src/help.c

   1 /* Hypertext file browser.
   2    Copyright (C) 1994, 1995, 1998, 1999, 2000, 2001, 2002, 2003, 2004,
   3    2005, 2006, 2007 Free Software Foundation, Inc.
   4
   5    This program is free software; you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 2 of the License, or
   8    (at your option) any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program; if not, write to the Free Software
  17    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18 */
  19
  20
  21 /** \file help.c
  22  *  \brief Source: hypertext file browser
  23  *
  24  *  Implements the hypertext file viewer.
  25  *  The hypertext file is a file that may have one or more nodes.  Each
  26  *  node ends with a ^D character and starts with a bracket, then the
  27  *  name of the node and then a closing bracket. Right after the closing
  28  *  bracket a newline is placed. This newline is not to be displayed by
  29  *  the help viewer and must be skipped - its sole purpose is to faciliate
  30  *  the work of the people managing the help file template (xnc.hlp) .
  31  *
  32  *  Links in the hypertext file are specified like this: the text that
  33  *  will be highlighted should have a leading ^A, then it comes the
  34  *  text, then a ^B indicating that highlighting is done, then the name
  35  *  of the node you want to link to and then a ^C.
  36  *
  37  *  The file must contain a ^D at the beginning and at the end of the
  38  *  file or the program will not be able to detect the end of file.
  39  *
  40  *  Lazyness/widgeting attack: This file does use the dialog manager
  41  *  and uses mainly the dialog to achieve the help work.  there is only
  42  *  one specialized widget and it's only used to forward the mouse messages
  43  *  to the appropiate routine.
  44  */
  45
  46
  47 #include <config.h>
  48
  49 #include <errno.h>
  50 #include <stdio.h>
  51 #include <sys/types.h>
  52 #include <sys/stat.h>
  53
  54 #include "global.h"
  55
  56 #include "../src/tty/tty.h"
  57 #include "../src/skin/skin.h"
  58 #include "../src/tty/mouse.h"
  59 #include "../src/tty/key.h"
  60
  61 #include "dialog.h"             /* For Dlg_head */
  62 #include "widget.h"             /* For Widget */
  63 #include "wtools.h"             /* For common_dialog_repaint() */
  64 #include "strutil.h"
  65 #include "cmddef.h"
  66 #include "keybind.h"
  67 #include "help.h"
  68
  69 const global_keymap_t *help_map;
  70
  71 #define MAXLINKNAME 80
  72 #define HISTORY_SIZE 20
  73 #define HELP_WINDOW_WIDTH (HELP_TEXT_WIDTH + 4)
  74
  75 #define STRING_LINK_START       "\01"
  76 #define STRING_LINK_POINTER     "\02"
  77 #define STRING_LINK_END         "\03"
  78 #define STRING_NODE_END         "\04"
  79
  80
  81 static char *fdata = NULL;              /* Pointer to the loaded data file */
  82 static int help_lines;                  /* Lines in help viewer */
  83 static int  history_ptr;                /* For the history queue */
  84 static const char *main_node;           /* The main node */
  85 static const char *last_shown = NULL;   /* Last byte shown in a screen */
  86 static gboolean end_of_node = FALSE;    /* Flag: the last character of the node shown? */
  87 static const char *currentpoint;
  88 static const char *selected_item;
  89
  90 /* The widget variables */
  91 static Dlg_head *whelp;
  92
  93 static struct {
  94     const char *page;           /* Pointer to the selected page */
  95     const char *link;           /* Pointer to the selected link */
  96 } history [HISTORY_SIZE];
  97
  98 /* Link areas for the mouse */
  99 typedef struct Link_Area {
 100     int x1, y1, x2, y2;
 101     const char *link_name;
 102     struct Link_Area *next;
 103 } Link_Area;
 104
 105 static Link_Area *link_area = NULL;
 106 static gboolean inside_link_area = FALSE;
 107
 108 static cb_ret_t help_callback (Dlg_head *h, Widget *sender,
 109                                 dlg_msg_t msg, int parm, void *data);
 110
 111 /* returns the position where text was found in the start buffer */
 112 /* or 0 if not found */
 113 static const char *
 114 search_string (const char *start, const char *text)
 115 {
 116     const char *result = NULL;
 117     char *local_text = g_strdup (text);
 118     char *d = local_text;
 119     const char *e = start;
 120
 121     /* fmt sometimes replaces a space with a newline in the help file */
 122     /* Replace the newlines in the link name with spaces to correct the situation */
 123     while (*d != '\0') {
 124         if (*d == '\n')
 125             *d = ' ';
 126         str_next_char (&d);
 127     }
 128
 129     /* Do search */
 130     for (d = local_text; *e; e++){
 131         if (*d == *e)
 132             d++;
 133         else
 134             d = local_text;
 135         if (*d == '\0') {
 136             result = e + 1;
 137             break;
 138         }
 139     }
 140
 141     g_free (local_text);
 142     return result;
 143 }
 144
 145 /* Searches text in the buffer pointed by start.  Search ends */
 146 /* if the CHAR_NODE_END is found in the text.  Returns 0 on failure */
 147 static const char *
 148 search_string_node (const char *start, const char *text)
 149 {
 150     const char *d = text;
 151     const char *e = start;
 152
 153     if (start != NULL)
 154         for (; *e && *e != CHAR_NODE_END; e++) {
 155             if (*d == *e)
 156                 d++;
 157             else
 158                 d = text;
 159             if (*d == '\0')
 160                 return e + 1;
 161         }
 162
 163     return NULL;
 164 }
 165
 166 /* Searches the_char in the buffer pointer by start and searches */
 167 /* it can search forward (direction = 1) or backward (direction = -1) */
 168 static const char *
 169 search_char_node (const char *start, char the_char, int direction)
 170 {
 171     const char *e;
 172
 173     for (e = start; (*e != '\0') && (*e != CHAR_NODE_END); e += direction)
 174         if (*e == the_char)
 175             return e;
 176
 177     return NULL;
 178 }
 179
 180 /* Returns the new current pointer when moved lines lines */
 181 static const char *
 182 move_forward2 (const char *c, int lines)
 183 {
 184     const char *p;
 185     int line;
 186
 187     currentpoint = c;
 188     for (line = 0, p = currentpoint; (*p != '\0') && (*p != CHAR_NODE_END);
 189                 str_cnext_char (&p)) {
 190         if (line == lines)
 191             return currentpoint = p;
 192
 193         if (*p == '\n')
 194             line++;
 195     }
 196     return currentpoint = c;
 197 }
 198
 199 static const char *
 200 move_backward2 (const char *c, int lines)
 201 {
 202     const char *p;
 203     int line;
 204
 205     currentpoint = c;
 206     for (line = 0, p = currentpoint; (*p != '\0') && ((int) (p - fdata) >= 0);
 207                 str_cprev_char (&p)) {
 208         if (*p == CHAR_NODE_END) {
 209             /* We reached the beginning of the node */
 210             /* Skip the node headers */
 211             while (*p != ']')
 212                 str_cnext_char (&p);
 213             return currentpoint = p + 2; /* Skip the newline following the start of the node */
 214         }
 215
 216         if (*(p - 1) == '\n')
 217             line++;
 218         if (line == lines)
 219             return currentpoint = p;
 220     }
 221     return currentpoint = c;
 222 }
 223
 224 static void
 225 move_forward (int i)
 226 {
 227     if (!end_of_node)
 228         currentpoint = move_forward2 (currentpoint, i);
 229 }
 230
 231 static void
 232 move_backward (int i)
 233 {
 234     currentpoint = move_backward2 (currentpoint, ++i);
 235 }
 236
 237 static void
 238 move_to_top (void)
 239 {
 240     while (((int) (currentpoint > fdata) > 0) && (*currentpoint != CHAR_NODE_END))
 241         currentpoint--;
 242
 243     while (*currentpoint != ']')
 244         currentpoint++;
 245     currentpoint = currentpoint + 2; /* Skip the newline following the start of the node */
 246     selected_item = NULL;
 247 }
 248
 249 static void
 250 move_to_bottom (void)
 251 {
 252     while ((*currentpoint != '\0') && (*currentpoint != CHAR_NODE_END))
 253         currentpoint++;
 254     currentpoint--;
 255     move_backward (help_lines - 1);
 256 }
 257
 258 static const char *
 259 help_follow_link (const char *start, const char *lc_selected_item)
 260 {
 261     char link_name [MAXLINKNAME];
 262     const char *p;
 263     int i = 0;
 264
 265     if (lc_selected_item == NULL)
 266         return start;
 267
 268     for (p = lc_selected_item; *p && *p != CHAR_NODE_END && *p != CHAR_LINK_POINTER; p++)
 269         ;
 270     if (*p == CHAR_LINK_POINTER){
 271         link_name [0] = '[';
 272         for (i = 1; *p != CHAR_LINK_END && *p && *p != CHAR_NODE_END && i < MAXLINKNAME-3; )
 273             link_name [i++] = *++p;
 274         link_name [i - 1] = ']';
 275         link_name [i] = '\0';
 276         p = search_string (fdata, link_name);
 277         if (p != NULL) {
 278             p += 1; /* Skip the newline following the start of the node */
 279             return p;
 280         }
 281     }
 282
 283     /* Create a replacement page with the error message */
 284     return _(" Help file format error\n");
 285 }
 286
 287 static const char *
 288 select_next_link (const char *current_link)
 289 {
 290     const char *p;
 291
 292     if (current_link == NULL)
 293         return NULL;
 294
 295     p = search_string_node (current_link, STRING_LINK_END);
 296     if (p == NULL)
 297         return NULL;
 298     p = search_string_node (p, STRING_LINK_START);
 299     if (p == NULL)
 300         return NULL;
 301     return p - 1;
 302 }
 303
 304 static const char *
 305 select_prev_link (const char *current_link)
 306 {
 307     return current_link == NULL
 308             ? NULL
 309             : search_char_node (current_link - 1, CHAR_LINK_START, -1);
 310 }
 311
 312 static void
 313 start_link_area (int x, int y, const char *link_name)
 314 {
 315     Link_Area *new;
 316
 317     if (inside_link_area)
 318         message (D_NORMAL, _("Warning"), _(" Internal bug: Double start of link area "));
 319
 320     /* Allocate memory for a new link area */
 321     new = g_new (Link_Area, 1);
 322     new->next = link_area;
 323     link_area = new;
 324
 325     /* Save the beginning coordinates of the link area */
 326     link_area->x1 = x;
 327     link_area->y1 = y;
 328
 329     /* Save the name of the destination anchor */
 330     link_area->link_name = link_name;
 331
 332     inside_link_area = TRUE;
 333 }
 334
 335 static void
 336 end_link_area (int x, int y)
 337 {
 338     if (inside_link_area) {
 339         /* Save the end coordinates of the link area */
 340         link_area->x2 = x;
 341         link_area->y2 = y;
 342         inside_link_area = FALSE;
 343     }
 344 }
 345
 346 static void
 347 clear_link_areas (void)
 348 {
 349     Link_Area *current;
 350
 351     while (link_area != NULL) {
 352         current = link_area;
 353         link_area = current->next;
 354         g_free (current);
 355     }
 356
 357     inside_link_area = FALSE;
 358 }
 359
 360 static void
 361 help_show (Dlg_head *h, const char *paint_start)
 362 {
 363     const char *p, *n;
 364     int col, line, c, w;
 365     gboolean painting = TRUE;
 366     gboolean acs;                       /* Flag: Alternate character set active? */
 367     gboolean repeat_paint;
 368     int active_col, active_line;        /* Active link position */
 369     static char buff[MB_LEN_MAX + 1];
 370
 371     tty_setcolor (HELP_NORMAL_COLOR);
 372     do {
 373         line = col = active_col = active_line = 0;
 374         repeat_paint = FALSE;
 375         acs = FALSE;
 376
 377         clear_link_areas ();
 378         if ((int) (selected_item - paint_start) < 0)
 379             selected_item = NULL;
 380
 381         p = paint_start;
 382         n = paint_start;
 383         while (n[0] != '\0' && n[0] != CHAR_NODE_END && line < help_lines) {
 384             p = n;
 385             n = str_cget_next_char (p);
 386             memcpy (buff, p, n - p);
 387             buff[n - p] = '\0';
 388
 389             c = (unsigned char) buff[0];
 390             switch (c){
 391             case CHAR_LINK_START:
 392                 if (selected_item == NULL)
 393                     selected_item = p;
 394                 if (p == selected_item){
 395                     tty_setcolor (HELP_SLINK_COLOR);
 396
 397                     /* Store the coordinates of the link */
 398                     active_col = col + 2;
 399                     active_line = line + 2;
 400                 }
 401                 else
 402                     tty_setcolor (HELP_LINK_COLOR);
 403                 start_link_area (col, line, p);
 404                 break;
 405             case CHAR_LINK_POINTER:
 406                 painting = FALSE;
 407                 end_link_area (col - 1, line);
 408                 break;
 409             case CHAR_LINK_END:
 410                 painting = TRUE;
 411                 tty_setcolor (HELP_NORMAL_COLOR);
 412                 break;
 413             case CHAR_ALTERNATE:
 414                 acs = TRUE;
 415                 break;
 416             case CHAR_NORMAL:
 417                 acs = FALSE;
 418                 break;
 419             case CHAR_VERSION:
 420                 dlg_move (h, line+2, col+2);
 421                 tty_print_string (VERSION);
 422                 col += str_term_width1 (VERSION);
 423                 break;
 424             case CHAR_FONT_BOLD:
 425                 tty_setcolor (HELP_BOLD_COLOR);
 426                 break;
 427             case CHAR_FONT_ITALIC:
 428                 tty_setcolor (HELP_ITALIC_COLOR);
 429                 break;
 430             case CHAR_FONT_NORMAL:
 431                 tty_setcolor (HELP_NORMAL_COLOR);
 432                 break;
 433             case '\n':
 434                 line++;
 435                 col = 0;
 436                 break;
 437             case '\t':
 438                 col = (col / 8 + 1) * 8;
 439                 break;
 440             default:
 441                 if (!painting)
 442                     continue;
 443                 w = str_term_width1 (buff);
 444                 if (col + w > HELP_WINDOW_WIDTH)
 445                     continue;
 446
 447                 dlg_move (h, line + 2, col + 2);
 448                 if (!acs)
 449                     tty_print_string (buff);
 450                 else if (c == ' ' || c == '.')
 451                     tty_print_char (c);
 452                 else
 453 #ifndef HAVE_SLANG
 454                     tty_print_char (acs_map [c]);
 455 #else
 456                     SLsmg_draw_object (h->y + line + 2, h->x + col + 2, c);
 457 #endif
 458                 col += w;
 459                 break;
 460             }
 461         }
 462
 463         last_shown = p;
 464         end_of_node = line < help_lines;
 465         tty_setcolor (HELP_NORMAL_COLOR);
 466         if ((int) (selected_item - last_shown) >= 0) {
 467             if (link_area == NULL)
 468                 selected_item = NULL;
 469             else {
 470                 selected_item = link_area->link_name;
 471                 repeat_paint = TRUE;
 472             }
 473         }
 474     } while (repeat_paint);
 475
 476     /* Position the cursor over a nice link */
 477     if (active_col)
 478         dlg_move (h, active_line, active_col);
 479 }
 480
 481 static int
 482 help_event (Gpm_Event *event, void *vp)
 483 {
 484     Widget *w = vp;
 485     Link_Area *current_area;
 486
 487     if ((event->type & GPM_UP) == 0)
 488         return 0;
 489
 490     /* The event is relative to the dialog window, adjust it: */
 491     event->x -= 2;
 492     event->y -= 2;
 493
 494     if (event->buttons & GPM_B_RIGHT){
 495         currentpoint = history [history_ptr].page;
 496         selected_item = history [history_ptr].link;
 497         history_ptr--;
 498         if (history_ptr < 0)
 499             history_ptr = HISTORY_SIZE-1;
 500
 501         help_callback (w->parent, NULL, DLG_DRAW, 0, NULL);
 502         return 0;
 503     }
 504
 505     /* Test whether the mouse click is inside one of the link areas */
 506     current_area = link_area;
 507     while (current_area != NULL)
 508     {
 509         /* Test one line link area */
 510         if (event->y == current_area->y1 && event->x >= current_area->x1 &&
 511             event->y == current_area->y2 && event->x <= current_area->x2)
 512             break;
 513         /* Test two line link area */
 514         if (current_area->y1 + 1 == current_area->y2){
 515             /* The first line */
 516             if (event->y == current_area->y1 && event->x >= current_area->x1)
 517                 break;
 518             /* The second line */
 519             if (event->y == current_area->y2 && event->x <= current_area->x2)
 520                 break;
 521         }
 522         /* Mouse will not work with link areas of more than two lines */
 523
 524         current_area = current_area->next;
 525     }
 526
 527     /* Test whether a link area was found */
 528     if (current_area != NULL) {
 529         /* The click was inside a link area -> follow the link */
 530         history_ptr = (history_ptr+1) % HISTORY_SIZE;
 531         history [history_ptr].page = currentpoint;
 532         history [history_ptr].link = current_area->link_name;
 533         currentpoint = help_follow_link (currentpoint, current_area->link_name);
 534         selected_item = NULL;
 535     } else if (event->y < 0)
 536         move_backward (help_lines - 1);
 537     else if (event->y >= help_lines)
 538         move_forward (help_lines - 1);
 539     else if (event->y < help_lines/2)
 540         move_backward (1);
 541     else
 542         move_forward (1);
 543
 544     /* Show the new node */
 545     help_callback (w->parent, NULL, DLG_DRAW, 0, NULL);
 546
 547     return 0;
 548 }
 549
 550 /* show help */
 551 static void
 552 help_help (Dlg_head *h)
 553 {
 554     const char *p;
 555
 556     history_ptr = (history_ptr + 1) % HISTORY_SIZE;
 557     history [history_ptr].page = currentpoint;
 558     history [history_ptr].link = selected_item;
 559
 560     p = search_string (fdata, "[How to use help]");
 561     if (p != NULL) {
 562         currentpoint = p + 1; /* Skip the newline following the start of the node */
 563         selected_item = NULL;
 564         help_callback (h, NULL, DLG_DRAW, 0, NULL);
 565     }
 566 }
 567
 568 static void
 569 help_index (Dlg_head *h)
 570 {
 571     const char *new_item;
 572
 573     new_item = search_string (fdata, "[Contents]");
 574
 575     if (new_item == NULL)
 576         message (D_ERROR, MSG_ERROR, _(" Cannot find node %s in help file "),
 577                  "[Contents]");
 578     else {
 579         history_ptr = (history_ptr + 1) % HISTORY_SIZE;
 580         history[history_ptr].page = currentpoint;
 581         history[history_ptr].link = selected_item;
 582
 583         currentpoint = new_item + 1; /* Skip the newline following the start of the node */
 584         selected_item = NULL;
 585         help_callback (h, NULL, DLG_DRAW, 0, NULL);
 586     }
 587 }
 588
 589 static void
 590 help_back (Dlg_head *h)
 591 {
 592     currentpoint = history [history_ptr].page;
 593     selected_item = history [history_ptr].link;
 594     history_ptr--;
 595     if (history_ptr < 0)
 596         history_ptr = HISTORY_SIZE - 1;
 597
 598     help_callback (h, NULL, DLG_DRAW, 0, NULL); /* FIXME: unneeded? */
 599 }
 600
 601 static void
 602 help_cmk_move_backward(void *vp, int lines)
 603 {
 604     (void) &vp;
 605     move_backward (lines);
 606 }
 607
 608 static void
 609 help_cmk_move_forward(void *vp, int lines)
 610 {
 611     (void) &vp;
 612     move_forward (lines);
 613 }
 614
 615 static void
 616 help_cmk_moveto_top(void *vp, int lines)
 617 {
 618     (void) &vp;
 619     (void) &lines;
 620     move_to_top ();
 621 }
 622
 623 static void
 624 help_cmk_moveto_bottom(void *vp, int lines)
 625 {
 626     (void) &vp;
 627     (void) &lines;
 628     move_to_bottom ();
 629 }
 630
 631 static void
 632 help_next_link (gboolean move_down)
 633  {
 634     const char *new_item;
 635
 636     new_item = select_next_link (selected_item);
 637     if (new_item != NULL) {
 638         selected_item = new_item;
 639         if ((int) (selected_item - last_shown) >= 0) {
 640             if (move_down)
 641                 move_forward (1);
 642             else
 643                 selected_item = NULL;
 644         }
 645     } else if (move_down)
 646         move_forward (1);
 647     else
 648         selected_item = NULL;
 649 }
 650
 651 static void
 652 help_prev_link (gboolean move_up)
 653 {
 654     const char *new_item;
 655
 656     new_item = select_prev_link (selected_item);
 657     selected_item = new_item;
 658     if ((selected_item == NULL) || (selected_item < currentpoint)) {
 659         if (move_up)
 660             move_backward (1);
 661         else if (link_area != NULL)
 662             selected_item = link_area->link_name;
 663         else
 664             selected_item = NULL;
 665     }
 666 }
 667
 668 static void
 669 help_next_node (void)
 670 {
 671     const char *new_item;
 672
 673     new_item = currentpoint;
 674     while ((*new_item != '\0') && (*new_item != CHAR_NODE_END))
 675         new_item++;
 676
 677     if (*++new_item == '[')
 678         while (*++new_item != '\0')
 679             if ((*new_item == ']') && (*++new_item != '\0')
 680                     && (*++new_item != '\0')) {
 681                 currentpoint = new_item;
 682                 selected_item = NULL;
 683                 break;
 684             }
 685 }
 686
 687 static void
 688 help_prev_node (void)
 689 {
 690     const char *new_item;
 691
 692     new_item = currentpoint;
 693     while (((int) (new_item - fdata) > 1) && (*new_item != CHAR_NODE_END))
 694         new_item--;
 695     new_item--;
 696     while (((int) (new_item - fdata) > 0) && (*new_item != CHAR_NODE_END))
 697         new_item--;
 698     while (*new_item != ']')
 699         new_item++;
 700     currentpoint = new_item + 2;
 701     selected_item = NULL;
 702 }
 703
 704 static void
 705 help_select_link (void)
 706 {
 707     /* follow link */
 708     if (selected_item == NULL) {
 709 #ifdef WE_WANT_TO_GO_BACKWARD_ON_KEY_RIGHT
 710         /* Is there any reason why the right key would take us
 711          * backward if there are no links selected?, I agree
 712          * with Torben than doing nothing in this case is better
 713          */
 714         /* If there are no links, go backward in history */
 715         history_ptr--;
 716         if (history_ptr < 0)
 717             history_ptr = HISTORY_SIZE-1;
 718
 719         currentpoint = history [history_ptr].page;
 720         selected_item = history [history_ptr].link;
 721 #endif
 722     } else {
 723         history_ptr = (history_ptr + 1) % HISTORY_SIZE;
 724         history [history_ptr].page = currentpoint;
 725         history [history_ptr].link = selected_item;
 726         currentpoint = help_follow_link (currentpoint, selected_item);
 727     }
 728
 729     selected_item = NULL;
 730 }
 731
 732 static cb_ret_t
 733 help_execute_cmd (unsigned long command)
 734 {
 735     cb_ret_t ret = MSG_HANDLED;
 736
 737     switch (command) {
 738     case CK_HelpHelp:
 739         help_help (whelp);
 740         break;
 741     case CK_HelpIndex:
 742         help_index (whelp);
 743         break;
 744     case CK_HelpBack:
 745         help_back (whelp);
 746         break;
 747     case CK_HelpMoveUp:
 748         help_prev_link (TRUE);
 749         break;
 750     case CK_HelpMoveDown:
 751         help_next_link (TRUE);
 752         break;
 753     case CK_HelpSelectLink:
 754         help_select_link ();
 755         break;
 756     case CK_HelpNextLink:
 757         help_next_link (FALSE);
 758         break;
 759     case CK_HelpPrevLink:
 760         help_prev_link (FALSE);
 761         break;
 762     case CK_HelpNextNode:
 763         help_next_node ();
 764         break;
 765     case CK_HelpPrevNode:
 766         help_prev_node ();
 767         break;
 768     case CK_HelpQuit:
 769         dlg_stop (whelp);
 770         break;
 771     default:
 772         ret = MSG_NOT_HANDLED;
 773     }
 774
 775     return ret;
 776 }
 777
 778 static cb_ret_t
 779 help_handle_key (Dlg_head *h, int c)
 780 {
 781     if (c != KEY_UP && c != KEY_DOWN &&
 782         check_movement_keys (c, help_lines, NULL,
 783                              help_cmk_move_backward,
 784                              help_cmk_move_forward,
 785                              help_cmk_moveto_top,
 786                              help_cmk_moveto_bottom) == MSG_HANDLED) {
 787         /* Nothing */;
 788     } else {
 789         unsigned long command;
 790
 791         command = lookup_keymap_command (help_map, c);
 792         if ((command == CK_Ignore_Key)
 793             || (help_execute_cmd (command) == MSG_NOT_HANDLED))
 794                 return MSG_NOT_HANDLED;
 795     }
 796
 797     help_callback (h, NULL, DLG_DRAW, 0, NULL);
 798     return MSG_HANDLED;
 799 }
 800
 801 static cb_ret_t
 802 help_callback (Dlg_head *h, Widget *sender,
 803                 dlg_msg_t msg, int parm, void *data)
 804 {
 805     WButtonBar *bb;
 806
 807     switch (msg) {
 808     case DLG_RESIZE:
 809         help_lines = min (LINES - 4, max (2 * LINES / 3, 18));
 810         dlg_set_size (h, help_lines + 4, HELP_WINDOW_WIDTH + 4);
 811         bb = find_buttonbar (h);
 812         widget_set_size (&bb->widget, LINES - 1, 0, 1, COLS);
 813         return MSG_HANDLED;
 814
 815     case DLG_DRAW:
 816         common_dialog_repaint (h);
 817         help_show (h, currentpoint);
 818         return MSG_HANDLED;
 819
 820     case DLG_KEY:
 821         return help_handle_key (h, parm);
 822
 823     case DLG_ACTION:
 824         /* command from buttonbar */
 825         return help_execute_cmd (parm);
 826
 827     default:
 828         return default_dlg_callback (h, sender, msg, parm, data);
 829     }
 830 }
 831
 832 static void
 833 interactive_display_finish (void)
 834 {
 835     clear_link_areas ();
 836 }
 837
 838 /* translate help file into terminal encoding */
 839 static void
 840 translate_file (char *filedata)
 841 {
 842     GIConv conv;
 843     GString *translated_data;
 844
 845     translated_data = g_string_new ("");
 846
 847     conv = str_crt_conv_from ("UTF-8");
 848
 849     if (conv == INVALID_CONV)
 850         g_string_free (translated_data, TRUE);
 851     else {
 852         g_free (fdata);
 853
 854         if (str_convert (conv, filedata, translated_data) != ESTR_FAILURE) {
 855             fdata = translated_data->str;
 856             g_string_free (translated_data, FALSE);
 857         } else {
 858             fdata = NULL;
 859             g_string_free (translated_data, TRUE);
 860         }
 861         str_close_conv (conv);
 862     }
 863 }
 864
 865 static cb_ret_t
 866 md_callback (Widget *w, widget_msg_t msg, int parm)
 867 {
 868     switch (msg) {
 869     case WIDGET_RESIZED:
 870         w->lines = help_lines;
 871         return MSG_HANDLED;
 872
 873     default:
 874         return default_proc (msg, parm);
 875     }
 876 }
 877
 878 static Widget *
 879 mousedispatch_new (int y, int x, int yl, int xl)
 880 {
 881     Widget *w = g_new (Widget, 1);
 882     init_widget (w, y, x, yl, xl, md_callback, help_event);
 883     return w;
 884 }
 885
 886 void
 887 interactive_display (const char *filename, const char *node)
 888 {
 889     WButtonBar *help_bar;
 890     Widget *md;
 891     char *hlpfile = NULL;
 892     char *filedata;
 893
 894     if (filename != NULL)
 895         filedata = load_file (filename);
 896     else
 897         filedata = load_mc_home_file ("mc.hlp", &hlpfile);
 898
 899     if (filedata == NULL)
 900         message (D_ERROR, MSG_ERROR, _(" Cannot open file %s \n %s "), filename ? filename : hlpfile,
 901                  unix_error_string (errno));
 902
 903     g_free (hlpfile);
 904
 905     if (filedata == NULL)
 906         return;
 907
 908     translate_file (filedata);
 909
 910     g_free (filedata);
 911
 912     if (fdata == NULL)
 913         return;
 914
 915     if ((node == NULL) || (*node == '\0'))
 916         node = "[main]";
 917
 918     main_node = search_string (fdata, node);
 919
 920     if (main_node == NULL) {
 921         message (D_ERROR, MSG_ERROR, _(" Cannot find node %s in help file "),
 922                  node);
 923
 924         /* Fallback to [main], return if it also cannot be found */
 925         main_node = search_string (fdata, "[main]");
 926         if (main_node == NULL) {
 927             interactive_display_finish ();
 928             return;
 929         }
 930     }
 931
 932     help_lines = min (LINES - 4, max (2 * LINES / 3, 18));
 933
 934     whelp =
 935         create_dlg (0, 0, help_lines + 4, HELP_WINDOW_WIDTH + 4,
 936                     dialog_colors, help_callback, "[Help]", _("Help"),
 937                     DLG_TRYUP | DLG_CENTER | DLG_WANT_TAB);
 938
 939     selected_item = search_string_node (main_node, STRING_LINK_START) - 1;
 940     currentpoint = main_node + 1; /* Skip the newline following the start of the node */
 941
 942     for (history_ptr = HISTORY_SIZE; history_ptr;) {
 943         history_ptr--;
 944         history[history_ptr].page = currentpoint;
 945         history[history_ptr].link = selected_item;
 946     }
 947
 948     help_bar = buttonbar_new (TRUE);
 949     help_bar->widget.y -= whelp->y;
 950     help_bar->widget.x -= whelp->x;
 951
 952     md = mousedispatch_new (1, 1, help_lines, HELP_WINDOW_WIDTH - 2);
 953
 954     add_widget (whelp, md);
 955     add_widget (whelp, help_bar);
 956
 957     buttonbar_set_label (help_bar, 1, Q_("ButtonBar|Help"), help_map, NULL);
 958     buttonbar_set_label (help_bar, 2, Q_("ButtonBar|Index"), help_map, NULL);
 959     buttonbar_set_label (help_bar, 3, Q_("ButtonBar|Prev"), help_map, NULL);
 960     buttonbar_set_label (help_bar, 4, "", help_map, NULL);
 961     buttonbar_set_label (help_bar, 5, "", help_map, NULL);
 962     buttonbar_set_label (help_bar, 6, "", help_map, NULL);
 963     buttonbar_set_label (help_bar, 7, "", help_map, NULL);
 964     buttonbar_set_label (help_bar, 8, "", help_map, NULL);
 965     buttonbar_set_label (help_bar, 9, "", help_map, NULL);
 966     buttonbar_set_label (help_bar, 10, Q_("ButtonBar|Quit"), help_map, NULL);
 967
 968     run_dlg (whelp);
 969     interactive_display_finish ();
 970     destroy_dlg (whelp);
 971 }