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, 2013
   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 "help.h"
  71
  72 /*** global variables ****************************************************************************/
  73
  74 /*** file scope macro definitions ****************************************************************/
  75
  76 #define MAXLINKNAME 80
  77 #define HISTORY_SIZE 20
  78 #define HELP_WINDOW_WIDTH min(80, COLS - 16)
  79
  80 #define STRING_LINK_START       "\01"
  81 #define STRING_LINK_POINTER     "\02"
  82 #define STRING_LINK_END         "\03"
  83 #define STRING_NODE_END         "\04"
  84
  85 /*** file scope type declarations ****************************************************************/
  86
  87 /* Link areas for the mouse */
  88 typedef struct Link_Area
  89 {
  90     int x1, y1, x2, y2;
  91     const char *link_name;
  92 } Link_Area;
  93
  94 /*** file scope variables ************************************************************************/
  95
  96 static char *fdata = NULL;      /* Pointer to the loaded data file */
  97 static int help_lines;          /* Lines in help viewer */
  98 static int history_ptr;         /* For the history queue */
  99 static const char *main_node;   /* The main node */
 100 static const char *last_shown = NULL;   /* Last byte shown in a screen */
 101 static gboolean end_of_node = FALSE;    /* Flag: the last character of the node shown? */
 102 static const char *currentpoint;
 103 static const char *selected_item;
 104
 105 /* The widget variables */
 106 static WDialog *whelp;
 107
 108 static struct
 109 {
 110     const char *page;           /* Pointer to the selected page */
 111     const char *link;           /* Pointer to the selected link */
 112 } history[HISTORY_SIZE];
 113
 114 static GSList *link_area = NULL;
 115 static gboolean inside_link_area = FALSE;
 116
 117 static cb_ret_t help_callback (Widget * w, Widget * sender, widget_msg_t msg, int parm, void *data);
 118
 119 /*** file scope functions ************************************************************************/
 120 /* --------------------------------------------------------------------------------------------- */
 121
 122 /** returns the position where text was found in the start buffer
 123  * or 0 if not found
 124  */
 125 static const char *
 126 search_string (const char *start, const char *text)
 127 {
 128     const char *result = NULL;
 129     char *local_text = g_strdup (text);
 130     char *d = local_text;
 131     const char *e = start;
 132
 133     /* fmt sometimes replaces a space with a newline in the help file */
 134     /* Replace the newlines in the link name with spaces to correct the situation */
 135     while (*d != '\0')
 136     {
 137         if (*d == '\n')
 138             *d = ' ';
 139         str_next_char (&d);
 140     }
 141
 142     /* Do search */
 143     for (d = local_text; *e; e++)
 144     {
 145         if (*d == *e)
 146             d++;
 147         else
 148             d = local_text;
 149         if (*d == '\0')
 150         {
 151             result = e + 1;
 152             break;
 153         }
 154     }
 155
 156     g_free (local_text);
 157     return result;
 158 }
 159
 160 /* --------------------------------------------------------------------------------------------- */
 161 /** Searches text in the buffer pointed by start.  Search ends
 162  * if the CHAR_NODE_END is found in the text.
 163  * @return NULL on failure
 164  */
 165
 166 static const char *
 167 search_string_node (const char *start, const char *text)
 168 {
 169     const char *d = text;
 170     const char *e = start;
 171
 172     if (start != NULL)
 173         for (; *e && *e != CHAR_NODE_END; e++)
 174         {
 175             if (*d == *e)
 176                 d++;
 177             else
 178                 d = text;
 179             if (*d == '\0')
 180                 return e + 1;
 181         }
 182
 183     return NULL;
 184 }
 185
 186 /* --------------------------------------------------------------------------------------------- */
 187 /** Searches the_char in the buffer pointer by start and searches
 188  * it can search forward (direction = 1) or backward (direction = -1)
 189  */
 190
 191 static const char *
 192 search_char_node (const char *start, char the_char, int direction)
 193 {
 194     const char *e;
 195
 196     for (e = start; (*e != '\0') && (*e != CHAR_NODE_END); e += direction)
 197         if (*e == the_char)
 198             return e;
 199
 200     return NULL;
 201 }
 202
 203 /* --------------------------------------------------------------------------------------------- */
 204 /** Returns the new current pointer when moved lines lines */
 205
 206 static const char *
 207 move_forward2 (const char *c, int lines)
 208 {
 209     const char *p;
 210     int line;
 211
 212     currentpoint = c;
 213     for (line = 0, p = currentpoint; (*p != '\0') && (*p != CHAR_NODE_END); str_cnext_char (&p))
 214     {
 215         if (line == lines)
 216             return currentpoint = p;
 217
 218         if (*p == '\n')
 219             line++;
 220     }
 221     return currentpoint = c;
 222 }
 223
 224 /* --------------------------------------------------------------------------------------------- */
 225
 226 static const char *
 227 move_backward2 (const char *c, int lines)
 228 {
 229     const char *p;
 230     int line;
 231
 232     currentpoint = c;
 233     for (line = 0, p = currentpoint; (*p != '\0') && ((int) (p - fdata) >= 0); str_cprev_char (&p))
 234     {
 235         if (*p == CHAR_NODE_END)
 236         {
 237             /* We reached the beginning of the node */
 238             /* Skip the node headers */
 239             while (*p != ']')
 240                 str_cnext_char (&p);
 241             return currentpoint = p + 2;        /* Skip the newline following the start of the node */
 242         }
 243
 244         if (*(p - 1) == '\n')
 245             line++;
 246         if (line == lines)
 247             return currentpoint = p;
 248     }
 249     return currentpoint = c;
 250 }
 251
 252 /* --------------------------------------------------------------------------------------------- */
 253
 254 static void
 255 move_forward (int i)
 256 {
 257     if (!end_of_node)
 258         currentpoint = move_forward2 (currentpoint, i);
 259 }
 260
 261 /* --------------------------------------------------------------------------------------------- */
 262
 263 static void
 264 move_backward (int i)
 265 {
 266     currentpoint = move_backward2 (currentpoint, ++i);
 267 }
 268
 269 /* --------------------------------------------------------------------------------------------- */
 270
 271 static void
 272 move_to_top (void)
 273 {
 274     while (((int) (currentpoint > fdata) > 0) && (*currentpoint != CHAR_NODE_END))
 275         currentpoint--;
 276
 277     while (*currentpoint != ']')
 278         currentpoint++;
 279     currentpoint = currentpoint + 2;    /* Skip the newline following the start of the node */
 280     selected_item = NULL;
 281 }
 282
 283 /* --------------------------------------------------------------------------------------------- */
 284
 285 static void
 286 move_to_bottom (void)
 287 {
 288     while ((*currentpoint != '\0') && (*currentpoint != CHAR_NODE_END))
 289         currentpoint++;
 290     currentpoint--;
 291     move_backward (1);
 292 }
 293
 294 /* --------------------------------------------------------------------------------------------- */
 295
 296 static const char *
 297 help_follow_link (const char *start, const char *lc_selected_item)
 298 {
 299     char link_name[MAXLINKNAME];
 300     const char *p;
 301     int i = 0;
 302
 303     if (lc_selected_item == NULL)
 304         return start;
 305
 306     for (p = lc_selected_item; *p && *p != CHAR_NODE_END && *p != CHAR_LINK_POINTER; p++)
 307         ;
 308     if (*p == CHAR_LINK_POINTER)
 309     {
 310         link_name[0] = '[';
 311         for (i = 1; *p != CHAR_LINK_END && *p && *p != CHAR_NODE_END && i < MAXLINKNAME - 3;)
 312             link_name[i++] = *++p;
 313         link_name[i - 1] = ']';
 314         link_name[i] = '\0';
 315         p = search_string (fdata, link_name);
 316         if (p != NULL)
 317         {
 318             p += 1;             /* Skip the newline following the start of the node */
 319             return p;
 320         }
 321     }
 322
 323     /* Create a replacement page with the error message */
 324     return _("Help file format error\n");
 325 }
 326
 327 /* --------------------------------------------------------------------------------------------- */
 328
 329 static const char *
 330 select_next_link (const char *current_link)
 331 {
 332     const char *p;
 333
 334     if (current_link == NULL)
 335         return NULL;
 336
 337     p = search_string_node (current_link, STRING_LINK_END);
 338     if (p == NULL)
 339         return NULL;
 340     p = search_string_node (p, STRING_LINK_START);
 341     if (p == NULL)
 342         return NULL;
 343     return p - 1;
 344 }
 345
 346 /* --------------------------------------------------------------------------------------------- */
 347
 348 static const char *
 349 select_prev_link (const char *current_link)
 350 {
 351     return current_link == NULL ? NULL : search_char_node (current_link - 1, CHAR_LINK_START, -1);
 352 }
 353
 354 /* --------------------------------------------------------------------------------------------- */
 355
 356 static void
 357 start_link_area (int x, int y, const char *link_name)
 358 {
 359     Link_Area *la;
 360
 361     if (inside_link_area)
 362         message (D_NORMAL, _("Warning"), _("Internal bug: Double start of link area"));
 363
 364     /* Allocate memory for a new link area */
 365     la = g_new (Link_Area, 1);
 366     /* Save the beginning coordinates of the link area */
 367     la->x1 = x;
 368     la->y1 = y;
 369     /* Save the name of the destination anchor */
 370     la->link_name = link_name;
 371     link_area = g_slist_prepend (link_area, la);
 372
 373     inside_link_area = TRUE;
 374 }
 375
 376 /* --------------------------------------------------------------------------------------------- */
 377
 378 static void
 379 end_link_area (int x, int y)
 380 {
 381     if (inside_link_area)
 382     {
 383         Link_Area *la = (Link_Area *) link_area->data;
 384         /* Save the end coordinates of the link area */
 385         la->x2 = x;
 386         la->y2 = y;
 387         inside_link_area = FALSE;
 388     }
 389 }
 390
 391 /* --------------------------------------------------------------------------------------------- */
 392
 393 static void
 394 clear_link_areas (void)
 395 {
 396     g_slist_foreach (link_area, (GFunc) g_free, NULL);
 397     g_slist_free (link_area);
 398     link_area = NULL;
 399     inside_link_area = FALSE;
 400 }
 401
 402 /* --------------------------------------------------------------------------------------------- */
 403
 404 static void
 405 help_print_word (WDialog * h, GString * word, int *col, int *line, gboolean add_space)
 406 {
 407     if (*line >= help_lines)
 408         g_string_set_size (word, 0);
 409     else
 410     {
 411         int w;
 412
 413         w = str_term_width1 (word->str);
 414         if (*col + w >= HELP_WINDOW_WIDTH)
 415         {
 416             *col = 0;
 417             (*line)++;
 418         }
 419
 420         if (*line >= help_lines)
 421             g_string_set_size (word, 0);
 422         else
 423         {
 424             widget_move (h, *line + 2, *col + 2);
 425             tty_print_string (word->str);
 426             g_string_set_size (word, 0);
 427             *col += w;
 428         }
 429     }
 430
 431     if (add_space)
 432     {
 433         if (*col < HELP_WINDOW_WIDTH - 1)
 434         {
 435             tty_print_char (' ');
 436             (*col)++;
 437         }
 438         else
 439         {
 440             *col = 0;
 441             (*line)++;
 442         }
 443     }
 444 }
 445
 446 /* --------------------------------------------------------------------------------------------- */
 447
 448 static void
 449 help_show (WDialog * h, const char *paint_start)
 450 {
 451     const char *p, *n;
 452     int col, line, c;
 453     gboolean painting = TRUE;
 454     gboolean acs;               /* Flag: Alternate character set active? */
 455     gboolean repeat_paint;
 456     int active_col, active_line;        /* Active link position */
 457     char buff[MB_LEN_MAX + 1];
 458     GString *word;
 459
 460     word = g_string_sized_new (32);
 461
 462     tty_setcolor (HELP_NORMAL_COLOR);
 463     do
 464     {
 465         line = col = active_col = active_line = 0;
 466         repeat_paint = FALSE;
 467         acs = FALSE;
 468
 469         clear_link_areas ();
 470         if ((int) (selected_item - paint_start) < 0)
 471             selected_item = NULL;
 472
 473         p = paint_start;
 474         n = paint_start;
 475         while ((n[0] != '\0') && (n[0] != CHAR_NODE_END) && (line < help_lines))
 476         {
 477             p = n;
 478             n = str_cget_next_char (p);
 479             memcpy (buff, p, n - p);
 480             buff[n - p] = '\0';
 481
 482             c = (unsigned char) buff[0];
 483             switch (c)
 484             {
 485             case CHAR_LINK_START:
 486                 if (selected_item == NULL)
 487                     selected_item = p;
 488                 if (p != selected_item)
 489                     tty_setcolor (HELP_LINK_COLOR);
 490                 else
 491                 {
 492                     tty_setcolor (HELP_SLINK_COLOR);
 493
 494                     /* Store the coordinates of the link */
 495                     active_col = col + 2;
 496                     active_line = line + 2;
 497                 }
 498                 start_link_area (col, line, p);
 499                 break;
 500             case CHAR_LINK_POINTER:
 501                 painting = FALSE;
 502                 break;
 503             case CHAR_LINK_END:
 504                 painting = TRUE;
 505                 help_print_word (h, word, &col, &line, FALSE);
 506                 end_link_area (col - 1, line);
 507                 tty_setcolor (HELP_NORMAL_COLOR);
 508                 break;
 509             case CHAR_ALTERNATE:
 510                 acs = TRUE;
 511                 break;
 512             case CHAR_NORMAL:
 513                 acs = FALSE;
 514                 break;
 515             case CHAR_VERSION:
 516                 widget_move (h, line + 2, col + 2);
 517                 tty_print_string (VERSION);
 518                 col += str_term_width1 (VERSION);
 519                 break;
 520             case CHAR_FONT_BOLD:
 521                 tty_setcolor (HELP_BOLD_COLOR);
 522                 break;
 523             case CHAR_FONT_ITALIC:
 524                 tty_setcolor (HELP_ITALIC_COLOR);
 525                 break;
 526             case CHAR_FONT_NORMAL:
 527                 help_print_word (h, word, &col, &line, FALSE);
 528                 tty_setcolor (HELP_NORMAL_COLOR);
 529                 break;
 530             case '\n':
 531                 if (painting)
 532                     help_print_word (h, word, &col, &line, FALSE);
 533                 line++;
 534                 col = 0;
 535                 break;
 536             case '\t':
 537                 col = (col / 8 + 1) * 8;
 538                 if (col >= HELP_WINDOW_WIDTH)
 539                 {
 540                     line++;
 541                     col = 8;
 542                 }
 543                 break;
 544             case ' ':
 545                 /* word delimeter */
 546                 if (painting)
 547                     help_print_word (h, word, &col, &line, TRUE);
 548                 break;
 549             default:
 550                 if (painting && (line < help_lines))
 551                 {
 552                     if (!acs)
 553                         /* accumulate symbols in a word */
 554                         g_string_append (word, buff);
 555                     else if (col < HELP_WINDOW_WIDTH)
 556                     {
 557                         widget_move (h, line + 2, col + 2);
 558
 559                         if ((c == ' ') || (c == '.'))
 560                             tty_print_char (c);
 561                         else
 562 #ifndef HAVE_SLANG
 563                             tty_print_char (acs_map[c]);
 564 #else
 565                             SLsmg_draw_object (WIDGET (h)->y + line + 2, WIDGET (h)->x + col + 2,
 566                                                c);
 567 #endif
 568                         col++;
 569                     }
 570                 }
 571             }
 572         }
 573
 574         /* print last word */
 575         if (n[0] == CHAR_NODE_END)
 576             help_print_word (h, word, &col, &line, FALSE);
 577
 578         last_shown = p;
 579         end_of_node = line < help_lines;
 580         tty_setcolor (HELP_NORMAL_COLOR);
 581         if ((int) (selected_item - last_shown) >= 0)
 582         {
 583             if ((link_area == NULL) || (link_area->data == NULL))
 584                 selected_item = NULL;
 585             else
 586             {
 587                 selected_item = ((Link_Area *) link_area->data)->link_name;
 588                 repeat_paint = TRUE;
 589             }
 590         }
 591     }
 592     while (repeat_paint);
 593
 594     g_string_free (word, TRUE);
 595
 596     /* Position the cursor over a nice link */
 597     if (active_col)
 598         widget_move (h, active_line, active_col);
 599 }
 600
 601 /* --------------------------------------------------------------------------------------------- */
 602
 603 static int
 604 help_event (Gpm_Event * event, void *vp)
 605 {
 606     Widget *w = WIDGET (vp);
 607     GSList *current_area;
 608     Gpm_Event local;
 609
 610     if (!mouse_global_in_widget (event, w))
 611         return MOU_UNHANDLED;
 612
 613     if ((event->type & GPM_UP) == 0)
 614         return MOU_NORMAL;
 615
 616     local = mouse_get_local (event, w);
 617
 618     /* The event is relative to the dialog window, adjust it: */
 619     local.x -= 2;
 620     local.y -= 2;
 621
 622     if ((local.buttons & GPM_B_RIGHT) != 0)
 623     {
 624         currentpoint = history[history_ptr].page;
 625         selected_item = history[history_ptr].link;
 626         history_ptr--;
 627         if (history_ptr < 0)
 628             history_ptr = HISTORY_SIZE - 1;
 629
 630         send_message (w->owner, NULL, MSG_DRAW, 0, NULL);
 631         return MOU_NORMAL;
 632     }
 633
 634     /* Test whether the mouse click is inside one of the link areas */
 635     for (current_area = link_area; current_area != NULL; current_area = g_slist_next (current_area))
 636     {
 637         Link_Area *la = (Link_Area *) current_area->data;
 638
 639         /* Test one line link area */
 640         if (local.y == la->y1 && local.x >= la->x1 && local.y == la->y2 && local.x <= la->x2)
 641             break;
 642
 643         /* Test two line link area */
 644         if (la->y1 + 1 == la->y2)
 645         {
 646             /* The first line */
 647             if (local.y == la->y1 && local.x >= la->x1)
 648                 break;
 649             /* The second line */
 650             if (local.y == la->y2 && local.x <= la->x2)
 651                 break;
 652         }
 653         /* Mouse will not work with link areas of more than two lines */
 654     }
 655
 656     /* Test whether a link area was found */
 657     if (current_area != NULL)
 658     {
 659         Link_Area *la = (Link_Area *) current_area->data;
 660
 661         /* The click was inside a link area -> follow the link */
 662         history_ptr = (history_ptr + 1) % HISTORY_SIZE;
 663         history[history_ptr].page = currentpoint;
 664         history[history_ptr].link = la->link_name;
 665         currentpoint = help_follow_link (currentpoint, la->link_name);
 666         selected_item = NULL;
 667     }
 668     else if (local.y < 0)
 669         move_backward (help_lines - 1);
 670     else if (local.y >= help_lines)
 671         move_forward (help_lines - 1);
 672     else if (local.y < help_lines / 2)
 673         move_backward (1);
 674     else
 675         move_forward (1);
 676
 677     /* Show the new node */
 678     send_message (w->owner, NULL, MSG_DRAW, 0, NULL);
 679
 680     return MOU_NORMAL;
 681 }
 682
 683 /* --------------------------------------------------------------------------------------------- */
 684 /** show help */
 685
 686 static void
 687 help_help (WDialog * h)
 688 {
 689     const char *p;
 690
 691     history_ptr = (history_ptr + 1) % HISTORY_SIZE;
 692     history[history_ptr].page = currentpoint;
 693     history[history_ptr].link = selected_item;
 694
 695     p = search_string (fdata, "[How to use help]");
 696     if (p != NULL)
 697     {
 698         currentpoint = p + 1;   /* Skip the newline following the start of the node */
 699         selected_item = NULL;
 700         send_message (h, NULL, MSG_DRAW, 0, NULL);
 701     }
 702 }
 703
 704 /* --------------------------------------------------------------------------------------------- */
 705
 706 static void
 707 help_index (WDialog * h)
 708 {
 709     const char *new_item;
 710
 711     new_item = search_string (fdata, "[Contents]");
 712
 713     if (new_item == NULL)
 714         message (D_ERROR, MSG_ERROR, _("Cannot find node %s in help file"), "[Contents]");
 715     else
 716     {
 717         history_ptr = (history_ptr + 1) % HISTORY_SIZE;
 718         history[history_ptr].page = currentpoint;
 719         history[history_ptr].link = selected_item;
 720
 721         currentpoint = new_item + 1;    /* Skip the newline following the start of the node */
 722         selected_item = NULL;
 723         send_message (h, NULL, MSG_DRAW, 0, NULL);
 724     }
 725 }
 726
 727 /* --------------------------------------------------------------------------------------------- */
 728
 729 static void
 730 help_back (WDialog * h)
 731 {
 732     currentpoint = history[history_ptr].page;
 733     selected_item = history[history_ptr].link;
 734     history_ptr--;
 735     if (history_ptr < 0)
 736         history_ptr = HISTORY_SIZE - 1;
 737
 738     send_message (h, NULL, MSG_DRAW, 0, NULL);  /* FIXME: unneeded? */
 739 }
 740
 741 /* --------------------------------------------------------------------------------------------- */
 742
 743 static void
 744 help_next_link (gboolean move_down)
 745 {
 746     const char *new_item;
 747
 748     new_item = select_next_link (selected_item);
 749     if (new_item != NULL)
 750     {
 751         selected_item = new_item;
 752         if ((int) (selected_item - last_shown) >= 0)
 753         {
 754             if (move_down)
 755                 move_forward (1);
 756             else
 757                 selected_item = NULL;
 758         }
 759     }
 760     else if (move_down)
 761         move_forward (1);
 762     else
 763         selected_item = NULL;
 764 }
 765
 766 /* --------------------------------------------------------------------------------------------- */
 767
 768 static void
 769 help_prev_link (gboolean move_up)
 770 {
 771     const char *new_item;
 772
 773     new_item = select_prev_link (selected_item);
 774     selected_item = new_item;
 775     if ((selected_item == NULL) || (selected_item < currentpoint))
 776     {
 777         if (move_up)
 778             move_backward (1);
 779         else if ((link_area != NULL) && (link_area->data != NULL))
 780             selected_item = ((Link_Area *) link_area->data)->link_name;
 781         else
 782             selected_item = NULL;
 783     }
 784 }
 785
 786 /* --------------------------------------------------------------------------------------------- */
 787
 788 static void
 789 help_next_node (void)
 790 {
 791     const char *new_item;
 792
 793     new_item = currentpoint;
 794     while ((*new_item != '\0') && (*new_item != CHAR_NODE_END))
 795         new_item++;
 796
 797     if (*++new_item == '[')
 798         while (*++new_item != '\0')
 799             if ((*new_item == ']') && (*++new_item != '\0') && (*++new_item != '\0'))
 800             {
 801                 currentpoint = new_item;
 802                 selected_item = NULL;
 803                 break;
 804             }
 805 }
 806
 807 /* --------------------------------------------------------------------------------------------- */
 808
 809 static void
 810 help_prev_node (void)
 811 {
 812     const char *new_item;
 813
 814     new_item = currentpoint;
 815     while (((int) (new_item - fdata) > 1) && (*new_item != CHAR_NODE_END))
 816         new_item--;
 817     new_item--;
 818     while (((int) (new_item - fdata) > 0) && (*new_item != CHAR_NODE_END))
 819         new_item--;
 820     while (*new_item != ']')
 821         new_item++;
 822     currentpoint = new_item + 2;
 823     selected_item = NULL;
 824 }
 825
 826 /* --------------------------------------------------------------------------------------------- */
 827
 828 static void
 829 help_select_link (void)
 830 {
 831     /* follow link */
 832     if (selected_item == NULL)
 833     {
 834 #ifdef WE_WANT_TO_GO_BACKWARD_ON_KEY_RIGHT
 835         /* Is there any reason why the right key would take us
 836          * backward if there are no links selected?, I agree
 837          * with Torben than doing nothing in this case is better
 838          */
 839         /* If there are no links, go backward in history */
 840         history_ptr--;
 841         if (history_ptr < 0)
 842             history_ptr = HISTORY_SIZE - 1;
 843
 844         currentpoint = history[history_ptr].page;
 845         selected_item = history[history_ptr].link;
 846 #endif
 847     }
 848     else
 849     {
 850         history_ptr = (history_ptr + 1) % HISTORY_SIZE;
 851         history[history_ptr].page = currentpoint;
 852         history[history_ptr].link = selected_item;
 853         currentpoint = help_follow_link (currentpoint, selected_item);
 854     }
 855
 856     selected_item = NULL;
 857 }
 858
 859 /* --------------------------------------------------------------------------------------------- */
 860
 861 static cb_ret_t
 862 help_execute_cmd (unsigned long command)
 863 {
 864     cb_ret_t ret = MSG_HANDLED;
 865
 866     switch (command)
 867     {
 868     case CK_Help:
 869         help_help (whelp);
 870         break;
 871     case CK_Index:
 872         help_index (whelp);
 873         break;
 874     case CK_Back:
 875         help_back (whelp);
 876         break;
 877     case CK_Up:
 878         help_prev_link (TRUE);
 879         break;
 880     case CK_Down:
 881         help_next_link (TRUE);
 882         break;
 883     case CK_PageDown:
 884         move_forward (help_lines - 1);
 885         break;
 886     case CK_PageUp:
 887         move_backward (help_lines - 1);
 888         break;
 889     case CK_HalfPageDown:
 890         move_forward (help_lines / 2);
 891         break;
 892     case CK_HalfPageUp:
 893         move_backward (help_lines / 2);
 894         break;
 895     case CK_Top:
 896         move_to_top ();
 897         break;
 898     case CK_Bottom:
 899         move_to_bottom ();
 900         break;
 901     case CK_Enter:
 902         help_select_link ();
 903         break;
 904     case CK_LinkNext:
 905         help_next_link (FALSE);
 906         break;
 907     case CK_LinkPrev:
 908         help_prev_link (FALSE);
 909         break;
 910     case CK_NodeNext:
 911         help_next_node ();
 912         break;
 913     case CK_NodePrev:
 914         help_prev_node ();
 915         break;
 916     case CK_Quit:
 917         dlg_stop (whelp);
 918         break;
 919     default:
 920         ret = MSG_NOT_HANDLED;
 921     }
 922
 923     return ret;
 924 }
 925
 926 /* --------------------------------------------------------------------------------------------- */
 927
 928 static cb_ret_t
 929 help_handle_key (WDialog * h, int c)
 930 {
 931     unsigned long command;
 932
 933     command = keybind_lookup_keymap_command (help_map, c);
 934     if ((command == CK_IgnoreKey) || (help_execute_cmd (command) == MSG_NOT_HANDLED))
 935         return MSG_NOT_HANDLED;
 936
 937     send_message (h, NULL, MSG_DRAW, 0, NULL);
 938     return MSG_HANDLED;
 939 }
 940
 941 /* --------------------------------------------------------------------------------------------- */
 942
 943 static cb_ret_t
 944 help_callback (Widget * w, Widget * sender, widget_msg_t msg, int parm, void *data)
 945 {
 946     WDialog *h = DIALOG (w);
 947
 948     switch (msg)
 949     {
 950     case MSG_RESIZE:
 951         {
 952             WButtonBar *bb;
 953
 954             help_lines = min (LINES - 4, max (2 * LINES / 3, 18));
 955             dlg_set_size (h, help_lines + 4, HELP_WINDOW_WIDTH + 4);
 956             bb = find_buttonbar (h);
 957             widget_set_size (WIDGET (bb), LINES - 1, 0, 1, COLS);
 958             return MSG_HANDLED;
 959         }
 960
 961     case MSG_DRAW:
 962         dlg_default_repaint (h);
 963         help_show (h, currentpoint);
 964         return MSG_HANDLED;
 965
 966     case MSG_KEY:
 967         return help_handle_key (h, parm);
 968
 969     case MSG_ACTION:
 970         /* shortcut */
 971         if (sender == NULL)
 972             return help_execute_cmd (parm);
 973         /* message from buttonbar */
 974         if (sender == WIDGET (find_buttonbar (h)))
 975         {
 976             if (data != NULL)
 977                 return send_message (data, NULL, MSG_ACTION, parm, NULL);
 978             return help_execute_cmd (parm);
 979         }
 980         return MSG_NOT_HANDLED;
 981
 982     default:
 983         return dlg_default_callback (w, sender, msg, parm, data);
 984     }
 985 }
 986
 987 /* --------------------------------------------------------------------------------------------- */
 988
 989 static void
 990 interactive_display_finish (void)
 991 {
 992     clear_link_areas ();
 993 }
 994
 995 /* --------------------------------------------------------------------------------------------- */
 996 /** translate help file into terminal encoding */
 997
 998 static void
 999 translate_file (char *filedata)
1000 {
1001     GIConv conv;
1002     GString *translated_data;
1003
1004     /* initial allocation for largest whole help file */
1005     translated_data = g_string_sized_new (32 * 1024);
1006
1007     conv = str_crt_conv_from ("UTF-8");
1008
1009     if (conv == INVALID_CONV)
1010         g_string_free (translated_data, TRUE);
1011     else
1012     {
1013         g_free (fdata);
1014
1015         if (str_convert (conv, filedata, translated_data) != ESTR_FAILURE)
1016             fdata = g_string_free (translated_data, FALSE);
1017         else
1018         {
1019             fdata = NULL;
1020             g_string_free (translated_data, TRUE);
1021         }
1022         str_close_conv (conv);
1023     }
1024 }
1025
1026 /* --------------------------------------------------------------------------------------------- */
1027
1028 static cb_ret_t
1029 md_callback (Widget * w, Widget * sender, widget_msg_t msg, int parm, void *data)
1030 {
1031     switch (msg)
1032     {
1033     case MSG_RESIZE:
1034         w->lines = help_lines;
1035         return MSG_HANDLED;
1036
1037     default:
1038         return widget_default_callback (w, sender, msg, parm, data);
1039     }
1040 }
1041
1042 /* --------------------------------------------------------------------------------------------- */
1043
1044 static Widget *
1045 mousedispatch_new (int y, int x, int yl, int xl)
1046 {
1047     Widget *w;
1048
1049     w = g_new (Widget, 1);
1050     widget_init (w, y, x, yl, xl, md_callback, help_event);
1051     return w;
1052 }
1053
1054 /* --------------------------------------------------------------------------------------------- */
1055 /*** public functions ****************************************************************************/
1056 /* --------------------------------------------------------------------------------------------- */
1057
1058 /* event callback */
1059 gboolean
1060 help_interactive_display (const gchar * event_group_name, const gchar * event_name,
1061                           gpointer init_data, gpointer data)
1062 {
1063     const dlg_colors_t help_colors = {
1064         HELP_NORMAL_COLOR,      /* common text color */
1065         0,                      /* unused in help */
1066         HELP_BOLD_COLOR,        /* bold text color */
1067         0,                      /* unused in help */
1068         HELP_TITLE_COLOR        /* title color */
1069     };
1070
1071     WButtonBar *help_bar;
1072     Widget *md;
1073     char *hlpfile = NULL;
1074     char *filedata;
1075     ev_help_t *event_data = (ev_help_t *) data;
1076
1077     (void) event_group_name;
1078     (void) event_name;
1079     (void) init_data;
1080
1081     if (event_data->filename != NULL)
1082         g_file_get_contents (event_data->filename, &filedata, NULL, NULL);
1083     else
1084         filedata = load_mc_home_file (mc_global.share_data_dir, MC_HELP, &hlpfile);
1085
1086     if (filedata == NULL)
1087         message (D_ERROR, MSG_ERROR, _("Cannot open file %s\n%s"),
1088                  event_data->filename ? event_data->filename : hlpfile, unix_error_string (errno));
1089
1090     g_free (hlpfile);
1091
1092     if (filedata == NULL)
1093         return TRUE;
1094
1095     translate_file (filedata);
1096
1097     g_free (filedata);
1098
1099     if (fdata == NULL)
1100         return TRUE;
1101
1102     if ((event_data->node == NULL) || (*event_data->node == '\0'))
1103         event_data->node = "[main]";
1104
1105     main_node = search_string (fdata, event_data->node);
1106
1107     if (main_node == NULL)
1108     {
1109         message (D_ERROR, MSG_ERROR, _("Cannot find node %s in help file"), event_data->node);
1110
1111         /* Fallback to [main], return if it also cannot be found */
1112         main_node = search_string (fdata, "[main]");
1113         if (main_node == NULL)
1114         {
1115             interactive_display_finish ();
1116             return TRUE;
1117         }
1118     }
1119
1120     help_lines = min (LINES - 4, max (2 * LINES / 3, 18));
1121
1122     whelp =
1123         dlg_create (TRUE, 0, 0, help_lines + 4, HELP_WINDOW_WIDTH + 4,
1124                     help_colors, help_callback, NULL, "[Help]", _("Help"),
1125                     DLG_TRYUP | DLG_CENTER | DLG_WANT_TAB);
1126
1127     selected_item = search_string_node (main_node, STRING_LINK_START) - 1;
1128     currentpoint = main_node + 1;       /* Skip the newline following the start of the node */
1129
1130     for (history_ptr = HISTORY_SIZE; history_ptr;)
1131     {
1132         history_ptr--;
1133         history[history_ptr].page = currentpoint;
1134         history[history_ptr].link = selected_item;
1135     }
1136
1137     help_bar = buttonbar_new (TRUE);
1138     WIDGET (help_bar)->y -= WIDGET (whelp)->y;
1139     WIDGET (help_bar)->x -= WIDGET (whelp)->x;
1140
1141     md = mousedispatch_new (1, 1, help_lines, HELP_WINDOW_WIDTH - 2);
1142
1143     add_widget (whelp, md);
1144     add_widget (whelp, help_bar);
1145
1146     buttonbar_set_label (help_bar, 1, Q_ ("ButtonBar|Help"), help_map, NULL);
1147     buttonbar_set_label (help_bar, 2, Q_ ("ButtonBar|Index"), help_map, NULL);
1148     buttonbar_set_label (help_bar, 3, Q_ ("ButtonBar|Prev"), help_map, NULL);
1149     buttonbar_set_label (help_bar, 4, "", help_map, NULL);
1150     buttonbar_set_label (help_bar, 5, "", help_map, NULL);
1151     buttonbar_set_label (help_bar, 6, "", help_map, NULL);
1152     buttonbar_set_label (help_bar, 7, "", help_map, NULL);
1153     buttonbar_set_label (help_bar, 8, "", help_map, NULL);
1154     buttonbar_set_label (help_bar, 9, "", help_map, NULL);
1155     buttonbar_set_label (help_bar, 10, Q_ ("ButtonBar|Quit"), help_map, NULL);
1156
1157     dlg_run (whelp);
1158     interactive_display_finish ();
1159     dlg_destroy (whelp);
1160     return TRUE;
1161 }
1162
1163 /* --------------------------------------------------------------------------------------------- */