Recipe 15.21 Program: Small termcap Program

15.21.1 Description

This program clears your screen and scribbles all over it until you interrupt it. It shows how to use Term::Cap to clear the screen, move the cursor, and write anywhere on the screen. It also uses Recipe 16.6.

The program text is shown in Example 15-8.

Example 15-8. tcapdemo

  #!/usr/bin/perl -w   # tcapdemo - show off direct cursor placement      use POSIX;   use Term::Cap;          init( );                     # Initialize Term::Cap.   zip( );                      # Bounce lines around the screen.   finish( );                   # Clean up afterward.   exit( );      # Two convenience functions.  clear_screen is obvious, and   # clear_end clears to the end of the screen.   sub clear_screen { $tcap->Tputs('cl', 1, *STDOUT) }    sub clear_end    { $tcap->Tputs('cd', 1, *STDOUT) }       # Move the cursor to a particular location.   sub gotoxy {       my($x, $y) = @_;       $tcap->Tgoto('cm', $x, $y, *STDOUT);   }       # Get the terminal speed through the POSIX module and use that   # to initialize Term::Cap.   sub init {        $| = 1;       $delay = (shift( ) || 0) * 0.005;       my $termios = POSIX::Termios->new( );       $termios->getattr;       my $ospeed = $termios->getospeed;       $tcap = Term::Cap->Tgetent ({ TERM => undef, OSPEED => $ospeed });       $tcap->Trequire(qw(cl cm cd));   }      # Bounce lines around the screen until the user interrupts with   # Ctrl-C.   sub zip {        clear_screen( );       ($maxrow, $maxcol) = ($tcap->{_li} - 1, $tcap->{_co} - 1);          @chars = qw(* - / | \ _ );       sub circle { push(@chars, shift @chars); }          $interrupted = 0;       $SIG{INT} = sub { ++$interrupted };          $col = $row = 0;       ($row_sign, $col_sign) = (1,1);          do {           gotoxy($col, $row);           print $chars[0];           select(undef, undef, undef, $delay);              $row += $row_sign;           $col += $col_sign;              if    ($row =  = $maxrow) { $row_sign = -1; circle; }            elsif ($row =  = 0 )      { $row_sign = +1; circle; }              if    ($col =  = $maxcol) { $col_sign = -1; circle; }            elsif ($col =  = 0 )      { $col_sign = +1; circle; }              } until $interrupted;      }      # Clean up the screen.   sub finish {        gotoxy(0, $maxrow);       clear_end( );   }

This is what it looks like in mid-run:

*     _                       /     |                       \     -  *   _ \                     - /   | /                     | \   - *   * _   \                   -   / |   /                   |   \ -   *    *     \                 -     |     /                 |     -     *   _ *     \               -     | /     /               |     - \     *  _   *     \             -     |   /     /             |     -   \     * *     *     \           -     |     /     /           |     -     \     *  *     *     \         -     |       /     /         |     -       \     *   *     *     \       -     |         /     /       |     -         \     *    *     *     \     -     |           /     /     |     -           \     *     *     *     \   -     |             /     /   |     -             \     *      *     *     \ -     |               /     / |     -               \            *     -     \     |                 /     /     -                 \            *   - *   - \   |                   /   | /   -                   \            * -   * -   \ |                     / |   / -                     \ _          -     -     \                       |     /                       _

15.21.2 See Also

termcap(5) (if you have it); the documentation for the standard Term::Cap module