src/help.c

   1 /*
   2    Hypertext file browser.
   3
   4    Copyright (C) 1994-2023
   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 facilitate
  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  *  Laziness/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 <limits.h>             /* MB_LEN_MAX */
  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/skin.h"
  62 #include "lib/strutil.h"
  63 #include "lib/fileloc.h"
  64 #include "lib/util.h"
  65 #include "lib/widget.h"
  66 #include "lib/event-types.h"
  67
  68 #include "keymap.h"
  69 #include "help.h"
  70
  71 /*** global variables ****************************************************************************/
  72
  73 /*** file scope macro definitions ****************************************************************/
  74
  75 #define MAXLINKNAME 80
  76 #define HISTORY_SIZE 20
  77 #define HELP_WINDOW_WIDTH MIN(80, COLS - 16)
  78
  79 #define STRING_LINK_START       "\01"
  80 #define STRING_LINK_POINTER     "\02"
  81 #define STRING_LINK_END         "\03"
  82 #define STRING_NODE_END         "\04"
  83
  84 /*** file scope type declarations ****************************************************************/
  85
  86 /* Link areas for the mouse */
  87 typedef struct Link_Area
  88 {
  89     int x1, y1, x2, y2;
  90     const char *link_name;
  91 } Link_Area;
  92
  93 /*** file scope variables ************************************************************************/
  94
  95 static char *fdata = NULL;      /* Pointer to the loaded data file */
  96 static int help_lines;          /* Lines in help viewer */
  97 static int history_ptr;         /* For the history queue */
  98 static const char *main_node;   /* The main node */
  99 static const char *last_shown = NULL;   /* Last byte shown in a screen */
 100 static gboolean end_of_node = FALSE;    /* Flag: the last character of the node shown? */
 101 static const char *currentpoint;
 102 static const char *selected_item;
 103
 104 /* The widget variables */
 105 static WDialog *whelp;
 106
 107 static struct
 108 {
 109     const char *page;           /* Pointer to the selected page */
 110     const char *link;           /* Pointer to the selected link */
 111 } history[HISTORY_SIZE];
 112
 113 static GSList *link_area = NULL;
 114 static gboolean inside_link_area = FALSE;
 115
 116 static cb_ret_t help_callback (Widget * w, Widget * sender, widget_msg_t msg, int parm, void *data);
 117
 118 /*** file scope functions ************************************************************************/
 119 /* --------------------------------------------------------------------------------------------- */
 120
 121 /** returns the position where text was found in the start buffer
 122  * or 0 if not found
 123  */
 124 static const char *
 125 search_string (const char *start, const char *text)
 126 {
 127     const char *result = NULL;
 128     char *local_text = g_strdup (text);
 129     char *d = local_text;
 130     const char *e = start;
 131
 132     /* fmt sometimes replaces a space with a newline in the help file */
 133     /* Replace the newlines in the link name with spaces to correct the situation */
 134     while (*d != '\0')
 135     {
 136         if (*d == '\n')
 137             *d = ' ';
 138         str_next_char (&d);
 139     }
 140
 141     /* Do search */
 142     for (d = local_text; *e; e++)
 143     {
 144         if (*d == *e)
 145             d++;
 146         else
 147             d = local_text;
 148         if (*d == '\0')
 149         {
 150             result = e + 1;
 151             break;
 152         }
 153     }
 154
 155     g_free (local_text);
 156     return result;
 157 }
 158
 159 /* --------------------------------------------------------------------------------------------- */
 160 /** Searches text in the buffer pointed by start.  Search ends
 161  * if the CHAR_NODE_END is found in the text.
 162  * @return NULL on failure
 163  */
 164
 165 static const char *
 166 search_string_node (const char *start, const char *text)
 167 {
 168     const char *d = text;
 169     const char *e = start;
 170
 171     if (start != NULL)
 172         for (; *e && *e != CHAR_NODE_END; e++)
 173         {
 174             if (*d == *e)
 175                 d++;
 176             else
 177                 d = text;
 178             if (*d == '\0')
 179                 return e + 1;
 180         }
 181
 182     return NULL;
 183 }
 184
 185 /* --------------------------------------------------------------------------------------------- */
 186 /** Searches the_char in the buffer pointer by start and searches
 187  * it can search forward (direction = 1) or backward (direction = -1)
 188  */
 189
 190 static const char *
 191 search_char_node (const char *start, char the_char, int direction)
 192 {
 193     const char *e;
 194
 195     for (e = start; (*e != '\0') && (*e != CHAR_NODE_END); e += direction)
 196         if (*e == the_char)
 197             return e;
 198
 199     return NULL;
 200 }
 201
 202 /* --------------------------------------------------------------------------------------------- */
 203 /** Returns the new current pointer when moved lines lines */
 204
 205 static const char *
 206 move_forward2 (const char *c, int lines)
 207 {
 208     const char *p;
 209     int line;
 210
 211     currentpoint = c;
 212     for (line = 0, p = currentpoint; (*p != '\0') && (*p != CHAR_NODE_END); str_cnext_char (&p))
 213     {
 214         if (line == lines)
 215             return currentpoint = p;
 216
 217         if (*p == '\n')
 218             line++;
 219     }
 220     return currentpoint = c;
 221 }
 222
 223 /* --------------------------------------------------------------------------------------------- */
 224
 225 static const char *
 226 move_backward2 (const char *c, int lines)
 227 {
 228     const char *p;
 229     int line;
 230
 231     currentpoint = c;
 232     for (line = 0, p = currentpoint; (*p != '\0') && ((int) (p - fdata) >= 0); str_cprev_char (&p))
 233     {
 234         if (*p == CHAR_NODE_END)
 235         {
 236             /* We reached the beginning of the node */
 237             /* Skip the node headers */
 238             while (*p != ']')
 239                 str_cnext_char (&p);
 240             return currentpoint = p + 2;        /* Skip the newline following the start of the node */
 241         }
 242
 243         if (*(p - 1) == '\n')
 244             line++;
 245         if (line == lines)
 246             return currentpoint = p;
 247     }
 248     return currentpoint = c;
 249 }
 250
 251 /* --------------------------------------------------------------------------------------------- */
 252
 253 static void
 254 move_forward (int i)
 255 {
 256     if (!end_of_node)
 257         currentpoint = move_forward2 (currentpoint, i);
 258 }
 259
 260 /* --------------------------------------------------------------------------------------------- */
 261
 262 static void
 263 move_backward (int i)
 264 {
 265     currentpoint = move_backward2 (currentpoint, ++i);
 266 }
 267
 268 /* --------------------------------------------------------------------------------------------- */
 269
 270 static void
 271 move_to_top (void)
 272 {
 273     while (((int) (currentpoint > fdata) > 0) && (*currentpoint != CHAR_NODE_END))
 274         currentpoint--;
 275
 276     while (*currentpoint != ']')
 277         currentpoint++;
 278     currentpoint = currentpoint + 2;    /* Skip the newline following the start of the node */
 279     selected_item = NULL;
 280 }
 281
 282 /* --------------------------------------------------------------------------------------------- */
 283
 284 static void
 285 move_to_bottom (void)
 286 {
 287     while ((*currentpoint != '\0') && (*currentpoint != CHAR_NODE_END))
 288         currentpoint++;
 289     currentpoint--;
 290     move_backward (1);
 291 }
 292
 293 /* --------------------------------------------------------------------------------------------- */
 294
 295 static const char *
 296 help_follow_link (const char *start, const char *lc_selected_item)
 297 {
 298     const char *p;
 299
 300     if (lc_selected_item == NULL)
 301         return start;
 302
 303     for (p = lc_selected_item; *p && *p != CHAR_NODE_END && *p != CHAR_LINK_POINTER; p++)
 304         ;
 305     if (*p == CHAR_LINK_POINTER)
 306     {
 307         int i;
 308         char link_name[MAXLINKNAME];
 309
 310         link_name[0] = '[';
 311         for (i = 1; *p != CHAR_LINK_END && *p && *p != CHAR_NODE_END && i < MAXLINKNAME - 3;)
 312             link_name[i++] = *++p;
 313         link_name[i - 1] = ']';
 314         link_name[i] = '\0';
 315         p = search_string (fdata, link_name);
 316         if (p != NULL)
 317         {
 318             p += 1;             /* Skip the newline following the start of the node */
 319             return p;
 320         }
 321     }
 322
 323     /* Create a replacement page with the error message */
 324     return _("Help file format error\n");
 325 }
 326
 327 /* --------------------------------------------------------------------------------------------- */
 328
 329 static const char *
 330 select_next_link (const char *current_link)
 331 {
 332     const char *p;
 333
 334     if (current_link == NULL)
 335         return NULL;
 336
 337     p = search_string_node (current_link, STRING_LINK_END);
 338     if (p == NULL)
 339         return NULL;
 340     p = search_string_node (p, STRING_LINK_START);
 341     if (p == NULL)
 342         return NULL;
 343     return p - 1;
 344 }
 345
 346 /* --------------------------------------------------------------------------------------------- */
 347
 348 static const char *
 349 select_prev_link (const char *current_link)
 350 {
 351     return current_link == NULL ? NULL : search_char_node (current_link - 1, CHAR_LINK_START, -1);
 352 }
 353
 354 /* --------------------------------------------------------------------------------------------- */
 355
 356 static void
 357 start_link_area (int x, int y, const char *link_name)
 358 {
 359     Link_Area *la;
 360
 361     if (inside_link_area)
 362         message (D_NORMAL, _("Warning"), "%s", _("Internal bug: Double start of link area"));
 363
 364     /* Allocate memory for a new link area */
 365     la = g_new (Link_Area, 1);
 366     /* Save the beginning coordinates of the link area */
 367     la->x1 = x;
 368     la->y1 = y;
 369     /* Save the name of the destination anchor */
 370     la->link_name = link_name;
 371     link_area = g_slist_prepend (link_area, la);
 372
 373     inside_link_area = TRUE;
 374 }
 375
 376 /* --------------------------------------------------------------------------------------------- */
 377
 378 static void
 379 end_link_area (int x, int y)
 380 {
 381     if (inside_link_area)
 382     {
 383         Link_Area *la = (Link_Area *) link_area->data;
 384         /* Save the end coordinates of the link area */
 385         la->x2 = x;
 386         la->y2 = y;
 387         inside_link_area = FALSE;
 388     }
 389 }
 390
 391 /* --------------------------------------------------------------------------------------------- */
 392
 393 static void
 394 clear_link_areas (void)
 395 {
 396     g_clear_slist (&link_area, g_free);
 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_gotoyx (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_gotoyx (h, line + 2, col + 2);
 515                 tty_print_string (mc_global.mc_version);
 516                 col += str_term_width1 (mc_global.mc_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 ' ':
 535             case '\t':
 536                 /* word delimiter */
 537                 if (painting)
 538                 {
 539                     help_print_word (h, word, &col, &line, c == ' ');
 540                     if (c == '\t')
 541                     {
 542                         col = (col / 8 + 1) * 8;
 543                         if (col >= HELP_WINDOW_WIDTH)
 544                         {
 545                             line++;
 546                             col = 8;
 547                         }
 548                     }
 549                 }
 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                         widget_gotoyx (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 (WIDGET (h)->rect.y + line + 2,
 568                                                WIDGET (h)->rect.x + col + 2, c);
 569 #endif
 570                         col++;
 571                     }
 572                 }
 573             }
 574         }
 575
 576         /* print last word */
 577         if (n[0] == CHAR_NODE_END)
 578             help_print_word (h, word, &col, &line, FALSE);
 579
 580         last_shown = p;
 581         end_of_node = line < help_lines;
 582         tty_setcolor (HELP_NORMAL_COLOR);
 583         if ((int) (selected_item - last_shown) >= 0)
 584         {
 585             if ((link_area == NULL) || (link_area->data == NULL))
 586                 selected_item = NULL;
 587             else
 588             {
 589                 selected_item = ((Link_Area *) link_area->data)->link_name;
 590                 repeat_paint = TRUE;
 591             }
 592         }
 593     }
 594     while (repeat_paint);
 595
 596     g_string_free (word, TRUE);
 597
 598     /* Position the cursor over a nice link */
 599     if (active_col)
 600         widget_gotoyx (h, active_line, active_col);
 601 }
 602
 603 /* --------------------------------------------------------------------------------------------- */
 604 /** show help */
 605
 606 static void
 607 help_help (WDialog * h)
 608 {
 609     const char *p;
 610
 611     history_ptr = (history_ptr + 1) % HISTORY_SIZE;
 612     history[history_ptr].page = currentpoint;
 613     history[history_ptr].link = selected_item;
 614
 615     p = search_string (fdata, "[How to use help]");
 616     if (p != NULL)
 617     {
 618         currentpoint = p + 1;   /* Skip the newline following the start of the node */
 619         selected_item = NULL;
 620         widget_draw (WIDGET (h));
 621     }
 622 }
 623
 624 /* --------------------------------------------------------------------------------------------- */
 625
 626 static void
 627 help_index (WDialog * h)
 628 {
 629     const char *new_item;
 630
 631     new_item = search_string (fdata, "[Contents]");
 632
 633     if (new_item == NULL)
 634         message (D_ERROR, MSG_ERROR, _("Cannot find node %s in help file"), "[Contents]");
 635     else
 636     {
 637         history_ptr = (history_ptr + 1) % HISTORY_SIZE;
 638         history[history_ptr].page = currentpoint;
 639         history[history_ptr].link = selected_item;
 640
 641         currentpoint = new_item + 1;    /* Skip the newline following the start of the node */
 642         selected_item = NULL;
 643         widget_draw (WIDGET (h));
 644     }
 645 }
 646
 647 /* --------------------------------------------------------------------------------------------- */
 648
 649 static void
 650 help_back (WDialog * h)
 651 {
 652     currentpoint = history[history_ptr].page;
 653     selected_item = history[history_ptr].link;
 654     history_ptr--;
 655     if (history_ptr < 0)
 656         history_ptr = HISTORY_SIZE - 1;
 657
 658     widget_draw (WIDGET (h));   /* FIXME: unneeded? */
 659 }
 660
 661 /* --------------------------------------------------------------------------------------------- */
 662
 663 static void
 664 help_next_link (gboolean move_down)
 665 {
 666     const char *new_item;
 667
 668     new_item = select_next_link (selected_item);
 669     if (new_item != NULL)
 670     {
 671         selected_item = new_item;
 672         if ((int) (selected_item - last_shown) >= 0)
 673         {
 674             if (move_down)
 675                 move_forward (1);
 676             else
 677                 selected_item = NULL;
 678         }
 679     }
 680     else if (move_down)
 681         move_forward (1);
 682     else
 683         selected_item = NULL;
 684 }
 685
 686 /* --------------------------------------------------------------------------------------------- */
 687
 688 static void
 689 help_prev_link (gboolean move_up)
 690 {
 691     const char *new_item;
 692
 693     new_item = select_prev_link (selected_item);
 694     selected_item = new_item;
 695     if ((selected_item == NULL) || (selected_item < currentpoint))
 696     {
 697         if (move_up)
 698             move_backward (1);
 699         else if ((link_area != NULL) && (link_area->data != NULL))
 700             selected_item = ((Link_Area *) link_area->data)->link_name;
 701         else
 702             selected_item = NULL;
 703     }
 704 }
 705
 706 /* --------------------------------------------------------------------------------------------- */
 707
 708 static void
 709 help_next_node (void)
 710 {
 711     const char *new_item;
 712
 713     new_item = currentpoint;
 714     while ((*new_item != '\0') && (*new_item != CHAR_NODE_END))
 715         new_item++;
 716
 717     if (*++new_item == '[')
 718         while (*++new_item != '\0')
 719             if ((*new_item == ']') && (*++new_item != '\0') && (*++new_item != '\0'))
 720             {
 721                 currentpoint = new_item;
 722                 selected_item = NULL;
 723                 break;
 724             }
 725 }
 726
 727 /* --------------------------------------------------------------------------------------------- */
 728
 729 static void
 730 help_prev_node (void)
 731 {
 732     const char *new_item;
 733
 734     new_item = currentpoint;
 735     while (((int) (new_item - fdata) > 1) && (*new_item != CHAR_NODE_END))
 736         new_item--;
 737     new_item--;
 738     while (((int) (new_item - fdata) > 0) && (*new_item != CHAR_NODE_END))
 739         new_item--;
 740     while (*new_item != ']')
 741         new_item++;
 742     currentpoint = new_item + 2;
 743     selected_item = NULL;
 744 }
 745
 746 /* --------------------------------------------------------------------------------------------- */
 747
 748 static void
 749 help_select_link (void)
 750 {
 751     /* follow link */
 752     if (selected_item == NULL)
 753     {
 754 #ifdef WE_WANT_TO_GO_BACKWARD_ON_KEY_RIGHT
 755         /* Is there any reason why the right key would take us
 756          * backward if there are no links selected?, I agree
 757          * with Torben than doing nothing in this case is better
 758          */
 759         /* If there are no links, go backward in history */
 760         history_ptr--;
 761         if (history_ptr < 0)
 762             history_ptr = HISTORY_SIZE - 1;
 763
 764         currentpoint = history[history_ptr].page;
 765         selected_item = history[history_ptr].link;
 766 #endif
 767     }
 768     else
 769     {
 770         history_ptr = (history_ptr + 1) % HISTORY_SIZE;
 771         history[history_ptr].page = currentpoint;
 772         history[history_ptr].link = selected_item;
 773         currentpoint = help_follow_link (currentpoint, selected_item);
 774     }
 775
 776     selected_item = NULL;
 777 }
 778
 779 /* --------------------------------------------------------------------------------------------- */
 780
 781 static cb_ret_t
 782 help_execute_cmd (long command)
 783 {
 784     cb_ret_t ret = MSG_HANDLED;
 785
 786     switch (command)
 787     {
 788     case CK_Help:
 789         help_help (whelp);
 790         break;
 791     case CK_Index:
 792         help_index (whelp);
 793         break;
 794     case CK_Back:
 795         help_back (whelp);
 796         break;
 797     case CK_Up:
 798         help_prev_link (TRUE);
 799         break;
 800     case CK_Down:
 801         help_next_link (TRUE);
 802         break;
 803     case CK_PageDown:
 804         move_forward (help_lines - 1);
 805         break;
 806     case CK_PageUp:
 807         move_backward (help_lines - 1);
 808         break;
 809     case CK_HalfPageDown:
 810         move_forward (help_lines / 2);
 811         break;
 812     case CK_HalfPageUp:
 813         move_backward (help_lines / 2);
 814         break;
 815     case CK_Top:
 816         move_to_top ();
 817         break;
 818     case CK_Bottom:
 819         move_to_bottom ();
 820         break;
 821     case CK_Enter:
 822         help_select_link ();
 823         break;
 824     case CK_LinkNext:
 825         help_next_link (FALSE);
 826         break;
 827     case CK_LinkPrev:
 828         help_prev_link (FALSE);
 829         break;
 830     case CK_NodeNext:
 831         help_next_node ();
 832         break;
 833     case CK_NodePrev:
 834         help_prev_node ();
 835         break;
 836     case CK_Quit:
 837         dlg_stop (whelp);
 838         break;
 839     default:
 840         ret = MSG_NOT_HANDLED;
 841     }
 842
 843     return ret;
 844 }
 845
 846 /* --------------------------------------------------------------------------------------------- */
 847
 848 static cb_ret_t
 849 help_handle_key (WDialog * h, int key)
 850 {
 851     Widget *w = WIDGET (h);
 852     long command;
 853
 854     command = widget_lookup_key (w, key);
 855     if (command == CK_IgnoreKey)
 856         return MSG_NOT_HANDLED;
 857
 858     return help_execute_cmd (command);
 859 }
 860
 861 /* --------------------------------------------------------------------------------------------- */
 862
 863 static cb_ret_t
 864 help_bg_callback (Widget * w, Widget * sender, widget_msg_t msg, int parm, void *data)
 865 {
 866     switch (msg)
 867     {
 868     case MSG_DRAW:
 869         frame_callback (w, NULL, MSG_DRAW, 0, NULL);
 870         help_show (DIALOG (w->owner), currentpoint);
 871         return MSG_HANDLED;
 872
 873     default:
 874         return frame_callback (w, sender, msg, parm, data);
 875     }
 876 }
 877
 878 /* --------------------------------------------------------------------------------------------- */
 879
 880 static cb_ret_t
 881 help_resize (WDialog * h)
 882 {
 883     Widget *w = WIDGET (h);
 884     WButtonBar *bb;
 885     WRect r = w->rect;
 886
 887     help_lines = MIN (LINES - 4, MAX (2 * LINES / 3, 18));
 888     r.lines = help_lines + 4;
 889     r.cols = HELP_WINDOW_WIDTH + 4;
 890     dlg_default_callback (w, NULL, MSG_RESIZE, 0, &r);
 891     bb = find_buttonbar (h);
 892     widget_set_size (WIDGET (bb), LINES - 1, 0, 1, COLS);
 893
 894     return MSG_HANDLED;
 895 }
 896
 897 /* --------------------------------------------------------------------------------------------- */
 898
 899 static cb_ret_t
 900 help_callback (Widget * w, Widget * sender, widget_msg_t msg, int parm, void *data)
 901 {
 902     WDialog *h = DIALOG (w);
 903
 904     switch (msg)
 905     {
 906     case MSG_RESIZE:
 907         return help_resize (h);
 908
 909     case MSG_KEY:
 910         {
 911             cb_ret_t ret;
 912
 913             ret = help_handle_key (h, parm);
 914             if (ret == MSG_HANDLED)
 915                 widget_draw (w);
 916
 917             return ret;
 918         }
 919
 920     case MSG_ACTION:
 921         /* Handle shortcuts and buttonbar. */
 922         return help_execute_cmd (parm);
 923
 924     default:
 925         return dlg_default_callback (w, sender, msg, parm, data);
 926     }
 927 }
 928
 929 /* --------------------------------------------------------------------------------------------- */
 930
 931 static void
 932 interactive_display_finish (void)
 933 {
 934     clear_link_areas ();
 935 }
 936
 937 /* --------------------------------------------------------------------------------------------- */
 938 /** translate help file into terminal encoding */
 939
 940 static void
 941 translate_file (char *filedata)
 942 {
 943     GIConv conv;
 944
 945     conv = str_crt_conv_from ("UTF-8");
 946     if (conv != INVALID_CONV)
 947     {
 948         GString *translated_data;
 949         gboolean nok;
 950
 951         g_free (fdata);
 952
 953         /* initial allocation for largest whole help file */
 954         translated_data = g_string_sized_new (32 * 1024);
 955         nok = (str_convert (conv, filedata, translated_data) == ESTR_FAILURE);
 956         fdata = g_string_free (translated_data, nok);
 957
 958         str_close_conv (conv);
 959     }
 960 }
 961
 962 /* --------------------------------------------------------------------------------------------- */
 963
 964 static cb_ret_t
 965 md_callback (Widget * w, Widget * sender, widget_msg_t msg, int parm, void *data)
 966 {
 967     switch (msg)
 968     {
 969     case MSG_RESIZE:
 970         widget_default_callback (w, NULL, MSG_RESIZE, 0, data);
 971         w->rect.lines = help_lines;
 972         return MSG_HANDLED;
 973
 974     default:
 975         return widget_default_callback (w, sender, msg, parm, data);
 976     }
 977 }
 978
 979 /* --------------------------------------------------------------------------------------------- */
 980
 981 static void
 982 help_mouse_callback (Widget * w, mouse_msg_t msg, mouse_event_t * event)
 983 {
 984     int x, y;
 985     GSList *current_area;
 986
 987     if (msg != MSG_MOUSE_CLICK)
 988         return;
 989
 990     if ((event->buttons & GPM_B_RIGHT) != 0)
 991     {
 992         /* Right button click */
 993         help_back (whelp);
 994         return;
 995     }
 996
 997     /* Left bytton click */
 998
 999     /* The event is relative to the dialog window, adjust it: */
1000     x = event->x - 1;
1001     y = event->y - 1;
1002
1003     /* Test whether the mouse click is inside one of the link areas */
1004     for (current_area = link_area; current_area != NULL; current_area = g_slist_next (current_area))
1005     {
1006         Link_Area *la = (Link_Area *) current_area->data;
1007
1008         /* Test one line link area */
1009         if (y == la->y1 && x >= la->x1 && y == la->y2 && x <= la->x2)
1010             break;
1011
1012         /* Test two line link area */
1013         if (la->y1 + 1 == la->y2)
1014         {
1015             /* The first line || The second line */
1016             if ((y == la->y1 && x >= la->x1) || (y == la->y2 && x <= la->x2))
1017                 break;
1018         }
1019         /* Mouse will not work with link areas of more than two lines */
1020     }
1021
1022     /* Test whether a link area was found */
1023     if (current_area != NULL)
1024     {
1025         Link_Area *la = (Link_Area *) current_area->data;
1026
1027         /* The click was inside a link area -> follow the link */
1028         history_ptr = (history_ptr + 1) % HISTORY_SIZE;
1029         history[history_ptr].page = currentpoint;
1030         history[history_ptr].link = la->link_name;
1031         currentpoint = help_follow_link (currentpoint, la->link_name);
1032         selected_item = NULL;
1033     }
1034     else if (y < 0)
1035         move_backward (help_lines - 1);
1036     else if (y >= help_lines)
1037         move_forward (help_lines - 1);
1038     else if (y < help_lines / 2)
1039         move_backward (1);
1040     else
1041         move_forward (1);
1042
1043     /* Show the new node */
1044     widget_draw (WIDGET (w->owner));
1045 }
1046
1047 /* --------------------------------------------------------------------------------------------- */
1048
1049 static Widget *
1050 mousedispatch_new (const WRect * r)
1051 {
1052     Widget *w;
1053
1054     w = g_new0 (Widget, 1);
1055     widget_init (w, r, md_callback, help_mouse_callback);
1056     w->options |= WOP_SELECTABLE | WOP_WANT_CURSOR;
1057
1058     return w;
1059 }
1060
1061 /* --------------------------------------------------------------------------------------------- */
1062 /*** public functions ****************************************************************************/
1063 /* --------------------------------------------------------------------------------------------- */
1064
1065 /* event callback */
1066 gboolean
1067 help_interactive_display (const gchar * event_group_name, const gchar * event_name,
1068                           gpointer init_data, gpointer data)
1069 {
1070     const dlg_colors_t help_colors = {
1071         HELP_NORMAL_COLOR,      /* common text color */
1072         0,                      /* unused in help */
1073         HELP_BOLD_COLOR,        /* bold text color */
1074         0,                      /* unused in help */
1075         HELP_TITLE_COLOR        /* title color */
1076     };
1077
1078     Widget *wh;
1079     WGroup *g;
1080     WButtonBar *help_bar;
1081     Widget *md;
1082     char *hlpfile = NULL;
1083     char *filedata;
1084     ev_help_t *event_data = (ev_help_t *) data;
1085     WRect r = { 1, 1, 1, 1 };
1086
1087     (void) event_group_name;
1088     (void) event_name;
1089     (void) init_data;
1090
1091     if (event_data->filename != NULL)
1092         g_file_get_contents (event_data->filename, &filedata, NULL, NULL);
1093     else
1094         filedata = load_mc_home_file (mc_global.share_data_dir, MC_HELP, &hlpfile, NULL);
1095
1096     if (filedata == NULL)
1097         message (D_ERROR, MSG_ERROR, _("Cannot open file %s\n%s"),
1098                  event_data->filename ? event_data->filename : hlpfile, unix_error_string (errno));
1099
1100     g_free (hlpfile);
1101
1102     if (filedata == NULL)
1103         return TRUE;
1104
1105     translate_file (filedata);
1106
1107     g_free (filedata);
1108
1109     if (fdata == NULL)
1110         return TRUE;
1111
1112     if ((event_data->node == NULL) || (*event_data->node == '\0'))
1113         event_data->node = "[main]";
1114
1115     main_node = search_string (fdata, event_data->node);
1116
1117     if (main_node == NULL)
1118     {
1119         message (D_ERROR, MSG_ERROR, _("Cannot find node %s in help file"), event_data->node);
1120
1121         /* Fallback to [main], return if it also cannot be found */
1122         main_node = search_string (fdata, "[main]");
1123         if (main_node == NULL)
1124         {
1125             interactive_display_finish ();
1126             return TRUE;
1127         }
1128     }
1129
1130     help_lines = MIN (LINES - 4, MAX (2 * LINES / 3, 18));
1131
1132     whelp =
1133         dlg_create (TRUE, 0, 0, help_lines + 4, HELP_WINDOW_WIDTH + 4, WPOS_CENTER | WPOS_TRYUP,
1134                     FALSE, help_colors, help_callback, NULL, "[Help]", _("Help"));
1135     wh = WIDGET (whelp);
1136     g = GROUP (whelp);
1137     wh->keymap = help_map;
1138     widget_want_tab (wh, TRUE);
1139     /* draw background */
1140     whelp->bg->callback = help_bg_callback;
1141
1142     selected_item = search_string_node (main_node, STRING_LINK_START) - 1;
1143     currentpoint = main_node + 1;       /* Skip the newline following the start of the node */
1144
1145     for (history_ptr = HISTORY_SIZE; history_ptr;)
1146     {
1147         history_ptr--;
1148         history[history_ptr].page = currentpoint;
1149         history[history_ptr].link = selected_item;
1150     }
1151
1152     help_bar = buttonbar_new ();
1153     WIDGET (help_bar)->rect.y -= wh->rect.y;
1154     WIDGET (help_bar)->rect.x -= wh->rect.x;
1155
1156     r.lines = help_lines;
1157     r.cols = HELP_WINDOW_WIDTH - 2;
1158     md = mousedispatch_new (&r);
1159
1160     group_add_widget (g, md);
1161     group_add_widget (g, help_bar);     /* FIXME */
1162
1163     buttonbar_set_label (help_bar, 1, Q_ ("ButtonBar|Help"), wh->keymap, NULL);
1164     buttonbar_set_label (help_bar, 2, Q_ ("ButtonBar|Index"), wh->keymap, NULL);
1165     buttonbar_set_label (help_bar, 3, Q_ ("ButtonBar|Prev"), wh->keymap, NULL);
1166     buttonbar_set_label (help_bar, 4, "", wh->keymap, NULL);
1167     buttonbar_set_label (help_bar, 5, "", wh->keymap, NULL);
1168     buttonbar_set_label (help_bar, 6, "", wh->keymap, NULL);
1169     buttonbar_set_label (help_bar, 7, "", wh->keymap, NULL);
1170     buttonbar_set_label (help_bar, 8, "", wh->keymap, NULL);
1171     buttonbar_set_label (help_bar, 9, "", wh->keymap, NULL);
1172     buttonbar_set_label (help_bar, 10, Q_ ("ButtonBar|Quit"), wh->keymap, NULL);
1173
1174     dlg_run (whelp);
1175     interactive_display_finish ();
1176     widget_destroy (wh);
1177     return TRUE;
1178 }
1179
1180 /* --------------------------------------------------------------------------------------------- */