src/help.c

   1 /* Hypertext file browser.
   2    Copyright (C) 1994, 1995, 1998, 1999, 2000, 2001, 2002, 2003, 2004,
   3    2005, 2006, 2007 Free Software Foundation, Inc.
   4
   5    This program is free software; you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 2 of the License, or
   8    (at your option) any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program; if not, write to the Free Software
  17    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  */
  19
  20
  21 /** \file help.c
  22  *  \brief Source: hypertext file browser
  23  *
  24  *  Implements the hypertext file viewer.
  25  *  The hypertext file is a file that may have one or more nodes.  Each
  26  *  node ends with a ^D character and starts with a bracket, then the
  27  *  name of the node and then a closing bracket. Right after the closing
  28  *  bracket a newline is placed. This newline is not to be displayed by
  29  *  the help viewer and must be skipped - its sole purpose is to faciliate
  30  *  the work of the people managing the help file template (xnc.hlp) .
  31  *
  32  *  Links in the hypertext file are specified like this: the text that
  33  *  will be highlighted should have a leading ^A, then it comes the
  34  *  text, then a ^B indicating that highlighting is done, then the name
  35  *  of the node you want to link to and then a ^C.
  36  *
  37  *  The file must contain a ^D at the beginning and at the end of the
  38  *  file or the program will not be able to detect the end of file.
  39  *
  40  *  Lazyness/widgeting attack: This file does use the dialog manager
  41  *  and uses mainly the dialog to achieve the help work.  there is only
  42  *  one specialized widget and it's only used to forward the mouse messages
  43  *  to the appropiate routine.
  44  */
  45
  46
  47 #include <config.h>
  48
  49 #include <errno.h>
  50 #include <stdio.h>
  51 #include <sys/types.h>
  52 #include <sys/stat.h>
  53
  54 #include "lib/global.h"
  55
  56 #include "lib/tty/tty.h"
  57 #include "lib/tty/mouse.h"
  58 #include "lib/skin.h"
  59 #include "lib/strutil.h"
  60 #include "lib/fileloc.h"
  61 #include "lib/util.h"
  62 #include "lib/widget.h"
  63
  64 #include "keybind-defaults.h"
  65 #include "keybind-defaults.h"
  66 #include "help.h"
  67 #include "main.h"
  68
  69 /*** global variables ****************************************************************************/
  70
  71 /*** file scope macro definitions ****************************************************************/
  72
  73 #define MAXLINKNAME 80
  74 #define HISTORY_SIZE 20
  75 #define HELP_WINDOW_WIDTH min(80, COLS - 16)
  76
  77 #define STRING_LINK_START       "\01"
  78 #define STRING_LINK_POINTER     "\02"
  79 #define STRING_LINK_END         "\03"
  80 #define STRING_NODE_END         "\04"
  81
  82 /*** file scope type declarations ****************************************************************/
  83
  84 /* Link areas for the mouse */
  85 typedef struct Link_Area
  86 {
  87     int x1, y1, x2, y2;
  88     const char *link_name;
  89 } Link_Area;
  90
  91 /*** file scope variables ************************************************************************/
  92
  93 static char *fdata = NULL;      /* Pointer to the loaded data file */
  94 static int help_lines;          /* Lines in help viewer */
  95 static int history_ptr;         /* For the history queue */
  96 static const char *main_node;   /* The main node */
  97 static const char *last_shown = NULL;   /* Last byte shown in a screen */
  98 static gboolean end_of_node = FALSE;    /* Flag: the last character of the node shown? */
  99 static const char *currentpoint;
 100 static const char *selected_item;
 101
 102 /* The widget variables */
 103 static Dlg_head *whelp;
 104
 105 static struct
 106 {
 107     const char *page;           /* Pointer to the selected page */
 108     const char *link;           /* Pointer to the selected link */
 109 } history[HISTORY_SIZE];
 110
 111 static GSList *link_area = NULL;
 112 static gboolean inside_link_area = FALSE;
 113
 114 static cb_ret_t help_callback (Dlg_head * h, Widget * sender, dlg_msg_t msg, int parm, void *data);
 115
 116 /*** file scope functions ************************************************************************/
 117 /* --------------------------------------------------------------------------------------------- */
 118
 119 /** returns the position where text was found in the start buffer
 120  * or 0 if not found
 121  */
 122 static const char *
 123 search_string (const char *start, const char *text)
 124 {
 125     const char *result = NULL;
 126     char *local_text = g_strdup (text);
 127     char *d = local_text;
 128     const char *e = start;
 129
 130     /* fmt sometimes replaces a space with a newline in the help file */
 131     /* Replace the newlines in the link name with spaces to correct the situation */
 132     while (*d != '\0')
 133     {
 134         if (*d == '\n')
 135             *d = ' ';
 136         str_next_char (&d);
 137     }
 138
 139     /* Do search */
 140     for (d = local_text; *e; e++)
 141     {
 142         if (*d == *e)
 143             d++;
 144         else
 145             d = local_text;
 146         if (*d == '\0')
 147         {
 148             result = e + 1;
 149             break;
 150         }
 151     }
 152
 153     g_free (local_text);
 154     return result;
 155 }
 156
 157 /* --------------------------------------------------------------------------------------------- */
 158 /** Searches text in the buffer pointed by start.  Search ends
 159  * if the CHAR_NODE_END is found in the text.
 160  * @returns 0 on failure
 161  */
 162
 163 static const char *
 164 search_string_node (const char *start, const char *text)
 165 {
 166     const char *d = text;
 167     const char *e = start;
 168
 169     if (start != NULL)
 170         for (; *e && *e != CHAR_NODE_END; e++)
 171         {
 172             if (*d == *e)
 173                 d++;
 174             else
 175                 d = text;
 176             if (*d == '\0')
 177                 return e + 1;
 178         }
 179
 180     return NULL;
 181 }
 182
 183 /* --------------------------------------------------------------------------------------------- */
 184 /** Searches the_char in the buffer pointer by start and searches
 185  * it can search forward (direction = 1) or backward (direction = -1)
 186  */
 187
 188 static const char *
 189 search_char_node (const char *start, char the_char, int direction)
 190 {
 191     const char *e;
 192
 193     for (e = start; (*e != '\0') && (*e != CHAR_NODE_END); e += direction)
 194         if (*e == the_char)
 195             return e;
 196
 197     return NULL;
 198 }
 199
 200 /* --------------------------------------------------------------------------------------------- */
 201 /** Returns the new current pointer when moved lines lines */
 202
 203 static const char *
 204 move_forward2 (const char *c, int lines)
 205 {
 206     const char *p;
 207     int line;
 208
 209     currentpoint = c;
 210     for (line = 0, p = currentpoint; (*p != '\0') && (*p != CHAR_NODE_END); str_cnext_char (&p))
 211     {
 212         if (line == lines)
 213             return currentpoint = p;
 214
 215         if (*p == '\n')
 216             line++;
 217     }
 218     return currentpoint = c;
 219 }
 220
 221 /* --------------------------------------------------------------------------------------------- */
 222
 223 static const char *
 224 move_backward2 (const char *c, int lines)
 225 {
 226     const char *p;
 227     int line;
 228
 229     currentpoint = c;
 230     for (line = 0, p = currentpoint; (*p != '\0') && ((int) (p - fdata) >= 0); str_cprev_char (&p))
 231     {
 232         if (*p == CHAR_NODE_END)
 233         {
 234             /* We reached the beginning of the node */
 235             /* Skip the node headers */
 236             while (*p != ']')
 237                 str_cnext_char (&p);
 238             return currentpoint = p + 2;        /* Skip the newline following the start of the node */
 239         }
 240
 241         if (*(p - 1) == '\n')
 242             line++;
 243         if (line == lines)
 244             return currentpoint = p;
 245     }
 246     return currentpoint = c;
 247 }
 248
 249 /* --------------------------------------------------------------------------------------------- */
 250
 251 static void
 252 move_forward (int i)
 253 {
 254     if (!end_of_node)
 255         currentpoint = move_forward2 (currentpoint, i);
 256 }
 257
 258 /* --------------------------------------------------------------------------------------------- */
 259
 260 static void
 261 move_backward (int i)
 262 {
 263     currentpoint = move_backward2 (currentpoint, ++i);
 264 }
 265
 266 /* --------------------------------------------------------------------------------------------- */
 267
 268 static void
 269 move_to_top (void)
 270 {
 271     while (((int) (currentpoint > fdata) > 0) && (*currentpoint != CHAR_NODE_END))
 272         currentpoint--;
 273
 274     while (*currentpoint != ']')
 275         currentpoint++;
 276     currentpoint = currentpoint + 2;    /* Skip the newline following the start of the node */
 277     selected_item = NULL;
 278 }
 279
 280 /* --------------------------------------------------------------------------------------------- */
 281
 282 static void
 283 move_to_bottom (void)
 284 {
 285     while ((*currentpoint != '\0') && (*currentpoint != CHAR_NODE_END))
 286         currentpoint++;
 287     currentpoint--;
 288     move_backward (1);
 289 }
 290
 291 /* --------------------------------------------------------------------------------------------- */
 292
 293 static const char *
 294 help_follow_link (const char *start, const char *lc_selected_item)
 295 {
 296     char link_name[MAXLINKNAME];
 297     const char *p;
 298     int i = 0;
 299
 300     if (lc_selected_item == NULL)
 301         return start;
 302
 303     for (p = lc_selected_item; *p && *p != CHAR_NODE_END && *p != CHAR_LINK_POINTER; p++)
 304         ;
 305     if (*p == CHAR_LINK_POINTER)
 306     {
 307         link_name[0] = '[';
 308         for (i = 1; *p != CHAR_LINK_END && *p && *p != CHAR_NODE_END && i < MAXLINKNAME - 3;)
 309             link_name[i++] = *++p;
 310         link_name[i - 1] = ']';
 311         link_name[i] = '\0';
 312         p = search_string (fdata, link_name);
 313         if (p != NULL)
 314         {
 315             p += 1;             /* Skip the newline following the start of the node */
 316             return p;
 317         }
 318     }
 319
 320     /* Create a replacement page with the error message */
 321     return _("Help file format error\n");
 322 }
 323
 324 /* --------------------------------------------------------------------------------------------- */
 325
 326 static const char *
 327 select_next_link (const char *current_link)
 328 {
 329     const char *p;
 330
 331     if (current_link == NULL)
 332         return NULL;
 333
 334     p = search_string_node (current_link, STRING_LINK_END);
 335     if (p == NULL)
 336         return NULL;
 337     p = search_string_node (p, STRING_LINK_START);
 338     if (p == NULL)
 339         return NULL;
 340     return p - 1;
 341 }
 342
 343 /* --------------------------------------------------------------------------------------------- */
 344
 345 static const char *
 346 select_prev_link (const char *current_link)
 347 {
 348     return current_link == NULL ? NULL : search_char_node (current_link - 1, CHAR_LINK_START, -1);
 349 }
 350
 351 /* --------------------------------------------------------------------------------------------- */
 352
 353 static void
 354 start_link_area (int x, int y, const char *link_name)
 355 {
 356     Link_Area *la;
 357
 358     if (inside_link_area)
 359         message (D_NORMAL, _("Warning"), _("Internal bug: Double start of link area"));
 360
 361     /* Allocate memory for a new link area */
 362     la = g_new (Link_Area, 1);
 363     /* Save the beginning coordinates of the link area */
 364     la->x1 = x;
 365     la->y1 = y;
 366     /* Save the name of the destination anchor */
 367     la->link_name = link_name;
 368     link_area = g_slist_prepend (link_area, la);
 369
 370     inside_link_area = TRUE;
 371 }
 372
 373 /* --------------------------------------------------------------------------------------------- */
 374
 375 static void
 376 end_link_area (int x, int y)
 377 {
 378     if (inside_link_area)
 379     {
 380         Link_Area *la = (Link_Area *) link_area->data;
 381         /* Save the end coordinates of the link area */
 382         la->x2 = x;
 383         la->y2 = y;
 384         inside_link_area = FALSE;
 385     }
 386 }
 387
 388 /* --------------------------------------------------------------------------------------------- */
 389
 390 static void
 391 clear_link_areas (void)
 392 {
 393     g_slist_foreach (link_area, (GFunc) g_free, NULL);
 394     g_slist_free (link_area);
 395     link_area = NULL;
 396     inside_link_area = FALSE;
 397 }
 398
 399 /* --------------------------------------------------------------------------------------------- */
 400
 401 static void
 402 help_print_word (Dlg_head * h, GString * word, int *col, int *line, gboolean add_space)
 403 {
 404     if (*line >= help_lines)
 405         g_string_set_size (word, 0);
 406     else
 407     {
 408         int w;
 409
 410         w = str_term_width1 (word->str);
 411         if (*col + w >= HELP_WINDOW_WIDTH)
 412         {
 413             *col = 0;
 414             (*line)++;
 415         }
 416
 417         if (*line >= help_lines)
 418             g_string_set_size (word, 0);
 419         else
 420         {
 421             dlg_move (h, *line + 2, *col + 2);
 422             tty_print_string (word->str);
 423             g_string_set_size (word, 0);
 424             *col += w;
 425         }
 426     }
 427
 428     if (add_space)
 429     {
 430         if (*col < HELP_WINDOW_WIDTH - 1)
 431         {
 432             tty_print_char (' ');
 433             (*col)++;
 434         }
 435         else
 436         {
 437             *col = 0;
 438             (*line)++;
 439         }
 440     }
 441 }
 442
 443 /* --------------------------------------------------------------------------------------------- */
 444
 445 static void
 446 help_show (Dlg_head * h, const char *paint_start)
 447 {
 448     const char *p, *n;
 449     int col, line, c;
 450     gboolean painting = TRUE;
 451     gboolean acs;               /* Flag: Alternate character set active? */
 452     gboolean repeat_paint;
 453     int active_col, active_line;        /* Active link position */
 454     char buff[MB_LEN_MAX + 1];
 455     GString *word;
 456
 457     word = g_string_sized_new (32);
 458
 459     tty_setcolor (HELP_NORMAL_COLOR);
 460     do
 461     {
 462         line = col = active_col = active_line = 0;
 463         repeat_paint = FALSE;
 464         acs = FALSE;
 465
 466         clear_link_areas ();
 467         if ((int) (selected_item - paint_start) < 0)
 468             selected_item = NULL;
 469
 470         p = paint_start;
 471         n = paint_start;
 472         while ((n[0] != '\0') && (n[0] != CHAR_NODE_END) && (line < help_lines))
 473         {
 474             p = n;
 475             n = str_cget_next_char (p);
 476             memcpy (buff, p, n - p);
 477             buff[n - p] = '\0';
 478
 479             c = (unsigned char) buff[0];
 480             switch (c)
 481             {
 482             case CHAR_LINK_START:
 483                 if (selected_item == NULL)
 484                     selected_item = p;
 485                 if (p != selected_item)
 486                     tty_setcolor (HELP_LINK_COLOR);
 487                 else
 488                 {
 489                     tty_setcolor (HELP_SLINK_COLOR);
 490
 491                     /* Store the coordinates of the link */
 492                     active_col = col + 2;
 493                     active_line = line + 2;
 494                 }
 495                 start_link_area (col, line, p);
 496                 break;
 497             case CHAR_LINK_POINTER:
 498                 painting = FALSE;
 499                 end_link_area (col - 1, line);
 500                 break;
 501             case CHAR_LINK_END:
 502                 painting = TRUE;
 503                 help_print_word (h, word, &col, &line, FALSE);
 504                 tty_setcolor (HELP_NORMAL_COLOR);
 505                 break;
 506             case CHAR_ALTERNATE:
 507                 acs = TRUE;
 508                 break;
 509             case CHAR_NORMAL:
 510                 acs = FALSE;
 511                 break;
 512             case CHAR_VERSION:
 513                 dlg_move (h, line + 2, col + 2);
 514                 tty_print_string (VERSION);
 515                 col += str_term_width1 (VERSION);
 516                 break;
 517             case CHAR_FONT_BOLD:
 518                 tty_setcolor (HELP_BOLD_COLOR);
 519                 break;
 520             case CHAR_FONT_ITALIC:
 521                 tty_setcolor (HELP_ITALIC_COLOR);
 522                 break;
 523             case CHAR_FONT_NORMAL:
 524                 help_print_word (h, word, &col, &line, FALSE);
 525                 tty_setcolor (HELP_NORMAL_COLOR);
 526                 break;
 527             case '\n':
 528                 if (painting)
 529                     help_print_word (h, word, &col, &line, FALSE);
 530                 line++;
 531                 col = 0;
 532                 break;
 533             case '\t':
 534                 col = (col / 8 + 1) * 8;
 535                 if (col >= HELP_WINDOW_WIDTH)
 536                 {
 537                     line++;
 538                     col = 8;
 539                 }
 540                 break;
 541             case ' ':
 542                 /* word delimeter */
 543                 if (painting)
 544                     help_print_word (h, word, &col, &line, TRUE);
 545                 break;
 546             default:
 547                 if (painting && (line < help_lines))
 548                 {
 549                     if (!acs)
 550                         /* accumulate symbols in a word */
 551                         g_string_append (word, buff);
 552                     else if (col < HELP_WINDOW_WIDTH)
 553                     {
 554                         dlg_move (h, line + 2, col + 2);
 555
 556                         if ((c == ' ') || (c == '.'))
 557                             tty_print_char (c);
 558                         else
 559 #ifndef HAVE_SLANG
 560                             tty_print_char (acs_map[c]);
 561 #else
 562                             SLsmg_draw_object (h->y + line + 2, h->x + col + 2, c);
 563 #endif
 564                         col++;
 565                     }
 566                 }
 567             }
 568         }
 569
 570         /* print last word */
 571         if (n[0] == CHAR_NODE_END)
 572             help_print_word (h, word, &col, &line, FALSE);
 573
 574         last_shown = p;
 575         end_of_node = line < help_lines;
 576         tty_setcolor (HELP_NORMAL_COLOR);
 577         if ((int) (selected_item - last_shown) >= 0)
 578         {
 579             if ((link_area == NULL) || (link_area->data == NULL))
 580                 selected_item = NULL;
 581             else
 582             {
 583                 selected_item = ((Link_Area *) link_area->data)->link_name;
 584                 repeat_paint = TRUE;
 585             }
 586         }
 587     }
 588     while (repeat_paint);
 589
 590     g_string_free (word, TRUE);
 591
 592     /* Position the cursor over a nice link */
 593     if (active_col)
 594         dlg_move (h, active_line, active_col);
 595 }
 596
 597 /* --------------------------------------------------------------------------------------------- */
 598
 599 static int
 600 help_event (Gpm_Event * event, void *vp)
 601 {
 602     Widget *w = vp;
 603     GSList *current_area;
 604
 605     if ((event->type & GPM_UP) == 0)
 606         return 0;
 607
 608     /* The event is relative to the dialog window, adjust it: */
 609     event->x -= 2;
 610     event->y -= 2;
 611
 612     if (event->buttons & GPM_B_RIGHT)
 613     {
 614         currentpoint = history[history_ptr].page;
 615         selected_item = history[history_ptr].link;
 616         history_ptr--;
 617         if (history_ptr < 0)
 618             history_ptr = HISTORY_SIZE - 1;
 619
 620         help_callback (w->owner, NULL, DLG_DRAW, 0, NULL);
 621         return 0;
 622     }
 623
 624     /* Test whether the mouse click is inside one of the link areas */
 625     for (current_area = link_area; current_area != NULL; current_area = g_slist_next (current_area))
 626     {
 627         Link_Area *la = (Link_Area *) current_area->data;
 628         /* Test one line link area */
 629         if (event->y == la->y1 && event->x >= la->x1 && event->y == la->y2 && event->x <= la->x2)
 630             break;
 631         /* Test two line link area */
 632         if (la->y1 + 1 == la->y2)
 633         {
 634             /* The first line */
 635             if (event->y == la->y1 && event->x >= la->x1)
 636                 break;
 637             /* The second line */
 638             if (event->y == la->y2 && event->x <= la->x2)
 639                 break;
 640         }
 641         /* Mouse will not work with link areas of more than two lines */
 642     }
 643
 644     /* Test whether a link area was found */
 645     if (current_area != NULL)
 646     {
 647         Link_Area *la = (Link_Area *) current_area->data;
 648
 649         /* The click was inside a link area -> follow the link */
 650         history_ptr = (history_ptr + 1) % HISTORY_SIZE;
 651         history[history_ptr].page = currentpoint;
 652         history[history_ptr].link = la->link_name;
 653         currentpoint = help_follow_link (currentpoint, la->link_name);
 654         selected_item = NULL;
 655     }
 656     else if (event->y < 0)
 657         move_backward (help_lines - 1);
 658     else if (event->y >= help_lines)
 659         move_forward (help_lines - 1);
 660     else if (event->y < help_lines / 2)
 661         move_backward (1);
 662     else
 663         move_forward (1);
 664
 665     /* Show the new node */
 666     help_callback (w->owner, NULL, DLG_DRAW, 0, NULL);
 667
 668     return 0;
 669 }
 670
 671 /* --------------------------------------------------------------------------------------------- */
 672 /** show help */
 673
 674 static void
 675 help_help (Dlg_head * h)
 676 {
 677     const char *p;
 678
 679     history_ptr = (history_ptr + 1) % HISTORY_SIZE;
 680     history[history_ptr].page = currentpoint;
 681     history[history_ptr].link = selected_item;
 682
 683     p = search_string (fdata, "[How to use help]");
 684     if (p != NULL)
 685     {
 686         currentpoint = p + 1;   /* Skip the newline following the start of the node */
 687         selected_item = NULL;
 688         help_callback (h, NULL, DLG_DRAW, 0, NULL);
 689     }
 690 }
 691
 692 /* --------------------------------------------------------------------------------------------- */
 693
 694 static void
 695 help_index (Dlg_head * h)
 696 {
 697     const char *new_item;
 698
 699     new_item = search_string (fdata, "[Contents]");
 700
 701     if (new_item == NULL)
 702         message (D_ERROR, MSG_ERROR, _("Cannot find node %s in help file"), "[Contents]");
 703     else
 704     {
 705         history_ptr = (history_ptr + 1) % HISTORY_SIZE;
 706         history[history_ptr].page = currentpoint;
 707         history[history_ptr].link = selected_item;
 708
 709         currentpoint = new_item + 1;    /* Skip the newline following the start of the node */
 710         selected_item = NULL;
 711         help_callback (h, NULL, DLG_DRAW, 0, NULL);
 712     }
 713 }
 714
 715 /* --------------------------------------------------------------------------------------------- */
 716
 717 static void
 718 help_back (Dlg_head * h)
 719 {
 720     currentpoint = history[history_ptr].page;
 721     selected_item = history[history_ptr].link;
 722     history_ptr--;
 723     if (history_ptr < 0)
 724         history_ptr = HISTORY_SIZE - 1;
 725
 726     help_callback (h, NULL, DLG_DRAW, 0, NULL); /* FIXME: unneeded? */
 727 }
 728
 729 /* --------------------------------------------------------------------------------------------- */
 730
 731 static void
 732 help_next_link (gboolean move_down)
 733 {
 734     const char *new_item;
 735
 736     new_item = select_next_link (selected_item);
 737     if (new_item != NULL)
 738     {
 739         selected_item = new_item;
 740         if ((int) (selected_item - last_shown) >= 0)
 741         {
 742             if (move_down)
 743                 move_forward (1);
 744             else
 745                 selected_item = NULL;
 746         }
 747     }
 748     else if (move_down)
 749         move_forward (1);
 750     else
 751         selected_item = NULL;
 752 }
 753
 754 /* --------------------------------------------------------------------------------------------- */
 755
 756 static void
 757 help_prev_link (gboolean move_up)
 758 {
 759     const char *new_item;
 760
 761     new_item = select_prev_link (selected_item);
 762     selected_item = new_item;
 763     if ((selected_item == NULL) || (selected_item < currentpoint))
 764     {
 765         if (move_up)
 766             move_backward (1);
 767         else if ((link_area != NULL) && (link_area->data != NULL))
 768             selected_item = ((Link_Area *) link_area->data)->link_name;
 769         else
 770             selected_item = NULL;
 771     }
 772 }
 773
 774 /* --------------------------------------------------------------------------------------------- */
 775
 776 static void
 777 help_next_node (void)
 778 {
 779     const char *new_item;
 780
 781     new_item = currentpoint;
 782     while ((*new_item != '\0') && (*new_item != CHAR_NODE_END))
 783         new_item++;
 784
 785     if (*++new_item == '[')
 786         while (*++new_item != '\0')
 787             if ((*new_item == ']') && (*++new_item != '\0') && (*++new_item != '\0'))
 788             {
 789                 currentpoint = new_item;
 790                 selected_item = NULL;
 791                 break;
 792             }
 793 }
 794
 795 /* --------------------------------------------------------------------------------------------- */
 796
 797 static void
 798 help_prev_node (void)
 799 {
 800     const char *new_item;
 801
 802     new_item = currentpoint;
 803     while (((int) (new_item - fdata) > 1) && (*new_item != CHAR_NODE_END))
 804         new_item--;
 805     new_item--;
 806     while (((int) (new_item - fdata) > 0) && (*new_item != CHAR_NODE_END))
 807         new_item--;
 808     while (*new_item != ']')
 809         new_item++;
 810     currentpoint = new_item + 2;
 811     selected_item = NULL;
 812 }
 813
 814 /* --------------------------------------------------------------------------------------------- */
 815
 816 static void
 817 help_select_link (void)
 818 {
 819     /* follow link */
 820     if (selected_item == NULL)
 821     {
 822 #ifdef WE_WANT_TO_GO_BACKWARD_ON_KEY_RIGHT
 823         /* Is there any reason why the right key would take us
 824          * backward if there are no links selected?, I agree
 825          * with Torben than doing nothing in this case is better
 826          */
 827         /* If there are no links, go backward in history */
 828         history_ptr--;
 829         if (history_ptr < 0)
 830             history_ptr = HISTORY_SIZE - 1;
 831
 832         currentpoint = history[history_ptr].page;
 833         selected_item = history[history_ptr].link;
 834 #endif
 835     }
 836     else
 837     {
 838         history_ptr = (history_ptr + 1) % HISTORY_SIZE;
 839         history[history_ptr].page = currentpoint;
 840         history[history_ptr].link = selected_item;
 841         currentpoint = help_follow_link (currentpoint, selected_item);
 842     }
 843
 844     selected_item = NULL;
 845 }
 846
 847 /* --------------------------------------------------------------------------------------------- */
 848
 849 static cb_ret_t
 850 help_execute_cmd (unsigned long command)
 851 {
 852     cb_ret_t ret = MSG_HANDLED;
 853
 854     switch (command)
 855     {
 856     case CK_HelpHelp:
 857         help_help (whelp);
 858         break;
 859     case CK_HelpIndex:
 860         help_index (whelp);
 861         break;
 862     case CK_HelpBack:
 863         help_back (whelp);
 864         break;
 865     case CK_HelpMoveUp:
 866         help_prev_link (TRUE);
 867         break;
 868     case CK_HelpMoveDown:
 869         help_next_link (TRUE);
 870         break;
 871     case CK_HelpMovePgDn:
 872         move_forward (help_lines - 1);
 873         break;
 874     case CK_HelpMovePgUp:
 875         move_backward (help_lines - 1);
 876         break;
 877     case CK_HelpMoveHalfPgDn:
 878         move_forward (help_lines / 2);
 879         break;
 880     case CK_HelpMoveHalfPgUp:
 881         move_backward (help_lines / 2);
 882         break;
 883     case CK_HelpMoveTop:
 884         move_to_top ();
 885         break;
 886     case CK_HelpMoveBottom:
 887         move_to_bottom ();
 888         break;
 889     case CK_HelpSelectLink:
 890         help_select_link ();
 891         break;
 892     case CK_HelpNextLink:
 893         help_next_link (FALSE);
 894         break;
 895     case CK_HelpPrevLink:
 896         help_prev_link (FALSE);
 897         break;
 898     case CK_HelpNextNode:
 899         help_next_node ();
 900         break;
 901     case CK_HelpPrevNode:
 902         help_prev_node ();
 903         break;
 904     case CK_HelpQuit:
 905         dlg_stop (whelp);
 906         break;
 907     default:
 908         ret = MSG_NOT_HANDLED;
 909     }
 910
 911     return ret;
 912 }
 913
 914 /* --------------------------------------------------------------------------------------------- */
 915
 916 static cb_ret_t
 917 help_handle_key (Dlg_head * h, int c)
 918 {
 919     unsigned long command;
 920
 921     command = keybind_lookup_keymap_command (help_map, c);
 922     if ((command == CK_Ignore_Key) || (help_execute_cmd (command) == MSG_NOT_HANDLED))
 923         return MSG_NOT_HANDLED;
 924
 925     help_callback (h, NULL, DLG_DRAW, 0, NULL);
 926     return MSG_HANDLED;
 927 }
 928
 929 /* --------------------------------------------------------------------------------------------- */
 930
 931 static cb_ret_t
 932 help_callback (Dlg_head * h, Widget * sender, dlg_msg_t msg, int parm, void *data)
 933 {
 934     WButtonBar *bb;
 935
 936     switch (msg)
 937     {
 938     case DLG_RESIZE:
 939         help_lines = min (LINES - 4, max (2 * LINES / 3, 18));
 940         dlg_set_size (h, help_lines + 4, HELP_WINDOW_WIDTH + 4);
 941         bb = find_buttonbar (h);
 942         widget_set_size (&bb->widget, LINES - 1, 0, 1, COLS);
 943         return MSG_HANDLED;
 944
 945     case DLG_DRAW:
 946         common_dialog_repaint (h);
 947         help_show (h, currentpoint);
 948         return MSG_HANDLED;
 949
 950     case DLG_KEY:
 951         return help_handle_key (h, parm);
 952
 953     case DLG_ACTION:
 954         /* command from buttonbar */
 955         return help_execute_cmd (parm);
 956
 957     default:
 958         return default_dlg_callback (h, sender, msg, parm, data);
 959     }
 960 }
 961
 962 /* --------------------------------------------------------------------------------------------- */
 963
 964 static void
 965 interactive_display_finish (void)
 966 {
 967     clear_link_areas ();
 968 }
 969
 970 /* --------------------------------------------------------------------------------------------- */
 971 /** translate help file into terminal encoding */
 972
 973 static void
 974 translate_file (char *filedata)
 975 {
 976     GIConv conv;
 977     GString *translated_data;
 978
 979     /* initial allocation for largest whole help file */
 980     translated_data = g_string_sized_new (32 * 1024);
 981
 982     conv = str_crt_conv_from ("UTF-8");
 983
 984     if (conv == INVALID_CONV)
 985         g_string_free (translated_data, TRUE);
 986     else
 987     {
 988         g_free (fdata);
 989
 990         if (str_convert (conv, filedata, translated_data) != ESTR_FAILURE)
 991             fdata = g_string_free (translated_data, FALSE);
 992         else
 993         {
 994             fdata = NULL;
 995             g_string_free (translated_data, TRUE);
 996         }
 997         str_close_conv (conv);
 998     }
 999 }
1000
1001 /* --------------------------------------------------------------------------------------------- */
1002
1003 static cb_ret_t
1004 md_callback (Widget * w, widget_msg_t msg, int parm)
1005 {
1006     switch (msg)
1007     {
1008     case WIDGET_RESIZED:
1009         w->lines = help_lines;
1010         return MSG_HANDLED;
1011
1012     default:
1013         return default_proc (msg, parm);
1014     }
1015 }
1016
1017 /* --------------------------------------------------------------------------------------------- */
1018
1019 static Widget *
1020 mousedispatch_new (int y, int x, int yl, int xl)
1021 {
1022     Widget *w = g_new (Widget, 1);
1023     init_widget (w, y, x, yl, xl, md_callback, help_event);
1024     return w;
1025 }
1026
1027 /* --------------------------------------------------------------------------------------------- */
1028 /*** public functions ****************************************************************************/
1029 /* --------------------------------------------------------------------------------------------- */
1030
1031 void
1032 interactive_display (const char *filename, const char *node)
1033 {
1034     const dlg_colors_t help_colors = {
1035         HELP_NORMAL_COLOR,      /* common text color */
1036         0,                      /* unused in help */
1037         HELP_BOLD_COLOR,        /* bold text color */
1038         0,                      /* unused in help */
1039         HELP_TITLE_COLOR        /* title color */
1040     };
1041
1042     WButtonBar *help_bar;
1043     Widget *md;
1044     char *hlpfile = NULL;
1045     char *filedata;
1046
1047     if (filename != NULL)
1048         g_file_get_contents (filename, &filedata, NULL, NULL);
1049     else
1050         filedata = load_mc_home_file (mc_share_data_dir, MC_HELP, &hlpfile);
1051
1052     if (filedata == NULL)
1053         message (D_ERROR, MSG_ERROR, _("Cannot open file %s\n%s"),
1054                  filename ? filename : hlpfile, unix_error_string (errno));
1055
1056     g_free (hlpfile);
1057
1058     if (filedata == NULL)
1059         return;
1060
1061     translate_file (filedata);
1062
1063     g_free (filedata);
1064
1065     if (fdata == NULL)
1066         return;
1067
1068     if ((node == NULL) || (*node == '\0'))
1069         node = "[main]";
1070
1071     main_node = search_string (fdata, node);
1072
1073     if (main_node == NULL)
1074     {
1075         message (D_ERROR, MSG_ERROR, _("Cannot find node %s in help file"), node);
1076
1077         /* Fallback to [main], return if it also cannot be found */
1078         main_node = search_string (fdata, "[main]");
1079         if (main_node == NULL)
1080         {
1081             interactive_display_finish ();
1082             return;
1083         }
1084     }
1085
1086     help_lines = min (LINES - 4, max (2 * LINES / 3, 18));
1087
1088     whelp =
1089         create_dlg (TRUE, 0, 0, help_lines + 4, HELP_WINDOW_WIDTH + 4,
1090                     help_colors, help_callback, "[Help]", _("Help"),
1091                     DLG_TRYUP | DLG_CENTER | DLG_WANT_TAB);
1092
1093     selected_item = search_string_node (main_node, STRING_LINK_START) - 1;
1094     currentpoint = main_node + 1;       /* Skip the newline following the start of the node */
1095
1096     for (history_ptr = HISTORY_SIZE; history_ptr;)
1097     {
1098         history_ptr--;
1099         history[history_ptr].page = currentpoint;
1100         history[history_ptr].link = selected_item;
1101     }
1102
1103     help_bar = buttonbar_new (TRUE);
1104     help_bar->widget.y -= whelp->y;
1105     help_bar->widget.x -= whelp->x;
1106
1107     md = mousedispatch_new (1, 1, help_lines, HELP_WINDOW_WIDTH - 2);
1108
1109     add_widget (whelp, md);
1110     add_widget (whelp, help_bar);
1111
1112     buttonbar_set_label (help_bar, 1, Q_ ("ButtonBar|Help"), help_map, NULL);
1113     buttonbar_set_label (help_bar, 2, Q_ ("ButtonBar|Index"), help_map, NULL);
1114     buttonbar_set_label (help_bar, 3, Q_ ("ButtonBar|Prev"), help_map, NULL);
1115     buttonbar_set_label (help_bar, 4, "", help_map, NULL);
1116     buttonbar_set_label (help_bar, 5, "", help_map, NULL);
1117     buttonbar_set_label (help_bar, 6, "", help_map, NULL);
1118     buttonbar_set_label (help_bar, 7, "", help_map, NULL);
1119     buttonbar_set_label (help_bar, 8, "", help_map, NULL);
1120     buttonbar_set_label (help_bar, 9, "", help_map, NULL);
1121     buttonbar_set_label (help_bar, 10, Q_ ("ButtonBar|Quit"), help_map, NULL);
1122
1123     run_dlg (whelp);
1124     interactive_display_finish ();
1125     destroy_dlg (whelp);
1126 }
1127
1128 /* --------------------------------------------------------------------------------------------- */