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
  73 /*** global variables ****************************************************************************/
  74
  75 /*** file scope macro definitions ****************************************************************/
  76
  77 #define MAXLINKNAME 80
  78 #define HISTORY_SIZE 20
  79 #define HELP_WINDOW_WIDTH min(80, COLS - 16)
  80
  81 #define STRING_LINK_START       "\01"
  82 #define STRING_LINK_POINTER     "\02"
  83 #define STRING_LINK_END         "\03"
  84 #define STRING_NODE_END         "\04"
  85
  86 /*** file scope type declarations ****************************************************************/
  87
  88 /* Link areas for the mouse */
  89 typedef struct Link_Area
  90 {
  91     int x1, y1, x2, y2;
  92     const char *link_name;
  93 } Link_Area;
  94
  95 /*** file scope variables ************************************************************************/
  96
  97 static char *fdata = NULL;      /* Pointer to the loaded data file */
  98 static int help_lines;          /* Lines in help viewer */
  99 static int history_ptr;         /* For the history queue */
 100 static const char *main_node;   /* The main node */
 101 static const char *last_shown = NULL;   /* Last byte shown in a screen */
 102 static gboolean end_of_node = FALSE;    /* Flag: the last character of the node shown? */
 103 static const char *currentpoint;
 104 static const char *selected_item;
 105
 106 /* The widget variables */
 107 static Dlg_head *whelp;
 108
 109 static struct
 110 {
 111     const char *page;           /* Pointer to the selected page */
 112     const char *link;           /* Pointer to the selected link */
 113 } history[HISTORY_SIZE];
 114
 115 static GSList *link_area = NULL;
 116 static gboolean inside_link_area = FALSE;
 117
 118 static cb_ret_t help_callback (Dlg_head * h, Widget * sender, dlg_msg_t msg, int parm, void *data);
 119
 120 /*** file scope functions ************************************************************************/
 121 /* --------------------------------------------------------------------------------------------- */
 122
 123 /** returns the position where text was found in the start buffer
 124  * or 0 if not found
 125  */
 126 static const char *
 127 search_string (const char *start, const char *text)
 128 {
 129     const char *result = NULL;
 130     char *local_text = g_strdup (text);
 131     char *d = local_text;
 132     const char *e = start;
 133
 134     /* fmt sometimes replaces a space with a newline in the help file */
 135     /* Replace the newlines in the link name with spaces to correct the situation */
 136     while (*d != '\0')
 137     {
 138         if (*d == '\n')
 139             *d = ' ';
 140         str_next_char (&d);
 141     }
 142
 143     /* Do search */
 144     for (d = local_text; *e; e++)
 145     {
 146         if (*d == *e)
 147             d++;
 148         else
 149             d = local_text;
 150         if (*d == '\0')
 151         {
 152             result = e + 1;
 153             break;
 154         }
 155     }
 156
 157     g_free (local_text);
 158     return result;
 159 }
 160
 161 /* --------------------------------------------------------------------------------------------- */
 162 /** Searches text in the buffer pointed by start.  Search ends
 163  * if the CHAR_NODE_END is found in the text.
 164  * @return NULL on failure
 165  */
 166
 167 static const char *
 168 search_string_node (const char *start, const char *text)
 169 {
 170     const char *d = text;
 171     const char *e = start;
 172
 173     if (start != NULL)
 174         for (; *e && *e != CHAR_NODE_END; e++)
 175         {
 176             if (*d == *e)
 177                 d++;
 178             else
 179                 d = text;
 180             if (*d == '\0')
 181                 return e + 1;
 182         }
 183
 184     return NULL;
 185 }
 186
 187 /* --------------------------------------------------------------------------------------------- */
 188 /** Searches the_char in the buffer pointer by start and searches
 189  * it can search forward (direction = 1) or backward (direction = -1)
 190  */
 191
 192 static const char *
 193 search_char_node (const char *start, char the_char, int direction)
 194 {
 195     const char *e;
 196
 197     for (e = start; (*e != '\0') && (*e != CHAR_NODE_END); e += direction)
 198         if (*e == the_char)
 199             return e;
 200
 201     return NULL;
 202 }
 203
 204 /* --------------------------------------------------------------------------------------------- */
 205 /** Returns the new current pointer when moved lines lines */
 206
 207 static const char *
 208 move_forward2 (const char *c, int lines)
 209 {
 210     const char *p;
 211     int line;
 212
 213     currentpoint = c;
 214     for (line = 0, p = currentpoint; (*p != '\0') && (*p != CHAR_NODE_END); str_cnext_char (&p))
 215     {
 216         if (line == lines)
 217             return currentpoint = p;
 218
 219         if (*p == '\n')
 220             line++;
 221     }
 222     return currentpoint = c;
 223 }
 224
 225 /* --------------------------------------------------------------------------------------------- */
 226
 227 static const char *
 228 move_backward2 (const char *c, int lines)
 229 {
 230     const char *p;
 231     int line;
 232
 233     currentpoint = c;
 234     for (line = 0, p = currentpoint; (*p != '\0') && ((int) (p - fdata) >= 0); str_cprev_char (&p))
 235     {
 236         if (*p == CHAR_NODE_END)
 237         {
 238             /* We reached the beginning of the node */
 239             /* Skip the node headers */
 240             while (*p != ']')
 241                 str_cnext_char (&p);
 242             return currentpoint = p + 2;        /* Skip the newline following the start of the node */
 243         }
 244
 245         if (*(p - 1) == '\n')
 246             line++;
 247         if (line == lines)
 248             return currentpoint = p;
 249     }
 250     return currentpoint = c;
 251 }
 252
 253 /* --------------------------------------------------------------------------------------------- */
 254
 255 static void
 256 move_forward (int i)
 257 {
 258     if (!end_of_node)
 259         currentpoint = move_forward2 (currentpoint, i);
 260 }
 261
 262 /* --------------------------------------------------------------------------------------------- */
 263
 264 static void
 265 move_backward (int i)
 266 {
 267     currentpoint = move_backward2 (currentpoint, ++i);
 268 }
 269
 270 /* --------------------------------------------------------------------------------------------- */
 271
 272 static void
 273 move_to_top (void)
 274 {
 275     while (((int) (currentpoint > fdata) > 0) && (*currentpoint != CHAR_NODE_END))
 276         currentpoint--;
 277
 278     while (*currentpoint != ']')
 279         currentpoint++;
 280     currentpoint = currentpoint + 2;    /* Skip the newline following the start of the node */
 281     selected_item = NULL;
 282 }
 283
 284 /* --------------------------------------------------------------------------------------------- */
 285
 286 static void
 287 move_to_bottom (void)
 288 {
 289     while ((*currentpoint != '\0') && (*currentpoint != CHAR_NODE_END))
 290         currentpoint++;
 291     currentpoint--;
 292     move_backward (1);
 293 }
 294
 295 /* --------------------------------------------------------------------------------------------- */
 296
 297 static const char *
 298 help_follow_link (const char *start, const char *lc_selected_item)
 299 {
 300     char link_name[MAXLINKNAME];
 301     const char *p;
 302     int i = 0;
 303
 304     if (lc_selected_item == NULL)
 305         return start;
 306
 307     for (p = lc_selected_item; *p && *p != CHAR_NODE_END && *p != CHAR_LINK_POINTER; p++)
 308         ;
 309     if (*p == CHAR_LINK_POINTER)
 310     {
 311         link_name[0] = '[';
 312         for (i = 1; *p != CHAR_LINK_END && *p && *p != CHAR_NODE_END && i < MAXLINKNAME - 3;)
 313             link_name[i++] = *++p;
 314         link_name[i - 1] = ']';
 315         link_name[i] = '\0';
 316         p = search_string (fdata, link_name);
 317         if (p != NULL)
 318         {
 319             p += 1;             /* Skip the newline following the start of the node */
 320             return p;
 321         }
 322     }
 323
 324     /* Create a replacement page with the error message */
 325     return _("Help file format error\n");
 326 }
 327
 328 /* --------------------------------------------------------------------------------------------- */
 329
 330 static const char *
 331 select_next_link (const char *current_link)
 332 {
 333     const char *p;
 334
 335     if (current_link == NULL)
 336         return NULL;
 337
 338     p = search_string_node (current_link, STRING_LINK_END);
 339     if (p == NULL)
 340         return NULL;
 341     p = search_string_node (p, STRING_LINK_START);
 342     if (p == NULL)
 343         return NULL;
 344     return p - 1;
 345 }
 346
 347 /* --------------------------------------------------------------------------------------------- */
 348
 349 static const char *
 350 select_prev_link (const char *current_link)
 351 {
 352     return current_link == NULL ? NULL : search_char_node (current_link - 1, CHAR_LINK_START, -1);
 353 }
 354
 355 /* --------------------------------------------------------------------------------------------- */
 356
 357 static void
 358 start_link_area (int x, int y, const char *link_name)
 359 {
 360     Link_Area *la;
 361
 362     if (inside_link_area)
 363         message (D_NORMAL, _("Warning"), _("Internal bug: Double start of link area"));
 364
 365     /* Allocate memory for a new link area */
 366     la = g_new (Link_Area, 1);
 367     /* Save the beginning coordinates of the link area */
 368     la->x1 = x;
 369     la->y1 = y;
 370     /* Save the name of the destination anchor */
 371     la->link_name = link_name;
 372     link_area = g_slist_prepend (link_area, la);
 373
 374     inside_link_area = TRUE;
 375 }
 376
 377 /* --------------------------------------------------------------------------------------------- */
 378
 379 static void
 380 end_link_area (int x, int y)
 381 {
 382     if (inside_link_area)
 383     {
 384         Link_Area *la = (Link_Area *) link_area->data;
 385         /* Save the end coordinates of the link area */
 386         la->x2 = x;
 387         la->y2 = y;
 388         inside_link_area = FALSE;
 389     }
 390 }
 391
 392 /* --------------------------------------------------------------------------------------------- */
 393
 394 static void
 395 clear_link_areas (void)
 396 {
 397     g_slist_foreach (link_area, (GFunc) g_free, NULL);
 398     g_slist_free (link_area);
 399     link_area = NULL;
 400     inside_link_area = FALSE;
 401 }
 402
 403 /* --------------------------------------------------------------------------------------------- */
 404
 405 static void
 406 help_print_word (Dlg_head * h, GString * word, int *col, int *line, gboolean add_space)
 407 {
 408     if (*line >= help_lines)
 409         g_string_set_size (word, 0);
 410     else
 411     {
 412         int w;
 413
 414         w = str_term_width1 (word->str);
 415         if (*col + w >= HELP_WINDOW_WIDTH)
 416         {
 417             *col = 0;
 418             (*line)++;
 419         }
 420
 421         if (*line >= help_lines)
 422             g_string_set_size (word, 0);
 423         else
 424         {
 425             dlg_move (h, *line + 2, *col + 2);
 426             tty_print_string (word->str);
 427             g_string_set_size (word, 0);
 428             *col += w;
 429         }
 430     }
 431
 432     if (add_space)
 433     {
 434         if (*col < HELP_WINDOW_WIDTH - 1)
 435         {
 436             tty_print_char (' ');
 437             (*col)++;
 438         }
 439         else
 440         {
 441             *col = 0;
 442             (*line)++;
 443         }
 444     }
 445 }
 446
 447 /* --------------------------------------------------------------------------------------------- */
 448
 449 static void
 450 help_show (Dlg_head * h, const char *paint_start)
 451 {
 452     const char *p, *n;
 453     int col, line, c;
 454     gboolean painting = TRUE;
 455     gboolean acs;               /* Flag: Alternate character set active? */
 456     gboolean repeat_paint;
 457     int active_col, active_line;        /* Active link position */
 458     char buff[MB_LEN_MAX + 1];
 459     GString *word;
 460
 461     word = g_string_sized_new (32);
 462
 463     tty_setcolor (HELP_NORMAL_COLOR);
 464     do
 465     {
 466         line = col = active_col = active_line = 0;
 467         repeat_paint = FALSE;
 468         acs = FALSE;
 469
 470         clear_link_areas ();
 471         if ((int) (selected_item - paint_start) < 0)
 472             selected_item = NULL;
 473
 474         p = paint_start;
 475         n = paint_start;
 476         while ((n[0] != '\0') && (n[0] != CHAR_NODE_END) && (line < help_lines))
 477         {
 478             p = n;
 479             n = str_cget_next_char (p);
 480             memcpy (buff, p, n - p);
 481             buff[n - p] = '\0';
 482
 483             c = (unsigned char) buff[0];
 484             switch (c)
 485             {
 486             case CHAR_LINK_START:
 487                 if (selected_item == NULL)
 488                     selected_item = p;
 489                 if (p != selected_item)
 490                     tty_setcolor (HELP_LINK_COLOR);
 491                 else
 492                 {
 493                     tty_setcolor (HELP_SLINK_COLOR);
 494
 495                     /* Store the coordinates of the link */
 496                     active_col = col + 2;
 497                     active_line = line + 2;
 498                 }
 499                 start_link_area (col, line, p);
 500                 break;
 501             case CHAR_LINK_POINTER:
 502                 painting = FALSE;
 503                 break;
 504             case CHAR_LINK_END:
 505                 painting = TRUE;
 506                 help_print_word (h, word, &col, &line, FALSE);
 507                 end_link_area (col - 1, line);
 508                 tty_setcolor (HELP_NORMAL_COLOR);
 509                 break;
 510             case CHAR_ALTERNATE:
 511                 acs = TRUE;
 512                 break;
 513             case CHAR_NORMAL:
 514                 acs = FALSE;
 515                 break;
 516             case CHAR_VERSION:
 517                 dlg_move (h, line + 2, col + 2);
 518                 tty_print_string (VERSION);
 519                 col += str_term_width1 (VERSION);
 520                 break;
 521             case CHAR_FONT_BOLD:
 522                 tty_setcolor (HELP_BOLD_COLOR);
 523                 break;
 524             case CHAR_FONT_ITALIC:
 525                 tty_setcolor (HELP_ITALIC_COLOR);
 526                 break;
 527             case CHAR_FONT_NORMAL:
 528                 help_print_word (h, word, &col, &line, FALSE);
 529                 tty_setcolor (HELP_NORMAL_COLOR);
 530                 break;
 531             case '\n':
 532                 if (painting)
 533                     help_print_word (h, word, &col, &line, FALSE);
 534                 line++;
 535                 col = 0;
 536                 break;
 537             case '\t':
 538                 col = (col / 8 + 1) * 8;
 539                 if (col >= HELP_WINDOW_WIDTH)
 540                 {
 541                     line++;
 542                     col = 8;
 543                 }
 544                 break;
 545             case ' ':
 546                 /* word delimeter */
 547                 if (painting)
 548                     help_print_word (h, word, &col, &line, TRUE);
 549                 break;
 550             default:
 551                 if (painting && (line < help_lines))
 552                 {
 553                     if (!acs)
 554                         /* accumulate symbols in a word */
 555                         g_string_append (word, buff);
 556                     else if (col < HELP_WINDOW_WIDTH)
 557                     {
 558                         dlg_move (h, line + 2, col + 2);
 559
 560                         if ((c == ' ') || (c == '.'))
 561                             tty_print_char (c);
 562                         else
 563 #ifndef HAVE_SLANG
 564                             tty_print_char (acs_map[c]);
 565 #else
 566                             SLsmg_draw_object (h->y + line + 2, h->x + col + 2, c);
 567 #endif
 568                         col++;
 569                     }
 570                 }
 571             }
 572         }
 573
 574         /* print last word */
 575         if (n[0] == CHAR_NODE_END)
 576             help_print_word (h, word, &col, &line, FALSE);
 577
 578         last_shown = p;
 579         end_of_node = line < help_lines;
 580         tty_setcolor (HELP_NORMAL_COLOR);
 581         if ((int) (selected_item - last_shown) >= 0)
 582         {
 583             if ((link_area == NULL) || (link_area->data == NULL))
 584                 selected_item = NULL;
 585             else
 586             {
 587                 selected_item = ((Link_Area *) link_area->data)->link_name;
 588                 repeat_paint = TRUE;
 589             }
 590         }
 591     }
 592     while (repeat_paint);
 593
 594     g_string_free (word, TRUE);
 595
 596     /* Position the cursor over a nice link */
 597     if (active_col)
 598         dlg_move (h, active_line, active_col);
 599 }
 600
 601 /* --------------------------------------------------------------------------------------------- */
 602
 603 static int
 604 help_event (Gpm_Event * event, void *vp)
 605 {
 606     Widget *w = (Widget *) vp;
 607     GSList *current_area;
 608     Gpm_Event local;
 609
 610     if (!mouse_global_in_widget (event, w))
 611         return MOU_UNHANDLED;
 612
 613     if ((event->type & GPM_UP) == 0)
 614         return MOU_NORMAL;
 615
 616     local = mouse_get_local (event, w);
 617
 618     /* The event is relative to the dialog window, adjust it: */
 619     local.x -= 2;
 620     local.y -= 2;
 621
 622     if ((local.buttons & GPM_B_RIGHT) != 0)
 623     {
 624         currentpoint = history[history_ptr].page;
 625         selected_item = history[history_ptr].link;
 626         history_ptr--;
 627         if (history_ptr < 0)
 628             history_ptr = HISTORY_SIZE - 1;
 629
 630         help_callback (w->owner, NULL, DLG_DRAW, 0, NULL);
 631         return MOU_NORMAL;
 632     }
 633
 634     /* Test whether the mouse click is inside one of the link areas */
 635     for (current_area = link_area; current_area != NULL; current_area = g_slist_next (current_area))
 636     {
 637         Link_Area *la = (Link_Area *) current_area->data;
 638
 639         /* Test one line link area */
 640         if (local.y == la->y1 && local.x >= la->x1 && local.y == la->y2 && local.x <= la->x2)
 641             break;
 642
 643         /* Test two line link area */
 644         if (la->y1 + 1 == la->y2)
 645         {
 646             /* The first line */
 647             if (local.y == la->y1 && local.x >= la->x1)
 648                 break;
 649             /* The second line */
 650             if (local.y == la->y2 && local.x <= la->x2)
 651                 break;
 652         }
 653         /* Mouse will not work with link areas of more than two lines */
 654     }
 655
 656     /* Test whether a link area was found */
 657     if (current_area != NULL)
 658     {
 659         Link_Area *la = (Link_Area *) current_area->data;
 660
 661         /* The click was inside a link area -> follow the link */
 662         history_ptr = (history_ptr + 1) % HISTORY_SIZE;
 663         history[history_ptr].page = currentpoint;
 664         history[history_ptr].link = la->link_name;
 665         currentpoint = help_follow_link (currentpoint, la->link_name);
 666         selected_item = NULL;
 667     }
 668     else if (local.y < 0)
 669         move_backward (help_lines - 1);
 670     else if (local.y >= help_lines)
 671         move_forward (help_lines - 1);
 672     else if (local.y < help_lines / 2)
 673         move_backward (1);
 674     else
 675         move_forward (1);
 676
 677     /* Show the new node */
 678     help_callback (w->owner, NULL, DLG_DRAW, 0, NULL);
 679
 680     return MOU_NORMAL;
 681 }
 682
 683 /* --------------------------------------------------------------------------------------------- */
 684 /** show help */
 685
 686 static void
 687 help_help (Dlg_head * h)
 688 {
 689     const char *p;
 690
 691     history_ptr = (history_ptr + 1) % HISTORY_SIZE;
 692     history[history_ptr].page = currentpoint;
 693     history[history_ptr].link = selected_item;
 694
 695     p = search_string (fdata, "[How to use help]");
 696     if (p != NULL)
 697     {
 698         currentpoint = p + 1;   /* Skip the newline following the start of the node */
 699         selected_item = NULL;
 700         help_callback (h, NULL, DLG_DRAW, 0, NULL);
 701     }
 702 }
 703
 704 /* --------------------------------------------------------------------------------------------- */
 705
 706 static void
 707 help_index (Dlg_head * h)
 708 {
 709     const char *new_item;
 710
 711     new_item = search_string (fdata, "[Contents]");
 712
 713     if (new_item == NULL)
 714         message (D_ERROR, MSG_ERROR, _("Cannot find node %s in help file"), "[Contents]");
 715     else
 716     {
 717         history_ptr = (history_ptr + 1) % HISTORY_SIZE;
 718         history[history_ptr].page = currentpoint;
 719         history[history_ptr].link = selected_item;
 720
 721         currentpoint = new_item + 1;    /* Skip the newline following the start of the node */
 722         selected_item = NULL;
 723         help_callback (h, NULL, DLG_DRAW, 0, NULL);
 724     }
 725 }
 726
 727 /* --------------------------------------------------------------------------------------------- */
 728
 729 static void
 730 help_back (Dlg_head * h)
 731 {
 732     currentpoint = history[history_ptr].page;
 733     selected_item = history[history_ptr].link;
 734     history_ptr--;
 735     if (history_ptr < 0)
 736         history_ptr = HISTORY_SIZE - 1;
 737
 738     help_callback (h, NULL, DLG_DRAW, 0, NULL); /* FIXME: unneeded? */
 739 }
 740
 741 /* --------------------------------------------------------------------------------------------- */
 742
 743 static void
 744 help_next_link (gboolean move_down)
 745 {
 746     const char *new_item;
 747
 748     new_item = select_next_link (selected_item);
 749     if (new_item != NULL)
 750     {
 751         selected_item = new_item;
 752         if ((int) (selected_item - last_shown) >= 0)
 753         {
 754             if (move_down)
 755                 move_forward (1);
 756             else
 757                 selected_item = NULL;
 758         }
 759     }
 760     else if (move_down)
 761         move_forward (1);
 762     else
 763         selected_item = NULL;
 764 }
 765
 766 /* --------------------------------------------------------------------------------------------- */
 767
 768 static void
 769 help_prev_link (gboolean move_up)
 770 {
 771     const char *new_item;
 772
 773     new_item = select_prev_link (selected_item);
 774     selected_item = new_item;
 775     if ((selected_item == NULL) || (selected_item < currentpoint))
 776     {
 777         if (move_up)
 778             move_backward (1);
 779         else if ((link_area != NULL) && (link_area->data != NULL))
 780             selected_item = ((Link_Area *) link_area->data)->link_name;
 781         else
 782             selected_item = NULL;
 783     }
 784 }
 785
 786 /* --------------------------------------------------------------------------------------------- */
 787
 788 static void
 789 help_next_node (void)
 790 {
 791     const char *new_item;
 792
 793     new_item = currentpoint;
 794     while ((*new_item != '\0') && (*new_item != CHAR_NODE_END))
 795         new_item++;
 796
 797     if (*++new_item == '[')
 798         while (*++new_item != '\0')
 799             if ((*new_item == ']') && (*++new_item != '\0') && (*++new_item != '\0'))
 800             {
 801                 currentpoint = new_item;
 802                 selected_item = NULL;
 803                 break;
 804             }
 805 }
 806
 807 /* --------------------------------------------------------------------------------------------- */
 808
 809 static void
 810 help_prev_node (void)
 811 {
 812     const char *new_item;
 813
 814     new_item = currentpoint;
 815     while (((int) (new_item - fdata) > 1) && (*new_item != CHAR_NODE_END))
 816         new_item--;
 817     new_item--;
 818     while (((int) (new_item - fdata) > 0) && (*new_item != CHAR_NODE_END))
 819         new_item--;
 820     while (*new_item != ']')
 821         new_item++;
 822     currentpoint = new_item + 2;
 823     selected_item = NULL;
 824 }
 825
 826 /* --------------------------------------------------------------------------------------------- */
 827
 828 static void
 829 help_select_link (void)
 830 {
 831     /* follow link */
 832     if (selected_item == NULL)
 833     {
 834 #ifdef WE_WANT_TO_GO_BACKWARD_ON_KEY_RIGHT
 835         /* Is there any reason why the right key would take us
 836          * backward if there are no links selected?, I agree
 837          * with Torben than doing nothing in this case is better
 838          */
 839         /* If there are no links, go backward in history */
 840         history_ptr--;
 841         if (history_ptr < 0)
 842             history_ptr = HISTORY_SIZE - 1;
 843
 844         currentpoint = history[history_ptr].page;
 845         selected_item = history[history_ptr].link;
 846 #endif
 847     }
 848     else
 849     {
 850         history_ptr = (history_ptr + 1) % HISTORY_SIZE;
 851         history[history_ptr].page = currentpoint;
 852         history[history_ptr].link = selected_item;
 853         currentpoint = help_follow_link (currentpoint, selected_item);
 854     }
 855
 856     selected_item = NULL;
 857 }
 858
 859 /* --------------------------------------------------------------------------------------------- */
 860
 861 static cb_ret_t
 862 help_execute_cmd (unsigned long command)
 863 {
 864     cb_ret_t ret = MSG_HANDLED;
 865
 866     switch (command)
 867     {
 868     case CK_Help:
 869         help_help (whelp);
 870         break;
 871     case CK_Index:
 872         help_index (whelp);
 873         break;
 874     case CK_Back:
 875         help_back (whelp);
 876         break;
 877     case CK_Up:
 878         help_prev_link (TRUE);
 879         break;
 880     case CK_Down:
 881         help_next_link (TRUE);
 882         break;
 883     case CK_PageDown:
 884         move_forward (help_lines - 1);
 885         break;
 886     case CK_PageUp:
 887         move_backward (help_lines - 1);
 888         break;
 889     case CK_HalfPageDown:
 890         move_forward (help_lines / 2);
 891         break;
 892     case CK_HalfPageUp:
 893         move_backward (help_lines / 2);
 894         break;
 895     case CK_Top:
 896         move_to_top ();
 897         break;
 898     case CK_Bottom:
 899         move_to_bottom ();
 900         break;
 901     case CK_Enter:
 902         help_select_link ();
 903         break;
 904     case CK_LinkNext:
 905         help_next_link (FALSE);
 906         break;
 907     case CK_LinkPrev:
 908         help_prev_link (FALSE);
 909         break;
 910     case CK_NodeNext:
 911         help_next_node ();
 912         break;
 913     case CK_NodePrev:
 914         help_prev_node ();
 915         break;
 916     case CK_Quit:
 917         dlg_stop (whelp);
 918         break;
 919     default:
 920         ret = MSG_NOT_HANDLED;
 921     }
 922
 923     return ret;
 924 }
 925
 926 /* --------------------------------------------------------------------------------------------- */
 927
 928 static cb_ret_t
 929 help_handle_key (Dlg_head * h, int c)
 930 {
 931     unsigned long command;
 932
 933     command = keybind_lookup_keymap_command (help_map, c);
 934     if ((command == CK_IgnoreKey) || (help_execute_cmd (command) == MSG_NOT_HANDLED))
 935         return MSG_NOT_HANDLED;
 936
 937     help_callback (h, NULL, DLG_DRAW, 0, NULL);
 938     return MSG_HANDLED;
 939 }
 940
 941 /* --------------------------------------------------------------------------------------------- */
 942
 943 static cb_ret_t
 944 help_callback (Dlg_head * h, Widget * sender, dlg_msg_t msg, int parm, void *data)
 945 {
 946     WButtonBar *bb;
 947
 948     switch (msg)
 949     {
 950     case DLG_RESIZE:
 951         help_lines = min (LINES - 4, max (2 * LINES / 3, 18));
 952         dlg_set_size (h, help_lines + 4, HELP_WINDOW_WIDTH + 4);
 953         bb = find_buttonbar (h);
 954         widget_set_size (&bb->widget, LINES - 1, 0, 1, COLS);
 955         return MSG_HANDLED;
 956
 957     case DLG_DRAW:
 958         common_dialog_repaint (h);
 959         help_show (h, currentpoint);
 960         return MSG_HANDLED;
 961
 962     case DLG_KEY:
 963         return help_handle_key (h, parm);
 964
 965     case DLG_ACTION:
 966         /* shortcut */
 967         if (sender == NULL)
 968             return help_execute_cmd (parm);
 969         /* message from buttonbar */
 970         if (sender == (Widget *) find_buttonbar (h))
 971         {
 972             if (data != NULL)
 973                 return send_message ((Widget *) data, WIDGET_COMMAND, parm);
 974             return help_execute_cmd (parm);
 975         }
 976         return MSG_NOT_HANDLED;
 977
 978     default:
 979         return default_dlg_callback (h, sender, msg, parm, data);
 980     }
 981 }
 982
 983 /* --------------------------------------------------------------------------------------------- */
 984
 985 static void
 986 interactive_display_finish (void)
 987 {
 988     clear_link_areas ();
 989 }
 990
 991 /* --------------------------------------------------------------------------------------------- */
 992 /** translate help file into terminal encoding */
 993
 994 static void
 995 translate_file (char *filedata)
 996 {
 997     GIConv conv;
 998     GString *translated_data;
 999
1000     /* initial allocation for largest whole help file */
1001     translated_data = g_string_sized_new (32 * 1024);
1002
1003     conv = str_crt_conv_from ("UTF-8");
1004
1005     if (conv == INVALID_CONV)
1006         g_string_free (translated_data, TRUE);
1007     else
1008     {
1009         g_free (fdata);
1010
1011         if (str_convert (conv, filedata, translated_data) != ESTR_FAILURE)
1012             fdata = g_string_free (translated_data, FALSE);
1013         else
1014         {
1015             fdata = NULL;
1016             g_string_free (translated_data, TRUE);
1017         }
1018         str_close_conv (conv);
1019     }
1020 }
1021
1022 /* --------------------------------------------------------------------------------------------- */
1023
1024 static cb_ret_t
1025 md_callback (Widget * w, widget_msg_t msg, int parm)
1026 {
1027     switch (msg)
1028     {
1029     case WIDGET_RESIZED:
1030         w->lines = help_lines;
1031         return MSG_HANDLED;
1032
1033     default:
1034         return default_proc (msg, parm);
1035     }
1036 }
1037
1038 /* --------------------------------------------------------------------------------------------- */
1039
1040 static Widget *
1041 mousedispatch_new (int y, int x, int yl, int xl)
1042 {
1043     Widget *w = g_new (Widget, 1);
1044     init_widget (w, y, x, yl, xl, md_callback, help_event);
1045     return w;
1046 }
1047
1048 /* --------------------------------------------------------------------------------------------- */
1049 /*** public functions ****************************************************************************/
1050 /* --------------------------------------------------------------------------------------------- */
1051
1052 /* event callback */
1053 gboolean
1054 help_interactive_display (const gchar * event_group_name, const gchar * event_name,
1055                           gpointer init_data, gpointer data)
1056 {
1057     const dlg_colors_t help_colors = {
1058         HELP_NORMAL_COLOR,      /* common text color */
1059         0,                      /* unused in help */
1060         HELP_BOLD_COLOR,        /* bold text color */
1061         0,                      /* unused in help */
1062         HELP_TITLE_COLOR        /* title color */
1063     };
1064
1065     WButtonBar *help_bar;
1066     Widget *md;
1067     char *hlpfile = NULL;
1068     char *filedata;
1069     ev_help_t *event_data = (ev_help_t *) data;
1070
1071     (void) event_group_name;
1072     (void) event_name;
1073     (void) init_data;
1074
1075     if (event_data->filename != NULL)
1076         g_file_get_contents (event_data->filename, &filedata, NULL, NULL);
1077     else
1078         filedata = load_mc_home_file (mc_global.share_data_dir, MC_HELP, &hlpfile);
1079
1080     if (filedata == NULL)
1081         message (D_ERROR, MSG_ERROR, _("Cannot open file %s\n%s"),
1082                  event_data->filename ? event_data->filename : hlpfile, unix_error_string (errno));
1083
1084     g_free (hlpfile);
1085
1086     if (filedata == NULL)
1087         return TRUE;
1088
1089     translate_file (filedata);
1090
1091     g_free (filedata);
1092
1093     if (fdata == NULL)
1094         return TRUE;
1095
1096     if ((event_data->node == NULL) || (*event_data->node == '\0'))
1097         event_data->node = "[main]";
1098
1099     main_node = search_string (fdata, event_data->node);
1100
1101     if (main_node == NULL)
1102     {
1103         message (D_ERROR, MSG_ERROR, _("Cannot find node %s in help file"), event_data->node);
1104
1105         /* Fallback to [main], return if it also cannot be found */
1106         main_node = search_string (fdata, "[main]");
1107         if (main_node == NULL)
1108         {
1109             interactive_display_finish ();
1110             return TRUE;
1111         }
1112     }
1113
1114     help_lines = min (LINES - 4, max (2 * LINES / 3, 18));
1115
1116     whelp =
1117         create_dlg (TRUE, 0, 0, help_lines + 4, HELP_WINDOW_WIDTH + 4,
1118                     help_colors, help_callback, NULL, "[Help]", _("Help"),
1119                     DLG_TRYUP | DLG_CENTER | DLG_WANT_TAB);
1120
1121     selected_item = search_string_node (main_node, STRING_LINK_START) - 1;
1122     currentpoint = main_node + 1;       /* Skip the newline following the start of the node */
1123
1124     for (history_ptr = HISTORY_SIZE; history_ptr;)
1125     {
1126         history_ptr--;
1127         history[history_ptr].page = currentpoint;
1128         history[history_ptr].link = selected_item;
1129     }
1130
1131     help_bar = buttonbar_new (TRUE);
1132     help_bar->widget.y -= whelp->y;
1133     help_bar->widget.x -= whelp->x;
1134
1135     md = mousedispatch_new (1, 1, help_lines, HELP_WINDOW_WIDTH - 2);
1136
1137     add_widget (whelp, md);
1138     add_widget (whelp, help_bar);
1139
1140     buttonbar_set_label (help_bar, 1, Q_ ("ButtonBar|Help"), help_map, NULL);
1141     buttonbar_set_label (help_bar, 2, Q_ ("ButtonBar|Index"), help_map, NULL);
1142     buttonbar_set_label (help_bar, 3, Q_ ("ButtonBar|Prev"), help_map, NULL);
1143     buttonbar_set_label (help_bar, 4, "", help_map, NULL);
1144     buttonbar_set_label (help_bar, 5, "", help_map, NULL);
1145     buttonbar_set_label (help_bar, 6, "", help_map, NULL);
1146     buttonbar_set_label (help_bar, 7, "", help_map, NULL);
1147     buttonbar_set_label (help_bar, 8, "", help_map, NULL);
1148     buttonbar_set_label (help_bar, 9, "", help_map, NULL);
1149     buttonbar_set_label (help_bar, 10, Q_ ("ButtonBar|Quit"), help_map, NULL);
1150
1151     run_dlg (whelp);
1152     interactive_display_finish ();
1153     destroy_dlg (whelp);
1154     return TRUE;
1155 }
1156
1157 /* --------------------------------------------------------------------------------------------- */