src/help.c

   1 /* Hypertext file browser.
   2    Copyright (C) 1994, 1995 Miguel de Icaza.
   3    Copyright (C) 1994, 1995 Janne Kukonlehto
   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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  18
  19    Implements the hypertext file viewer.
  20    The hypertext file is a file that may have one or more nodes.  Each
  21    node ends with a ^D character and starts with a bracket, then the
  22    name of the node and then a closing bracket.
  23
  24    Links in the hypertext file are specified like this: the text that
  25    will be highlighted should have a leading ^A, then it comes the
  26    text, then a ^B indicating that highlighting is done, then the name
  27    of the node you want to link to and then a ^C.
  28
  29    The file must contain a ^D at the beginning and at the end of the
  30    file or the program will not be able to detect the end of file.
  31
  32    Lazyness/widgeting attack: This file does use the dialog manager
  33    and uses mainly the dialog to achieve the help work.  there is only
  34    one specialized widget and it's only used to forward the mouse messages
  35    to the appropiate routine.
  36
  37 */
  38
  39 #include <config.h>
  40 #include <stdio.h>
  41 #include <sys/types.h>
  42 #include <sys/stat.h>
  43 #include <errno.h>
  44
  45 #include "global.h"
  46 #include "tty.h"
  47 #include "color.h"
  48 #include "dialog.h"
  49 #include "win.h"
  50 #include "mouse.h"
  51 #include "key.h"        /* For mi_getch() */
  52 #include "help.h"
  53 #include "dlg.h"                /* For Dlg_head */
  54 #include "widget.h"             /* For Widget */
  55 #include "wtools.h"             /* For common_dialog_repaint() */
  56
  57 #define MAXLINKNAME 80
  58 #define HISTORY_SIZE 20
  59 #define HELP_WINDOW_WIDTH (HELP_TEXT_WIDTH + 4)
  60
  61 #define STRING_LINK_START       "\01"
  62 #define STRING_LINK_POINTER     "\02"
  63 #define STRING_LINK_END         "\03"
  64 #define STRING_NODE_END         "\04"
  65
  66 static char *data;              /* Pointer to the loaded data file */
  67 static int help_lines;          /* Lines in help viewer */
  68 static int  history_ptr;        /* For the history queue */
  69 static char *main_node;         /* The main node */
  70 static char *last_shown = 0;    /* Last byte shown in a screen */
  71 static int end_of_node = 0;     /* Flag: the last character of the node shown? */
  72 static char *currentpoint, *startpoint;
  73 static char *selected_item;
  74
  75 /* The widget variables */
  76 static Dlg_head *whelp;
  77
  78 static struct {
  79     char *page;                 /* Pointer to the selected page */
  80     char *link;                 /* Pointer to the selected link */
  81 } history [HISTORY_SIZE];
  82
  83 /* Link areas for the mouse */
  84 typedef struct Link_Area {
  85     int x1, y1, x2, y2;
  86     char *link_name;
  87     struct Link_Area *next;
  88 } Link_Area;
  89
  90 static Link_Area *link_area = NULL;
  91 static int inside_link_area = 0;
  92
  93 static int help_callback (struct Dlg_head *h, int id, int msg);
  94
  95 #ifdef HAS_ACS_AS_PCCHARS
  96 static const struct {
  97     int acscode;
  98     int pccode;
  99 } acs2pc_table [] = {
 100     { 'q',  0xC4 },
 101     { 'x',  0xB3 },
 102     { 'l',  0xDA },
 103     { 'k',  0xBF },
 104     { 'm',  0xC0 },
 105     { 'j',  0xD9 },
 106     { 'a',  0xB0 },
 107     { 'u',  0xB4 },
 108     { 't',  0xC3 },
 109     { 'w',  0xC2 },
 110     { 'v',  0xC1 },
 111     { 'n',  0xC5 },
 112     { 0, 0 } };
 113
 114 static int acs2pc (int acscode)
 115 {
 116     int i;
 117
 118     for (i = 0; acs2pc_table[i].acscode != 0; i++)
 119         if (acscode == acs2pc_table[i].acscode) {
 120             return acs2pc_table[i].pccode;
 121         }
 122     return 0;
 123 }
 124 #endif
 125
 126 /* returns the position where text was found in the start buffer */
 127 /* or 0 if not found */
 128 static char *
 129 search_string (char *start, char *text)
 130 {
 131     char *d = text;
 132     char *e = start;
 133
 134     /* fmt sometimes replaces a space with a newline in the help file */
 135     /* Replace the newlines in the link name with spaces to correct the situation */
 136     while (*d){
 137         if (*d == '\n')
 138             *d = ' ';
 139         d++;
 140     }
 141     /* Do search */
 142     for (d = text; *e; e++){
 143         if (*d == *e)
 144             d++;
 145         else
 146             d = text;
 147         if (!*d)
 148             return e+1;
 149     }
 150     return 0;
 151 }
 152
 153 /* Searches text in the buffer pointed by start.  Search ends */
 154 /* if the CHAR_NODE_END is found in the text.  Returns 0 on failure */
 155 static char *search_string_node (char *start, char *text)
 156 {
 157     char *d = text;
 158     char *e = start;
 159
 160     if (!start)
 161         return 0;
 162
 163     for (; *e && *e != CHAR_NODE_END; e++){
 164         if (*d == *e)
 165             d++;
 166         else
 167             d = text;
 168         if (!*d)
 169             return e+1;
 170     }
 171     return 0;
 172 }
 173
 174 /* Searches the_char in the buffer pointer by start and searches */
 175 /* it can search forward (direction = 1) or backward (direction = -1) */
 176 static char *search_char_node (char *start, char the_char, int direction)
 177 {
 178     char *e;
 179
 180     e = start;
 181
 182     for (; *e && (*e != CHAR_NODE_END); e += direction){
 183         if (*e == the_char)
 184             return e;
 185     }
 186     return 0;
 187 }
 188
 189 /* Returns the new current pointer when moved lines lines */
 190 static char *move_forward2 (char *c, int lines)
 191 {
 192     char *p;
 193     int  line;
 194
 195     currentpoint = c;
 196     for (line = 0, p = currentpoint; *p && *p != CHAR_NODE_END; p++){
 197         if (line == lines)
 198             return currentpoint = p;
 199         if (*p == '\n')
 200             line++;
 201     }
 202     return currentpoint = c;
 203 }
 204
 205 static char *move_backward2 (char *c, int lines)
 206 {
 207     char *p;
 208     int line;
 209
 210     currentpoint = c;
 211     for (line = 0, p = currentpoint; *p && p >= data; p--){
 212         if (*p == CHAR_NODE_END)
 213         {
 214             /* We reached the beginning of the node */
 215             /* Skip the node headers */
 216             while (*p != ']') p++;
 217             return currentpoint = p + 2;
 218         }
 219         if (*(p - 1) == '\n')
 220             line++;
 221         if (line == lines)
 222             return currentpoint = p;
 223     }
 224     return currentpoint = c;
 225 }
 226
 227 static void move_forward (int i)
 228 {
 229     if (end_of_node)
 230         return;
 231     currentpoint = move_forward2 (currentpoint, i);
 232 }
 233
 234 static void move_backward (int i)
 235 {
 236     currentpoint = move_backward2 (currentpoint, ++i);
 237 }
 238
 239 static void move_to_top (int dummy)
 240 {
 241     while (currentpoint > data && *currentpoint != CHAR_NODE_END)
 242         currentpoint--;
 243     while (*currentpoint != ']')
 244         currentpoint++;
 245     currentpoint = currentpoint + 1;
 246     selected_item = NULL;
 247 }
 248
 249 static void move_to_bottom (int dummy)
 250 {
 251     while (*currentpoint && *currentpoint != CHAR_NODE_END)
 252         currentpoint++;
 253     currentpoint--;
 254     move_backward (help_lines - 1);
 255 }
 256
 257 static char *help_follow_link (char *start, char *selected_item)
 258 {
 259     char link_name [MAXLINKNAME];
 260     char *p;
 261     int  i = 0;
 262
 263     if (!selected_item)
 264         return start;
 265
 266     for (p = selected_item; *p && *p != CHAR_NODE_END && *p != CHAR_LINK_POINTER; p++)
 267         ;
 268     if (*p == CHAR_LINK_POINTER){
 269         link_name [0] = '[';
 270         for (i = 1; *p != CHAR_LINK_END && *p && *p != CHAR_NODE_END && i < MAXLINKNAME-3; )
 271             link_name [i++] = *++p;
 272         link_name [i-1] = ']';
 273         link_name [i] = 0;
 274         p = search_string (data, link_name);
 275         if (p)
 276             return p;
 277     }
 278     return _(" Help file format error\n\x4");   /*  */
 279 }
 280
 281 static char *select_next_link (char *start, char *current_link)
 282 {
 283     char *p;
 284
 285     if (!current_link)
 286         return 0;
 287
 288     p = search_string_node (current_link, STRING_LINK_END);
 289     if (!p)
 290         return NULL;
 291     p = search_string_node (p, STRING_LINK_START);
 292     if (!p)
 293         return NULL;
 294     return p - 1;
 295 }
 296
 297 static char *select_prev_link (char *start, char *current_link)
 298 {
 299     char *p;
 300
 301     if (!current_link)
 302         return 0;
 303
 304     p = current_link - 1;
 305     if (p <= start)
 306         return 0;
 307
 308     p = search_char_node (p, CHAR_LINK_START, -1);
 309     return p;
 310 }
 311
 312 static void start_link_area (int x, int y, char *link_name)
 313 {
 314     Link_Area *new;
 315
 316     if (inside_link_area)
 317         message (0, _(" Warning "), _(" Internal bug: Double start of link area "));
 318
 319     /* Allocate memory for a new link area */
 320     new = g_new (Link_Area, 1);
 321     new->next = link_area;
 322     link_area = new;
 323
 324     /* Save the beginning coordinates of the link area */
 325     link_area->x1 = x;
 326     link_area->y1 = y;
 327
 328     /* Save the name of the destination anchor */
 329     link_area->link_name = link_name;
 330
 331     inside_link_area = 1;
 332 }
 333
 334 static void end_link_area (int x, int y)
 335 {
 336     if (inside_link_area){
 337         /* Save the end coordinates of the link area */
 338         link_area->x2 = x;
 339         link_area->y2 = y;
 340
 341         inside_link_area = 0;
 342     }
 343 }
 344
 345 static void clear_link_areas (void)
 346 {
 347     Link_Area *current;
 348
 349     while (link_area){
 350         current = link_area;
 351         link_area = current -> next;
 352         g_free (current);
 353     }
 354     inside_link_area = 0;
 355 }
 356
 357 static void show (Dlg_head *h, char *paint_start)
 358 {
 359     char *p;
 360     int  col, line, c;
 361     int  painting = 1;
 362     int acs;                    /* Flag: Alternate character set active? */
 363     int repeat_paint;
 364     int active_col, active_line;/* Active link position */
 365
 366     attrset (HELP_NORMAL_COLOR);
 367     do {
 368
 369         line = col = acs = active_col = active_line = repeat_paint = 0;
 370
 371         clear_link_areas ();
 372         if (selected_item < paint_start)
 373             selected_item = NULL;
 374
 375         for (p = paint_start; *p && *p != CHAR_NODE_END && line < help_lines; p++) {
 376             c = (unsigned char)*p;
 377             switch (c){
 378             case CHAR_LINK_START:
 379                 if (selected_item == NULL)
 380                     selected_item = p;
 381                 if (p == selected_item){
 382                     attrset (HELP_SLINK_COLOR);
 383
 384                     /* Store the coordinates of the link */
 385                     active_col = col + 2;
 386                     active_line = line + 2;
 387                 }
 388                 else
 389                     attrset (HELP_LINK_COLOR);
 390                 start_link_area (col, line, p);
 391                 break;
 392             case CHAR_LINK_POINTER:
 393                 painting = 0;
 394                 end_link_area (col - 1, line);
 395                 break;
 396             case CHAR_LINK_END:
 397                 painting = 1;
 398                 attrset (HELP_NORMAL_COLOR);
 399                 break;
 400             case CHAR_ALTERNATE:
 401                 acs = 1;
 402                 break;
 403             case CHAR_NORMAL:
 404                 acs = 0;
 405                 break;
 406             case CHAR_VERSION:
 407                 dlg_move (h, line+2, col+2);
 408                 addstr (VERSION);
 409                 col += strlen (VERSION);
 410                 break;
 411             case CHAR_FONT_BOLD:
 412                 attrset (HELP_BOLD_COLOR);
 413                 break;
 414             case CHAR_FONT_ITALIC:
 415                 attrset (HELP_ITALIC_COLOR);
 416                 break;
 417             case CHAR_FONT_NORMAL:
 418                 attrset (HELP_NORMAL_COLOR);
 419                 break;
 420             case '\n':
 421                 line++;
 422                 col = 0;
 423                 break;
 424             case '\t':
 425                 col = (col/8 + 1) * 8;
 426                 break;
 427             case CHAR_MCLOGO:
 428             case CHAR_TEXTONLY_START:
 429             case CHAR_TEXTONLY_END:
 430                 break;
 431             case CHAR_XONLY_START:
 432                 while (*p && *p != CHAR_NODE_END && *p != CHAR_XONLY_END)
 433                     p++;
 434                 if (*p == CHAR_NODE_END || !*p)
 435                     p--;
 436                 break;
 437             default:
 438                 if (!painting)
 439                     continue;
 440                 if (col > HELP_WINDOW_WIDTH-1)
 441                     continue;
 442
 443                 dlg_move (h, line+2, col+2);
 444                 if (acs){
 445                     if (c == ' ' || c == '.')
 446                         addch (c);
 447                     else
 448 #ifndef NATIVE_WIN32
 449 #ifndef HAVE_SLANG
 450                         addch (acs_map [c]);
 451 #else
 452                         SLsmg_draw_object (h->y + line + 2, h->x + col + 2, c);
 453 #endif
 454 #else
 455                         addch (acs2pc (c));
 456 #endif /* NATIVE_WIN32 */
 457                 } else
 458                     addch (c);
 459                 col++;
 460                 break;
 461             }
 462         }
 463         last_shown = p;
 464         end_of_node = line < help_lines;
 465         attrset (HELP_NORMAL_COLOR);
 466         if (selected_item >= last_shown){
 467             if (link_area != NULL){
 468                 selected_item = link_area->link_name;
 469                 repeat_paint = 1;
 470             }
 471             else
 472                 selected_item = NULL;
 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 help_event (Gpm_Event *event, Widget *w)
 482 {
 483     Link_Area *current_area;
 484
 485     if (! (event->type & GPM_UP))
 486         return 0;
 487
 488     /* The event is relative to the dialog window, adjust it: */
 489     event->y -= 2;
 490
 491     if (event->buttons & GPM_B_RIGHT){
 492         currentpoint = startpoint = history [history_ptr].page;
 493         selected_item = history [history_ptr].link;
 494         history_ptr--;
 495         if (history_ptr < 0)
 496             history_ptr = HISTORY_SIZE-1;
 497
 498         help_callback (w->parent, 0, DLG_DRAW);
 499         return 0;
 500     }
 501
 502     /* Test whether the mouse click is inside one of the link areas */
 503     current_area = link_area;
 504     while (current_area)
 505     {
 506         /* Test one line link area */
 507         if (event->y == current_area->y1 && event->x >= current_area->x1 &&
 508             event->y == current_area->y2 && event->x <= current_area->x2)
 509             break;
 510         /* Test two line link area */
 511         if (current_area->y1 + 1 == current_area->y2){
 512             /* The first line */
 513             if (event->y == current_area->y1 && event->x >= current_area->x1)
 514                 break;
 515             /* The second line */
 516             if (event->y == current_area->y2 && event->x <= current_area->x2)
 517                 break;
 518         }
 519         /* Mouse will not work with link areas of more than two lines */
 520
 521         current_area = current_area -> next;
 522     }
 523
 524     /* Test whether a link area was found */
 525     if (current_area){
 526         /* The click was inside a link area -> follow the link */
 527         history_ptr = (history_ptr+1) % HISTORY_SIZE;
 528         history [history_ptr].page = currentpoint;
 529         history [history_ptr].link = current_area->link_name;
 530         currentpoint = startpoint = help_follow_link (currentpoint, current_area->link_name);
 531         selected_item = NULL;
 532     } else{
 533         if (event->y < 0)
 534             move_backward (help_lines - 1);
 535         else if (event->y >= help_lines)
 536             move_forward (help_lines - 1);
 537         else if (event->y < help_lines/2)
 538             move_backward (1);
 539         else
 540             move_forward (1);
 541     }
 542
 543     /* Show the new node */
 544     help_callback (w->parent, 0, DLG_DRAW);
 545
 546     return 0;
 547 }
 548
 549 /* show help */
 550 static void
 551 help_help_cmd (Dlg_head *h)
 552 {
 553     history_ptr = (history_ptr+1) % HISTORY_SIZE;
 554     history [history_ptr].page = currentpoint;
 555     history [history_ptr].link = selected_item;
 556     currentpoint = startpoint = search_string (data, "[How to use help]") + 1;
 557     selected_item = NULL;
 558     help_callback (h, 0, DLG_DRAW);
 559 }
 560
 561 static void
 562 help_index_cmd (Dlg_head * h)
 563 {
 564     char *new_item;
 565
 566     if (!(new_item = search_string (data, "[Contents]"))) {
 567         message (1, MSG_ERROR, _(" Cannot find node %s in help file "),
 568                  "[Contents]");
 569         return;
 570     }
 571
 572     history_ptr = (history_ptr + 1) % HISTORY_SIZE;
 573     history[history_ptr].page = currentpoint;
 574     history[history_ptr].link = selected_item;
 575
 576     currentpoint = startpoint = new_item + 1;
 577     selected_item = NULL;
 578     help_callback (h, 0, DLG_DRAW);
 579 }
 580
 581 static void quit_cmd (void *x)
 582 {
 583     dlg_stop ((Dlg_head *)x);
 584 }
 585
 586 static void prev_node_cmd (Dlg_head *h)
 587 {
 588     currentpoint = startpoint = history [history_ptr].page;
 589     selected_item = history [history_ptr].link;
 590     history_ptr--;
 591     if (history_ptr < 0)
 592         history_ptr = HISTORY_SIZE-1;
 593
 594     help_callback (h, 0, DLG_DRAW);
 595 }
 596
 597 static int md_callback (Dlg_head *h, Widget *w, int msg, int par)
 598 {
 599     return default_proc (h, msg, par);
 600 }
 601
 602 static Widget *mousedispatch_new (int y, int x, int yl, int xl)
 603 {
 604     Widget *w = g_new (Widget, 1);
 605
 606     init_widget (w, y, x, yl, xl,
 607                  (callback_fn) md_callback, 0, (mouse_h)  help_event, NULL);
 608
 609     return w;
 610 }
 611
 612 static int help_handle_key (struct Dlg_head *h, int c)
 613 {
 614     char *new_item;
 615
 616     if (c != KEY_UP && c != KEY_DOWN &&
 617         check_movement_keys (c, 1, help_lines, currentpoint,
 618                              (movefn) move_backward2,
 619                              (movefn) move_forward2,
 620                              (movefn) move_to_top,
 621                              (movefn) move_to_bottom))
 622         /* Nothing */;
 623     else switch (c){
 624     case 'l':
 625     case KEY_LEFT:
 626         prev_node_cmd (h);
 627         break;
 628
 629     case '\n':
 630     case KEY_RIGHT:
 631         /* follow link */
 632         if (!selected_item){
 633 #ifdef WE_WANT_TO_GO_BACKWARD_ON_KEY_RIGHT
 634             /* Is there any reason why the right key would take us
 635              * backward if there are no links selected?, I agree
 636              * with Torben than doing nothing in this case is better
 637              */
 638             /* If there are no links, go backward in history */
 639             history_ptr--;
 640             if (history_ptr < 0)
 641                 history_ptr = HISTORY_SIZE-1;
 642
 643             currentpoint = startpoint = history [history_ptr].page;
 644             selected_item   = history [history_ptr].link;
 645 #endif
 646         } else {
 647             history_ptr = (history_ptr+1) % HISTORY_SIZE;
 648             history [history_ptr].page = currentpoint;
 649             history [history_ptr].link = selected_item;
 650             currentpoint = startpoint = help_follow_link (currentpoint, selected_item) + 1;
 651         }
 652         selected_item = NULL;
 653         break;
 654
 655     case KEY_DOWN:
 656     case '\t':
 657         /* select next link */
 658         new_item = select_next_link (startpoint, selected_item);
 659         if (new_item){
 660             selected_item = new_item;
 661             if (selected_item >= last_shown){
 662                 if (c == KEY_DOWN)
 663                     move_forward (1);
 664                 else
 665                     selected_item = NULL;
 666             }
 667         } else if (c == KEY_DOWN)
 668             move_forward (1);
 669         else
 670             selected_item = NULL;
 671         break;
 672
 673     case KEY_UP:
 674     case ALT ('\t'):
 675         /* select previous link */
 676         new_item = select_prev_link (startpoint, selected_item);
 677         selected_item = new_item;
 678         if (selected_item < currentpoint || selected_item >= last_shown){
 679             if (c == KEY_UP)
 680                 move_backward (1);
 681             else{
 682                 if (link_area != NULL)
 683                     selected_item = link_area->link_name;
 684                 else
 685                     selected_item = NULL;
 686             }
 687         }
 688         break;
 689
 690     case 'n':
 691         /* Next node */
 692         new_item = currentpoint;
 693         while (*new_item && *new_item != CHAR_NODE_END)
 694             new_item++;
 695         if (*++new_item == '['){
 696             while (*++new_item) {
 697                 if (*new_item == ']' && *++new_item && *++new_item) {
 698                     currentpoint = new_item;
 699                     selected_item = NULL;
 700                     break;
 701                 }
 702             }
 703         }
 704         break;
 705
 706     case 'p':
 707         /* Previous node */
 708         new_item = currentpoint;
 709         while (new_item > data + 1 && *new_item != CHAR_NODE_END)
 710             new_item--;
 711         new_item--;
 712         while (new_item > data && *new_item != CHAR_NODE_END)
 713             new_item--;
 714         while (*new_item != ']')
 715             new_item++;
 716         currentpoint = new_item + 2;
 717         selected_item = NULL;
 718         break;
 719
 720     case 'c':
 721         help_index_cmd (h);
 722         break;
 723
 724     case ESC_CHAR:
 725     case XCTRL('g'):
 726         dlg_stop (h);
 727         break;
 728
 729     default:
 730         return 0;
 731
 732     }
 733     help_callback (h, 0, DLG_DRAW);
 734     return 1;
 735 }
 736
 737 static int help_callback (struct Dlg_head *h, int id, int msg)
 738 {
 739     switch (msg){
 740     case DLG_DRAW:
 741         common_dialog_repaint (h);
 742         show (h, currentpoint);
 743         break;
 744
 745     case DLG_KEY:
 746         return help_handle_key (h, id);
 747     }
 748     return 0;
 749 }
 750
 751 static void
 752 interactive_display_finish (void)
 753 {
 754     clear_link_areas ();
 755     g_free (data);
 756 }
 757
 758 void
 759 interactive_display (char *filename, char *node)
 760 {
 761     WButtonBar *help_bar;
 762     Widget *md;
 763     char *hlpfile = filename;
 764
 765     if (filename)
 766         data = load_file (filename);
 767     else
 768         data = load_mc_home_file ("mc.hlp", &hlpfile);
 769
 770     if (data == NULL) {
 771         message (1, MSG_ERROR, _(" Cannot open file %s \n %s "), hlpfile,
 772                  unix_error_string (errno));
 773     }
 774
 775     if (!filename)
 776         g_free (hlpfile);
 777
 778     if (!data)
 779         return;
 780
 781     if (!node || !*node)
 782         node = "[main]";
 783
 784     if (!(main_node = search_string (data, node))) {
 785         message (1, MSG_ERROR, _(" Cannot find node %s in help file "),
 786                  node);
 787
 788         /* Fallback to [main], return if it also cannot be found */
 789         main_node = search_string (data, "[main]");
 790         if (!main_node) {
 791             interactive_display_finish ();
 792             return;
 793         }
 794     }
 795
 796     help_lines = min (LINES - 4, max (2 * LINES / 3, 18));
 797
 798     whelp =
 799         create_dlg (0, 0, help_lines + 4, HELP_WINDOW_WIDTH + 4,
 800                     dialog_colors, help_callback, "[Help]", _("Help"),
 801                     DLG_TRYUP | DLG_CENTER | DLG_WANT_TAB);
 802
 803     selected_item = search_string_node (main_node, STRING_LINK_START) - 1;
 804     currentpoint = startpoint = main_node + 1;
 805
 806     for (history_ptr = HISTORY_SIZE; history_ptr;) {
 807         history_ptr--;
 808         history[history_ptr].page = currentpoint;
 809         history[history_ptr].link = selected_item;
 810     }
 811
 812     help_bar = buttonbar_new (1);
 813     help_bar->widget.y -= whelp->y;
 814     help_bar->widget.x -= whelp->x;
 815
 816     md = mousedispatch_new (1, 1, help_lines, HELP_WINDOW_WIDTH - 2);
 817
 818     add_widget (whelp, help_bar);
 819     add_widget (whelp, md);
 820
 821     define_label_data (whelp, (Widget *) NULL, 1, _("Help"),
 822                        (buttonbarfn) help_help_cmd, whelp);
 823     define_label_data (whelp, (Widget *) NULL, 2, _("Index"),
 824                        (buttonbarfn) help_index_cmd, whelp);
 825     define_label_data (whelp, (Widget *) NULL, 3, _("Prev"),
 826                        (buttonbarfn) prev_node_cmd, whelp);
 827     define_label (whelp, (Widget *) NULL, 4, "", 0);
 828     define_label (whelp, (Widget *) NULL, 5, "", 0);
 829     define_label (whelp, (Widget *) NULL, 6, "", 0);
 830     define_label (whelp, (Widget *) NULL, 7, "", 0);
 831     define_label (whelp, (Widget *) NULL, 8, "", 0);
 832     define_label (whelp, (Widget *) NULL, 9, "", 0);
 833     define_label_data (whelp, (Widget *) NULL, 10, _("Quit"), quit_cmd,
 834                        whelp);
 835
 836     run_dlg (whelp);
 837     interactive_display_finish ();
 838     destroy_dlg (whelp);
 839 }
 840