src/help.c

   1 /*
   2    Hypertext file browser.
   3
   4    Copyright (C) 1994-2016
   5    Free Software Foundation, Inc.
   6
   7    This file is part of the Midnight Commander.
   8
   9    The Midnight Commander is free software: you can redistribute it
  10    and/or modify it under the terms of the GNU General Public License as
  11    published by the Free Software Foundation, either version 3 of the License,
  12    or (at your option) any later version.
  13
  14    The Midnight Commander is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  21  */
  22
  23
  24 /** \file help.c
  25  *  \brief Source: hypertext file browser
  26  *
  27  *  Implements the hypertext file viewer.
  28  *  The hypertext file is a file that may have one or more nodes.  Each
  29  *  node ends with a ^D character and starts with a bracket, then the
  30  *  name of the node and then a closing bracket. Right after the closing
  31  *  bracket a newline is placed. This newline is not to be displayed by
  32  *  the help viewer and must be skipped - its sole purpose is to faciliate
  33  *  the work of the people managing the help file template (xnc.hlp) .
  34  *
  35  *  Links in the hypertext file are specified like this: the text that
  36  *  will be highlighted should have a leading ^A, then it comes the
  37  *  text, then a ^B indicating that highlighting is done, then the name
  38  *  of the node you want to link to and then a ^C.
  39  *
  40  *  The file must contain a ^D at the beginning and at the end of the
  41  *  file or the program will not be able to detect the end of file.
  42  *
  43  *  Lazyness/widgeting attack: This file does use the dialog manager
  44  *  and uses mainly the dialog to achieve the help work.  there is only
  45  *  one specialized widget and it's only used to forward the mouse messages
  46  *  to the appropriate routine.
  47  */
  48
  49
  50 #include <config.h>
  51
  52 #include <errno.h>
  53 #include <stdio.h>
  54 #include <sys/types.h>
  55 #include <sys/stat.h>
  56
  57 #include "lib/global.h"
  58
  59 #include "lib/tty/tty.h"
  60 #include "lib/skin.h"
  61 #include "lib/strutil.h"
  62 #include "lib/fileloc.h"
  63 #include "lib/util.h"
  64 #include "lib/widget.h"
  65 #include "lib/event-types.h"
  66
  67 #include "keybind-defaults.h"
  68 #include "help.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 WDialog *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 (Widget * w, Widget * sender, widget_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  * @return NULL 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     const char *p;
 298
 299     if (lc_selected_item == NULL)
 300         return start;
 301
 302     for (p = lc_selected_item; *p && *p != CHAR_NODE_END && *p != CHAR_LINK_POINTER; p++)
 303         ;
 304     if (*p == CHAR_LINK_POINTER)
 305     {
 306         int i;
 307         char link_name[MAXLINKNAME];
 308
 309         link_name[0] = '[';
 310         for (i = 1; *p != CHAR_LINK_END && *p && *p != CHAR_NODE_END && i < MAXLINKNAME - 3;)
 311             link_name[i++] = *++p;
 312         link_name[i - 1] = ']';
 313         link_name[i] = '\0';
 314         p = search_string (fdata, link_name);
 315         if (p != NULL)
 316         {
 317             p += 1;             /* Skip the newline following the start of the node */
 318             return p;
 319         }
 320     }
 321
 322     /* Create a replacement page with the error message */
 323     return _("Help file format error\n");
 324 }
 325
 326 /* --------------------------------------------------------------------------------------------- */
 327
 328 static const char *
 329 select_next_link (const char *current_link)
 330 {
 331     const char *p;
 332
 333     if (current_link == NULL)
 334         return NULL;
 335
 336     p = search_string_node (current_link, STRING_LINK_END);
 337     if (p == NULL)
 338         return NULL;
 339     p = search_string_node (p, STRING_LINK_START);
 340     if (p == NULL)
 341         return NULL;
 342     return p - 1;
 343 }
 344
 345 /* --------------------------------------------------------------------------------------------- */
 346
 347 static const char *
 348 select_prev_link (const char *current_link)
 349 {
 350     return current_link == NULL ? NULL : search_char_node (current_link - 1, CHAR_LINK_START, -1);
 351 }
 352
 353 /* --------------------------------------------------------------------------------------------- */
 354
 355 static void
 356 start_link_area (int x, int y, const char *link_name)
 357 {
 358     Link_Area *la;
 359
 360     if (inside_link_area)
 361         message (D_NORMAL, _("Warning"), _("Internal bug: Double start of link area"));
 362
 363     /* Allocate memory for a new link area */
 364     la = g_new (Link_Area, 1);
 365     /* Save the beginning coordinates of the link area */
 366     la->x1 = x;
 367     la->y1 = y;
 368     /* Save the name of the destination anchor */
 369     la->link_name = link_name;
 370     link_area = g_slist_prepend (link_area, la);
 371
 372     inside_link_area = TRUE;
 373 }
 374
 375 /* --------------------------------------------------------------------------------------------- */
 376
 377 static void
 378 end_link_area (int x, int y)
 379 {
 380     if (inside_link_area)
 381     {
 382         Link_Area *la = (Link_Area *) link_area->data;
 383         /* Save the end coordinates of the link area */
 384         la->x2 = x;
 385         la->y2 = y;
 386         inside_link_area = FALSE;
 387     }
 388 }
 389
 390 /* --------------------------------------------------------------------------------------------- */
 391
 392 static void
 393 clear_link_areas (void)
 394 {
 395     g_slist_free_full (link_area, g_free);
 396     link_area = NULL;
 397     inside_link_area = FALSE;
 398 }
 399
 400 /* --------------------------------------------------------------------------------------------- */
 401
 402 static void
 403 help_print_word (WDialog * 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             widget_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 (WDialog * 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                 break;
 501             case CHAR_LINK_END:
 502                 painting = TRUE;
 503                 help_print_word (h, word, &col, &line, FALSE);
 504                 end_link_area (col - 1, line);
 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                 widget_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 delimiter */
 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                         widget_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 (WIDGET (h)->y + line + 2, WIDGET (h)->x + col + 2,
 564                                                c);
 565 #endif
 566                         col++;
 567                     }
 568                 }
 569             }
 570         }
 571
 572         /* print last word */
 573         if (n[0] == CHAR_NODE_END)
 574             help_print_word (h, word, &col, &line, FALSE);
 575
 576         last_shown = p;
 577         end_of_node = line < help_lines;
 578         tty_setcolor (HELP_NORMAL_COLOR);
 579         if ((int) (selected_item - last_shown) >= 0)
 580         {
 581             if ((link_area == NULL) || (link_area->data == NULL))
 582                 selected_item = NULL;
 583             else
 584             {
 585                 selected_item = ((Link_Area *) link_area->data)->link_name;
 586                 repeat_paint = TRUE;
 587             }
 588         }
 589     }
 590     while (repeat_paint);
 591
 592     g_string_free (word, TRUE);
 593
 594     /* Position the cursor over a nice link */
 595     if (active_col)
 596         widget_move (h, active_line, active_col);
 597 }
 598
 599 /* --------------------------------------------------------------------------------------------- */
 600 /** show help */
 601
 602 static void
 603 help_help (WDialog * h)
 604 {
 605     const char *p;
 606
 607     history_ptr = (history_ptr + 1) % HISTORY_SIZE;
 608     history[history_ptr].page = currentpoint;
 609     history[history_ptr].link = selected_item;
 610
 611     p = search_string (fdata, "[How to use help]");
 612     if (p != NULL)
 613     {
 614         currentpoint = p + 1;   /* Skip the newline following the start of the node */
 615         selected_item = NULL;
 616         send_message (h, NULL, MSG_DRAW, 0, NULL);
 617     }
 618 }
 619
 620 /* --------------------------------------------------------------------------------------------- */
 621
 622 static void
 623 help_index (WDialog * h)
 624 {
 625     const char *new_item;
 626
 627     new_item = search_string (fdata, "[Contents]");
 628
 629     if (new_item == NULL)
 630         message (D_ERROR, MSG_ERROR, _("Cannot find node %s in help file"), "[Contents]");
 631     else
 632     {
 633         history_ptr = (history_ptr + 1) % HISTORY_SIZE;
 634         history[history_ptr].page = currentpoint;
 635         history[history_ptr].link = selected_item;
 636
 637         currentpoint = new_item + 1;    /* Skip the newline following the start of the node */
 638         selected_item = NULL;
 639         send_message (h, NULL, MSG_DRAW, 0, NULL);
 640     }
 641 }
 642
 643 /* --------------------------------------------------------------------------------------------- */
 644
 645 static void
 646 help_back (WDialog * h)
 647 {
 648     currentpoint = history[history_ptr].page;
 649     selected_item = history[history_ptr].link;
 650     history_ptr--;
 651     if (history_ptr < 0)
 652         history_ptr = HISTORY_SIZE - 1;
 653
 654     send_message (h, NULL, MSG_DRAW, 0, NULL);  /* FIXME: unneeded? */
 655 }
 656
 657 /* --------------------------------------------------------------------------------------------- */
 658
 659 static void
 660 help_next_link (gboolean move_down)
 661 {
 662     const char *new_item;
 663
 664     new_item = select_next_link (selected_item);
 665     if (new_item != NULL)
 666     {
 667         selected_item = new_item;
 668         if ((int) (selected_item - last_shown) >= 0)
 669         {
 670             if (move_down)
 671                 move_forward (1);
 672             else
 673                 selected_item = NULL;
 674         }
 675     }
 676     else if (move_down)
 677         move_forward (1);
 678     else
 679         selected_item = NULL;
 680 }
 681
 682 /* --------------------------------------------------------------------------------------------- */
 683
 684 static void
 685 help_prev_link (gboolean move_up)
 686 {
 687     const char *new_item;
 688
 689     new_item = select_prev_link (selected_item);
 690     selected_item = new_item;
 691     if ((selected_item == NULL) || (selected_item < currentpoint))
 692     {
 693         if (move_up)
 694             move_backward (1);
 695         else if ((link_area != NULL) && (link_area->data != NULL))
 696             selected_item = ((Link_Area *) link_area->data)->link_name;
 697         else
 698             selected_item = NULL;
 699     }
 700 }
 701
 702 /* --------------------------------------------------------------------------------------------- */
 703
 704 static void
 705 help_next_node (void)
 706 {
 707     const char *new_item;
 708
 709     new_item = currentpoint;
 710     while ((*new_item != '\0') && (*new_item != CHAR_NODE_END))
 711         new_item++;
 712
 713     if (*++new_item == '[')
 714         while (*++new_item != '\0')
 715             if ((*new_item == ']') && (*++new_item != '\0') && (*++new_item != '\0'))
 716             {
 717                 currentpoint = new_item;
 718                 selected_item = NULL;
 719                 break;
 720             }
 721 }
 722
 723 /* --------------------------------------------------------------------------------------------- */
 724
 725 static void
 726 help_prev_node (void)
 727 {
 728     const char *new_item;
 729
 730     new_item = currentpoint;
 731     while (((int) (new_item - fdata) > 1) && (*new_item != CHAR_NODE_END))
 732         new_item--;
 733     new_item--;
 734     while (((int) (new_item - fdata) > 0) && (*new_item != CHAR_NODE_END))
 735         new_item--;
 736     while (*new_item != ']')
 737         new_item++;
 738     currentpoint = new_item + 2;
 739     selected_item = NULL;
 740 }
 741
 742 /* --------------------------------------------------------------------------------------------- */
 743
 744 static void
 745 help_select_link (void)
 746 {
 747     /* follow link */
 748     if (selected_item == NULL)
 749     {
 750 #ifdef WE_WANT_TO_GO_BACKWARD_ON_KEY_RIGHT
 751         /* Is there any reason why the right key would take us
 752          * backward if there are no links selected?, I agree
 753          * with Torben than doing nothing in this case is better
 754          */
 755         /* If there are no links, go backward in history */
 756         history_ptr--;
 757         if (history_ptr < 0)
 758             history_ptr = HISTORY_SIZE - 1;
 759
 760         currentpoint = history[history_ptr].page;
 761         selected_item = history[history_ptr].link;
 762 #endif
 763     }
 764     else
 765     {
 766         history_ptr = (history_ptr + 1) % HISTORY_SIZE;
 767         history[history_ptr].page = currentpoint;
 768         history[history_ptr].link = selected_item;
 769         currentpoint = help_follow_link (currentpoint, selected_item);
 770     }
 771
 772     selected_item = NULL;
 773 }
 774
 775 /* --------------------------------------------------------------------------------------------- */
 776
 777 static cb_ret_t
 778 help_execute_cmd (long command)
 779 {
 780     cb_ret_t ret = MSG_HANDLED;
 781
 782     switch (command)
 783     {
 784     case CK_Help:
 785         help_help (whelp);
 786         break;
 787     case CK_Index:
 788         help_index (whelp);
 789         break;
 790     case CK_Back:
 791         help_back (whelp);
 792         break;
 793     case CK_Up:
 794         help_prev_link (TRUE);
 795         break;
 796     case CK_Down:
 797         help_next_link (TRUE);
 798         break;
 799     case CK_PageDown:
 800         move_forward (help_lines - 1);
 801         break;
 802     case CK_PageUp:
 803         move_backward (help_lines - 1);
 804         break;
 805     case CK_HalfPageDown:
 806         move_forward (help_lines / 2);
 807         break;
 808     case CK_HalfPageUp:
 809         move_backward (help_lines / 2);
 810         break;
 811     case CK_Top:
 812         move_to_top ();
 813         break;
 814     case CK_Bottom:
 815         move_to_bottom ();
 816         break;
 817     case CK_Enter:
 818         help_select_link ();
 819         break;
 820     case CK_LinkNext:
 821         help_next_link (FALSE);
 822         break;
 823     case CK_LinkPrev:
 824         help_prev_link (FALSE);
 825         break;
 826     case CK_NodeNext:
 827         help_next_node ();
 828         break;
 829     case CK_NodePrev:
 830         help_prev_node ();
 831         break;
 832     case CK_Quit:
 833         dlg_stop (whelp);
 834         break;
 835     default:
 836         ret = MSG_NOT_HANDLED;
 837     }
 838
 839     return ret;
 840 }
 841
 842 /* --------------------------------------------------------------------------------------------- */
 843
 844 static cb_ret_t
 845 help_handle_key (WDialog * h, int c)
 846 {
 847     long command;
 848
 849     command = keybind_lookup_keymap_command (help_map, c);
 850     if ((command == CK_IgnoreKey) || (help_execute_cmd (command) == MSG_NOT_HANDLED))
 851         return MSG_NOT_HANDLED;
 852
 853     send_message (h, NULL, MSG_DRAW, 0, NULL);
 854     return MSG_HANDLED;
 855 }
 856
 857 /* --------------------------------------------------------------------------------------------- */
 858
 859 static cb_ret_t
 860 help_callback (Widget * w, Widget * sender, widget_msg_t msg, int parm, void *data)
 861 {
 862     WDialog *h = DIALOG (w);
 863
 864     switch (msg)
 865     {
 866     case MSG_RESIZE:
 867         {
 868             WButtonBar *bb;
 869
 870             help_lines = MIN (LINES - 4, MAX (2 * LINES / 3, 18));
 871             dlg_set_size (h, help_lines + 4, HELP_WINDOW_WIDTH + 4);
 872             bb = find_buttonbar (h);
 873             widget_set_size (WIDGET (bb), LINES - 1, 0, 1, COLS);
 874             return MSG_HANDLED;
 875         }
 876
 877     case MSG_DRAW:
 878         dlg_default_repaint (h);
 879         help_show (h, currentpoint);
 880         return MSG_HANDLED;
 881
 882     case MSG_KEY:
 883         return help_handle_key (h, parm);
 884
 885     case MSG_ACTION:
 886         /* Handle shortcuts and buttonbar. */
 887         return help_execute_cmd (parm);
 888
 889     default:
 890         return dlg_default_callback (w, sender, msg, parm, data);
 891     }
 892 }
 893
 894 /* --------------------------------------------------------------------------------------------- */
 895
 896 static void
 897 interactive_display_finish (void)
 898 {
 899     clear_link_areas ();
 900 }
 901
 902 /* --------------------------------------------------------------------------------------------- */
 903 /** translate help file into terminal encoding */
 904
 905 static void
 906 translate_file (char *filedata)
 907 {
 908     GIConv conv;
 909     GString *translated_data;
 910
 911     /* initial allocation for largest whole help file */
 912     translated_data = g_string_sized_new (32 * 1024);
 913
 914     conv = str_crt_conv_from ("UTF-8");
 915
 916     if (conv == INVALID_CONV)
 917         g_string_free (translated_data, TRUE);
 918     else
 919     {
 920         g_free (fdata);
 921
 922         if (str_convert (conv, filedata, translated_data) != ESTR_FAILURE)
 923             fdata = g_string_free (translated_data, FALSE);
 924         else
 925         {
 926             fdata = NULL;
 927             g_string_free (translated_data, TRUE);
 928         }
 929         str_close_conv (conv);
 930     }
 931 }
 932
 933 /* --------------------------------------------------------------------------------------------- */
 934
 935 static cb_ret_t
 936 md_callback (Widget * w, Widget * sender, widget_msg_t msg, int parm, void *data)
 937 {
 938     switch (msg)
 939     {
 940     case MSG_RESIZE:
 941         w->lines = help_lines;
 942         return MSG_HANDLED;
 943
 944     default:
 945         return widget_default_callback (w, sender, msg, parm, data);
 946     }
 947 }
 948
 949 /* --------------------------------------------------------------------------------------------- */
 950
 951 static void
 952 help_mouse_callback (Widget * w, mouse_msg_t msg, mouse_event_t * event)
 953 {
 954     int x, y;
 955     GSList *current_area;
 956
 957     if (msg != MSG_MOUSE_CLICK)
 958         return;
 959
 960     if ((event->buttons & GPM_B_RIGHT) != 0)
 961     {
 962         /* Right button click */
 963         help_back (whelp);
 964         return;
 965     }
 966
 967     /* Left bytton click */
 968
 969     /* The event is relative to the dialog window, adjust it: */
 970     x = event->x - 1;
 971     y = event->y - 1;
 972
 973     /* Test whether the mouse click is inside one of the link areas */
 974     for (current_area = link_area; current_area != NULL; current_area = g_slist_next (current_area))
 975     {
 976         Link_Area *la = (Link_Area *) current_area->data;
 977
 978         /* Test one line link area */
 979         if (y == la->y1 && x >= la->x1 && y == la->y2 && x <= la->x2)
 980             break;
 981
 982         /* Test two line link area */
 983         if (la->y1 + 1 == la->y2)
 984         {
 985             /* The first line || The second line */
 986             if ((y == la->y1 && x >= la->x1) || (y == la->y2 && x <= la->x2))
 987                 break;
 988         }
 989         /* Mouse will not work with link areas of more than two lines */
 990     }
 991
 992     /* Test whether a link area was found */
 993     if (current_area != NULL)
 994     {
 995         Link_Area *la = (Link_Area *) current_area->data;
 996
 997         /* The click was inside a link area -> follow the link */
 998         history_ptr = (history_ptr + 1) % HISTORY_SIZE;
 999         history[history_ptr].page = currentpoint;
1000         history[history_ptr].link = la->link_name;
1001         currentpoint = help_follow_link (currentpoint, la->link_name);
1002         selected_item = NULL;
1003     }
1004     else if (y < 0)
1005         move_backward (help_lines - 1);
1006     else if (y >= help_lines)
1007         move_forward (help_lines - 1);
1008     else if (y < help_lines / 2)
1009         move_backward (1);
1010     else
1011         move_forward (1);
1012
1013     /* Show the new node */
1014     send_message (w->owner, NULL, MSG_DRAW, 0, NULL);
1015 }
1016
1017 /* --------------------------------------------------------------------------------------------- */
1018
1019 static Widget *
1020 mousedispatch_new (int y, int x, int yl, int xl)
1021 {
1022     Widget *w;
1023
1024     w = g_new0 (Widget, 1);
1025     widget_init (w, y, x, yl, xl, md_callback, help_mouse_callback);
1026     w->options |= WOP_SELECTABLE | WOP_WANT_CURSOR;
1027
1028     return w;
1029 }
1030
1031 /* --------------------------------------------------------------------------------------------- */
1032 /*** public functions ****************************************************************************/
1033 /* --------------------------------------------------------------------------------------------- */
1034
1035 /* event callback */
1036 gboolean
1037 help_interactive_display (const gchar * event_group_name, const gchar * event_name,
1038                           gpointer init_data, gpointer data)
1039 {
1040     const dlg_colors_t help_colors = {
1041         HELP_NORMAL_COLOR,      /* common text color */
1042         0,                      /* unused in help */
1043         HELP_BOLD_COLOR,        /* bold text color */
1044         0,                      /* unused in help */
1045         HELP_TITLE_COLOR        /* title color */
1046     };
1047
1048     WButtonBar *help_bar;
1049     Widget *md;
1050     char *hlpfile = NULL;
1051     char *filedata;
1052     ev_help_t *event_data = (ev_help_t *) data;
1053
1054     (void) event_group_name;
1055     (void) event_name;
1056     (void) init_data;
1057
1058     if (event_data->filename != NULL)
1059         g_file_get_contents (event_data->filename, &filedata, NULL, NULL);
1060     else
1061         filedata = load_mc_home_file (mc_global.share_data_dir, MC_HELP, &hlpfile, NULL);
1062
1063     if (filedata == NULL)
1064         message (D_ERROR, MSG_ERROR, _("Cannot open file %s\n%s"),
1065                  event_data->filename ? event_data->filename : hlpfile, unix_error_string (errno));
1066
1067     g_free (hlpfile);
1068
1069     if (filedata == NULL)
1070         return TRUE;
1071
1072     translate_file (filedata);
1073
1074     g_free (filedata);
1075
1076     if (fdata == NULL)
1077         return TRUE;
1078
1079     if ((event_data->node == NULL) || (*event_data->node == '\0'))
1080         event_data->node = "[main]";
1081
1082     main_node = search_string (fdata, event_data->node);
1083
1084     if (main_node == NULL)
1085     {
1086         message (D_ERROR, MSG_ERROR, _("Cannot find node %s in help file"), event_data->node);
1087
1088         /* Fallback to [main], return if it also cannot be found */
1089         main_node = search_string (fdata, "[main]");
1090         if (main_node == NULL)
1091         {
1092             interactive_display_finish ();
1093             return TRUE;
1094         }
1095     }
1096
1097     help_lines = MIN (LINES - 4, MAX (2 * LINES / 3, 18));
1098
1099     whelp =
1100         dlg_create (TRUE, 0, 0, help_lines + 4, HELP_WINDOW_WIDTH + 4, WPOS_CENTER | WPOS_TRYUP,
1101                     FALSE, help_colors, help_callback, NULL, "[Help]", _("Help"));
1102     widget_want_tab (WIDGET (whelp), TRUE);
1103
1104     selected_item = search_string_node (main_node, STRING_LINK_START) - 1;
1105     currentpoint = main_node + 1;       /* Skip the newline following the start of the node */
1106
1107     for (history_ptr = HISTORY_SIZE; history_ptr;)
1108     {
1109         history_ptr--;
1110         history[history_ptr].page = currentpoint;
1111         history[history_ptr].link = selected_item;
1112     }
1113
1114     help_bar = buttonbar_new (TRUE);
1115     WIDGET (help_bar)->y -= WIDGET (whelp)->y;
1116     WIDGET (help_bar)->x -= WIDGET (whelp)->x;
1117
1118     md = mousedispatch_new (1, 1, help_lines, HELP_WINDOW_WIDTH - 2);
1119
1120     add_widget (whelp, md);
1121     add_widget (whelp, help_bar);
1122
1123     buttonbar_set_label (help_bar, 1, Q_ ("ButtonBar|Help"), help_map, NULL);
1124     buttonbar_set_label (help_bar, 2, Q_ ("ButtonBar|Index"), help_map, NULL);
1125     buttonbar_set_label (help_bar, 3, Q_ ("ButtonBar|Prev"), help_map, NULL);
1126     buttonbar_set_label (help_bar, 4, "", help_map, NULL);
1127     buttonbar_set_label (help_bar, 5, "", help_map, NULL);
1128     buttonbar_set_label (help_bar, 6, "", help_map, NULL);
1129     buttonbar_set_label (help_bar, 7, "", help_map, NULL);
1130     buttonbar_set_label (help_bar, 8, "", help_map, NULL);
1131     buttonbar_set_label (help_bar, 9, "", help_map, NULL);
1132     buttonbar_set_label (help_bar, 10, Q_ ("ButtonBar|Quit"), help_map, NULL);
1133
1134     dlg_run (whelp);
1135     interactive_display_finish ();
1136     dlg_destroy (whelp);
1137     return TRUE;
1138 }
1139
1140 /* --------------------------------------------------------------------------------------------- */