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/tty/mouse.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 "keybind-defaults.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"), _("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_slist_free_full (link_area, g_free);
 397     link_area = NULL;
 398     inside_link_area = FALSE;
 399 }
 400
 401 /* --------------------------------------------------------------------------------------------- */
 402
 403 static void
 404 help_print_word (WDialog * h, GString * word, int *col, int *line, gboolean add_space)
 405 {
 406     if (*line >= help_lines)
 407         g_string_set_size (word, 0);
 408     else
 409     {
 410         int w;
 411
 412         w = str_term_width1 (word->str);
 413         if (*col + w >= HELP_WINDOW_WIDTH)
 414         {
 415             *col = 0;
 416             (*line)++;
 417         }
 418
 419         if (*line >= help_lines)
 420             g_string_set_size (word, 0);
 421         else
 422         {
 423             widget_move (h, *line + 2, *col + 2);
 424             tty_print_string (word->str);
 425             g_string_set_size (word, 0);
 426             *col += w;
 427         }
 428     }
 429
 430     if (add_space)
 431     {
 432         if (*col < HELP_WINDOW_WIDTH - 1)
 433         {
 434             tty_print_char (' ');
 435             (*col)++;
 436         }
 437         else
 438         {
 439             *col = 0;
 440             (*line)++;
 441         }
 442     }
 443 }
 444
 445 /* --------------------------------------------------------------------------------------------- */
 446
 447 static void
 448 help_show (WDialog * h, const char *paint_start)
 449 {
 450     const char *p, *n;
 451     int col, line, c;
 452     gboolean painting = TRUE;
 453     gboolean acs;               /* Flag: Alternate character set active? */
 454     gboolean repeat_paint;
 455     int active_col, active_line;        /* Active link position */
 456     char buff[MB_LEN_MAX + 1];
 457     GString *word;
 458
 459     word = g_string_sized_new (32);
 460
 461     tty_setcolor (HELP_NORMAL_COLOR);
 462     do
 463     {
 464         line = col = active_col = active_line = 0;
 465         repeat_paint = FALSE;
 466         acs = FALSE;
 467
 468         clear_link_areas ();
 469         if ((int) (selected_item - paint_start) < 0)
 470             selected_item = NULL;
 471
 472         p = paint_start;
 473         n = paint_start;
 474         while ((n[0] != '\0') && (n[0] != CHAR_NODE_END) && (line < help_lines))
 475         {
 476             p = n;
 477             n = str_cget_next_char (p);
 478             memcpy (buff, p, n - p);
 479             buff[n - p] = '\0';
 480
 481             c = (unsigned char) buff[0];
 482             switch (c)
 483             {
 484             case CHAR_LINK_START:
 485                 if (selected_item == NULL)
 486                     selected_item = p;
 487                 if (p != selected_item)
 488                     tty_setcolor (HELP_LINK_COLOR);
 489                 else
 490                 {
 491                     tty_setcolor (HELP_SLINK_COLOR);
 492
 493                     /* Store the coordinates of the link */
 494                     active_col = col + 2;
 495                     active_line = line + 2;
 496                 }
 497                 start_link_area (col, line, p);
 498                 break;
 499             case CHAR_LINK_POINTER:
 500                 painting = FALSE;
 501                 break;
 502             case CHAR_LINK_END:
 503                 painting = TRUE;
 504                 help_print_word (h, word, &col, &line, FALSE);
 505                 end_link_area (col - 1, line);
 506                 tty_setcolor (HELP_NORMAL_COLOR);
 507                 break;
 508             case CHAR_ALTERNATE:
 509                 acs = TRUE;
 510                 break;
 511             case CHAR_NORMAL:
 512                 acs = FALSE;
 513                 break;
 514             case CHAR_VERSION:
 515                 widget_move (h, line + 2, col + 2);
 516                 tty_print_string (VERSION);
 517                 col += str_term_width1 (VERSION);
 518                 break;
 519             case CHAR_FONT_BOLD:
 520                 tty_setcolor (HELP_BOLD_COLOR);
 521                 break;
 522             case CHAR_FONT_ITALIC:
 523                 tty_setcolor (HELP_ITALIC_COLOR);
 524                 break;
 525             case CHAR_FONT_NORMAL:
 526                 help_print_word (h, word, &col, &line, FALSE);
 527                 tty_setcolor (HELP_NORMAL_COLOR);
 528                 break;
 529             case '\n':
 530                 if (painting)
 531                     help_print_word (h, word, &col, &line, FALSE);
 532                 line++;
 533                 col = 0;
 534                 break;
 535             case '\t':
 536                 col = (col / 8 + 1) * 8;
 537                 if (col >= HELP_WINDOW_WIDTH)
 538                 {
 539                     line++;
 540                     col = 8;
 541                 }
 542                 break;
 543             case ' ':
 544                 /* word delimiter */
 545                 if (painting)
 546                     help_print_word (h, word, &col, &line, TRUE);
 547                 break;
 548             default:
 549                 if (painting && (line < help_lines))
 550                 {
 551                     if (!acs)
 552                         /* accumulate symbols in a word */
 553                         g_string_append (word, buff);
 554                     else if (col < HELP_WINDOW_WIDTH)
 555                     {
 556                         widget_move (h, line + 2, col + 2);
 557
 558                         if ((c == ' ') || (c == '.'))
 559                             tty_print_char (c);
 560                         else
 561 #ifndef HAVE_SLANG
 562                             tty_print_char (acs_map[c]);
 563 #else
 564                             SLsmg_draw_object (WIDGET (h)->y + line + 2, WIDGET (h)->x + col + 2,
 565                                                c);
 566 #endif
 567                         col++;
 568                     }
 569                 }
 570             }
 571         }
 572
 573         /* print last word */
 574         if (n[0] == CHAR_NODE_END)
 575             help_print_word (h, word, &col, &line, FALSE);
 576
 577         last_shown = p;
 578         end_of_node = line < help_lines;
 579         tty_setcolor (HELP_NORMAL_COLOR);
 580         if ((int) (selected_item - last_shown) >= 0)
 581         {
 582             if ((link_area == NULL) || (link_area->data == NULL))
 583                 selected_item = NULL;
 584             else
 585             {
 586                 selected_item = ((Link_Area *) link_area->data)->link_name;
 587                 repeat_paint = TRUE;
 588             }
 589         }
 590     }
 591     while (repeat_paint);
 592
 593     g_string_free (word, TRUE);
 594
 595     /* Position the cursor over a nice link */
 596     if (active_col)
 597         widget_move (h, active_line, active_col);
 598 }
 599
 600 /* --------------------------------------------------------------------------------------------- */
 601
 602 static int
 603 help_event (Gpm_Event * event, void *vp)
 604 {
 605     Widget *w = WIDGET (vp);
 606     GSList *current_area;
 607     Gpm_Event local;
 608
 609     if (!mouse_global_in_widget (event, w))
 610         return MOU_UNHANDLED;
 611
 612     if ((event->type & GPM_UP) == 0)
 613         return MOU_NORMAL;
 614
 615     local = mouse_get_local (event, w);
 616
 617     /* The event is relative to the dialog window, adjust it: */
 618     local.x -= 2;
 619     local.y -= 2;
 620
 621     if ((local.buttons & GPM_B_RIGHT) != 0)
 622     {
 623         currentpoint = history[history_ptr].page;
 624         selected_item = history[history_ptr].link;
 625         history_ptr--;
 626         if (history_ptr < 0)
 627             history_ptr = HISTORY_SIZE - 1;
 628
 629         send_message (w->owner, NULL, MSG_DRAW, 0, NULL);
 630         return MOU_NORMAL;
 631     }
 632
 633     /* Test whether the mouse click is inside one of the link areas */
 634     for (current_area = link_area; current_area != NULL; current_area = g_slist_next (current_area))
 635     {
 636         Link_Area *la = (Link_Area *) current_area->data;
 637
 638         /* Test one line link area */
 639         if (local.y == la->y1 && local.x >= la->x1 && local.y == la->y2 && local.x <= la->x2)
 640             break;
 641
 642         /* Test two line link area */
 643         if (la->y1 + 1 == la->y2)
 644         {
 645             /* The first line */
 646             if (local.y == la->y1 && local.x >= la->x1)
 647                 break;
 648             /* The second line */
 649             if (local.y == la->y2 && local.x <= la->x2)
 650                 break;
 651         }
 652         /* Mouse will not work with link areas of more than two lines */
 653     }
 654
 655     /* Test whether a link area was found */
 656     if (current_area != NULL)
 657     {
 658         Link_Area *la = (Link_Area *) current_area->data;
 659
 660         /* The click was inside a link area -> follow the link */
 661         history_ptr = (history_ptr + 1) % HISTORY_SIZE;
 662         history[history_ptr].page = currentpoint;
 663         history[history_ptr].link = la->link_name;
 664         currentpoint = help_follow_link (currentpoint, la->link_name);
 665         selected_item = NULL;
 666     }
 667     else if (local.y < 0)
 668         move_backward (help_lines - 1);
 669     else if (local.y >= help_lines)
 670         move_forward (help_lines - 1);
 671     else if (local.y < help_lines / 2)
 672         move_backward (1);
 673     else
 674         move_forward (1);
 675
 676     /* Show the new node */
 677     send_message (w->owner, NULL, MSG_DRAW, 0, NULL);
 678
 679     return MOU_NORMAL;
 680 }
 681
 682 /* --------------------------------------------------------------------------------------------- */
 683 /** show help */
 684
 685 static void
 686 help_help (WDialog * h)
 687 {
 688     const char *p;
 689
 690     history_ptr = (history_ptr + 1) % HISTORY_SIZE;
 691     history[history_ptr].page = currentpoint;
 692     history[history_ptr].link = selected_item;
 693
 694     p = search_string (fdata, "[How to use help]");
 695     if (p != NULL)
 696     {
 697         currentpoint = p + 1;   /* Skip the newline following the start of the node */
 698         selected_item = NULL;
 699         send_message (h, NULL, MSG_DRAW, 0, NULL);
 700     }
 701 }
 702
 703 /* --------------------------------------------------------------------------------------------- */
 704
 705 static void
 706 help_index (WDialog * h)
 707 {
 708     const char *new_item;
 709
 710     new_item = search_string (fdata, "[Contents]");
 711
 712     if (new_item == NULL)
 713         message (D_ERROR, MSG_ERROR, _("Cannot find node %s in help file"), "[Contents]");
 714     else
 715     {
 716         history_ptr = (history_ptr + 1) % HISTORY_SIZE;
 717         history[history_ptr].page = currentpoint;
 718         history[history_ptr].link = selected_item;
 719
 720         currentpoint = new_item + 1;    /* Skip the newline following the start of the node */
 721         selected_item = NULL;
 722         send_message (h, NULL, MSG_DRAW, 0, NULL);
 723     }
 724 }
 725
 726 /* --------------------------------------------------------------------------------------------- */
 727
 728 static void
 729 help_back (WDialog * h)
 730 {
 731     currentpoint = history[history_ptr].page;
 732     selected_item = history[history_ptr].link;
 733     history_ptr--;
 734     if (history_ptr < 0)
 735         history_ptr = HISTORY_SIZE - 1;
 736
 737     send_message (h, NULL, MSG_DRAW, 0, NULL);  /* FIXME: unneeded? */
 738 }
 739
 740 /* --------------------------------------------------------------------------------------------- */
 741
 742 static void
 743 help_next_link (gboolean move_down)
 744 {
 745     const char *new_item;
 746
 747     new_item = select_next_link (selected_item);
 748     if (new_item != NULL)
 749     {
 750         selected_item = new_item;
 751         if ((int) (selected_item - last_shown) >= 0)
 752         {
 753             if (move_down)
 754                 move_forward (1);
 755             else
 756                 selected_item = NULL;
 757         }
 758     }
 759     else if (move_down)
 760         move_forward (1);
 761     else
 762         selected_item = NULL;
 763 }
 764
 765 /* --------------------------------------------------------------------------------------------- */
 766
 767 static void
 768 help_prev_link (gboolean move_up)
 769 {
 770     const char *new_item;
 771
 772     new_item = select_prev_link (selected_item);
 773     selected_item = new_item;
 774     if ((selected_item == NULL) || (selected_item < currentpoint))
 775     {
 776         if (move_up)
 777             move_backward (1);
 778         else if ((link_area != NULL) && (link_area->data != NULL))
 779             selected_item = ((Link_Area *) link_area->data)->link_name;
 780         else
 781             selected_item = NULL;
 782     }
 783 }
 784
 785 /* --------------------------------------------------------------------------------------------- */
 786
 787 static void
 788 help_next_node (void)
 789 {
 790     const char *new_item;
 791
 792     new_item = currentpoint;
 793     while ((*new_item != '\0') && (*new_item != CHAR_NODE_END))
 794         new_item++;
 795
 796     if (*++new_item == '[')
 797         while (*++new_item != '\0')
 798             if ((*new_item == ']') && (*++new_item != '\0') && (*++new_item != '\0'))
 799             {
 800                 currentpoint = new_item;
 801                 selected_item = NULL;
 802                 break;
 803             }
 804 }
 805
 806 /* --------------------------------------------------------------------------------------------- */
 807
 808 static void
 809 help_prev_node (void)
 810 {
 811     const char *new_item;
 812
 813     new_item = currentpoint;
 814     while (((int) (new_item - fdata) > 1) && (*new_item != CHAR_NODE_END))
 815         new_item--;
 816     new_item--;
 817     while (((int) (new_item - fdata) > 0) && (*new_item != CHAR_NODE_END))
 818         new_item--;
 819     while (*new_item != ']')
 820         new_item++;
 821     currentpoint = new_item + 2;
 822     selected_item = NULL;
 823 }
 824
 825 /* --------------------------------------------------------------------------------------------- */
 826
 827 static void
 828 help_select_link (void)
 829 {
 830     /* follow link */
 831     if (selected_item == NULL)
 832     {
 833 #ifdef WE_WANT_TO_GO_BACKWARD_ON_KEY_RIGHT
 834         /* Is there any reason why the right key would take us
 835          * backward if there are no links selected?, I agree
 836          * with Torben than doing nothing in this case is better
 837          */
 838         /* If there are no links, go backward in history */
 839         history_ptr--;
 840         if (history_ptr < 0)
 841             history_ptr = HISTORY_SIZE - 1;
 842
 843         currentpoint = history[history_ptr].page;
 844         selected_item = history[history_ptr].link;
 845 #endif
 846     }
 847     else
 848     {
 849         history_ptr = (history_ptr + 1) % HISTORY_SIZE;
 850         history[history_ptr].page = currentpoint;
 851         history[history_ptr].link = selected_item;
 852         currentpoint = help_follow_link (currentpoint, selected_item);
 853     }
 854
 855     selected_item = NULL;
 856 }
 857
 858 /* --------------------------------------------------------------------------------------------- */
 859
 860 static cb_ret_t
 861 help_execute_cmd (long command)
 862 {
 863     cb_ret_t ret = MSG_HANDLED;
 864
 865     switch (command)
 866     {
 867     case CK_Help:
 868         help_help (whelp);
 869         break;
 870     case CK_Index:
 871         help_index (whelp);
 872         break;
 873     case CK_Back:
 874         help_back (whelp);
 875         break;
 876     case CK_Up:
 877         help_prev_link (TRUE);
 878         break;
 879     case CK_Down:
 880         help_next_link (TRUE);
 881         break;
 882     case CK_PageDown:
 883         move_forward (help_lines - 1);
 884         break;
 885     case CK_PageUp:
 886         move_backward (help_lines - 1);
 887         break;
 888     case CK_HalfPageDown:
 889         move_forward (help_lines / 2);
 890         break;
 891     case CK_HalfPageUp:
 892         move_backward (help_lines / 2);
 893         break;
 894     case CK_Top:
 895         move_to_top ();
 896         break;
 897     case CK_Bottom:
 898         move_to_bottom ();
 899         break;
 900     case CK_Enter:
 901         help_select_link ();
 902         break;
 903     case CK_LinkNext:
 904         help_next_link (FALSE);
 905         break;
 906     case CK_LinkPrev:
 907         help_prev_link (FALSE);
 908         break;
 909     case CK_NodeNext:
 910         help_next_node ();
 911         break;
 912     case CK_NodePrev:
 913         help_prev_node ();
 914         break;
 915     case CK_Quit:
 916         dlg_stop (whelp);
 917         break;
 918     default:
 919         ret = MSG_NOT_HANDLED;
 920     }
 921
 922     return ret;
 923 }
 924
 925 /* --------------------------------------------------------------------------------------------- */
 926
 927 static cb_ret_t
 928 help_handle_key (WDialog * h, int c)
 929 {
 930     long command;
 931
 932     command = keybind_lookup_keymap_command (help_map, c);
 933     if ((command == CK_IgnoreKey) || (help_execute_cmd (command) == MSG_NOT_HANDLED))
 934         return MSG_NOT_HANDLED;
 935
 936     send_message (h, NULL, MSG_DRAW, 0, NULL);
 937     return MSG_HANDLED;
 938 }
 939
 940 /* --------------------------------------------------------------------------------------------- */
 941
 942 static cb_ret_t
 943 help_callback (Widget * w, Widget * sender, widget_msg_t msg, int parm, void *data)
 944 {
 945     WDialog *h = DIALOG (w);
 946
 947     switch (msg)
 948     {
 949     case MSG_RESIZE:
 950         {
 951             WButtonBar *bb;
 952
 953             help_lines = min (LINES - 4, max (2 * LINES / 3, 18));
 954             dlg_set_size (h, help_lines + 4, HELP_WINDOW_WIDTH + 4);
 955             bb = find_buttonbar (h);
 956             widget_set_size (WIDGET (bb), LINES - 1, 0, 1, COLS);
 957             return MSG_HANDLED;
 958         }
 959
 960     case MSG_DRAW:
 961         dlg_default_repaint (h);
 962         help_show (h, currentpoint);
 963         return MSG_HANDLED;
 964
 965     case MSG_KEY:
 966         return help_handle_key (h, parm);
 967
 968     case MSG_ACTION:
 969         /* shortcut */
 970         if (sender == NULL)
 971             return help_execute_cmd (parm);
 972         /* message from buttonbar */
 973         if (sender == WIDGET (find_buttonbar (h)))
 974         {
 975             if (data != NULL)
 976                 return send_message (data, NULL, MSG_ACTION, parm, NULL);
 977             return help_execute_cmd (parm);
 978         }
 979         return MSG_NOT_HANDLED;
 980
 981     default:
 982         return dlg_default_callback (w, sender, msg, parm, data);
 983     }
 984 }
 985
 986 /* --------------------------------------------------------------------------------------------- */
 987
 988 static void
 989 interactive_display_finish (void)
 990 {
 991     clear_link_areas ();
 992 }
 993
 994 /* --------------------------------------------------------------------------------------------- */
 995 /** translate help file into terminal encoding */
 996
 997 static void
 998 translate_file (char *filedata)
 999 {
1000     GIConv conv;
1001     GString *translated_data;
1002
1003     /* initial allocation for largest whole help file */
1004     translated_data = g_string_sized_new (32 * 1024);
1005
1006     conv = str_crt_conv_from ("UTF-8");
1007
1008     if (conv == INVALID_CONV)
1009         g_string_free (translated_data, TRUE);
1010     else
1011     {
1012         g_free (fdata);
1013
1014         if (str_convert (conv, filedata, translated_data) != ESTR_FAILURE)
1015             fdata = g_string_free (translated_data, FALSE);
1016         else
1017         {
1018             fdata = NULL;
1019             g_string_free (translated_data, TRUE);
1020         }
1021         str_close_conv (conv);
1022     }
1023 }
1024
1025 /* --------------------------------------------------------------------------------------------- */
1026
1027 static cb_ret_t
1028 md_callback (Widget * w, Widget * sender, widget_msg_t msg, int parm, void *data)
1029 {
1030     switch (msg)
1031     {
1032     case MSG_RESIZE:
1033         w->lines = help_lines;
1034         return MSG_HANDLED;
1035
1036     default:
1037         return widget_default_callback (w, sender, msg, parm, data);
1038     }
1039 }
1040
1041 /* --------------------------------------------------------------------------------------------- */
1042
1043 static Widget *
1044 mousedispatch_new (int y, int x, int yl, int xl)
1045 {
1046     Widget *w;
1047
1048     w = g_new (Widget, 1);
1049     widget_init (w, y, x, yl, xl, md_callback, help_event);
1050     return w;
1051 }
1052
1053 /* --------------------------------------------------------------------------------------------- */
1054 /*** public functions ****************************************************************************/
1055 /* --------------------------------------------------------------------------------------------- */
1056
1057 /* event callback */
1058 gboolean
1059 help_interactive_display (const gchar * event_group_name, const gchar * event_name,
1060                           gpointer init_data, gpointer data)
1061 {
1062     const dlg_colors_t help_colors = {
1063         HELP_NORMAL_COLOR,      /* common text color */
1064         0,                      /* unused in help */
1065         HELP_BOLD_COLOR,        /* bold text color */
1066         0,                      /* unused in help */
1067         HELP_TITLE_COLOR        /* title color */
1068     };
1069
1070     WButtonBar *help_bar;
1071     Widget *md;
1072     char *hlpfile = NULL;
1073     char *filedata;
1074     ev_help_t *event_data = (ev_help_t *) data;
1075
1076     (void) event_group_name;
1077     (void) event_name;
1078     (void) init_data;
1079
1080     if (event_data->filename != NULL)
1081         g_file_get_contents (event_data->filename, &filedata, NULL, NULL);
1082     else
1083         filedata = load_mc_home_file (mc_global.share_data_dir, MC_HELP, &hlpfile);
1084
1085     if (filedata == NULL)
1086         message (D_ERROR, MSG_ERROR, _("Cannot open file %s\n%s"),
1087                  event_data->filename ? event_data->filename : hlpfile, unix_error_string (errno));
1088
1089     g_free (hlpfile);
1090
1091     if (filedata == NULL)
1092         return TRUE;
1093
1094     translate_file (filedata);
1095
1096     g_free (filedata);
1097
1098     if (fdata == NULL)
1099         return TRUE;
1100
1101     if ((event_data->node == NULL) || (*event_data->node == '\0'))
1102         event_data->node = "[main]";
1103
1104     main_node = search_string (fdata, event_data->node);
1105
1106     if (main_node == NULL)
1107     {
1108         message (D_ERROR, MSG_ERROR, _("Cannot find node %s in help file"), event_data->node);
1109
1110         /* Fallback to [main], return if it also cannot be found */
1111         main_node = search_string (fdata, "[main]");
1112         if (main_node == NULL)
1113         {
1114             interactive_display_finish ();
1115             return TRUE;
1116         }
1117     }
1118
1119     help_lines = min (LINES - 4, max (2 * LINES / 3, 18));
1120
1121     whelp =
1122         dlg_create (TRUE, 0, 0, help_lines + 4, HELP_WINDOW_WIDTH + 4,
1123                     help_colors, help_callback, NULL, "[Help]", _("Help"),
1124                     DLG_TRYUP | DLG_CENTER | DLG_WANT_TAB);
1125
1126     selected_item = search_string_node (main_node, STRING_LINK_START) - 1;
1127     currentpoint = main_node + 1;       /* Skip the newline following the start of the node */
1128
1129     for (history_ptr = HISTORY_SIZE; history_ptr;)
1130     {
1131         history_ptr--;
1132         history[history_ptr].page = currentpoint;
1133         history[history_ptr].link = selected_item;
1134     }
1135
1136     help_bar = buttonbar_new (TRUE);
1137     WIDGET (help_bar)->y -= WIDGET (whelp)->y;
1138     WIDGET (help_bar)->x -= WIDGET (whelp)->x;
1139
1140     md = mousedispatch_new (1, 1, help_lines, HELP_WINDOW_WIDTH - 2);
1141
1142     add_widget (whelp, md);
1143     add_widget (whelp, help_bar);
1144
1145     buttonbar_set_label (help_bar, 1, Q_ ("ButtonBar|Help"), help_map, NULL);
1146     buttonbar_set_label (help_bar, 2, Q_ ("ButtonBar|Index"), help_map, NULL);
1147     buttonbar_set_label (help_bar, 3, Q_ ("ButtonBar|Prev"), help_map, NULL);
1148     buttonbar_set_label (help_bar, 4, "", help_map, NULL);
1149     buttonbar_set_label (help_bar, 5, "", help_map, NULL);
1150     buttonbar_set_label (help_bar, 6, "", help_map, NULL);
1151     buttonbar_set_label (help_bar, 7, "", help_map, NULL);
1152     buttonbar_set_label (help_bar, 8, "", help_map, NULL);
1153     buttonbar_set_label (help_bar, 9, "", help_map, NULL);
1154     buttonbar_set_label (help_bar, 10, Q_ ("ButtonBar|Quit"), help_map, NULL);
1155
1156     dlg_run (whelp);
1157     interactive_display_finish ();
1158     dlg_destroy (whelp);
1159     return TRUE;
1160 }
1161
1162 /* --------------------------------------------------------------------------------------------- */