ncurses/lib_scroll.c

   1
   2 /***************************************************************************
   3 *                            COPYRIGHT NOTICE                              *
   4 ****************************************************************************
   5 *                ncurses is copyright (C) 1992-1995                        *
   6 *                          Zeyd M. Ben-Halim                               *
   7 *                          zmbenhal@netcom.com                             *
   8 *                          Eric S. Raymond                                 *
   9 *                          esr@snark.thyrsus.com                           *
  10 *                                                                          *
  11 *        Permission is hereby granted to reproduce and distribute ncurses  *
  12 *        by any means and for any fee, whether alone or as part of a       *
  13 *        larger distribution, in source or in binary form, PROVIDED        *
  14 *        this notice is included with any such distribution, and is not    *
  15 *        removed from any of its header files. Mention of ncurses in any   *
  16 *        applications linked with it is highly appreciated.                *
  17 *                                                                          *
  18 *        ncurses comes AS IS with no warranty, implied or expressed.       *
  19 *                                                                          *
  20 ***************************************************************************/
  21
  22
  23
  24 /*
  25 **      lib_scroll.c
  26 **
  27 **      The routine wscrl(win, n).
  28 **  positive n scroll the window up (ie. move lines down)
  29 **  negative n scroll the window down (ie. move lines up)
  30 **
  31 */
  32
  33 #include <curses.priv.h>
  34
  35 MODULE_ID("$Id: lib_scroll.c,v 1.11 1997/02/01 23:22:54 tom Exp $")
  36
  37 void _nc_scroll_window(WINDOW *win, int const n, short const top, short const bottom)
  38 {
  39 int     line, j;
  40 chtype  blank = _nc_background(win);
  41 size_t  to_copy = (size_t)(sizeof(chtype) * (win->_maxx + 1));
  42
  43         TR(TRACE_MOVE, ("_nc_scroll_window(%p, %d, %d, %d)", win, n, top,bottom));
  44
  45         /*
  46          * This used to do a line-text pointer-shuffle instead of text copies.
  47          * That (a) doesn't work when the window is derived and doesn't have
  48          * its own storage, (b) doesn't save you a lot on modern machines
  49          * anyway.  Your typical memcpy implementations are coded in
  50          * assembler using a tight BLT loop; for the size of copies we're
  51          * talking here, the total execution time is dominated by the one-time
  52          * setup cost.  So there is no point in trying to be excessively
  53          * clever -- esr.
  54          */
  55
  56         /* shift n lines downwards */
  57         if (n < 0) {
  58                 for (line = bottom; line >= top-n; line--) {
  59                         memcpy(win->_line[line].text,
  60                                win->_line[line+n].text,
  61                                to_copy);
  62                         win->_line[line].oldindex = win->_line[line+n].oldindex;
  63                 }
  64                 for (line = top; line < top-n; line++) {
  65                         for (j = 0; j <= win->_maxx; j ++)
  66                                 win->_line[line].text[j] = blank;
  67                         win->_line[line].oldindex = _NEWINDEX;
  68                         win->_line[line].firstchar = 0;
  69                         win->_line[line].lastchar = win->_maxx;
  70                 }
  71         }
  72
  73         /* shift n lines upwards */
  74         if (n > 0) {
  75                 for (line = top; line <= bottom-n; line++) {
  76                         memcpy(win->_line[line].text,
  77                                win->_line[line+n].text,
  78                                to_copy);
  79                         win->_line[line].oldindex = win->_line[line+n].oldindex;
  80                 }
  81                 for (line = bottom; line > bottom-n; line--) {
  82                         for (j = 0; j <= win->_maxx; j ++)
  83                                 win->_line[line].text[j] = blank;
  84                         win->_line[line].oldindex = _NEWINDEX;
  85                         win->_line[line].firstchar = 0;
  86                         win->_line[line].lastchar = win->_maxx;
  87                 }
  88         }
  89 }
  90
  91 int
  92 wscrl(WINDOW *win, int n)
  93 {
  94         T((T_CALLED("wscrl(%p,%d)"), win, n));
  95
  96         if (! win->_scroll)
  97                 returnCode(ERR);
  98
  99         if (n == 0)
 100                 returnCode(OK);
 101
 102         if ((n > (win->_regbottom - win->_regtop)) ||
 103             (-n > (win->_regbottom - win->_regtop)))
 104             returnCode(ERR);
 105
 106         _nc_scroll_window(win, n, win->_regtop, win->_regbottom);
 107         touchline(win, win->_regtop, (int)(win->_regbottom - win->_regtop + 1));
 108
 109         _nc_synchook(win);
 110         returnCode(OK);
 111 }