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 #include "lib/event-types.h"
  64
  65 #include "keybind-defaults.h"
  66 #include "keybind-defaults.h"
  67 #include "help.h"
  68 #include "main.h"
  69
  70 /*** global variables ****************************************************************************/
  71
  72 /*** file scope macro definitions ****************************************************************/
  73
  74 #define MAXLINKNAME 80
  75 #define HISTORY_SIZE 20
  76 #define HELP_WINDOW_WIDTH min(80, COLS - 16)
  77
  78 #define STRING_LINK_START       "\01"
  79 #define STRING_LINK_POINTER     "\02"
  80 #define STRING_LINK_END         "\03"
  81 #define STRING_NODE_END         "\04"
  82
  83 /*** file scope type declarations ****************************************************************/
  84
  85 /* Link areas for the mouse */
  86 typedef struct Link_Area
  87 {
  88     int x1, y1, x2, y2;
  89     const char *link_name;
  90 } Link_Area;
  91
  92 /*** file scope variables ************************************************************************/
  93
  94 static char *fdata = NULL;      /* Pointer to the loaded data file */
  95 static int help_lines;          /* Lines in help viewer */
  96 static int history_ptr;         /* For the history queue */
  97 static const char *main_node;   /* The main node */
  98 static const char *last_shown = NULL;   /* Last byte shown in a screen */
  99 static gboolean end_of_node = FALSE;    /* Flag: the last character of the node shown? */
 100 static const char *currentpoint;
 101 static const char *selected_item;
 102
 103 /* The widget variables */
 104 static Dlg_head *whelp;
 105
 106 static struct
 107 {
 108     const char *page;           /* Pointer to the selected page */
 109     const char *link;           /* Pointer to the selected link */
 110 } history[HISTORY_SIZE];
 111
 112 static GSList *link_area = NULL;
 113 static gboolean inside_link_area = FALSE;
 114
 115 static cb_ret_t help_callback (Dlg_head * h, Widget * sender, dlg_msg_t msg, int parm, void *data);
 116
 117 /*** file scope functions ************************************************************************/
 118 /* --------------------------------------------------------------------------------------------- */
 119
 120 /** returns the position where text was found in the start buffer
 121  * or 0 if not found
 122  */
 123 static const char *
 124 search_string (const char *start, const char *text)
 125 {
 126     const char *result = NULL;
 127     char *local_text = g_strdup (text);
 128     char *d = local_text;
 129     const char *e = start;
 130
 131     /* fmt sometimes replaces a space with a newline in the help file */
 132     /* Replace the newlines in the link name with spaces to correct the situation */
 133     while (*d != '\0')
 134     {
 135         if (*d == '\n')
 136             *d = ' ';
 137         str_next_char (&d);
 138     }
 139
 140     /* Do search */
 141     for (d = local_text; *e; e++)
 142     {
 143         if (*d == *e)
 144             d++;
 145         else
 146             d = local_text;
 147         if (*d == '\0')
 148         {
 149             result = e + 1;
 150             break;
 151         }
 152     }
 153
 154     g_free (local_text);
 155     return result;
 156 }
 157
 158 /* --------------------------------------------------------------------------------------------- */
 159 /** Searches text in the buffer pointed by start.  Search ends
 160  * if the CHAR_NODE_END is found in the text.
 161  * @returns 0 on failure
 162  */
 163
 164 static const char *
 165 search_string_node (const char *start, const char *text)
 166 {
 167     const char *d = text;
 168     const char *e = start;
 169
 170     if (start != NULL)
 171         for (; *e && *e != CHAR_NODE_END; e++)
 172         {
 173             if (*d == *e)
 174                 d++;
 175             else
 176                 d = text;
 177             if (*d == '\0')
 178                 return e + 1;
 179         }
 180
 181     return NULL;
 182 }
 183
 184 /* --------------------------------------------------------------------------------------------- */
 185 /** Searches the_char in the buffer pointer by start and searches
 186  * it can search forward (direction = 1) or backward (direction = -1)
 187  */
 188
 189 static const char *
 190 search_char_node (const char *start, char the_char, int direction)
 191 {
 192     const char *e;
 193
 194     for (e = start; (*e != '\0') && (*e != CHAR_NODE_END); e += direction)
 195         if (*e == the_char)
 196             return e;
 197
 198     return NULL;
 199 }
 200
 201 /* --------------------------------------------------------------------------------------------- */
 202 /** Returns the new current pointer when moved lines lines */
 203
 204 static const char *
 205 move_forward2 (const char *c, int lines)
 206 {
 207     const char *p;
 208     int line;
 209
 210     currentpoint = c;
 211     for (line = 0, p = currentpoint; (*p != '\0') && (*p != CHAR_NODE_END); str_cnext_char (&p))
 212     {
 213         if (line == lines)
 214             return currentpoint = p;
 215
 216         if (*p == '\n')
 217             line++;
 218     }
 219     return currentpoint = c;
 220 }
 221
 222 /* --------------------------------------------------------------------------------------------- */
 223
 224 static const char *
 225 move_backward2 (const char *c, int lines)
 226 {
 227     const char *p;
 228     int line;
 229
 230     currentpoint = c;
 231     for (line = 0, p = currentpoint; (*p != '\0') && ((int) (p - fdata) >= 0); str_cprev_char (&p))
 232     {
 233         if (*p == CHAR_NODE_END)
 234         {
 235             /* We reached the beginning of the node */
 236             /* Skip the node headers */
 237             while (*p != ']')
 238                 str_cnext_char (&p);
 239             return currentpoint = p + 2;        /* Skip the newline following the start of the node */
 240         }
 241
 242         if (*(p - 1) == '\n')
 243             line++;
 244         if (line == lines)
 245             return currentpoint = p;
 246     }
 247     return currentpoint = c;
 248 }
 249
 250 /* --------------------------------------------------------------------------------------------- */
 251
 252 static void
 253 move_forward (int i)
 254 {
 255     if (!end_of_node)
 256         currentpoint = move_forward2 (currentpoint, i);
 257 }
 258
 259 /* --------------------------------------------------------------------------------------------- */
 260
 261 static void
 262 move_backward (int i)
 263 {
 264     currentpoint = move_backward2 (currentpoint, ++i);
 265 }
 266
 267 /* --------------------------------------------------------------------------------------------- */
 268
 269 static void
 270 move_to_top (void)
 271 {
 272     while (((int) (currentpoint > fdata) > 0) && (*currentpoint != CHAR_NODE_END))
 273         currentpoint--;
 274
 275     while (*currentpoint != ']')
 276         currentpoint++;
 277     currentpoint = currentpoint + 2;    /* Skip the newline following the start of the node */
 278     selected_item = NULL;
 279 }
 280
 281 /* --------------------------------------------------------------------------------------------- */
 282
 283 static void
 284 move_to_bottom (void)
 285 {
 286     while ((*currentpoint != '\0') && (*currentpoint != CHAR_NODE_END))
 287         currentpoint++;
 288     currentpoint--;
 289     move_backward (1);
 290 }
 291
 292 /* --------------------------------------------------------------------------------------------- */
 293
 294 static const char *
 295 help_follow_link (const char *start, const char *lc_selected_item)
 296 {
 297     char link_name[MAXLINKNAME];
 298     const char *p;
 299     int i = 0;
 300
 301     if (lc_selected_item == NULL)
 302         return start;
 303
 304     for (p = lc_selected_item; *p && *p != CHAR_NODE_END && *p != CHAR_LINK_POINTER; p++)
 305         ;
 306     if (*p == CHAR_LINK_POINTER)
 307     {
 308         link_name[0] = '[';
 309         for (i = 1; *p != CHAR_LINK_END && *p && *p != CHAR_NODE_END && i < MAXLINKNAME - 3;)
 310             link_name[i++] = *++p;
 311         link_name[i - 1] = ']';
 312         link_name[i] = '\0';
 313         p = search_string (fdata, link_name);
 314         if (p != NULL)
 315         {
 316             p += 1;             /* Skip the newline following the start of the node */
 317             return p;
 318         }
 319     }
 320
 321     /* Create a replacement page with the error message */
 322     return _("Help file format error\n");
 323 }
 324
 325 /* --------------------------------------------------------------------------------------------- */
 326
 327 static const char *
 328 select_next_link (const char *current_link)
 329 {
 330     const char *p;
 331
 332     if (current_link == NULL)
 333         return NULL;
 334
 335     p = search_string_node (current_link, STRING_LINK_END);
 336     if (p == NULL)
 337         return NULL;
 338     p = search_string_node (p, STRING_LINK_START);
 339     if (p == NULL)
 340         return NULL;
 341     return p - 1;
 342 }
 343
 344 /* --------------------------------------------------------------------------------------------- */
 345
 346 static const char *
 347 select_prev_link (const char *current_link)
 348 {
 349     return current_link == NULL ? NULL : search_char_node (current_link - 1, CHAR_LINK_START, -1);
 350 }
 351
 352 /* --------------------------------------------------------------------------------------------- */
 353
 354 static void
 355 start_link_area (int x, int y, const char *link_name)
 356 {
 357     Link_Area *la;
 358
 359     if (inside_link_area)
 360         message (D_NORMAL, _("Warning"), _("Internal bug: Double start of link area"));
 361
 362     /* Allocate memory for a new link area */
 363     la = g_new (Link_Area, 1);
 364     /* Save the beginning coordinates of the link area */
 365     la->x1 = x;
 366     la->y1 = y;
 367     /* Save the name of the destination anchor */
 368     la->link_name = link_name;
 369     link_area = g_slist_prepend (link_area, la);
 370
 371     inside_link_area = TRUE;
 372 }
 373
 374 /* --------------------------------------------------------------------------------------------- */
 375
 376 static void
 377 end_link_area (int x, int y)
 378 {
 379     if (inside_link_area)
 380     {
 381         Link_Area *la = (Link_Area *) link_area->data;
 382         /* Save the end coordinates of the link area */
 383         la->x2 = x;
 384         la->y2 = y;
 385         inside_link_area = FALSE;
 386     }
 387 }
 388
 389 /* --------------------------------------------------------------------------------------------- */
 390
 391 static void
 392 clear_link_areas (void)
 393 {
 394     g_slist_foreach (link_area, (GFunc) g_free, NULL);
 395     g_slist_free (link_area);
 396     link_area = NULL;
 397     inside_link_area = FALSE;
 398 }
 399
 400 /* --------------------------------------------------------------------------------------------- */
 401
 402 static void
 403 help_print_word (Dlg_head * h, GString * word, int *col, int *line, gboolean add_space)
 404 {
 405     if (*line >= help_lines)
 406         g_string_set_size (word, 0);
 407     else
 408     {
 409         int w;
 410
 411         w = str_term_width1 (word->str);
 412         if (*col + w >= HELP_WINDOW_WIDTH)
 413         {
 414             *col = 0;
 415             (*line)++;
 416         }
 417
 418         if (*line >= help_lines)
 419             g_string_set_size (word, 0);
 420         else
 421         {
 422             dlg_move (h, *line + 2, *col + 2);
 423             tty_print_string (word->str);
 424             g_string_set_size (word, 0);
 425             *col += w;
 426         }
 427     }
 428
 429     if (add_space)
 430     {
 431         if (*col < HELP_WINDOW_WIDTH - 1)
 432         {
 433             tty_print_char (' ');
 434             (*col)++;
 435         }
 436         else
 437         {
 438             *col = 0;
 439             (*line)++;
 440         }
 441     }
 442 }
 443
 444 /* --------------------------------------------------------------------------------------------- */
 445
 446 static void
 447 help_show (Dlg_head * h, const char *paint_start)
 448 {
 449     const char *p, *n;
 450     int col, line, c;
 451     gboolean painting = TRUE;
 452     gboolean acs;               /* Flag: Alternate character set active? */
 453     gboolean repeat_paint;
 454     int active_col, active_line;        /* Active link position */
 455     char buff[MB_LEN_MAX + 1];
 456     GString *word;
 457
 458     word = g_string_sized_new (32);
 459
 460     tty_setcolor (HELP_NORMAL_COLOR);
 461     do
 462     {
 463         line = col = active_col = active_line = 0;
 464         repeat_paint = FALSE;
 465         acs = FALSE;
 466
 467         clear_link_areas ();
 468         if ((int) (selected_item - paint_start) < 0)
 469             selected_item = NULL;
 470
 471         p = paint_start;
 472         n = paint_start;
 473         while ((n[0] != '\0') && (n[0] != CHAR_NODE_END) && (line < help_lines))
 474         {
 475             p = n;
 476             n = str_cget_next_char (p);
 477             memcpy (buff, p, n - p);
 478             buff[n - p] = '\0';
 479
 480             c = (unsigned char) buff[0];
 481             switch (c)
 482             {
 483             case CHAR_LINK_START:
 484                 if (selected_item == NULL)
 485                     selected_item = p;
 486                 if (p != selected_item)
 487                     tty_setcolor (HELP_LINK_COLOR);
 488                 else
 489                 {
 490                     tty_setcolor (HELP_SLINK_COLOR);
 491
 492                     /* Store the coordinates of the link */
 493                     active_col = col + 2;
 494                     active_line = line + 2;
 495                 }
 496                 start_link_area (col, line, p);
 497                 break;
 498             case CHAR_LINK_POINTER:
 499                 painting = FALSE;
 500                 end_link_area (col - 1, line);
 501                 break;
 502             case CHAR_LINK_END:
 503                 painting = TRUE;
 504                 help_print_word (h, word, &col, &line, FALSE);
 505                 tty_setcolor (HELP_NORMAL_COLOR);
 506                 break;
 507             case CHAR_ALTERNATE:
 508                 acs = TRUE;
 509                 break;
 510             case CHAR_NORMAL:
 511                 acs = FALSE;
 512                 break;
 513             case CHAR_VERSION:
 514                 dlg_move (h, line + 2, col + 2);
 515                 tty_print_string (VERSION);
 516                 col += str_term_width1 (VERSION);
 517                 break;
 518             case CHAR_FONT_BOLD:
 519                 tty_setcolor (HELP_BOLD_COLOR);
 520                 break;
 521             case CHAR_FONT_ITALIC:
 522                 tty_setcolor (HELP_ITALIC_COLOR);
 523                 break;
 524             case CHAR_FONT_NORMAL:
 525                 help_print_word (h, word, &col, &line, FALSE);
 526                 tty_setcolor (HELP_NORMAL_COLOR);
 527                 break;
 528             case '\n':
 529                 if (painting)
 530                     help_print_word (h, word, &col, &line, FALSE);
 531                 line++;
 532                 col = 0;
 533                 break;
 534             case '\t':
 535                 col = (col / 8 + 1) * 8;
 536                 if (col >= HELP_WINDOW_WIDTH)
 537                 {
 538                     line++;
 539                     col = 8;
 540                 }
 541                 break;
 542             case ' ':
 543                 /* word delimeter */
 544                 if (painting)
 545                     help_print_word (h, word, &col, &line, TRUE);
 546                 break;
 547             default:
 548                 if (painting && (line < help_lines))
 549                 {
 550                     if (!acs)
 551                         /* accumulate symbols in a word */
 552                         g_string_append (word, buff);
 553                     else if (col < HELP_WINDOW_WIDTH)
 554                     {
 555                         dlg_move (h, line + 2, col + 2);
 556
 557                         if ((c == ' ') || (c == '.'))
 558                             tty_print_char (c);
 559                         else
 560 #ifndef HAVE_SLANG
 561                             tty_print_char (acs_map[c]);
 562 #else
 563                             SLsmg_draw_object (h->y + line + 2, h->x + col + 2, c);
 564 #endif
 565                         col++;
 566                     }
 567                 }
 568             }
 569         }
 570
 571         /* print last word */
 572         if (n[0] == CHAR_NODE_END)
 573             help_print_word (h, word, &col, &line, FALSE);
 574
 575         last_shown = p;
 576         end_of_node = line < help_lines;
 577         tty_setcolor (HELP_NORMAL_COLOR);
 578         if ((int) (selected_item - last_shown) >= 0)
 579         {
 580             if ((link_area == NULL) || (link_area->data == NULL))
 581                 selected_item = NULL;
 582             else
 583             {
 584                 selected_item = ((Link_Area *) link_area->data)->link_name;
 585                 repeat_paint = TRUE;
 586             }
 587         }
 588     }
 589     while (repeat_paint);
 590
 591     g_string_free (word, TRUE);
 592
 593     /* Position the cursor over a nice link */
 594     if (active_col)
 595         dlg_move (h, active_line, active_col);
 596 }
 597
 598 /* --------------------------------------------------------------------------------------------- */
 599
 600 static int
 601 help_event (Gpm_Event * event, void *vp)
 602 {
 603     Widget *w = vp;
 604     GSList *current_area;
 605
 606     if ((event->type & GPM_UP) == 0)
 607         return 0;
 608
 609     /* The event is relative to the dialog window, adjust it: */
 610     event->x -= 2;
 611     event->y -= 2;
 612
 613     if (event->buttons & GPM_B_RIGHT)
 614     {
 615         currentpoint = history[history_ptr].page;
 616         selected_item = history[history_ptr].link;
 617         history_ptr--;
 618         if (history_ptr < 0)
 619             history_ptr = HISTORY_SIZE - 1;
 620
 621         help_callback (w->owner, NULL, DLG_DRAW, 0, NULL);
 622         return 0;
 623     }
 624
 625     /* Test whether the mouse click is inside one of the link areas */
 626     for (current_area = link_area; current_area != NULL; current_area = g_slist_next (current_area))
 627     {
 628         Link_Area *la = (Link_Area *) current_area->data;
 629         /* Test one line link area */
 630         if (event->y == la->y1 && event->x >= la->x1 && event->y == la->y2 && event->x <= la->x2)
 631             break;
 632         /* Test two line link area */
 633         if (la->y1 + 1 == la->y2)
 634         {
 635             /* The first line */
 636             if (event->y == la->y1 && event->x >= la->x1)
 637                 break;
 638             /* The second line */
 639             if (event->y == la->y2 && event->x <= la->x2)
 640                 break;
 641         }
 642         /* Mouse will not work with link areas of more than two lines */
 643     }
 644
 645     /* Test whether a link area was found */
 646     if (current_area != NULL)
 647     {
 648         Link_Area *la = (Link_Area *) current_area->data;
 649
 650         /* The click was inside a link area -> follow the link */
 651         history_ptr = (history_ptr + 1) % HISTORY_SIZE;
 652         history[history_ptr].page = currentpoint;
 653         history[history_ptr].link = la->link_name;
 654         currentpoint = help_follow_link (currentpoint, la->link_name);
 655         selected_item = NULL;
 656     }
 657     else if (event->y < 0)
 658         move_backward (help_lines - 1);
 659     else if (event->y >= help_lines)
 660         move_forward (help_lines - 1);
 661     else if (event->y < help_lines / 2)
 662         move_backward (1);
 663     else
 664         move_forward (1);
 665
 666     /* Show the new node */
 667     help_callback (w->owner, NULL, DLG_DRAW, 0, NULL);
 668
 669     return 0;
 670 }
 671
 672 /* --------------------------------------------------------------------------------------------- */
 673 /** show help */
 674
 675 static void
 676 help_help (Dlg_head * h)
 677 {
 678     const char *p;
 679
 680     history_ptr = (history_ptr + 1) % HISTORY_SIZE;
 681     history[history_ptr].page = currentpoint;
 682     history[history_ptr].link = selected_item;
 683
 684     p = search_string (fdata, "[How to use help]");
 685     if (p != NULL)
 686     {
 687         currentpoint = p + 1;   /* Skip the newline following the start of the node */
 688         selected_item = NULL;
 689         help_callback (h, NULL, DLG_DRAW, 0, NULL);
 690     }
 691 }
 692
 693 /* --------------------------------------------------------------------------------------------- */
 694
 695 static void
 696 help_index (Dlg_head * h)
 697 {
 698     const char *new_item;
 699
 700     new_item = search_string (fdata, "[Contents]");
 701
 702     if (new_item == NULL)
 703         message (D_ERROR, MSG_ERROR, _("Cannot find node %s in help file"), "[Contents]");
 704     else
 705     {
 706         history_ptr = (history_ptr + 1) % HISTORY_SIZE;
 707         history[history_ptr].page = currentpoint;
 708         history[history_ptr].link = selected_item;
 709
 710         currentpoint = new_item + 1;    /* Skip the newline following the start of the node */
 711         selected_item = NULL;
 712         help_callback (h, NULL, DLG_DRAW, 0, NULL);
 713     }
 714 }
 715
 716 /* --------------------------------------------------------------------------------------------- */
 717
 718 static void
 719 help_back (Dlg_head * h)
 720 {
 721     currentpoint = history[history_ptr].page;
 722     selected_item = history[history_ptr].link;
 723     history_ptr--;
 724     if (history_ptr < 0)
 725         history_ptr = HISTORY_SIZE - 1;
 726
 727     help_callback (h, NULL, DLG_DRAW, 0, NULL); /* FIXME: unneeded? */
 728 }
 729
 730 /* --------------------------------------------------------------------------------------------- */
 731
 732 static void
 733 help_next_link (gboolean move_down)
 734 {
 735     const char *new_item;
 736
 737     new_item = select_next_link (selected_item);
 738     if (new_item != NULL)
 739     {
 740         selected_item = new_item;
 741         if ((int) (selected_item - last_shown) >= 0)
 742         {
 743             if (move_down)
 744                 move_forward (1);
 745             else
 746                 selected_item = NULL;
 747         }
 748     }
 749     else if (move_down)
 750         move_forward (1);
 751     else
 752         selected_item = NULL;
 753 }
 754
 755 /* --------------------------------------------------------------------------------------------- */
 756
 757 static void
 758 help_prev_link (gboolean move_up)
 759 {
 760     const char *new_item;
 761
 762     new_item = select_prev_link (selected_item);
 763     selected_item = new_item;
 764     if ((selected_item == NULL) || (selected_item < currentpoint))
 765     {
 766         if (move_up)
 767             move_backward (1);
 768         else if ((link_area != NULL) && (link_area->data != NULL))
 769             selected_item = ((Link_Area *) link_area->data)->link_name;
 770         else
 771             selected_item = NULL;
 772     }
 773 }
 774
 775 /* --------------------------------------------------------------------------------------------- */
 776
 777 static void
 778 help_next_node (void)
 779 {
 780     const char *new_item;
 781
 782     new_item = currentpoint;
 783     while ((*new_item != '\0') && (*new_item != CHAR_NODE_END))
 784         new_item++;
 785
 786     if (*++new_item == '[')
 787         while (*++new_item != '\0')
 788             if ((*new_item == ']') && (*++new_item != '\0') && (*++new_item != '\0'))
 789             {
 790                 currentpoint = new_item;
 791                 selected_item = NULL;
 792                 break;
 793             }
 794 }
 795
 796 /* --------------------------------------------------------------------------------------------- */
 797
 798 static void
 799 help_prev_node (void)
 800 {
 801     const char *new_item;
 802
 803     new_item = currentpoint;
 804     while (((int) (new_item - fdata) > 1) && (*new_item != CHAR_NODE_END))
 805         new_item--;
 806     new_item--;
 807     while (((int) (new_item - fdata) > 0) && (*new_item != CHAR_NODE_END))
 808         new_item--;
 809     while (*new_item != ']')
 810         new_item++;
 811     currentpoint = new_item + 2;
 812     selected_item = NULL;
 813 }
 814
 815 /* --------------------------------------------------------------------------------------------- */
 816
 817 static void
 818 help_select_link (void)
 819 {
 820     /* follow link */
 821     if (selected_item == NULL)
 822     {
 823 #ifdef WE_WANT_TO_GO_BACKWARD_ON_KEY_RIGHT
 824         /* Is there any reason why the right key would take us
 825          * backward if there are no links selected?, I agree
 826          * with Torben than doing nothing in this case is better
 827          */
 828         /* If there are no links, go backward in history */
 829         history_ptr--;
 830         if (history_ptr < 0)
 831             history_ptr = HISTORY_SIZE - 1;
 832
 833         currentpoint = history[history_ptr].page;
 834         selected_item = history[history_ptr].link;
 835 #endif
 836     }
 837     else
 838     {
 839         history_ptr = (history_ptr + 1) % HISTORY_SIZE;
 840         history[history_ptr].page = currentpoint;
 841         history[history_ptr].link = selected_item;
 842         currentpoint = help_follow_link (currentpoint, selected_item);
 843     }
 844
 845     selected_item = NULL;
 846 }
 847
 848 /* --------------------------------------------------------------------------------------------- */
 849
 850 static cb_ret_t
 851 help_execute_cmd (unsigned long command)
 852 {
 853     cb_ret_t ret = MSG_HANDLED;
 854
 855     switch (command)
 856     {
 857     case CK_Help:
 858         help_help (whelp);
 859         break;
 860     case CK_Index:
 861         help_index (whelp);
 862         break;
 863     case CK_Back:
 864         help_back (whelp);
 865         break;
 866     case CK_Up:
 867         help_prev_link (TRUE);
 868         break;
 869     case CK_Down:
 870         help_next_link (TRUE);
 871         break;
 872     case CK_PageDown:
 873         move_forward (help_lines - 1);
 874         break;
 875     case CK_PageUp:
 876         move_backward (help_lines - 1);
 877         break;
 878     case CK_HalfPageDown:
 879         move_forward (help_lines / 2);
 880         break;
 881     case CK_HalfPageUp:
 882         move_backward (help_lines / 2);
 883         break;
 884     case CK_Top:
 885         move_to_top ();
 886         break;
 887     case CK_Bottom:
 888         move_to_bottom ();
 889         break;
 890     case CK_Enter:
 891         help_select_link ();
 892         break;
 893     case CK_LinkNext:
 894         help_next_link (FALSE);
 895         break;
 896     case CK_LinkPrev:
 897         help_prev_link (FALSE);
 898         break;
 899     case CK_NodeNext:
 900         help_next_node ();
 901         break;
 902     case CK_NodePrev:
 903         help_prev_node ();
 904         break;
 905     case CK_Quit:
 906         dlg_stop (whelp);
 907         break;
 908     case CK_Cancel:
 909         /* don't close help due to SIGINT */
 910         break;
 911     default:
 912         ret = MSG_NOT_HANDLED;
 913     }
 914
 915     return ret;
 916 }
 917
 918 /* --------------------------------------------------------------------------------------------- */
 919
 920 static cb_ret_t
 921 help_handle_key (Dlg_head * h, int c)
 922 {
 923     unsigned long command;
 924
 925     command = keybind_lookup_keymap_command (help_map, c);
 926     if ((command == CK_IgnoreKey) || (help_execute_cmd (command) == MSG_NOT_HANDLED))
 927         return MSG_NOT_HANDLED;
 928
 929     help_callback (h, NULL, DLG_DRAW, 0, NULL);
 930     return MSG_HANDLED;
 931 }
 932
 933 /* --------------------------------------------------------------------------------------------- */
 934
 935 static cb_ret_t
 936 help_callback (Dlg_head * h, Widget * sender, dlg_msg_t msg, int parm, void *data)
 937 {
 938     WButtonBar *bb;
 939
 940     switch (msg)
 941     {
 942     case DLG_RESIZE:
 943         help_lines = min (LINES - 4, max (2 * LINES / 3, 18));
 944         dlg_set_size (h, help_lines + 4, HELP_WINDOW_WIDTH + 4);
 945         bb = find_buttonbar (h);
 946         widget_set_size (&bb->widget, LINES - 1, 0, 1, COLS);
 947         return MSG_HANDLED;
 948
 949     case DLG_DRAW:
 950         common_dialog_repaint (h);
 951         help_show (h, currentpoint);
 952         return MSG_HANDLED;
 953
 954     case DLG_KEY:
 955         return help_handle_key (h, parm);
 956
 957     case DLG_ACTION:
 958         /* shortcut */
 959         if (sender == NULL)
 960             return help_execute_cmd (parm);
 961         /* message from buttonbar */
 962         if (sender == (Widget *) find_buttonbar (h))
 963         {
 964             if (data != NULL)
 965                 return send_message ((Widget *) data, WIDGET_COMMAND, parm);
 966             return help_execute_cmd (parm);
 967         }
 968         return MSG_NOT_HANDLED;
 969
 970     default:
 971         return default_dlg_callback (h, sender, msg, parm, data);
 972     }
 973 }
 974
 975 /* --------------------------------------------------------------------------------------------- */
 976
 977 static void
 978 interactive_display_finish (void)
 979 {
 980     clear_link_areas ();
 981 }
 982
 983 /* --------------------------------------------------------------------------------------------- */
 984 /** translate help file into terminal encoding */
 985
 986 static void
 987 translate_file (char *filedata)
 988 {
 989     GIConv conv;
 990     GString *translated_data;
 991
 992     /* initial allocation for largest whole help file */
 993     translated_data = g_string_sized_new (32 * 1024);
 994
 995     conv = str_crt_conv_from ("UTF-8");
 996
 997     if (conv == INVALID_CONV)
 998         g_string_free (translated_data, TRUE);
 999     else
1000     {
1001         g_free (fdata);
1002
1003         if (str_convert (conv, filedata, translated_data) != ESTR_FAILURE)
1004             fdata = g_string_free (translated_data, FALSE);
1005         else
1006         {
1007             fdata = NULL;
1008             g_string_free (translated_data, TRUE);
1009         }
1010         str_close_conv (conv);
1011     }
1012 }
1013
1014 /* --------------------------------------------------------------------------------------------- */
1015
1016 static cb_ret_t
1017 md_callback (Widget * w, widget_msg_t msg, int parm)
1018 {
1019     switch (msg)
1020     {
1021     case WIDGET_RESIZED:
1022         w->lines = help_lines;
1023         return MSG_HANDLED;
1024
1025     default:
1026         return default_proc (msg, parm);
1027     }
1028 }
1029
1030 /* --------------------------------------------------------------------------------------------- */
1031
1032 static Widget *
1033 mousedispatch_new (int y, int x, int yl, int xl)
1034 {
1035     Widget *w = g_new (Widget, 1);
1036     init_widget (w, y, x, yl, xl, md_callback, help_event);
1037     return w;
1038 }
1039
1040 /* --------------------------------------------------------------------------------------------- */
1041 /*** public functions ****************************************************************************/
1042 /* --------------------------------------------------------------------------------------------- */
1043
1044 /* event callback */
1045 gboolean
1046 help_interactive_display (const gchar * event_group_name, const gchar * event_name,
1047                           gpointer init_data, gpointer data)
1048 {
1049     const dlg_colors_t help_colors = {
1050         HELP_NORMAL_COLOR,      /* common text color */
1051         0,                      /* unused in help */
1052         HELP_BOLD_COLOR,        /* bold text color */
1053         0,                      /* unused in help */
1054         HELP_TITLE_COLOR        /* title color */
1055     };
1056
1057     WButtonBar *help_bar;
1058     Widget *md;
1059     char *hlpfile = NULL;
1060     char *filedata;
1061     ev_help_t *event_data = (ev_help_t *) data;
1062
1063     (void) event_group_name;
1064     (void) event_name;
1065     (void) init_data;
1066
1067     if (event_data->filename != NULL)
1068         g_file_get_contents (event_data->filename, &filedata, NULL, NULL);
1069     else
1070         filedata = load_mc_home_file (mc_global.share_data_dir, MC_HELP, &hlpfile);
1071
1072     if (filedata == NULL)
1073         message (D_ERROR, MSG_ERROR, _("Cannot open file %s\n%s"),
1074                  event_data->filename ? event_data->filename : hlpfile, unix_error_string (errno));
1075
1076     g_free (hlpfile);
1077
1078     if (filedata == NULL)
1079         return TRUE;
1080
1081     translate_file (filedata);
1082
1083     g_free (filedata);
1084
1085     if (fdata == NULL)
1086         return TRUE;
1087
1088     if ((event_data->node == NULL) || (*event_data->node == '\0'))
1089         event_data->node = "[main]";
1090
1091     main_node = search_string (fdata, event_data->node);
1092
1093     if (main_node == NULL)
1094     {
1095         message (D_ERROR, MSG_ERROR, _("Cannot find node %s in help file"), event_data->node);
1096
1097         /* Fallback to [main], return if it also cannot be found */
1098         main_node = search_string (fdata, "[main]");
1099         if (main_node == NULL)
1100         {
1101             interactive_display_finish ();
1102             return TRUE;
1103         }
1104     }
1105
1106     help_lines = min (LINES - 4, max (2 * LINES / 3, 18));
1107
1108     whelp =
1109         create_dlg (TRUE, 0, 0, help_lines + 4, HELP_WINDOW_WIDTH + 4,
1110                     help_colors, help_callback, "[Help]", _("Help"),
1111                     DLG_TRYUP | DLG_CENTER | DLG_WANT_TAB);
1112
1113     selected_item = search_string_node (main_node, STRING_LINK_START) - 1;
1114     currentpoint = main_node + 1;       /* Skip the newline following the start of the node */
1115
1116     for (history_ptr = HISTORY_SIZE; history_ptr;)
1117     {
1118         history_ptr--;
1119         history[history_ptr].page = currentpoint;
1120         history[history_ptr].link = selected_item;
1121     }
1122
1123     help_bar = buttonbar_new (TRUE);
1124     help_bar->widget.y -= whelp->y;
1125     help_bar->widget.x -= whelp->x;
1126
1127     md = mousedispatch_new (1, 1, help_lines, HELP_WINDOW_WIDTH - 2);
1128
1129     add_widget (whelp, md);
1130     add_widget (whelp, help_bar);
1131
1132     buttonbar_set_label (help_bar, 1, Q_ ("ButtonBar|Help"), help_map, NULL);
1133     buttonbar_set_label (help_bar, 2, Q_ ("ButtonBar|Index"), help_map, NULL);
1134     buttonbar_set_label (help_bar, 3, Q_ ("ButtonBar|Prev"), help_map, NULL);
1135     buttonbar_set_label (help_bar, 4, "", help_map, NULL);
1136     buttonbar_set_label (help_bar, 5, "", help_map, NULL);
1137     buttonbar_set_label (help_bar, 6, "", help_map, NULL);
1138     buttonbar_set_label (help_bar, 7, "", help_map, NULL);
1139     buttonbar_set_label (help_bar, 8, "", help_map, NULL);
1140     buttonbar_set_label (help_bar, 9, "", help_map, NULL);
1141     buttonbar_set_label (help_bar, 10, Q_ ("ButtonBar|Quit"), help_map, NULL);
1142
1143     run_dlg (whelp);
1144     interactive_display_finish ();
1145     destroy_dlg (whelp);
1146     return TRUE;
1147 }
1148
1149 /* --------------------------------------------------------------------------------------------- */