_eof[0] != '\0') 898 while (row < r->lines) 899 { 900 widget_gotoyx (view, r->y + row, r->x); 901 // TODO: should make it no wider than the viewport 902 tty_print_string (mcview_show_eof); 903 row++; 904 } 905 } 906 907 /* --------------------------------------------------------------------------------------------- */ 908 /** 909 * Move down. 910 * 911 * It's very simple. Just invisibly format the next "lines" lines, carefully carrying the formatter 912 * state in wrap mode. But before each step we need to check if we've already hit the end of the 913 * file, in that case we can no longer move. This is done by walking from dpy_state_bottom. 914 * 915 * Note that this relies on mcview_display_text() setting dpy_state_bottom to its correct value 916 * upon rendering the screen contents. So don't call this function from other functions (e.g. at 917 * the bottom of mcview_ascii_move_up()) which invalidate this value. 918 */ 919 void 920 mcview_ascii_move_down (WView *view, off_t lines) /*
*/ 921 { 922 while (lines-- != 0) 923 { 924 gboolean paragraph_ended; 925 926 /* See if there's still data below the bottom line, by imaginarily displaying one 927 * more line. This takes care of reading more data into growbuf, if required. 928 * If the end position didn't advance, we're at EOF and hence bail out. */ 929 if (mcview_display_line (view, &view->dpy_state_bottom, -1, ¶graph_ended, NULL) == 0) 930 break; 931 932 /* Okay, there's enough data. Move by 1 row at the top, too. No need to check for 933 * EOF, that can't happen. */ 934 if (!view->mode_flags.wrap) 935 { 936 view->dpy_start = mcview_eol (view, view->dpy_start); 937 view->dpy_paragraph_skip_lines = 0; 938 view->dpy_wrap_dirty = TRUE; 939 } 940 else 941 { 942 mcview_display_line (view, &view->dpy_state_top, -1, ¶graph_ended, NULL); 943 if (!paragraph_ended) 944 view->dpy_paragraph_skip_lines++; 945 else 946 { 947 view->dpy_start = view->dpy_state_top.offset; 948 view->dpy_paragraph_skip_lines = 0; 949 } 950 } 951 } 952 } 953 954 /* --------------------------------------------------------------------------------------------- */ 955 /** 956 * Move up. 957 * 958 * Unwrap mode: Piece of cake. Wrap mode: If we'd walk back more than the current line offset 959 * within the paragraph, we need to jump back to the previous paragraph and compute its height to 960 * see if we start from that paragraph, and repeat this if necessary. Once we're within the desired 961 * paragraph, we still need to format it from its beginning to know the state. 962 * 963 * See the top of this file for comments about MAX_BACKWARDS_WALK_IN_PARAGRAPH. 964 * 965 * force_max is a nice protection against the rare extreme case that the file underneath us 966 * changes, we don't want to endlessly consume a file of maybe full of zeros upon moving upwards. 967 */ 968 void 969 mcview_ascii_move_up (WView *view, off_t lines) /*
*/ 970 { 971 if (!view->mode_flags.wrap) 972 { 973 while (lines-- != 0) 974 view->dpy_start = mcview_bol (view, view->dpy_start - 1, 0); 975 view->dpy_paragraph_skip_lines = 0; 976 view->dpy_wrap_dirty = TRUE; 977 } 978 else 979 { 980 int i; 981 982 while (lines > view->dpy_paragraph_skip_lines) 983 { 984 // We need to go back to the previous paragraph. 985 if (view->dpy_start == 0) 986 { 987 // Oops, we're already in the first paragraph. 988 view->dpy_paragraph_skip_lines = 0; 989 mcview_state_machine_init (&view->dpy_state_top, 0); 990 return; 991 } 992 lines -= view->dpy_paragraph_skip_lines; 993 view->force_max = view->dpy_start; 994 view->dpy_start = mcview_bol (view, view->dpy_start - 1, 995 view->dpy_start - MAX_BACKWARDS_WALK_IN_PARAGRAPH); 996 mcview_state_machine_init (&view->dpy_state_top, view->dpy_start); 997 /* This is a tricky way of denoting that we're at the end of the paragraph. 998 * Normally we'd jump to the next paragraph and reset paragraph_skip_lines. But for 999 * walking backwards this is exactly what we need. */ 1000 view->dpy_paragraph_skip_lines = 1001 mcview_display_paragraph (view, &view->dpy_state_top, view->data_area.lines); 1002 view->force_max = -1; 1003 } 1004 1005 /* Okay, we have have dpy_start pointing to the desired paragraph, and we still need to 1006 * walk back "lines" lines from the current "dpy_paragraph_skip_lines" offset. We can't do 1007 * that, so walk from the beginning of the paragraph. */ 1008 mcview_state_machine_init (&view->dpy_state_top, view->dpy_start); 1009 view->dpy_paragraph_skip_lines -= lines; 1010 for (i = 0; i < view->dpy_paragraph_skip_lines; i++) 1011 mcview_display_line (view, &view->dpy_state_top, -1, NULL, NULL); 1012 } 1013 } 1014 1015 /* --------------------------------------------------------------------------------------------- */ 1016 1017 void 1018 mcview_ascii_moveto_bol (WView *view) /*
*/ 1019 { 1020 if (!view->mode_flags.wrap) 1021 view->dpy_text_column = 0; 1022 } 1023 1024 /* --------------------------------------------------------------------------------------------- */ 1025 1026 void 1027 mcview_ascii_moveto_eol (WView *view) /*
*/ 1028 { 1029 if (!view->mode_flags.wrap) 1030 { 1031 mcview_state_machine_t state; 1032 off_t linewidth; 1033 1034 // Get the width of the topmost paragraph. 1035 mcview_state_machine_init (&state, view->dpy_start); 1036 mcview_display_line (view, &state, -1, NULL, &linewidth); 1037 view->dpy_text_column = DOZ (linewidth, (off_t) view->data_area.cols); 1038 } 1039 } 1040 1041 /* --------------------------------------------------------------------------------------------- */ 1042 1043 void 1044 mcview_state_machine_init (mcview_state_machine_t *state, off_t offset) /*
*/ 1045 { 1046 memset (state, 0, sizeof (*state)); 1047 state->offset = offset; 1048 state->print_lonely_combining = TRUE; 1049 } 1050 1051 /* --------------------------------------------------------------------------------------------- */