src/help.c

   1 /*
   2    Hypertext file browser.
   3
   4    Copyright (C) 1994, 1995, 1998, 1999, 2000, 2001, 2002, 2003, 2004,
   5    2005, 2006, 2007, 2011
   6    The Free Software Foundation, Inc.
   7
   8    This file is part of the Midnight Commander.
   9
  10    The Midnight Commander is free software: you can redistribute it
  11    and/or modify it under the terms of the GNU General Public License as
  12    published by the Free Software Foundation, either version 3 of the License,
  13    or (at your option) any later version.
  14
  15    The Midnight Commander is distributed in the hope that it will be useful,
  16    but WITHOUT ANY WARRANTY; without even the implied warranty of
  17    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18    GNU General Public License for more details.
  19
  20    You should have received a copy of the GNU General Public License
  21    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  22  */
  23
  24
  25 /** \file help.c
  26  *  \brief Source: hypertext file browser
  27  *
  28  *  Implements the hypertext file viewer.
  29  *  The hypertext file is a file that may have one or more nodes.  Each
  30  *  node ends with a ^D character and starts with a bracket, then the
  31  *  name of the node and then a closing bracket. Right after the closing
  32  *  bracket a newline is placed. This newline is not to be displayed by
  33  *  the help viewer and must be skipped - its sole purpose is to faciliate
  34  *  the work of the people managing the help file template (xnc.hlp) .
  35  *
  36  *  Links in the hypertext file are specified like this: the text that
  37  *  will be highlighted should have a leading ^A, then it comes the
  38  *  text, then a ^B indicating that highlighting is done, then the name
  39  *  of the node you want to link to and then a ^C.
  40  *
  41  *  The file must contain a ^D at the beginning and at the end of the
  42  *  file or the program will not be able to detect the end of file.
  43  *
  44  *  Lazyness/widgeting attack: This file does use the dialog manager
  45  *  and uses mainly the dialog to achieve the help work.  there is only
  46  *  one specialized widget and it's only used to forward the mouse messages
  47  *  to the appropiate routine.
  48  */
  49
  50
  51 #include <config.h>
  52
  53 #include <errno.h>
  54 #include <stdio.h>
  55 #include <sys/types.h>
  56 #include <sys/stat.h>
  57
  58 #include "lib/global.h"
  59
  60 #include "lib/tty/tty.h"
  61 #include "lib/tty/mouse.h"
  62 #include "lib/skin.h"
  63 #include "lib/strutil.h"
  64 #include "lib/fileloc.h"
  65 #include "lib/util.h"
  66 #include "lib/widget.h"
  67 #include "lib/event-types.h"
  68
  69 #include "keybind-defaults.h"
  70 #include "keybind-defaults.h"
  71 #include "help.h"
  72 #include "main.h"
  73
  74 /*** global variables ****************************************************************************/
  75
  76 /*** file scope macro definitions ****************************************************************/
  77
  78 #define MAXLINKNAME 80
  79 #define HISTORY_SIZE 20
  80 #define HELP_WINDOW_WIDTH min(80, COLS - 16)
  81
  82 #define STRING_LINK_START       "\01"
  83 #define STRING_LINK_POINTER     "\02"
  84 #define STRING_LINK_END         "\03"
  85 #define STRING_NODE_END         "\04"
  86
  87 /*** file scope type declarations ****************************************************************/
  88
  89 /* Link areas for the mouse */
  90 typedef struct Link_Area
  91 {
  92     int x1, y1, x2, y2;
  93     const char *link_name;
  94 } Link_Area;
  95
  96 /*** file scope variables ************************************************************************/
  97
  98 static char *fdata = NULL;      /* Pointer to the loaded data file */
  99 static int help_lines;          /* Lines in help viewer */
 100 static int history_ptr;         /* For the history queue */
 101 static const char *main_node;   /* The main node */
 102 static const char *last_shown = NULL;   /* Last byte shown in a screen */
 103 static gboolean end_of_node = FALSE;    /* Flag: the last character of the node shown? */
 104 static const char *currentpoint;
 105 static const char *selected_item;
 106
 107 /* The widget variables */
 108 static Dlg_head *whelp;
 109
 110 static struct
 111 {
 112     const char *page;           /* Pointer to the selected page */
 113     const char *link;           /* Pointer to the selected link */
 114 } history[HISTORY_SIZE];
 115
 116 static GSList *link_area = NULL;
 117 static gboolean inside_link_area = FALSE;
 118
 119 static cb_ret_t help_callback (Dlg_head * h, Widget * sender, dlg_msg_t msg, int parm, void *data);
 120
 121 /*** file scope functions ************************************************************************/
 122 /* --------------------------------------------------------------------------------------------- */
 123
 124 /** returns the position where text was found in the start buffer
 125  * or 0 if not found
 126  */
 127 static const char *
 128 search_string (const char *start, const char *text)
 129 {
 130     const char *result = NULL;
 131     char *local_text = g_strdup (text);
 132     char *d = local_text;
 133     const char *e = start;
 134
 135     /* fmt sometimes replaces a space with a newline in the help file */
 136     /* Replace the newlines in the link name with spaces to correct the situation */
 137     while (*d != '\0')
 138     {
 139         if (*d == '\n')
 140             *d = ' ';
 141         str_next_char (&d);
 142     }
 143
 144     /* Do search */
 145     for (d = local_text; *e; e++)
 146     {
 147         if (*d == *e)
 148             d++;
 149         else
 150             d = local_text;
 151         if (*d == '\0')
 152         {
 153             result = e + 1;
 154             break;
 155         }
 156     }
 157
 158     g_free (local_text);
 159     return result;
 160 }
 161
 162 /* --------------------------------------------------------------------------------------------- */
 163 /** Searches text in the buffer pointed by start.  Search ends
 164  * if the CHAR_NODE_END is found in the text.
 165  * @returns 0 on failure
 166  */
 167
 168 static const char *
 169 search_string_node (const char *start, const char *text)
 170 {
 171     const char *d = text;
 172     const char *e = start;
 173
 174     if (start != NULL)
 175         for (; *e && *e != CHAR_NODE_END; e++)
 176         {
 177             if (*d == *e)
 178                 d++;
 179             else
 180                 d = text;
 181             if (*d == '\0')
 182                 return e + 1;
 183         }
 184
 185     return NULL;
 186 }
 187
 188 /* --------------------------------------------------------------------------------------------- */
 189 /** Searches the_char in the buffer pointer by start and searches
 190  * it can search forward (direction = 1) or backward (direction = -1)
 191  */
 192
 193 static const char *
 194 search_char_node (const char *start, char the_char, int direction)
 195 {
 196     const char *e;
 197
 198     for (e = start; (*e != '\0') && (*e != CHAR_NODE_END); e += direction)
 199         if (*e == the_char)
 200             return e;
 201
 202     return NULL;
 203 }
 204
 205 /* --------------------------------------------------------------------------------------------- */
 206 /** Returns the new current pointer when moved lines lines */
 207
 208 static const char *
 209 move_forward2 (const char *c, int lines)
 210 {
 211     const char *p;
 212     int line;
 213
 214     currentpoint = c;
 215     for (line = 0, p = currentpoint; (*p != '\0') && (*p != CHAR_NODE_END); str_cnext_char (&p))
 216     {
 217         if (line == lines)
 218             return currentpoint = p;
 219
 220         if (*p == '\n')
 221             line++;
 222     }
 223     return currentpoint = c;
 224 }
 225
 226 /* --------------------------------------------------------------------------------------------- */
 227
 228 static const char *
 229 move_backward2 (const char *c, int lines)
 230 {
 231     const char *p;
 232     int line;
 233
 234     currentpoint = c;
 235     for (line = 0, p = currentpoint; (*p != '\0') && ((int) (p - fdata) >= 0); str_cprev_char (&p))
 236     {
 237         if (*p == CHAR_NODE_END)
 238         {
 239             /* We reached the beginning of the node */
 240             /* Skip the node headers */
 241             while (*p != ']')
 242                 str_cnext_char (&p);
 243             return currentpoint = p + 2;        /* Skip the newline following the start of the node */
 244         }
 245
 246         if (*(p - 1) == '\n')
 247             line++;
 248         if (line == lines)
 249             return currentpoint = p;
 250     }
 251     return currentpoint = c;
 252 }
 253
 254 /* --------------------------------------------------------------------------------------------- */
 255
 256 static void
 257 move_forward (int i)
 258 {
 259     if (!end_of_node)
 260         currentpoint = move_forward2 (currentpoint, i);
 261 }
 262
 263 /* --------------------------------------------------------------------------------------------- */
 264
 265 static void
 266 move_backward (int i)
 267 {
 268     currentpoint = move_backward2 (currentpoint, ++i);
 269 }
 270
 271 /* --------------------------------------------------------------------------------------------- */
 272
 273 static void
 274 move_to_top (void)
 275 {
 276     while (((int) (currentpoint > fdata) > 0) && (*currentpoint != CHAR_NODE_END))
 277         currentpoint--;
 278
 279     while (*currentpoint != ']')
 280         currentpoint++;
 281     currentpoint = currentpoint + 2;    /* Skip the newline following the start of the node */
 282     selected_item = NULL;
 283 }
 284
 285 /* --------------------------------------------------------------------------------------------- */
 286
 287 static void
 288 move_to_bottom (void)
 289 {
 290     while ((*currentpoint != '\0') && (*currentpoint != CHAR_NODE_END))
 291         currentpoint++;
 292     currentpoint--;
 293     move_backward (1);
 294 }
 295
 296 /* --------------------------------------------------------------------------------------------- */
 297
 298 static const char *
 299 help_follow_link (const char *start, const char *lc_selected_item)
 300 {
 301     char link_name[MAXLINKNAME];
 302     const char *p;
 303     int i = 0;
 304
 305     if (lc_selected_item == NULL)
 306         return start;
 307
 308     for (p = lc_selected_item; *p && *p != CHAR_NODE_END && *p != CHAR_LINK_POINTER; p++)
 309         ;
 310     if (*p == CHAR_LINK_POINTER)
 311     {
 312         link_name[0] = '[';
 313         for (i = 1; *p != CHAR_LINK_END && *p && *p != CHAR_NODE_END && i < MAXLINKNAME - 3;)
 314             link_name[i++] = *++p;
 315         link_name[i - 1] = ']';
 316         link_name[i] = '\0';
 317         p = search_string (fdata, link_name);
 318         if (p != NULL)
 319         {
 320             p += 1;             /* Skip the newline following the start of the node */
 321             return p;
 322         }
 323     }
 324
 325     /* Create a replacement page with the error message */
 326     return _("Help file format error\n");
 327 }
 328
 329 /* --------------------------------------------------------------------------------------------- */
 330
 331 static const char *
 332 select_next_link (const char *current_link)
 333 {
 334     const char *p;
 335
 336     if (current_link == NULL)
 337         return NULL;
 338
 339     p = search_string_node (current_link, STRING_LINK_END);
 340     if (p == NULL)
 341         return NULL;
 342     p = search_string_node (p, STRING_LINK_START);
 343     if (p == NULL)
 344         return NULL;
 345     return p - 1;
 346 }
 347
 348 /* --------------------------------------------------------------------------------------------- */
 349
 350 static const char *
 351 select_prev_link (const char *current_link)
 352 {
 353     return current_link == NULL ? NULL : search_char_node (current_link - 1, CHAR_LINK_START, -1);
 354 }
 355
 356 /* --------------------------------------------------------------------------------------------- */
 357
 358 static void
 359 start_link_area (int x, int y, const char *link_name)
 360 {
 361     Link_Area *la;
 362
 363     if (inside_link_area)
 364         message (D_NORMAL, _("Warning"), _("Internal bug: Double start of link area"));
 365
 366     /* Allocate memory for a new link area */
 367     la = g_new (Link_Area, 1);
 368     /* Save the beginning coordinates of the link area */
 369     la->x1 = x;
 370     la->y1 = y;
 371     /* Save the name of the destination anchor */
 372     la->link_name = link_name;
 373     link_area = g_slist_prepend (link_area, la);
 374
 375     inside_link_area = TRUE;
 376 }
 377
 378 /* --------------------------------------------------------------------------------------------- */
 379
 380 static void
 381 end_link_area (int x, int y)
 382 {
 383     if (inside_link_area)
 384     {
 385         Link_Area *la = (Link_Area *) link_area->data;
 386         /* Save the end coordinates of the link area */
 387         la->x2 = x;
 388         la->y2 = y;
 389         inside_link_area = FALSE;
 390     }
 391 }
 392
 393 /* --------------------------------------------------------------------------------------------- */
 394
 395 static void
 396 clear_link_areas (void)
 397 {
 398     g_slist_foreach (link_area, (GFunc) g_free, NULL);
 399     g_slist_free (link_area);
 400     link_area = NULL;
 401     inside_link_area = FALSE;
 402 }
 403
 404 /* --------------------------------------------------------------------------------------------- */
 405
 406 static void
 407 help_print_word (Dlg_head * h, GString * word, int *col, int *line, gboolean add_space)
 408 {
 409     if (*line >= help_lines)
 410         g_string_set_size (word, 0);
 411     else
 412     {
 413         int w;
 414
 415         w = str_term_width1 (word->str);
 416         if (*col + w >= HELP_WINDOW_WIDTH)
 417         {
 418             *col = 0;
 419             (*line)++;
 420         }
 421
 422         if (*line >= help_lines)
 423             g_string_set_size (word, 0);
 424         else
 425         {
 426             dlg_move (h, *line + 2, *col + 2);
 427             tty_print_string (word->str);
 428             g_string_set_size (word, 0);
 429             *col += w;
 430         }
 431     }
 432
 433     if (add_space)
 434     {
 435         if (*col < HELP_WINDOW_WIDTH - 1)
 436         {
 437             tty_print_char (' ');
 438             (*col)++;
 439         }
 440         else
 441         {
 442             *col = 0;
 443             (*line)++;
 444         }
 445     }
 446 }
 447
 448 /* --------------------------------------------------------------------------------------------- */
 449
 450 static void
 451 help_show (Dlg_head * h, const char *paint_start)
 452 {
 453     const char *p, *n;
 454     int col, line, c;
 455     gboolean painting = TRUE;
 456     gboolean acs;               /* Flag: Alternate character set active? */
 457     gboolean repeat_paint;
 458     int active_col, active_line;        /* Active link position */
 459     char buff[MB_LEN_MAX + 1];
 460     GString *word;
 461
 462     word = g_string_sized_new (32);
 463
 464     tty_setcolor (HELP_NORMAL_COLOR);
 465     do
 466     {
 467         line = col = active_col = active_line = 0;
 468         repeat_paint = FALSE;
 469         acs = FALSE;
 470
 471         clear_link_areas ();
 472         if ((int) (selected_item - paint_start) < 0)
 473             selected_item = NULL;
 474
 475         p = paint_start;
 476         n = paint_start;
 477         while ((n[0] != '\0') && (n[0] != CHAR_NODE_END) && (line < help_lines))
 478         {
 479             p = n;
 480             n = str_cget_next_char (p);
 481             memcpy (buff, p, n - p);
 482             buff[n - p] = '\0';
 483
 484             c = (unsigned char) buff[0];
 485             switch (c)
 486             {
 487             case CHAR_LINK_START:
 488                 if (selected_item == NULL)
 489                     selected_item = p;
 490                 if (p != selected_item)
 491                     tty_setcolor (HELP_LINK_COLOR);
 492                 else
 493                 {
 494                     tty_setcolor (HELP_SLINK_COLOR);
 495
 496                     /* Store the coordinates of the link */
 497                     active_col = col + 2;
 498                     active_line = line + 2;
 499                 }
 500                 start_link_area (col, line, p);
 501                 break;
 502             case CHAR_LINK_POINTER:
 503                 painting = FALSE;
 504                 end_link_area (col - 1, line);
 505                 break;
 506             case CHAR_LINK_END:
 507                 painting = TRUE;
 508                 help_print_word (h, word, &col, &line, FALSE);
 509                 tty_setcolor (HELP_NORMAL_COLOR);
 510                 break;
 511             case CHAR_ALTERNATE:
 512                 acs = TRUE;
 513                 break;
 514             case CHAR_NORMAL:
 515                 acs = FALSE;
 516                 break;
 517             case CHAR_VERSION:
 518                 dlg_move (h, line + 2, col + 2);
 519                 tty_print_string (VERSION);
 520                 col += str_term_width1 (VERSION);
 521                 break;
 522             case CHAR_FONT_BOLD:
 523                 tty_setcolor (HELP_BOLD_COLOR);
 524                 break;
 525             case CHAR_FONT_ITALIC:
 526                 tty_setcolor (HELP_ITALIC_COLOR);
 527                 break;
 528             case CHAR_FONT_NORMAL:
 529                 help_print_word (h, word, &col, &line, FALSE);
 530                 tty_setcolor (HELP_NORMAL_COLOR);
 531                 break;
 532             case '\n':
 533                 if (painting)
 534                     help_print_word (h, word, &col, &line, FALSE);
 535                 line++;
 536                 col = 0;
 537                 break;
 538             case '\t':
 539                 col = (col / 8 + 1) * 8;
 540                 if (col >= HELP_WINDOW_WIDTH)
 541                 {
 542                     line++;
 543                     col = 8;
 544                 }
 545                 break;
 546             case ' ':
 547                 /* word delimeter */
 548                 if (painting)
 549                     help_print_word (h, word, &col, &line, TRUE);
 550                 break;
 551             default:
 552                 if (painting && (line < help_lines))
 553                 {
 554                     if (!acs)
 555                         /* accumulate symbols in a word */
 556                         g_string_append (word, buff);
 557                     else if (col < HELP_WINDOW_WIDTH)
 558                     {
 559                         dlg_move (h, line + 2, col + 2);
 560
 561                         if ((c == ' ') || (c == '.'))
 562                             tty_print_char (c);
 563                         else
 564 #ifndef HAVE_SLANG
 565                             tty_print_char (acs_map[c]);
 566 #else
 567                             SLsmg_draw_object (h->y + line + 2, h->x + col + 2, c);
 568 #endif
 569                         col++;
 570                     }
 571                 }
 572             }
 573         }
 574
 575         /* print last word */
 576         if (n[0] == CHAR_NODE_END)
 577             help_print_word (h, word, &col, &line, FALSE);
 578
 579         last_shown = p;
 580         end_of_node = line < help_lines;
 581         tty_setcolor (HELP_NORMAL_COLOR);
 582         if ((int) (selected_item - last_shown) >= 0)
 583         {
 584             if ((link_area == NULL) || (link_area->data == NULL))
 585                 selected_item = NULL;
 586             else
 587             {
 588                 selected_item = ((Link_Area *) link_area->data)->link_name;
 589                 repeat_paint = TRUE;
 590             }
 591         }
 592     }
 593     while (repeat_paint);
 594
 595     g_string_free (word, TRUE);
 596
 597     /* Position the cursor over a nice link */
 598     if (active_col)
 599         dlg_move (h, active_line, active_col);
 600 }
 601
 602 /* --------------------------------------------------------------------------------------------- */
 603
 604 static int
 605 help_event (Gpm_Event * event, void *vp)
 606 {
 607     Widget *w = vp;
 608     GSList *current_area;
 609
 610     if ((event->type & GPM_UP) == 0)
 611         return 0;
 612
 613     /* The event is relative to the dialog window, adjust it: */
 614     event->x -= 2;
 615     event->y -= 2;
 616
 617     if (event->buttons & GPM_B_RIGHT)
 618     {
 619         currentpoint = history[history_ptr].page;
 620         selected_item = history[history_ptr].link;
 621         history_ptr--;
 622         if (history_ptr < 0)
 623             history_ptr = HISTORY_SIZE - 1;
 624
 625         help_callback (w->owner, NULL, DLG_DRAW, 0, NULL);
 626         return 0;
 627     }
 628
 629     /* Test whether the mouse click is inside one of the link areas */
 630     for (current_area = link_area; current_area != NULL; current_area = g_slist_next (current_area))
 631     {
 632         Link_Area *la = (Link_Area *) current_area->data;
 633         /* Test one line link area */
 634         if (event->y == la->y1 && event->x >= la->x1 && event->y == la->y2 && event->x <= la->x2)
 635             break;
 636         /* Test two line link area */
 637         if (la->y1 + 1 == la->y2)
 638         {
 639             /* The first line */
 640             if (event->y == la->y1 && event->x >= la->x1)
 641                 break;
 642             /* The second line */
 643             if (event->y == la->y2 && event->x <= la->x2)
 644                 break;
 645         }
 646         /* Mouse will not work with link areas of more than two lines */
 647     }
 648
 649     /* Test whether a link area was found */
 650     if (current_area != NULL)
 651     {
 652         Link_Area *la = (Link_Area *) current_area->data;
 653
 654         /* The click was inside a link area -> follow the link */
 655         history_ptr = (history_ptr + 1) % HISTORY_SIZE;
 656         history[history_ptr].page = currentpoint;
 657         history[history_ptr].link = la->link_name;
 658         currentpoint = help_follow_link (currentpoint, la->link_name);
 659         selected_item = NULL;
 660     }
 661     else if (event->y < 0)
 662         move_backward (help_lines - 1);
 663     else if (event->y >= help_lines)
 664         move_forward (help_lines - 1);
 665     else if (event->y < help_lines / 2)
 666         move_backward (1);
 667     else
 668         move_forward (1);
 669
 670     /* Show the new node */
 671     help_callback (w->owner, NULL, DLG_DRAW, 0, NULL);
 672
 673     return 0;
 674 }
 675
 676 /* --------------------------------------------------------------------------------------------- */
 677 /** show help */
 678
 679 static void
 680 help_help (Dlg_head * h)
 681 {
 682     const char *p;
 683
 684     history_ptr = (history_ptr + 1) % HISTORY_SIZE;
 685     history[history_ptr].page = currentpoint;
 686     history[history_ptr].link = selected_item;
 687
 688     p = search_string (fdata, "[How to use help]");
 689     if (p != NULL)
 690     {
 691         currentpoint = p + 1;   /* Skip the newline following the start of the node */
 692         selected_item = NULL;
 693         help_callback (h, NULL, DLG_DRAW, 0, NULL);
 694     }
 695 }
 696
 697 /* --------------------------------------------------------------------------------------------- */
 698
 699 static void
 700 help_index (Dlg_head * h)
 701 {
 702     const char *new_item;
 703
 704     new_item = search_string (fdata, "[Contents]");
 705
 706     if (new_item == NULL)
 707         message (D_ERROR, MSG_ERROR, _("Cannot find node %s in help file"), "[Contents]");
 708     else
 709     {
 710         history_ptr = (history_ptr + 1) % HISTORY_SIZE;
 711         history[history_ptr].page = currentpoint;
 712         history[history_ptr].link = selected_item;
 713
 714         currentpoint = new_item + 1;    /* Skip the newline following the start of the node */
 715         selected_item = NULL;
 716         help_callback (h, NULL, DLG_DRAW, 0, NULL);
 717     }
 718 }
 719
 720 /* --------------------------------------------------------------------------------------------- */
 721
 722 static void
 723 help_back (Dlg_head * h)
 724 {
 725     currentpoint = history[history_ptr].page;
 726     selected_item = history[history_ptr].link;
 727     history_ptr--;
 728     if (history_ptr < 0)
 729         history_ptr = HISTORY_SIZE - 1;
 730
 731     help_callback (h, NULL, DLG_DRAW, 0, NULL); /* FIXME: unneeded? */
 732 }
 733
 734 /* --------------------------------------------------------------------------------------------- */
 735
 736 static void
 737 help_next_link (gboolean move_down)
 738 {
 739     const char *new_item;
 740
 741     new_item = select_next_link (selected_item);
 742     if (new_item != NULL)
 743     {
 744         selected_item = new_item;
 745         if ((int) (selected_item - last_shown) >= 0)
 746         {
 747             if (move_down)
 748                 move_forward (1);
 749             else
 750                 selected_item = NULL;
 751         }
 752     }
 753     else if (move_down)
 754         move_forward (1);
 755     else
 756         selected_item = NULL;
 757 }
 758
 759 /* --------------------------------------------------------------------------------------------- */
 760
 761 static void
 762 help_prev_link (gboolean move_up)
 763 {
 764     const char *new_item;
 765
 766     new_item = select_prev_link (selected_item);
 767     selected_item = new_item;
 768     if ((selected_item == NULL) || (selected_item < currentpoint))
 769     {
 770         if (move_up)
 771             move_backward (1);
 772         else if ((link_area != NULL) && (link_area->data != NULL))
 773             selected_item = ((Link_Area *) link_area->data)->link_name;
 774         else
 775             selected_item = NULL;
 776     }
 777 }
 778
 779 /* --------------------------------------------------------------------------------------------- */
 780
 781 static void
 782 help_next_node (void)
 783 {
 784     const char *new_item;
 785
 786     new_item = currentpoint;
 787     while ((*new_item != '\0') && (*new_item != CHAR_NODE_END))
 788         new_item++;
 789
 790     if (*++new_item == '[')
 791         while (*++new_item != '\0')
 792             if ((*new_item == ']') && (*++new_item != '\0') && (*++new_item != '\0'))
 793             {
 794                 currentpoint = new_item;
 795                 selected_item = NULL;
 796                 break;
 797             }
 798 }
 799
 800 /* --------------------------------------------------------------------------------------------- */
 801
 802 static void
 803 help_prev_node (void)
 804 {
 805     const char *new_item;
 806
 807     new_item = currentpoint;
 808     while (((int) (new_item - fdata) > 1) && (*new_item != CHAR_NODE_END))
 809         new_item--;
 810     new_item--;
 811     while (((int) (new_item - fdata) > 0) && (*new_item != CHAR_NODE_END))
 812         new_item--;
 813     while (*new_item != ']')
 814         new_item++;
 815     currentpoint = new_item + 2;
 816     selected_item = NULL;
 817 }
 818
 819 /* --------------------------------------------------------------------------------------------- */
 820
 821 static void
 822 help_select_link (void)
 823 {
 824     /* follow link */
 825     if (selected_item == NULL)
 826     {
 827 #ifdef WE_WANT_TO_GO_BACKWARD_ON_KEY_RIGHT
 828         /* Is there any reason why the right key would take us
 829          * backward if there are no links selected?, I agree
 830          * with Torben than doing nothing in this case is better
 831          */
 832         /* If there are no links, go backward in history */
 833         history_ptr--;
 834         if (history_ptr < 0)
 835             history_ptr = HISTORY_SIZE - 1;
 836
 837         currentpoint = history[history_ptr].page;
 838         selected_item = history[history_ptr].link;
 839 #endif
 840     }
 841     else
 842     {
 843         history_ptr = (history_ptr + 1) % HISTORY_SIZE;
 844         history[history_ptr].page = currentpoint;
 845         history[history_ptr].link = selected_item;
 846         currentpoint = help_follow_link (currentpoint, selected_item);
 847     }
 848
 849     selected_item = NULL;
 850 }
 851
 852 /* --------------------------------------------------------------------------------------------- */
 853
 854 static cb_ret_t
 855 help_execute_cmd (unsigned long command)
 856 {
 857     cb_ret_t ret = MSG_HANDLED;
 858
 859     switch (command)
 860     {
 861     case CK_Help:
 862         help_help (whelp);
 863         break;
 864     case CK_Index:
 865         help_index (whelp);
 866         break;
 867     case CK_Back:
 868         help_back (whelp);
 869         break;
 870     case CK_Up:
 871         help_prev_link (TRUE);
 872         break;
 873     case CK_Down:
 874         help_next_link (TRUE);
 875         break;
 876     case CK_PageDown:
 877         move_forward (help_lines - 1);
 878         break;
 879     case CK_PageUp:
 880         move_backward (help_lines - 1);
 881         break;
 882     case CK_HalfPageDown:
 883         move_forward (help_lines / 2);
 884         break;
 885     case CK_HalfPageUp:
 886         move_backward (help_lines / 2);
 887         break;
 888     case CK_Top:
 889         move_to_top ();
 890         break;
 891     case CK_Bottom:
 892         move_to_bottom ();
 893         break;
 894     case CK_Enter:
 895         help_select_link ();
 896         break;
 897     case CK_LinkNext:
 898         help_next_link (FALSE);
 899         break;
 900     case CK_LinkPrev:
 901         help_prev_link (FALSE);
 902         break;
 903     case CK_NodeNext:
 904         help_next_node ();
 905         break;
 906     case CK_NodePrev:
 907         help_prev_node ();
 908         break;
 909     case CK_Quit:
 910         dlg_stop (whelp);
 911         break;
 912     case CK_Cancel:
 913         /* don't close help due to SIGINT */
 914         break;
 915     default:
 916         ret = MSG_NOT_HANDLED;
 917     }
 918
 919     return ret;
 920 }
 921
 922 /* --------------------------------------------------------------------------------------------- */
 923
 924 static cb_ret_t
 925 help_handle_key (Dlg_head * h, int c)
 926 {
 927     unsigned long command;
 928
 929     command = keybind_lookup_keymap_command (help_map, c);
 930     if ((command == CK_IgnoreKey) || (help_execute_cmd (command) == MSG_NOT_HANDLED))
 931         return MSG_NOT_HANDLED;
 932
 933     help_callback (h, NULL, DLG_DRAW, 0, NULL);
 934     return MSG_HANDLED;
 935 }
 936
 937 /* --------------------------------------------------------------------------------------------- */
 938
 939 static cb_ret_t
 940 help_callback (Dlg_head * h, Widget * sender, dlg_msg_t msg, int parm, void *data)
 941 {
 942     WButtonBar *bb;
 943
 944     switch (msg)
 945     {
 946     case DLG_RESIZE:
 947         help_lines = min (LINES - 4, max (2 * LINES / 3, 18));
 948         dlg_set_size (h, help_lines + 4, HELP_WINDOW_WIDTH + 4);
 949         bb = find_buttonbar (h);
 950         widget_set_size (&bb->widget, LINES - 1, 0, 1, COLS);
 951         return MSG_HANDLED;
 952
 953     case DLG_DRAW:
 954         common_dialog_repaint (h);
 955         help_show (h, currentpoint);
 956         return MSG_HANDLED;
 957
 958     case DLG_KEY:
 959         return help_handle_key (h, parm);
 960
 961     case DLG_ACTION:
 962         /* shortcut */
 963         if (sender == NULL)
 964             return help_execute_cmd (parm);
 965         /* message from buttonbar */
 966         if (sender == (Widget *) find_buttonbar (h))
 967         {
 968             if (data != NULL)
 969                 return send_message ((Widget *) data, WIDGET_COMMAND, parm);
 970             return help_execute_cmd (parm);
 971         }
 972         return MSG_NOT_HANDLED;
 973
 974     default:
 975         return default_dlg_callback (h, sender, msg, parm, data);
 976     }
 977 }
 978
 979 /* --------------------------------------------------------------------------------------------- */
 980
 981 static void
 982 interactive_display_finish (void)
 983 {
 984     clear_link_areas ();
 985 }
 986
 987 /* --------------------------------------------------------------------------------------------- */
 988 /** translate help file into terminal encoding */
 989
 990 static void
 991 translate_file (char *filedata)
 992 {
 993     GIConv conv;
 994     GString *translated_data;
 995
 996     /* initial allocation for largest whole help file */
 997     translated_data = g_string_sized_new (32 * 1024);
 998
 999     conv = str_crt_conv_from ("UTF-8");
1000
1001     if (conv == INVALID_CONV)
1002         g_string_free (translated_data, TRUE);
1003     else
1004     {
1005         g_free (fdata);
1006
1007         if (str_convert (conv, filedata, translated_data) != ESTR_FAILURE)
1008             fdata = g_string_free (translated_data, FALSE);
1009         else
1010         {
1011             fdata = NULL;
1012             g_string_free (translated_data, TRUE);
1013         }
1014         str_close_conv (conv);
1015     }
1016 }
1017
1018 /* --------------------------------------------------------------------------------------------- */
1019
1020 static cb_ret_t
1021 md_callback (Widget * w, widget_msg_t msg, int parm)
1022 {
1023     switch (msg)
1024     {
1025     case WIDGET_RESIZED:
1026         w->lines = help_lines;
1027         return MSG_HANDLED;
1028
1029     default:
1030         return default_proc (msg, parm);
1031     }
1032 }
1033
1034 /* --------------------------------------------------------------------------------------------- */
1035
1036 static Widget *
1037 mousedispatch_new (int y, int x, int yl, int xl)
1038 {
1039     Widget *w = g_new (Widget, 1);
1040     init_widget (w, y, x, yl, xl, md_callback, help_event);
1041     return w;
1042 }
1043
1044 /* --------------------------------------------------------------------------------------------- */
1045 /*** public functions ****************************************************************************/
1046 /* --------------------------------------------------------------------------------------------- */
1047
1048 /* event callback */
1049 gboolean
1050 help_interactive_display (const gchar * event_group_name, const gchar * event_name,
1051                           gpointer init_data, gpointer data)
1052 {
1053     const dlg_colors_t help_colors = {
1054         HELP_NORMAL_COLOR,      /* common text color */
1055         0,                      /* unused in help */
1056         HELP_BOLD_COLOR,        /* bold text color */
1057         0,                      /* unused in help */
1058         HELP_TITLE_COLOR        /* title color */
1059     };
1060
1061     WButtonBar *help_bar;
1062     Widget *md;
1063     char *hlpfile = NULL;
1064     char *filedata;
1065     ev_help_t *event_data = (ev_help_t *) data;
1066
1067     (void) event_group_name;
1068     (void) event_name;
1069     (void) init_data;
1070
1071     if (event_data->filename != NULL)
1072         g_file_get_contents (event_data->filename, &filedata, NULL, NULL);
1073     else
1074         filedata = load_mc_home_file (mc_global.share_data_dir, MC_HELP, &hlpfile);
1075
1076     if (filedata == NULL)
1077         message (D_ERROR, MSG_ERROR, _("Cannot open file %s\n%s"),
1078                  event_data->filename ? event_data->filename : hlpfile, unix_error_string (errno));
1079
1080     g_free (hlpfile);
1081
1082     if (filedata == NULL)
1083         return TRUE;
1084
1085     translate_file (filedata);
1086
1087     g_free (filedata);
1088
1089     if (fdata == NULL)
1090         return TRUE;
1091
1092     if ((event_data->node == NULL) || (*event_data->node == '\0'))
1093         event_data->node = "[main]";
1094
1095     main_node = search_string (fdata, event_data->node);
1096
1097     if (main_node == NULL)
1098     {
1099         message (D_ERROR, MSG_ERROR, _("Cannot find node %s in help file"), event_data->node);
1100
1101         /* Fallback to [main], return if it also cannot be found */
1102         main_node = search_string (fdata, "[main]");
1103         if (main_node == NULL)
1104         {
1105             interactive_display_finish ();
1106             return TRUE;
1107         }
1108     }
1109
1110     help_lines = min (LINES - 4, max (2 * LINES / 3, 18));
1111
1112     whelp =
1113         create_dlg (TRUE, 0, 0, help_lines + 4, HELP_WINDOW_WIDTH + 4,
1114                     help_colors, help_callback, "[Help]", _("Help"),
1115                     DLG_TRYUP | DLG_CENTER | DLG_WANT_TAB);
1116
1117     selected_item = search_string_node (main_node, STRING_LINK_START) - 1;
1118     currentpoint = main_node + 1;       /* Skip the newline following the start of the node */
1119
1120     for (history_ptr = HISTORY_SIZE; history_ptr;)
1121     {
1122         history_ptr--;
1123         history[history_ptr].page = currentpoint;
1124         history[history_ptr].link = selected_item;
1125     }
1126
1127     help_bar = buttonbar_new (TRUE);
1128     help_bar->widget.y -= whelp->y;
1129     help_bar->widget.x -= whelp->x;
1130
1131     md = mousedispatch_new (1, 1, help_lines, HELP_WINDOW_WIDTH - 2);
1132
1133     add_widget (whelp, md);
1134     add_widget (whelp, help_bar);
1135
1136     buttonbar_set_label (help_bar, 1, Q_ ("ButtonBar|Help"), help_map, NULL);
1137     buttonbar_set_label (help_bar, 2, Q_ ("ButtonBar|Index"), help_map, NULL);
1138     buttonbar_set_label (help_bar, 3, Q_ ("ButtonBar|Prev"), help_map, NULL);
1139     buttonbar_set_label (help_bar, 4, "", help_map, NULL);
1140     buttonbar_set_label (help_bar, 5, "", help_map, NULL);
1141     buttonbar_set_label (help_bar, 6, "", help_map, NULL);
1142     buttonbar_set_label (help_bar, 7, "", help_map, NULL);
1143     buttonbar_set_label (help_bar, 8, "", help_map, NULL);
1144     buttonbar_set_label (help_bar, 9, "", help_map, NULL);
1145     buttonbar_set_label (help_bar, 10, Q_ ("ButtonBar|Quit"), help_map, NULL);
1146
1147     run_dlg (whelp);
1148     interactive_display_finish ();
1149     destroy_dlg (whelp);
1150     return TRUE;
1151 }
1152
1153 /* --------------------------------------------------------------------------------------------- */