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 "lib/global.h"
  55
  56 #include "lib/tty/tty.h"
  57 #include "lib/skin.h"
  58 #include "lib/tty/mouse.h"
  59 #include "lib/tty/key.h"
  60 #include "lib/strutil.h"
  61
  62 #include "dialog.h"             /* For Dlg_head */
  63 #include "widget.h"             /* For Widget */
  64 #include "wtools.h"             /* For common_dialog_repaint() */
  65 #include "cmddef.h"
  66 #include "keybind.h"
  67 #include "help.h"
  68 #include "main.h"
  69
  70 const global_keymap_t *help_map;
  71
  72 #define MAXLINKNAME 80
  73 #define HISTORY_SIZE 20
  74 #define HELP_WINDOW_WIDTH (HELP_TEXT_WIDTH + 4)
  75
  76 #define STRING_LINK_START       "\01"
  77 #define STRING_LINK_POINTER     "\02"
  78 #define STRING_LINK_END         "\03"
  79 #define STRING_NODE_END         "\04"
  80
  81
  82 static char *fdata = NULL;              /* Pointer to the loaded data file */
  83 static int help_lines;                  /* Lines in help viewer */
  84 static int  history_ptr;                /* For the history queue */
  85 static const char *main_node;           /* The main node */
  86 static const char *last_shown = NULL;   /* Last byte shown in a screen */
  87 static gboolean end_of_node = FALSE;    /* Flag: the last character of the node shown? */
  88 static const char *currentpoint;
  89 static const char *selected_item;
  90
  91 /* The widget variables */
  92 static Dlg_head *whelp;
  93
  94 static struct {
  95     const char *page;           /* Pointer to the selected page */
  96     const char *link;           /* Pointer to the selected link */
  97 } history [HISTORY_SIZE];
  98
  99 /* Link areas for the mouse */
 100 typedef struct Link_Area {
 101     int x1, y1, x2, y2;
 102     const char *link_name;
 103     struct Link_Area *next;
 104 } Link_Area;
 105
 106 static Link_Area *link_area = NULL;
 107 static gboolean inside_link_area = FALSE;
 108
 109 static cb_ret_t help_callback (Dlg_head *h, Widget *sender,
 110                                 dlg_msg_t msg, int parm, void *data);
 111
 112 /* returns the position where text was found in the start buffer */
 113 /* or 0 if not found */
 114 static const char *
 115 search_string (const char *start, const char *text)
 116 {
 117     const char *result = NULL;
 118     char *local_text = g_strdup (text);
 119     char *d = local_text;
 120     const char *e = start;
 121
 122     /* fmt sometimes replaces a space with a newline in the help file */
 123     /* Replace the newlines in the link name with spaces to correct the situation */
 124     while (*d != '\0') {
 125         if (*d == '\n')
 126             *d = ' ';
 127         str_next_char (&d);
 128     }
 129
 130     /* Do search */
 131     for (d = local_text; *e; e++){
 132         if (*d == *e)
 133             d++;
 134         else
 135             d = local_text;
 136         if (*d == '\0') {
 137             result = e + 1;
 138             break;
 139         }
 140     }
 141
 142     g_free (local_text);
 143     return result;
 144 }
 145
 146 /* Searches text in the buffer pointed by start.  Search ends */
 147 /* if the CHAR_NODE_END is found in the text.  Returns 0 on failure */
 148 static const char *
 149 search_string_node (const char *start, const char *text)
 150 {
 151     const char *d = text;
 152     const char *e = start;
 153
 154     if (start != NULL)
 155         for (; *e && *e != CHAR_NODE_END; e++) {
 156             if (*d == *e)
 157                 d++;
 158             else
 159                 d = text;
 160             if (*d == '\0')
 161                 return e + 1;
 162         }
 163
 164     return NULL;
 165 }
 166
 167 /* Searches the_char in the buffer pointer by start and searches */
 168 /* it can search forward (direction = 1) or backward (direction = -1) */
 169 static const char *
 170 search_char_node (const char *start, char the_char, int direction)
 171 {
 172     const char *e;
 173
 174     for (e = start; (*e != '\0') && (*e != CHAR_NODE_END); e += direction)
 175         if (*e == the_char)
 176             return e;
 177
 178     return NULL;
 179 }
 180
 181 /* Returns the new current pointer when moved lines lines */
 182 static const char *
 183 move_forward2 (const char *c, int lines)
 184 {
 185     const char *p;
 186     int line;
 187
 188     currentpoint = c;
 189     for (line = 0, p = currentpoint; (*p != '\0') && (*p != CHAR_NODE_END);
 190                 str_cnext_char (&p)) {
 191         if (line == lines)
 192             return currentpoint = p;
 193
 194         if (*p == '\n')
 195             line++;
 196     }
 197     return currentpoint = c;
 198 }
 199
 200 static const char *
 201 move_backward2 (const char *c, int lines)
 202 {
 203     const char *p;
 204     int line;
 205
 206     currentpoint = c;
 207     for (line = 0, p = currentpoint; (*p != '\0') && ((int) (p - fdata) >= 0);
 208                 str_cprev_char (&p)) {
 209         if (*p == CHAR_NODE_END) {
 210             /* We reached the beginning of the node */
 211             /* Skip the node headers */
 212             while (*p != ']')
 213                 str_cnext_char (&p);
 214             return currentpoint = p + 2; /* Skip the newline following the start of the node */
 215         }
 216
 217         if (*(p - 1) == '\n')
 218             line++;
 219         if (line == lines)
 220             return currentpoint = p;
 221     }
 222     return currentpoint = c;
 223 }
 224
 225 static void
 226 move_forward (int i)
 227 {
 228     if (!end_of_node)
 229         currentpoint = move_forward2 (currentpoint, i);
 230 }
 231
 232 static void
 233 move_backward (int i)
 234 {
 235     currentpoint = move_backward2 (currentpoint, ++i);
 236 }
 237
 238 static void
 239 move_to_top (void)
 240 {
 241     while (((int) (currentpoint > fdata) > 0) && (*currentpoint != CHAR_NODE_END))
 242         currentpoint--;
 243
 244     while (*currentpoint != ']')
 245         currentpoint++;
 246     currentpoint = currentpoint + 2; /* Skip the newline following the start of the node */
 247     selected_item = NULL;
 248 }
 249
 250 static void
 251 move_to_bottom (void)
 252 {
 253     while ((*currentpoint != '\0') && (*currentpoint != CHAR_NODE_END))
 254         currentpoint++;
 255     currentpoint--;
 256     move_backward (help_lines - 1);
 257 }
 258
 259 static const char *
 260 help_follow_link (const char *start, const char *lc_selected_item)
 261 {
 262     char link_name [MAXLINKNAME];
 263     const char *p;
 264     int i = 0;
 265
 266     if (lc_selected_item == NULL)
 267         return start;
 268
 269     for (p = lc_selected_item; *p && *p != CHAR_NODE_END && *p != CHAR_LINK_POINTER; p++)
 270         ;
 271     if (*p == CHAR_LINK_POINTER){
 272         link_name [0] = '[';
 273         for (i = 1; *p != CHAR_LINK_END && *p && *p != CHAR_NODE_END && i < MAXLINKNAME-3; )
 274             link_name [i++] = *++p;
 275         link_name [i - 1] = ']';
 276         link_name [i] = '\0';
 277         p = search_string (fdata, link_name);
 278         if (p != NULL) {
 279             p += 1; /* Skip the newline following the start of the node */
 280             return p;
 281         }
 282     }
 283
 284     /* Create a replacement page with the error message */
 285     return _(" Help file format error\n");
 286 }
 287
 288 static const char *
 289 select_next_link (const char *current_link)
 290 {
 291     const char *p;
 292
 293     if (current_link == NULL)
 294         return NULL;
 295
 296     p = search_string_node (current_link, STRING_LINK_END);
 297     if (p == NULL)
 298         return NULL;
 299     p = search_string_node (p, STRING_LINK_START);
 300     if (p == NULL)
 301         return NULL;
 302     return p - 1;
 303 }
 304
 305 static const char *
 306 select_prev_link (const char *current_link)
 307 {
 308     return current_link == NULL
 309             ? NULL
 310             : search_char_node (current_link - 1, CHAR_LINK_START, -1);
 311 }
 312
 313 static void
 314 start_link_area (int x, int y, const char *link_name)
 315 {
 316     Link_Area *new;
 317
 318     if (inside_link_area)
 319         message (D_NORMAL, _("Warning"), _(" Internal bug: Double start of link area "));
 320
 321     /* Allocate memory for a new link area */
 322     new = g_new (Link_Area, 1);
 323     new->next = link_area;
 324     link_area = new;
 325
 326     /* Save the beginning coordinates of the link area */
 327     link_area->x1 = x;
 328     link_area->y1 = y;
 329
 330     /* Save the name of the destination anchor */
 331     link_area->link_name = link_name;
 332
 333     inside_link_area = TRUE;
 334 }
 335
 336 static void
 337 end_link_area (int x, int y)
 338 {
 339     if (inside_link_area) {
 340         /* Save the end coordinates of the link area */
 341         link_area->x2 = x;
 342         link_area->y2 = y;
 343         inside_link_area = FALSE;
 344     }
 345 }
 346
 347 static void
 348 clear_link_areas (void)
 349 {
 350     Link_Area *current;
 351
 352     while (link_area != NULL) {
 353         current = link_area;
 354         link_area = current->next;
 355         g_free (current);
 356     }
 357
 358     inside_link_area = FALSE;
 359 }
 360
 361 static void
 362 help_show (Dlg_head *h, const char *paint_start)
 363 {
 364     const char *p, *n;
 365     int col, line, c, w;
 366     gboolean painting = TRUE;
 367     gboolean acs;                       /* Flag: Alternate character set active? */
 368     gboolean repeat_paint;
 369     int active_col, active_line;        /* Active link position */
 370     static char buff[MB_LEN_MAX + 1];
 371
 372     tty_setcolor (HELP_NORMAL_COLOR);
 373     do {
 374         line = col = active_col = active_line = 0;
 375         repeat_paint = FALSE;
 376         acs = FALSE;
 377
 378         clear_link_areas ();
 379         if ((int) (selected_item - paint_start) < 0)
 380             selected_item = NULL;
 381
 382         p = paint_start;
 383         n = paint_start;
 384         while (n[0] != '\0' && n[0] != CHAR_NODE_END && line < help_lines) {
 385             p = n;
 386             n = str_cget_next_char (p);
 387             memcpy (buff, p, n - p);
 388             buff[n - p] = '\0';
 389
 390             c = (unsigned char) buff[0];
 391             switch (c){
 392             case CHAR_LINK_START:
 393                 if (selected_item == NULL)
 394                     selected_item = p;
 395                 if (p == selected_item){
 396                     tty_setcolor (HELP_SLINK_COLOR);
 397
 398                     /* Store the coordinates of the link */
 399                     active_col = col + 2;
 400                     active_line = line + 2;
 401                 }
 402                 else
 403                     tty_setcolor (HELP_LINK_COLOR);
 404                 start_link_area (col, line, p);
 405                 break;
 406             case CHAR_LINK_POINTER:
 407                 painting = FALSE;
 408                 end_link_area (col - 1, line);
 409                 break;
 410             case CHAR_LINK_END:
 411                 painting = TRUE;
 412                 tty_setcolor (HELP_NORMAL_COLOR);
 413                 break;
 414             case CHAR_ALTERNATE:
 415                 acs = TRUE;
 416                 break;
 417             case CHAR_NORMAL:
 418                 acs = FALSE;
 419                 break;
 420             case CHAR_VERSION:
 421                 dlg_move (h, line+2, col+2);
 422                 tty_print_string (VERSION);
 423                 col += str_term_width1 (VERSION);
 424                 break;
 425             case CHAR_FONT_BOLD:
 426                 tty_setcolor (HELP_BOLD_COLOR);
 427                 break;
 428             case CHAR_FONT_ITALIC:
 429                 tty_setcolor (HELP_ITALIC_COLOR);
 430                 break;
 431             case CHAR_FONT_NORMAL:
 432                 tty_setcolor (HELP_NORMAL_COLOR);
 433                 break;
 434             case '\n':
 435                 line++;
 436                 col = 0;
 437                 break;
 438             case '\t':
 439                 col = (col / 8 + 1) * 8;
 440                 break;
 441             default:
 442                 if (!painting)
 443                     continue;
 444                 w = str_term_width1 (buff);
 445                 if (col + w > HELP_WINDOW_WIDTH)
 446                     continue;
 447
 448                 dlg_move (h, line + 2, col + 2);
 449                 if (!acs)
 450                     tty_print_string (buff);
 451                 else if (c == ' ' || c == '.')
 452                     tty_print_char (c);
 453                 else
 454 #ifndef HAVE_SLANG
 455                     tty_print_char (acs_map [c]);
 456 #else
 457                     SLsmg_draw_object (h->y + line + 2, h->x + col + 2, c);
 458 #endif
 459                 col += w;
 460                 break;
 461             }
 462         }
 463
 464         last_shown = p;
 465         end_of_node = line < help_lines;
 466         tty_setcolor (HELP_NORMAL_COLOR);
 467         if ((int) (selected_item - last_shown) >= 0) {
 468             if (link_area == NULL)
 469                 selected_item = NULL;
 470             else {
 471                 selected_item = link_area->link_name;
 472                 repeat_paint = TRUE;
 473             }
 474         }
 475     } while (repeat_paint);
 476
 477     /* Position the cursor over a nice link */
 478     if (active_col)
 479         dlg_move (h, active_line, active_col);
 480 }
 481
 482 static int
 483 help_event (Gpm_Event *event, void *vp)
 484 {
 485     Widget *w = vp;
 486     Link_Area *current_area;
 487
 488     if ((event->type & GPM_UP) == 0)
 489         return 0;
 490
 491     /* The event is relative to the dialog window, adjust it: */
 492     event->x -= 2;
 493     event->y -= 2;
 494
 495     if (event->buttons & GPM_B_RIGHT){
 496         currentpoint = history [history_ptr].page;
 497         selected_item = history [history_ptr].link;
 498         history_ptr--;
 499         if (history_ptr < 0)
 500             history_ptr = HISTORY_SIZE-1;
 501
 502         help_callback (w->parent, NULL, DLG_DRAW, 0, NULL);
 503         return 0;
 504     }
 505
 506     /* Test whether the mouse click is inside one of the link areas */
 507     current_area = link_area;
 508     while (current_area != NULL)
 509     {
 510         /* Test one line link area */
 511         if (event->y == current_area->y1 && event->x >= current_area->x1 &&
 512             event->y == current_area->y2 && event->x <= current_area->x2)
 513             break;
 514         /* Test two line link area */
 515         if (current_area->y1 + 1 == current_area->y2){
 516             /* The first line */
 517             if (event->y == current_area->y1 && event->x >= current_area->x1)
 518                 break;
 519             /* The second line */
 520             if (event->y == current_area->y2 && event->x <= current_area->x2)
 521                 break;
 522         }
 523         /* Mouse will not work with link areas of more than two lines */
 524
 525         current_area = current_area->next;
 526     }
 527
 528     /* Test whether a link area was found */
 529     if (current_area != NULL) {
 530         /* The click was inside a link area -> follow the link */
 531         history_ptr = (history_ptr+1) % HISTORY_SIZE;
 532         history [history_ptr].page = currentpoint;
 533         history [history_ptr].link = current_area->link_name;
 534         currentpoint = help_follow_link (currentpoint, current_area->link_name);
 535         selected_item = NULL;
 536     } else if (event->y < 0)
 537         move_backward (help_lines - 1);
 538     else if (event->y >= help_lines)
 539         move_forward (help_lines - 1);
 540     else if (event->y < help_lines/2)
 541         move_backward (1);
 542     else
 543         move_forward (1);
 544
 545     /* Show the new node */
 546     help_callback (w->parent, NULL, DLG_DRAW, 0, NULL);
 547
 548     return 0;
 549 }
 550
 551 /* show help */
 552 static void
 553 help_help (Dlg_head *h)
 554 {
 555     const char *p;
 556
 557     history_ptr = (history_ptr + 1) % HISTORY_SIZE;
 558     history [history_ptr].page = currentpoint;
 559     history [history_ptr].link = selected_item;
 560
 561     p = search_string (fdata, "[How to use help]");
 562     if (p != NULL) {
 563         currentpoint = p + 1; /* Skip the newline following the start of the node */
 564         selected_item = NULL;
 565         help_callback (h, NULL, DLG_DRAW, 0, NULL);
 566     }
 567 }
 568
 569 static void
 570 help_index (Dlg_head *h)
 571 {
 572     const char *new_item;
 573
 574     new_item = search_string (fdata, "[Contents]");
 575
 576     if (new_item == NULL)
 577         message (D_ERROR, MSG_ERROR, _(" Cannot find node %s in help file "),
 578                  "[Contents]");
 579     else {
 580         history_ptr = (history_ptr + 1) % HISTORY_SIZE;
 581         history[history_ptr].page = currentpoint;
 582         history[history_ptr].link = selected_item;
 583
 584         currentpoint = new_item + 1; /* Skip the newline following the start of the node */
 585         selected_item = NULL;
 586         help_callback (h, NULL, DLG_DRAW, 0, NULL);
 587     }
 588 }
 589
 590 static void
 591 help_back (Dlg_head *h)
 592 {
 593     currentpoint = history [history_ptr].page;
 594     selected_item = history [history_ptr].link;
 595     history_ptr--;
 596     if (history_ptr < 0)
 597         history_ptr = HISTORY_SIZE - 1;
 598
 599     help_callback (h, NULL, DLG_DRAW, 0, NULL); /* FIXME: unneeded? */
 600 }
 601
 602 static void
 603 help_cmk_move_backward(void *vp, int lines)
 604 {
 605     (void) &vp;
 606     move_backward (lines);
 607 }
 608
 609 static void
 610 help_cmk_move_forward(void *vp, int lines)
 611 {
 612     (void) &vp;
 613     move_forward (lines);
 614 }
 615
 616 static void
 617 help_cmk_moveto_top(void *vp, int lines)
 618 {
 619     (void) &vp;
 620     (void) &lines;
 621     move_to_top ();
 622 }
 623
 624 static void
 625 help_cmk_moveto_bottom(void *vp, int lines)
 626 {
 627     (void) &vp;
 628     (void) &lines;
 629     move_to_bottom ();
 630 }
 631
 632 static void
 633 help_next_link (gboolean move_down)
 634  {
 635     const char *new_item;
 636
 637     new_item = select_next_link (selected_item);
 638     if (new_item != NULL) {
 639         selected_item = new_item;
 640         if ((int) (selected_item - last_shown) >= 0) {
 641             if (move_down)
 642                 move_forward (1);
 643             else
 644                 selected_item = NULL;
 645         }
 646     } else if (move_down)
 647         move_forward (1);
 648     else
 649         selected_item = NULL;
 650 }
 651
 652 static void
 653 help_prev_link (gboolean move_up)
 654 {
 655     const char *new_item;
 656
 657     new_item = select_prev_link (selected_item);
 658     selected_item = new_item;
 659     if ((selected_item == NULL) || (selected_item < currentpoint)) {
 660         if (move_up)
 661             move_backward (1);
 662         else if (link_area != NULL)
 663             selected_item = link_area->link_name;
 664         else
 665             selected_item = NULL;
 666     }
 667 }
 668
 669 static void
 670 help_next_node (void)
 671 {
 672     const char *new_item;
 673
 674     new_item = currentpoint;
 675     while ((*new_item != '\0') && (*new_item != CHAR_NODE_END))
 676         new_item++;
 677
 678     if (*++new_item == '[')
 679         while (*++new_item != '\0')
 680             if ((*new_item == ']') && (*++new_item != '\0')
 681                     && (*++new_item != '\0')) {
 682                 currentpoint = new_item;
 683                 selected_item = NULL;
 684                 break;
 685             }
 686 }
 687
 688 static void
 689 help_prev_node (void)
 690 {
 691     const char *new_item;
 692
 693     new_item = currentpoint;
 694     while (((int) (new_item - fdata) > 1) && (*new_item != CHAR_NODE_END))
 695         new_item--;
 696     new_item--;
 697     while (((int) (new_item - fdata) > 0) && (*new_item != CHAR_NODE_END))
 698         new_item--;
 699     while (*new_item != ']')
 700         new_item++;
 701     currentpoint = new_item + 2;
 702     selected_item = NULL;
 703 }
 704
 705 static void
 706 help_select_link (void)
 707 {
 708     /* follow link */
 709     if (selected_item == NULL) {
 710 #ifdef WE_WANT_TO_GO_BACKWARD_ON_KEY_RIGHT
 711         /* Is there any reason why the right key would take us
 712          * backward if there are no links selected?, I agree
 713          * with Torben than doing nothing in this case is better
 714          */
 715         /* If there are no links, go backward in history */
 716         history_ptr--;
 717         if (history_ptr < 0)
 718             history_ptr = HISTORY_SIZE-1;
 719
 720         currentpoint = history [history_ptr].page;
 721         selected_item = history [history_ptr].link;
 722 #endif
 723     } else {
 724         history_ptr = (history_ptr + 1) % HISTORY_SIZE;
 725         history [history_ptr].page = currentpoint;
 726         history [history_ptr].link = selected_item;
 727         currentpoint = help_follow_link (currentpoint, selected_item);
 728     }
 729
 730     selected_item = NULL;
 731 }
 732
 733 static cb_ret_t
 734 help_execute_cmd (unsigned long command)
 735 {
 736     cb_ret_t ret = MSG_HANDLED;
 737
 738     switch (command) {
 739     case CK_HelpHelp:
 740         help_help (whelp);
 741         break;
 742     case CK_HelpIndex:
 743         help_index (whelp);
 744         break;
 745     case CK_HelpBack:
 746         help_back (whelp);
 747         break;
 748     case CK_HelpMoveUp:
 749         help_prev_link (TRUE);
 750         break;
 751     case CK_HelpMoveDown:
 752         help_next_link (TRUE);
 753         break;
 754     case CK_HelpSelectLink:
 755         help_select_link ();
 756         break;
 757     case CK_HelpNextLink:
 758         help_next_link (FALSE);
 759         break;
 760     case CK_HelpPrevLink:
 761         help_prev_link (FALSE);
 762         break;
 763     case CK_HelpNextNode:
 764         help_next_node ();
 765         break;
 766     case CK_HelpPrevNode:
 767         help_prev_node ();
 768         break;
 769     case CK_HelpQuit:
 770         dlg_stop (whelp);
 771         break;
 772     default:
 773         ret = MSG_NOT_HANDLED;
 774     }
 775
 776     return ret;
 777 }
 778
 779 static cb_ret_t
 780 help_handle_key (Dlg_head *h, int c)
 781 {
 782     if (c != KEY_UP && c != KEY_DOWN &&
 783         check_movement_keys (c, help_lines, NULL,
 784                              help_cmk_move_backward,
 785                              help_cmk_move_forward,
 786                              help_cmk_moveto_top,
 787                              help_cmk_moveto_bottom) == MSG_HANDLED) {
 788         /* Nothing */;
 789     } else {
 790         unsigned long command;
 791
 792         command = lookup_keymap_command (help_map, c);
 793         if ((command == CK_Ignore_Key)
 794             || (help_execute_cmd (command) == MSG_NOT_HANDLED))
 795                 return MSG_NOT_HANDLED;
 796     }
 797
 798     help_callback (h, NULL, DLG_DRAW, 0, NULL);
 799     return MSG_HANDLED;
 800 }
 801
 802 static cb_ret_t
 803 help_callback (Dlg_head *h, Widget *sender,
 804                 dlg_msg_t msg, int parm, void *data)
 805 {
 806     WButtonBar *bb;
 807
 808     switch (msg) {
 809     case DLG_RESIZE:
 810         help_lines = min (LINES - 4, max (2 * LINES / 3, 18));
 811         dlg_set_size (h, help_lines + 4, HELP_WINDOW_WIDTH + 4);
 812         bb = find_buttonbar (h);
 813         widget_set_size (&bb->widget, LINES - 1, 0, 1, COLS);
 814         return MSG_HANDLED;
 815
 816     case DLG_DRAW:
 817         common_dialog_repaint (h);
 818         help_show (h, currentpoint);
 819         return MSG_HANDLED;
 820
 821     case DLG_KEY:
 822         return help_handle_key (h, parm);
 823
 824     case DLG_ACTION:
 825         /* command from buttonbar */
 826         return help_execute_cmd (parm);
 827
 828     default:
 829         return default_dlg_callback (h, sender, msg, parm, data);
 830     }
 831 }
 832
 833 static void
 834 interactive_display_finish (void)
 835 {
 836     clear_link_areas ();
 837 }
 838
 839 /* translate help file into terminal encoding */
 840 static void
 841 translate_file (char *filedata)
 842 {
 843     GIConv conv;
 844     GString *translated_data;
 845
 846     translated_data = g_string_new ("");
 847
 848     conv = str_crt_conv_from ("UTF-8");
 849
 850     if (conv == INVALID_CONV)
 851         g_string_free (translated_data, TRUE);
 852     else {
 853         g_free (fdata);
 854
 855         if (str_convert (conv, filedata, translated_data) != ESTR_FAILURE) {
 856             fdata = translated_data->str;
 857             g_string_free (translated_data, FALSE);
 858         } else {
 859             fdata = NULL;
 860             g_string_free (translated_data, TRUE);
 861         }
 862         str_close_conv (conv);
 863     }
 864 }
 865
 866 static cb_ret_t
 867 md_callback (Widget *w, widget_msg_t msg, int parm)
 868 {
 869     switch (msg) {
 870     case WIDGET_RESIZED:
 871         w->lines = help_lines;
 872         return MSG_HANDLED;
 873
 874     default:
 875         return default_proc (msg, parm);
 876     }
 877 }
 878
 879 static Widget *
 880 mousedispatch_new (int y, int x, int yl, int xl)
 881 {
 882     Widget *w = g_new (Widget, 1);
 883     init_widget (w, y, x, yl, xl, md_callback, help_event);
 884     return w;
 885 }
 886
 887 void
 888 interactive_display (const char *filename, const char *node)
 889 {
 890     WButtonBar *help_bar;
 891     Widget *md;
 892     char *hlpfile = NULL;
 893     char *filedata;
 894
 895     if (filename != NULL)
 896         filedata = load_file (filename);
 897     else
 898         filedata = load_mc_home_file (mc_home, mc_home_alt, "mc.hlp", &hlpfile);
 899
 900     if (filedata == NULL)
 901         message (D_ERROR, MSG_ERROR, _(" Cannot open file %s \n %s "), filename ? filename : hlpfile,
 902                  unix_error_string (errno));
 903
 904     g_free (hlpfile);
 905
 906     if (filedata == NULL)
 907         return;
 908
 909     translate_file (filedata);
 910
 911     g_free (filedata);
 912
 913     if (fdata == NULL)
 914         return;
 915
 916     if ((node == NULL) || (*node == '\0'))
 917         node = "[main]";
 918
 919     main_node = search_string (fdata, node);
 920
 921     if (main_node == NULL) {
 922         message (D_ERROR, MSG_ERROR, _(" Cannot find node %s in help file "),
 923                  node);
 924
 925         /* Fallback to [main], return if it also cannot be found */
 926         main_node = search_string (fdata, "[main]");
 927         if (main_node == NULL) {
 928             interactive_display_finish ();
 929             return;
 930         }
 931     }
 932
 933     help_lines = min (LINES - 4, max (2 * LINES / 3, 18));
 934
 935     whelp =
 936         create_dlg (0, 0, help_lines + 4, HELP_WINDOW_WIDTH + 4,
 937                     dialog_colors, help_callback, "[Help]", _("Help"),
 938                     DLG_TRYUP | DLG_CENTER | DLG_WANT_TAB);
 939
 940     selected_item = search_string_node (main_node, STRING_LINK_START) - 1;
 941     currentpoint = main_node + 1; /* Skip the newline following the start of the node */
 942
 943     for (history_ptr = HISTORY_SIZE; history_ptr;) {
 944         history_ptr--;
 945         history[history_ptr].page = currentpoint;
 946         history[history_ptr].link = selected_item;
 947     }
 948
 949     help_bar = buttonbar_new (TRUE);
 950     help_bar->widget.y -= whelp->y;
 951     help_bar->widget.x -= whelp->x;
 952
 953     md = mousedispatch_new (1, 1, help_lines, HELP_WINDOW_WIDTH - 2);
 954
 955     add_widget (whelp, md);
 956     add_widget (whelp, help_bar);
 957
 958     buttonbar_set_label (help_bar, 1, Q_("ButtonBar|Help"), help_map, NULL);
 959     buttonbar_set_label (help_bar, 2, Q_("ButtonBar|Index"), help_map, NULL);
 960     buttonbar_set_label (help_bar, 3, Q_("ButtonBar|Prev"), help_map, NULL);
 961     buttonbar_set_label (help_bar, 4, "", help_map, NULL);
 962     buttonbar_set_label (help_bar, 5, "", help_map, NULL);
 963     buttonbar_set_label (help_bar, 6, "", help_map, NULL);
 964     buttonbar_set_label (help_bar, 7, "", help_map, NULL);
 965     buttonbar_set_label (help_bar, 8, "", help_map, NULL);
 966     buttonbar_set_label (help_bar, 9, "", help_map, NULL);
 967     buttonbar_set_label (help_bar, 10, Q_("ButtonBar|Quit"), help_map, NULL);
 968
 969     run_dlg (whelp);
 970     interactive_display_finish ();
 971     destroy_dlg (whelp);
 972 }