src/help.c

   1 /*
   2    Hypertext file browser.
   3
   4    Copyright (C) 1994, 1995, 1998, 1999, 2000, 2001, 2002, 2003, 2004,
   5    2005, 2006, 2007, 2011
   6    The Free Software Foundation, Inc.
   7
   8    This file is part of the Midnight Commander.
   9
  10    The Midnight Commander is free software: you can redistribute it
  11    and/or modify it under the terms of the GNU General Public License as
  12    published by the Free Software Foundation, either version 3 of the License,
  13    or (at your option) any later version.
  14
  15    The Midnight Commander is distributed in the hope that it will be useful,
  16    but WITHOUT ANY WARRANTY; without even the implied warranty of
  17    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18    GNU General Public License for more details.
  19
  20    You should have received a copy of the GNU General Public License
  21    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  22  */
  23
  24
  25 /** \file help.c
  26  *  \brief Source: hypertext file browser
  27  *
  28  *  Implements the hypertext file viewer.
  29  *  The hypertext file is a file that may have one or more nodes.  Each
  30  *  node ends with a ^D character and starts with a bracket, then the
  31  *  name of the node and then a closing bracket. Right after the closing
  32  *  bracket a newline is placed. This newline is not to be displayed by
  33  *  the help viewer and must be skipped - its sole purpose is to faciliate
  34  *  the work of the people managing the help file template (xnc.hlp) .
  35  *
  36  *  Links in the hypertext file are specified like this: the text that
  37  *  will be highlighted should have a leading ^A, then it comes the
  38  *  text, then a ^B indicating that highlighting is done, then the name
  39  *  of the node you want to link to and then a ^C.
  40  *
  41  *  The file must contain a ^D at the beginning and at the end of the
  42  *  file or the program will not be able to detect the end of file.
  43  *
  44  *  Lazyness/widgeting attack: This file does use the dialog manager
  45  *  and uses mainly the dialog to achieve the help work.  there is only
  46  *  one specialized widget and it's only used to forward the mouse messages
  47  *  to the appropiate routine.
  48  */
  49
  50
  51 #include <config.h>
  52
  53 #include <errno.h>
  54 #include <stdio.h>
  55 #include <sys/types.h>
  56 #include <sys/stat.h>
  57
  58 #include "lib/global.h"
  59
  60 #include "lib/tty/tty.h"
  61 #include "lib/tty/mouse.h"
  62 #include "lib/skin.h"
  63 #include "lib/strutil.h"
  64 #include "lib/fileloc.h"
  65 #include "lib/util.h"
  66 #include "lib/widget.h"
  67 #include "lib/event-types.h"
  68
  69 #include "keybind-defaults.h"
  70 #include "keybind-defaults.h"
  71 #include "help.h"
  72
  73 /*** global variables ****************************************************************************/
  74
  75 /*** file scope macro definitions ****************************************************************/
  76
  77 #define MAXLINKNAME 80
  78 #define HISTORY_SIZE 20
  79 #define HELP_WINDOW_WIDTH min(80, COLS - 16)
  80
  81 #define STRING_LINK_START       "\01"
  82 #define STRING_LINK_POINTER     "\02"
  83 #define STRING_LINK_END         "\03"
  84 #define STRING_NODE_END         "\04"
  85
  86 /*** file scope type declarations ****************************************************************/
  87
  88 /* Link areas for the mouse */
  89 typedef struct Link_Area
  90 {
  91     int x1, y1, x2, y2;
  92     const char *link_name;
  93 } Link_Area;
  94
  95 /*** file scope variables ************************************************************************/
  96
  97 static char *fdata = NULL;      /* Pointer to the loaded data file */
  98 static int help_lines;          /* Lines in help viewer */
  99 static int history_ptr;         /* For the history queue */
 100 static const char *main_node;   /* The main node */
 101 static const char *last_shown = NULL;   /* Last byte shown in a screen */
 102 static gboolean end_of_node = FALSE;    /* Flag: the last character of the node shown? */
 103 static const char *currentpoint;
 104 static const char *selected_item;
 105
 106 /* The widget variables */
 107 static WDialog *whelp;
 108
 109 static struct
 110 {
 111     const char *page;           /* Pointer to the selected page */
 112     const char *link;           /* Pointer to the selected link */
 113 } history[HISTORY_SIZE];
 114
 115 static GSList *link_area = NULL;
 116 static gboolean inside_link_area = FALSE;
 117
 118 static cb_ret_t help_callback (Widget * w, Widget * sender, widget_msg_t msg, int parm, void *data);
 119
 120 /*** file scope functions ************************************************************************/
 121 /* --------------------------------------------------------------------------------------------- */
 122
 123 /** returns the position where text was found in the start buffer
 124  * or 0 if not found
 125  */
 126 static const char *
 127 search_string (const char *start, const char *text)
 128 {
 129     const char *result = NULL;
 130     char *local_text = g_strdup (text);
 131     char *d = local_text;
 132     const 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 != '\0')
 137     {
 138         if (*d == '\n')
 139             *d = ' ';
 140         str_next_char (&d);
 141     }
 142
 143     /* Do search */
 144     for (d = local_text; *e; e++)
 145     {
 146         if (*d == *e)
 147             d++;
 148         else
 149             d = local_text;
 150         if (*d == '\0')
 151         {
 152             result = e + 1;
 153             break;
 154         }
 155     }
 156
 157     g_free (local_text);
 158     return result;
 159 }
 160
 161 /* --------------------------------------------------------------------------------------------- */
 162 /** Searches text in the buffer pointed by start.  Search ends
 163  * if the CHAR_NODE_END is found in the text.
 164  * @return NULL on failure
 165  */
 166
 167 static const char *
 168 search_string_node (const char *start, const char *text)
 169 {
 170     const char *d = text;
 171     const char *e = start;
 172
 173     if (start != NULL)
 174         for (; *e && *e != CHAR_NODE_END; e++)
 175         {
 176             if (*d == *e)
 177                 d++;
 178             else
 179                 d = text;
 180             if (*d == '\0')
 181                 return e + 1;
 182         }
 183
 184     return NULL;
 185 }
 186
 187 /* --------------------------------------------------------------------------------------------- */
 188 /** Searches the_char in the buffer pointer by start and searches
 189  * it can search forward (direction = 1) or backward (direction = -1)
 190  */
 191
 192 static const char *
 193 search_char_node (const char *start, char the_char, int direction)
 194 {
 195     const char *e;
 196
 197     for (e = start; (*e != '\0') && (*e != CHAR_NODE_END); e += direction)
 198         if (*e == the_char)
 199             return e;
 200
 201     return NULL;
 202 }
 203
 204 /* --------------------------------------------------------------------------------------------- */
 205 /** Returns the new current pointer when moved lines lines */
 206
 207 static const char *
 208 move_forward2 (const char *c, int lines)
 209 {
 210     const char *p;
 211     int line;
 212
 213     currentpoint = c;
 214     for (line = 0, p = currentpoint; (*p != '\0') && (*p != CHAR_NODE_END); str_cnext_char (&p))
 215     {
 216         if (line == lines)
 217             return currentpoint = p;
 218
 219         if (*p == '\n')
 220             line++;
 221     }
 222     return currentpoint = c;
 223 }
 224
 225 /* --------------------------------------------------------------------------------------------- */
 226
 227 static const char *
 228 move_backward2 (const char *c, int lines)
 229 {
 230     const char *p;
 231     int line;
 232
 233     currentpoint = c;
 234     for (line = 0, p = currentpoint; (*p != '\0') && ((int) (p - fdata) >= 0); str_cprev_char (&p))
 235     {
 236         if (*p == CHAR_NODE_END)
 237         {
 238             /* We reached the beginning of the node */
 239             /* Skip the node headers */
 240             while (*p != ']')
 241                 str_cnext_char (&p);
 242             return currentpoint = p + 2;        /* Skip the newline following the start of the node */
 243         }
 244
 245         if (*(p - 1) == '\n')
 246             line++;
 247         if (line == lines)
 248             return currentpoint = p;
 249     }
 250     return currentpoint = c;
 251 }
 252
 253 /* --------------------------------------------------------------------------------------------- */
 254
 255 static void
 256 move_forward (int i)
 257 {
 258     if (!end_of_node)
 259         currentpoint = move_forward2 (currentpoint, i);
 260 }
 261
 262 /* --------------------------------------------------------------------------------------------- */
 263
 264 static void
 265 move_backward (int i)
 266 {
 267     currentpoint = move_backward2 (currentpoint, ++i);
 268 }
 269
 270 /* --------------------------------------------------------------------------------------------- */
 271
 272 static void
 273 move_to_top (void)
 274 {
 275     while (((int) (currentpoint > fdata) > 0) && (*currentpoint != CHAR_NODE_END))
 276         currentpoint--;
 277
 278     while (*currentpoint != ']')
 279         currentpoint++;
 280     currentpoint = currentpoint + 2;    /* Skip the newline following the start of the node */
 281     selected_item = NULL;
 282 }
 283
 284 /* --------------------------------------------------------------------------------------------- */
 285
 286 static void
 287 move_to_bottom (void)
 288 {
 289     while ((*currentpoint != '\0') && (*currentpoint != CHAR_NODE_END))
 290         currentpoint++;
 291     currentpoint--;
 292     move_backward (1);
 293 }
 294
 295 /* --------------------------------------------------------------------------------------------- */
 296
 297 static const char *
 298 help_follow_link (const char *start, const char *lc_selected_item)
 299 {
 300     char link_name[MAXLINKNAME];
 301     const char *p;
 302     int i = 0;
 303
 304     if (lc_selected_item == NULL)
 305         return start;
 306
 307     for (p = lc_selected_item; *p && *p != CHAR_NODE_END && *p != CHAR_LINK_POINTER; p++)
 308         ;
 309     if (*p == CHAR_LINK_POINTER)
 310     {
 311         link_name[0] = '[';
 312         for (i = 1; *p != CHAR_LINK_END && *p && *p != CHAR_NODE_END && i < MAXLINKNAME - 3;)
 313             link_name[i++] = *++p;
 314         link_name[i - 1] = ']';
 315         link_name[i] = '\0';
 316         p = search_string (fdata, link_name);
 317         if (p != NULL)
 318         {
 319             p += 1;             /* Skip the newline following the start of the node */
 320             return p;
 321         }
 322     }
 323
 324     /* Create a replacement page with the error message */
 325     return _("Help file format error\n");
 326 }
 327
 328 /* --------------------------------------------------------------------------------------------- */
 329
 330 static const char *
 331 select_next_link (const char *current_link)
 332 {
 333     const char *p;
 334
 335     if (current_link == NULL)
 336         return NULL;
 337
 338     p = search_string_node (current_link, STRING_LINK_END);
 339     if (p == NULL)
 340         return NULL;
 341     p = search_string_node (p, STRING_LINK_START);
 342     if (p == NULL)
 343         return NULL;
 344     return p - 1;
 345 }
 346
 347 /* --------------------------------------------------------------------------------------------- */
 348
 349 static const char *
 350 select_prev_link (const char *current_link)
 351 {
 352     return current_link == NULL ? NULL : search_char_node (current_link - 1, CHAR_LINK_START, -1);
 353 }
 354
 355 /* --------------------------------------------------------------------------------------------- */
 356
 357 static void
 358 start_link_area (int x, int y, const char *link_name)
 359 {
 360     Link_Area *la;
 361
 362     if (inside_link_area)
 363         message (D_NORMAL, _("Warning"), _("Internal bug: Double start of link area"));
 364
 365     /* Allocate memory for a new link area */
 366     la = g_new (Link_Area, 1);
 367     /* Save the beginning coordinates of the link area */
 368     la->x1 = x;
 369     la->y1 = y;
 370     /* Save the name of the destination anchor */
 371     la->link_name = link_name;
 372     link_area = g_slist_prepend (link_area, la);
 373
 374     inside_link_area = TRUE;
 375 }
 376
 377 /* --------------------------------------------------------------------------------------------- */
 378
 379 static void
 380 end_link_area (int x, int y)
 381 {
 382     if (inside_link_area)
 383     {
 384         Link_Area *la = (Link_Area *) link_area->data;
 385         /* Save the end coordinates of the link area */
 386         la->x2 = x;
 387         la->y2 = y;
 388         inside_link_area = FALSE;
 389     }
 390 }
 391
 392 /* --------------------------------------------------------------------------------------------- */
 393
 394 static void
 395 clear_link_areas (void)
 396 {
 397     g_slist_foreach (link_area, (GFunc) g_free, NULL);
 398     g_slist_free (link_area);
 399     link_area = NULL;
 400     inside_link_area = FALSE;
 401 }
 402
 403 /* --------------------------------------------------------------------------------------------- */
 404
 405 static void
 406 help_print_word (WDialog * h, GString * word, int *col, int *line, gboolean add_space)
 407 {
 408     if (*line >= help_lines)
 409         g_string_set_size (word, 0);
 410     else
 411     {
 412         int w;
 413
 414         w = str_term_width1 (word->str);
 415         if (*col + w >= HELP_WINDOW_WIDTH)
 416         {
 417             *col = 0;
 418             (*line)++;
 419         }
 420
 421         if (*line >= help_lines)
 422             g_string_set_size (word, 0);
 423         else
 424         {
 425             widget_move (h, *line + 2, *col + 2);
 426             tty_print_string (word->str);
 427             g_string_set_size (word, 0);
 428             *col += w;
 429         }
 430     }
 431
 432     if (add_space)
 433     {
 434         if (*col < HELP_WINDOW_WIDTH - 1)
 435         {
 436             tty_print_char (' ');
 437             (*col)++;
 438         }
 439         else
 440         {
 441             *col = 0;
 442             (*line)++;
 443         }
 444     }
 445 }
 446
 447 /* --------------------------------------------------------------------------------------------- */
 448
 449 static void
 450 help_show (WDialog * h, const char *paint_start)
 451 {
 452     const char *p, *n;
 453     int col, line, c;
 454     gboolean painting = TRUE;
 455     gboolean acs;               /* Flag: Alternate character set active? */
 456     gboolean repeat_paint;
 457     int active_col, active_line;        /* Active link position */
 458     char buff[MB_LEN_MAX + 1];
 459     GString *word;
 460
 461     word = g_string_sized_new (32);
 462
 463     tty_setcolor (HELP_NORMAL_COLOR);
 464     do
 465     {
 466         line = col = active_col = active_line = 0;
 467         repeat_paint = FALSE;
 468         acs = FALSE;
 469
 470         clear_link_areas ();
 471         if ((int) (selected_item - paint_start) < 0)
 472             selected_item = NULL;
 473
 474         p = paint_start;
 475         n = paint_start;
 476         while ((n[0] != '\0') && (n[0] != CHAR_NODE_END) && (line < help_lines))
 477         {
 478             p = n;
 479             n = str_cget_next_char (p);
 480             memcpy (buff, p, n - p);
 481             buff[n - p] = '\0';
 482
 483             c = (unsigned char) buff[0];
 484             switch (c)
 485             {
 486             case CHAR_LINK_START:
 487                 if (selected_item == NULL)
 488                     selected_item = p;
 489                 if (p != selected_item)
 490                     tty_setcolor (HELP_LINK_COLOR);
 491                 else
 492                 {
 493                     tty_setcolor (HELP_SLINK_COLOR);
 494
 495                     /* Store the coordinates of the link */
 496                     active_col = col + 2;
 497                     active_line = line + 2;
 498                 }
 499                 start_link_area (col, line, p);
 500                 break;
 501             case CHAR_LINK_POINTER:
 502                 painting = FALSE;
 503                 break;
 504             case CHAR_LINK_END:
 505                 painting = TRUE;
 506                 help_print_word (h, word, &col, &line, FALSE);
 507                 end_link_area (col - 1, line);
 508                 tty_setcolor (HELP_NORMAL_COLOR);
 509                 break;
 510             case CHAR_ALTERNATE:
 511                 acs = TRUE;
 512                 break;
 513             case CHAR_NORMAL:
 514                 acs = FALSE;
 515                 break;
 516             case CHAR_VERSION:
 517                 widget_move (h, line + 2, col + 2);
 518                 tty_print_string (VERSION);
 519                 col += str_term_width1 (VERSION);
 520                 break;
 521             case CHAR_FONT_BOLD:
 522                 tty_setcolor (HELP_BOLD_COLOR);
 523                 break;
 524             case CHAR_FONT_ITALIC:
 525                 tty_setcolor (HELP_ITALIC_COLOR);
 526                 break;
 527             case CHAR_FONT_NORMAL:
 528                 help_print_word (h, word, &col, &line, FALSE);
 529                 tty_setcolor (HELP_NORMAL_COLOR);
 530                 break;
 531             case '\n':
 532                 if (painting)
 533                     help_print_word (h, word, &col, &line, FALSE);
 534                 line++;
 535                 col = 0;
 536                 break;
 537             case '\t':
 538                 col = (col / 8 + 1) * 8;
 539                 if (col >= HELP_WINDOW_WIDTH)
 540                 {
 541                     line++;
 542                     col = 8;
 543                 }
 544                 break;
 545             case ' ':
 546                 /* word delimeter */
 547                 if (painting)
 548                     help_print_word (h, word, &col, &line, TRUE);
 549                 break;
 550             default:
 551                 if (painting && (line < help_lines))
 552                 {
 553                     if (!acs)
 554                         /* accumulate symbols in a word */
 555                         g_string_append (word, buff);
 556                     else if (col < HELP_WINDOW_WIDTH)
 557                     {
 558                         widget_move (h, line + 2, col + 2);
 559
 560                         if ((c == ' ') || (c == '.'))
 561                             tty_print_char (c);
 562                         else
 563 #ifndef HAVE_SLANG
 564                             tty_print_char (acs_map[c]);
 565 #else
 566                             SLsmg_draw_object (WIDGET (h)->y + line + 2, WIDGET (h)->x + col + 2,
 567                                                c);
 568 #endif
 569                         col++;
 570                     }
 571                 }
 572             }
 573         }
 574
 575         /* print last word */
 576         if (n[0] == CHAR_NODE_END)
 577             help_print_word (h, word, &col, &line, FALSE);
 578
 579         last_shown = p;
 580         end_of_node = line < help_lines;
 581         tty_setcolor (HELP_NORMAL_COLOR);
 582         if ((int) (selected_item - last_shown) >= 0)
 583         {
 584             if ((link_area == NULL) || (link_area->data == NULL))
 585                 selected_item = NULL;
 586             else
 587             {
 588                 selected_item = ((Link_Area *) link_area->data)->link_name;
 589                 repeat_paint = TRUE;
 590             }
 591         }
 592     }
 593     while (repeat_paint);
 594
 595     g_string_free (word, TRUE);
 596
 597     /* Position the cursor over a nice link */
 598     if (active_col)
 599         widget_move (h, active_line, active_col);
 600 }
 601
 602 /* --------------------------------------------------------------------------------------------- */
 603
 604 static int
 605 help_event (Gpm_Event * event, void *vp)
 606 {
 607     Widget *w = WIDGET (vp);
 608     GSList *current_area;
 609     Gpm_Event local;
 610
 611     if (!mouse_global_in_widget (event, w))
 612         return MOU_UNHANDLED;
 613
 614     if ((event->type & GPM_UP) == 0)
 615         return MOU_NORMAL;
 616
 617     local = mouse_get_local (event, w);
 618
 619     /* The event is relative to the dialog window, adjust it: */
 620     local.x -= 2;
 621     local.y -= 2;
 622
 623     if ((local.buttons & GPM_B_RIGHT) != 0)
 624     {
 625         currentpoint = history[history_ptr].page;
 626         selected_item = history[history_ptr].link;
 627         history_ptr--;
 628         if (history_ptr < 0)
 629             history_ptr = HISTORY_SIZE - 1;
 630
 631         send_message (w->owner, NULL, MSG_DRAW, 0, NULL);
 632         return MOU_NORMAL;
 633     }
 634
 635     /* Test whether the mouse click is inside one of the link areas */
 636     for (current_area = link_area; current_area != NULL; current_area = g_slist_next (current_area))
 637     {
 638         Link_Area *la = (Link_Area *) current_area->data;
 639
 640         /* Test one line link area */
 641         if (local.y == la->y1 && local.x >= la->x1 && local.y == la->y2 && local.x <= la->x2)
 642             break;
 643
 644         /* Test two line link area */
 645         if (la->y1 + 1 == la->y2)
 646         {
 647             /* The first line */
 648             if (local.y == la->y1 && local.x >= la->x1)
 649                 break;
 650             /* The second line */
 651             if (local.y == la->y2 && local.x <= la->x2)
 652                 break;
 653         }
 654         /* Mouse will not work with link areas of more than two lines */
 655     }
 656
 657     /* Test whether a link area was found */
 658     if (current_area != NULL)
 659     {
 660         Link_Area *la = (Link_Area *) current_area->data;
 661
 662         /* The click was inside a link area -> follow the link */
 663         history_ptr = (history_ptr + 1) % HISTORY_SIZE;
 664         history[history_ptr].page = currentpoint;
 665         history[history_ptr].link = la->link_name;
 666         currentpoint = help_follow_link (currentpoint, la->link_name);
 667         selected_item = NULL;
 668     }
 669     else if (local.y < 0)
 670         move_backward (help_lines - 1);
 671     else if (local.y >= help_lines)
 672         move_forward (help_lines - 1);
 673     else if (local.y < help_lines / 2)
 674         move_backward (1);
 675     else
 676         move_forward (1);
 677
 678     /* Show the new node */
 679     send_message (w->owner, NULL, MSG_DRAW, 0, NULL);
 680
 681     return MOU_NORMAL;
 682 }
 683
 684 /* --------------------------------------------------------------------------------------------- */
 685 /** show help */
 686
 687 static void
 688 help_help (WDialog * h)
 689 {
 690     const char *p;
 691
 692     history_ptr = (history_ptr + 1) % HISTORY_SIZE;
 693     history[history_ptr].page = currentpoint;
 694     history[history_ptr].link = selected_item;
 695
 696     p = search_string (fdata, "[How to use help]");
 697     if (p != NULL)
 698     {
 699         currentpoint = p + 1;   /* Skip the newline following the start of the node */
 700         selected_item = NULL;
 701         send_message (h, NULL, MSG_DRAW, 0, NULL);
 702     }
 703 }
 704
 705 /* --------------------------------------------------------------------------------------------- */
 706
 707 static void
 708 help_index (WDialog * h)
 709 {
 710     const char *new_item;
 711
 712     new_item = search_string (fdata, "[Contents]");
 713
 714     if (new_item == NULL)
 715         message (D_ERROR, MSG_ERROR, _("Cannot find node %s in help file"), "[Contents]");
 716     else
 717     {
 718         history_ptr = (history_ptr + 1) % HISTORY_SIZE;
 719         history[history_ptr].page = currentpoint;
 720         history[history_ptr].link = selected_item;
 721
 722         currentpoint = new_item + 1;    /* Skip the newline following the start of the node */
 723         selected_item = NULL;
 724         send_message (h, NULL, MSG_DRAW, 0, NULL);
 725     }
 726 }
 727
 728 /* --------------------------------------------------------------------------------------------- */
 729
 730 static void
 731 help_back (WDialog * h)
 732 {
 733     currentpoint = history[history_ptr].page;
 734     selected_item = history[history_ptr].link;
 735     history_ptr--;
 736     if (history_ptr < 0)
 737         history_ptr = HISTORY_SIZE - 1;
 738
 739     send_message (h, NULL, MSG_DRAW, 0, NULL);  /* FIXME: unneeded? */
 740 }
 741
 742 /* --------------------------------------------------------------------------------------------- */
 743
 744 static void
 745 help_next_link (gboolean move_down)
 746 {
 747     const char *new_item;
 748
 749     new_item = select_next_link (selected_item);
 750     if (new_item != NULL)
 751     {
 752         selected_item = new_item;
 753         if ((int) (selected_item - last_shown) >= 0)
 754         {
 755             if (move_down)
 756                 move_forward (1);
 757             else
 758                 selected_item = NULL;
 759         }
 760     }
 761     else if (move_down)
 762         move_forward (1);
 763     else
 764         selected_item = NULL;
 765 }
 766
 767 /* --------------------------------------------------------------------------------------------- */
 768
 769 static void
 770 help_prev_link (gboolean move_up)
 771 {
 772     const char *new_item;
 773
 774     new_item = select_prev_link (selected_item);
 775     selected_item = new_item;
 776     if ((selected_item == NULL) || (selected_item < currentpoint))
 777     {
 778         if (move_up)
 779             move_backward (1);
 780         else if ((link_area != NULL) && (link_area->data != NULL))
 781             selected_item = ((Link_Area *) link_area->data)->link_name;
 782         else
 783             selected_item = NULL;
 784     }
 785 }
 786
 787 /* --------------------------------------------------------------------------------------------- */
 788
 789 static void
 790 help_next_node (void)
 791 {
 792     const char *new_item;
 793
 794     new_item = currentpoint;
 795     while ((*new_item != '\0') && (*new_item != CHAR_NODE_END))
 796         new_item++;
 797
 798     if (*++new_item == '[')
 799         while (*++new_item != '\0')
 800             if ((*new_item == ']') && (*++new_item != '\0') && (*++new_item != '\0'))
 801             {
 802                 currentpoint = new_item;
 803                 selected_item = NULL;
 804                 break;
 805             }
 806 }
 807
 808 /* --------------------------------------------------------------------------------------------- */
 809
 810 static void
 811 help_prev_node (void)
 812 {
 813     const char *new_item;
 814
 815     new_item = currentpoint;
 816     while (((int) (new_item - fdata) > 1) && (*new_item != CHAR_NODE_END))
 817         new_item--;
 818     new_item--;
 819     while (((int) (new_item - fdata) > 0) && (*new_item != CHAR_NODE_END))
 820         new_item--;
 821     while (*new_item != ']')
 822         new_item++;
 823     currentpoint = new_item + 2;
 824     selected_item = NULL;
 825 }
 826
 827 /* --------------------------------------------------------------------------------------------- */
 828
 829 static void
 830 help_select_link (void)
 831 {
 832     /* follow link */
 833     if (selected_item == NULL)
 834     {
 835 #ifdef WE_WANT_TO_GO_BACKWARD_ON_KEY_RIGHT
 836         /* Is there any reason why the right key would take us
 837          * backward if there are no links selected?, I agree
 838          * with Torben than doing nothing in this case is better
 839          */
 840         /* If there are no links, go backward in history */
 841         history_ptr--;
 842         if (history_ptr < 0)
 843             history_ptr = HISTORY_SIZE - 1;
 844
 845         currentpoint = history[history_ptr].page;
 846         selected_item = history[history_ptr].link;
 847 #endif
 848     }
 849     else
 850     {
 851         history_ptr = (history_ptr + 1) % HISTORY_SIZE;
 852         history[history_ptr].page = currentpoint;
 853         history[history_ptr].link = selected_item;
 854         currentpoint = help_follow_link (currentpoint, selected_item);
 855     }
 856
 857     selected_item = NULL;
 858 }
 859
 860 /* --------------------------------------------------------------------------------------------- */
 861
 862 static cb_ret_t
 863 help_execute_cmd (unsigned long command)
 864 {
 865     cb_ret_t ret = MSG_HANDLED;
 866
 867     switch (command)
 868     {
 869     case CK_Help:
 870         help_help (whelp);
 871         break;
 872     case CK_Index:
 873         help_index (whelp);
 874         break;
 875     case CK_Back:
 876         help_back (whelp);
 877         break;
 878     case CK_Up:
 879         help_prev_link (TRUE);
 880         break;
 881     case CK_Down:
 882         help_next_link (TRUE);
 883         break;
 884     case CK_PageDown:
 885         move_forward (help_lines - 1);
 886         break;
 887     case CK_PageUp:
 888         move_backward (help_lines - 1);
 889         break;
 890     case CK_HalfPageDown:
 891         move_forward (help_lines / 2);
 892         break;
 893     case CK_HalfPageUp:
 894         move_backward (help_lines / 2);
 895         break;
 896     case CK_Top:
 897         move_to_top ();
 898         break;
 899     case CK_Bottom:
 900         move_to_bottom ();
 901         break;
 902     case CK_Enter:
 903         help_select_link ();
 904         break;
 905     case CK_LinkNext:
 906         help_next_link (FALSE);
 907         break;
 908     case CK_LinkPrev:
 909         help_prev_link (FALSE);
 910         break;
 911     case CK_NodeNext:
 912         help_next_node ();
 913         break;
 914     case CK_NodePrev:
 915         help_prev_node ();
 916         break;
 917     case CK_Quit:
 918         dlg_stop (whelp);
 919         break;
 920     default:
 921         ret = MSG_NOT_HANDLED;
 922     }
 923
 924     return ret;
 925 }
 926
 927 /* --------------------------------------------------------------------------------------------- */
 928
 929 static cb_ret_t
 930 help_handle_key (WDialog * h, int c)
 931 {
 932     unsigned long command;
 933
 934     command = keybind_lookup_keymap_command (help_map, c);
 935     if ((command == CK_IgnoreKey) || (help_execute_cmd (command) == MSG_NOT_HANDLED))
 936         return MSG_NOT_HANDLED;
 937
 938     send_message (h, NULL, MSG_DRAW, 0, NULL);
 939     return MSG_HANDLED;
 940 }
 941
 942 /* --------------------------------------------------------------------------------------------- */
 943
 944 static cb_ret_t
 945 help_callback (Widget * w, Widget * sender, widget_msg_t msg, int parm, void *data)
 946 {
 947     WDialog *h = DIALOG (w);
 948
 949     switch (msg)
 950     {
 951     case MSG_RESIZE:
 952         {
 953             WButtonBar *bb;
 954
 955             help_lines = min (LINES - 4, max (2 * LINES / 3, 18));
 956             dlg_set_size (h, help_lines + 4, HELP_WINDOW_WIDTH + 4);
 957             bb = find_buttonbar (h);
 958             widget_set_size (WIDGET (bb), LINES - 1, 0, 1, COLS);
 959             return MSG_HANDLED;
 960         }
 961
 962     case MSG_DRAW:
 963         dlg_default_repaint (h);
 964         help_show (h, currentpoint);
 965         return MSG_HANDLED;
 966
 967     case MSG_KEY:
 968         return help_handle_key (h, parm);
 969
 970     case MSG_ACTION:
 971         /* shortcut */
 972         if (sender == NULL)
 973             return help_execute_cmd (parm);
 974         /* message from buttonbar */
 975         if (sender == WIDGET (find_buttonbar (h)))
 976         {
 977             if (data != NULL)
 978                 return send_message (data, NULL, MSG_ACTION, parm, NULL);
 979             return help_execute_cmd (parm);
 980         }
 981         return MSG_NOT_HANDLED;
 982
 983     default:
 984         return dlg_default_callback (w, sender, msg, parm, data);
 985     }
 986 }
 987
 988 /* --------------------------------------------------------------------------------------------- */
 989
 990 static void
 991 interactive_display_finish (void)
 992 {
 993     clear_link_areas ();
 994 }
 995
 996 /* --------------------------------------------------------------------------------------------- */
 997 /** translate help file into terminal encoding */
 998
 999 static void
1000 translate_file (char *filedata)
1001 {
1002     GIConv conv;
1003     GString *translated_data;
1004
1005     /* initial allocation for largest whole help file */
1006     translated_data = g_string_sized_new (32 * 1024);
1007
1008     conv = str_crt_conv_from ("UTF-8");
1009
1010     if (conv == INVALID_CONV)
1011         g_string_free (translated_data, TRUE);
1012     else
1013     {
1014         g_free (fdata);
1015
1016         if (str_convert (conv, filedata, translated_data) != ESTR_FAILURE)
1017             fdata = g_string_free (translated_data, FALSE);
1018         else
1019         {
1020             fdata = NULL;
1021             g_string_free (translated_data, TRUE);
1022         }
1023         str_close_conv (conv);
1024     }
1025 }
1026
1027 /* --------------------------------------------------------------------------------------------- */
1028
1029 static cb_ret_t
1030 md_callback (Widget * w, Widget * sender, widget_msg_t msg, int parm, void *data)
1031 {
1032     switch (msg)
1033     {
1034     case MSG_RESIZE:
1035         w->lines = help_lines;
1036         return MSG_HANDLED;
1037
1038     default:
1039         return widget_default_callback (w, sender, msg, parm, data);
1040     }
1041 }
1042
1043 /* --------------------------------------------------------------------------------------------- */
1044
1045 static Widget *
1046 mousedispatch_new (int y, int x, int yl, int xl)
1047 {
1048     Widget *w;
1049
1050     w = g_new (Widget, 1);
1051     init_widget (w, y, x, yl, xl, md_callback, help_event);
1052     return w;
1053 }
1054
1055 /* --------------------------------------------------------------------------------------------- */
1056 /*** public functions ****************************************************************************/
1057 /* --------------------------------------------------------------------------------------------- */
1058
1059 /* event callback */
1060 gboolean
1061 help_interactive_display (const gchar * event_group_name, const gchar * event_name,
1062                           gpointer init_data, gpointer data)
1063 {
1064     const dlg_colors_t help_colors = {
1065         HELP_NORMAL_COLOR,      /* common text color */
1066         0,                      /* unused in help */
1067         HELP_BOLD_COLOR,        /* bold text color */
1068         0,                      /* unused in help */
1069         HELP_TITLE_COLOR        /* title color */
1070     };
1071
1072     WButtonBar *help_bar;
1073     Widget *md;
1074     char *hlpfile = NULL;
1075     char *filedata;
1076     ev_help_t *event_data = (ev_help_t *) data;
1077
1078     (void) event_group_name;
1079     (void) event_name;
1080     (void) init_data;
1081
1082     if (event_data->filename != NULL)
1083         g_file_get_contents (event_data->filename, &filedata, NULL, NULL);
1084     else
1085         filedata = load_mc_home_file (mc_global.share_data_dir, MC_HELP, &hlpfile);
1086
1087     if (filedata == NULL)
1088         message (D_ERROR, MSG_ERROR, _("Cannot open file %s\n%s"),
1089                  event_data->filename ? event_data->filename : hlpfile, unix_error_string (errno));
1090
1091     g_free (hlpfile);
1092
1093     if (filedata == NULL)
1094         return TRUE;
1095
1096     translate_file (filedata);
1097
1098     g_free (filedata);
1099
1100     if (fdata == NULL)
1101         return TRUE;
1102
1103     if ((event_data->node == NULL) || (*event_data->node == '\0'))
1104         event_data->node = "[main]";
1105
1106     main_node = search_string (fdata, event_data->node);
1107
1108     if (main_node == NULL)
1109     {
1110         message (D_ERROR, MSG_ERROR, _("Cannot find node %s in help file"), event_data->node);
1111
1112         /* Fallback to [main], return if it also cannot be found */
1113         main_node = search_string (fdata, "[main]");
1114         if (main_node == NULL)
1115         {
1116             interactive_display_finish ();
1117             return TRUE;
1118         }
1119     }
1120
1121     help_lines = min (LINES - 4, max (2 * LINES / 3, 18));
1122
1123     whelp =
1124         create_dlg (TRUE, 0, 0, help_lines + 4, HELP_WINDOW_WIDTH + 4,
1125                     help_colors, help_callback, NULL, "[Help]", _("Help"),
1126                     DLG_TRYUP | DLG_CENTER | DLG_WANT_TAB);
1127
1128     selected_item = search_string_node (main_node, STRING_LINK_START) - 1;
1129     currentpoint = main_node + 1;       /* Skip the newline following the start of the node */
1130
1131     for (history_ptr = HISTORY_SIZE; history_ptr;)
1132     {
1133         history_ptr--;
1134         history[history_ptr].page = currentpoint;
1135         history[history_ptr].link = selected_item;
1136     }
1137
1138     help_bar = buttonbar_new (TRUE);
1139     WIDGET (help_bar)->y -= WIDGET (whelp)->y;
1140     WIDGET (help_bar)->x -= WIDGET (whelp)->x;
1141
1142     md = mousedispatch_new (1, 1, help_lines, HELP_WINDOW_WIDTH - 2);
1143
1144     add_widget (whelp, md);
1145     add_widget (whelp, help_bar);
1146
1147     buttonbar_set_label (help_bar, 1, Q_ ("ButtonBar|Help"), help_map, NULL);
1148     buttonbar_set_label (help_bar, 2, Q_ ("ButtonBar|Index"), help_map, NULL);
1149     buttonbar_set_label (help_bar, 3, Q_ ("ButtonBar|Prev"), help_map, NULL);
1150     buttonbar_set_label (help_bar, 4, "", help_map, NULL);
1151     buttonbar_set_label (help_bar, 5, "", help_map, NULL);
1152     buttonbar_set_label (help_bar, 6, "", help_map, NULL);
1153     buttonbar_set_label (help_bar, 7, "", help_map, NULL);
1154     buttonbar_set_label (help_bar, 8, "", help_map, NULL);
1155     buttonbar_set_label (help_bar, 9, "", help_map, NULL);
1156     buttonbar_set_label (help_bar, 10, Q_ ("ButtonBar|Quit"), help_map, NULL);
1157
1158     run_dlg (whelp);
1159     interactive_display_finish ();
1160     destroy_dlg (whelp);
1161     return TRUE;
1162 }
1163
1164 /* --------------------------------------------------------------------------------------------- */