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Term::VT102.3pm

NAME

Term::VT102 - a class to emulate a DEC VT102 terminal

SYNOPSIS

   use Term::VT102;
 
 

   my $vt = Term::VT102->new ('cols' => 80, 'rows' => 24);
   while (<>) { $vt->process ($_); }
 
 

DESCRIPTION

The VT102 class provides emulation of most of the functions of a DEC VT102 terminal. Once initialised, data passed to a VT102 object is processed and the in-memory ``screen'' modified accordingly. This ``screen'' can be interrogated by the external program in a variety of ways.

This allows your program to interface with full-screen console programs by running them in a subprocess and passing their output to a VT102 class. You can then see what the application has written on the screen by querying the class appropriately.

OPTIONS

Setting cols or rows in the new() hash allows you to change the size of the terminal being emulated. If you do not specify a size, the default is 80 columns by 24 rows.

After initialisation, you can read and set the following terminal options using the option_read() and option_set() methods:

   LINEWRAP      line wrapping; 1=on, 0=off. Default is OFF.
   LFTOCRLF      treat LF (\n) as CRLF (\r\n); 1=on, 0=off. Default OFF.
   IGNOREXOFF    ignore XON/XOFF characters; 1=on (ignore). Default ON.
 
 

METHODS

The following methods are provided:

attr_pack ($fg,$bg,$bo,$fa,$st,$ul,$bl,$rv)

Returns the packed version of the given attribute settings, which are given in the same order as returned by attr_unpack. The packed version will be a binary string not longer than 2 bytes.

attr_unpack ($data)

Returns a list of the contents of the given packed attribute settings, of the form ($fg,$bg,$bo,$fa,$st,$ul,$bl,$rv).

$fg and $bg are the ANSI foreground and background text colours, and $bo, $fa, $st, $ul, $bl, and $rv are flags (1 = on, 0 = off) for bold, faint, standout, underline, blink and reverse respectively.

callback_call ($name, $par1, $par2)

Calls the callback $name (eg 'ROWCHANGE') with parameters $par1 and $par2, as if the VT102 module had called it. Does nothing if that callback has not been set with callback_set ().

callback_set ($callback, $ref, $private)

Sets the callback callback to function reference ref with private data $private.

See the section on CALLBACKS below.

new (%config)

Returns a new VT102 object with options specified in %config (see the OPTIONS section for details).

option_read ($option)

Returns the current value of terminal option $option (see OPTIONS for details), or undef if that option does not exist. Note that you cannot read the terminal size with this call; use size() for that.

option_set ($option, $value)

Sets the current value of terminal option $option to $value, returning the old value or undef if no such terminal option exists or you have specified an undefined $value. Note that you cannot resize the terminal with this call; use resize() for that.

process ($string)

Processes the string $string (which can be zero-length), updating the VT102 object accordingly and calling any necessary callbacks on the way.

resize ($cols, $rows)

Resizes the VT102 terminal to cols columns by rows rows, eg $vt->resize (80, 24). The virtual screen is cleared first.

reset ()

Resets the object to its ``power-on'' state.

row_attr ($row, [$startcol, $endcol])

Returns the attributes for row $row (or undef if out of range) as a string of packed attributes, each character cell's attributes being 2 bytes long. To unpack the attributes for a given cell, use substr(), eg $attr=substr($row,4,2) would set $attr to the attributes for cell 3 (steps of 2: 0 .. 2 .. 4, so 4 means the 3rd character). You would then use the attr_unpack() method to unpack that character cell's attributes.

If $startcol and $endcol are defined, only returns the part of the row between columns $startcol and $endcol inclusive instead of the whole row.

row_plaintext ($row, [$startcol, $endcol])

Returns the textual contents of row $row (or undef if out of range), with unused characters being represented as spaces. If $startcol and $endcol are defined, only returns the part of the row between columns $startcol and $endcol inclusive instead of the whole row.

row_text ($row, [$startcol, $endcol])

Returns the textual contents of row $row (or undef if out of range), with totally unused characters being represented as NULL (\0). If $startcol and $endcol are defined, only returns the part of the row between columns $startcol and $endcol inclusive instead of the whole row.

cols ()

Return the number of columns in the VT102 object.

rows ()

Return the number of rows in the VT102 object.

size ()

Return a pair of values (columns,rows) denoting the size of the terminal in the VT102 object.

x ()

Return the current cursor X co-ordinate (1 being leftmost).

y ()

Return the current cursor Y co-ordinate (1 being topmost).

cursor ()

Return the current cursor state (1 being on, 0 being off).

xtitle ()

Return the current xterm window title.

xicon ()

Return the current xterm window icon name.

status ()

Return a list of values ($x,$y,$attr,$ti,$ic), where $x and $y are the cursor co-ordinates (1,1 = top left), $attr is a packed version of the current attributes (see attr_unpack), $ti is the xterm window title, and $ic is the xterm window icon name.

version ()

Return the version of the VT102 module being used.

CALLBACKS

Callbacks are the processing loop's way of letting your main program know that something has happened. They are called while in a process() loop.

To specify a callback, use the callback_set interface, giving a reference to the function to call. Your function should take five scalar arguments: the VT102 object being processed, the name of the callback, and two arguments whose value depends on the callback, as shown below. The final argument is the private data scalar you passed when you called callback_set.

The name of the callback is passed to the callback function so that you can have one function to handle all callbacks if you wish.

Available callback names are:

   BELL          BEL (beep, \007) character received
   CLEAR         screen about to be cleared
   OUTPUT        data (arg1) to be sent back to data source
   ROWCHANGE     screen row (row number is argument 1) content has changed
   SCROLL_DOWN   about to scroll down (arg1=top row, arg2=num to scroll)
   SCROLL_UP     about to scroll up (ditto)
   UNKNOWN       unknown/unsupported code (arg1=name, arg2=code/sequence)
   XICONNAME     xterm icon name to be changed to arg1
   XWINTITLE     xterm title name to be changed to arg2
 
 

Note that the wording of the above is significant in terms of exactly when the callback is called. For instance, CLEAR is called just before the screen is cleared, whereas ROWCHANGE is called after the given row has been changed.

A good callback handler for OUTPUT is to simply syswrite() argument 1 to your data source - eg if you're reading from a telnet session, write that argument straight to it. It is used for cursor position request responses and suchlike.

Note that SCROLL_DOWN is called when scrolling down, so text is about to move UP the screen; arg1 will be the row number of the bottom of the scrolling region, and arg2 will be the number of rows to be scrolled. Likewise, SCROLL_UP is called when text is about to move down; arg1 will be the row number of the top of the scrolling region.

Finally, note that ROWCHANGE is only triggered when text is being entered; screen scrolling or screen clearance does not trigger it, that would trigger a SCROLL_DOWN or SCROLL_UP or CLEAR. Line or character insertion or deletion will cause one or more ROWCHANGE callbacks, however.

SUPPORTED CODES

The following sequences are supported:

    007 (BEL)   beep
    010 (BS)    backspace
    011 (HT)    horizontal tab to next tab stop
    012 (LF)    line feed
    013 (VT)    line feed
    014 (FF)    line feed
    015 (CR)    carriage return
    021 (XON)   resume transmission (only if option IGNOREXOFF is cleared)
    023 (XOFF)  stop transmission (only if option IGNOREXOFF is cleared)
    030 (CAN)   interrupt escape sequence
    032 (SUB)   interrupt escape sequence
    033 (ESC)   start escape sequence
    177 (DEL)   ignored
    233 (CSI)   same as ESC [
 
 

    ESC 7 (DECSC)   save state
    ESC 8 (DECRC)   restore most recently saved state
 
 

    ESC # 8 (DECALN)  DEC screen alignment test - fill screen with E's
 
 

    CSI @ (ICH)     insert blank characters
    CSI A (CUU)     move cursor up
    CSI B (CUD)     move cursor down
    CSI C (CUF)     move cursor right
    CSI D (CUB)     move cursor left
    CSI E (CNL)     move cursor down and to column 1
    CSI F (CPL)     move cursor up and to column 1
    CSI G (CHA)     move cursor to column in current row
    CSI H (CUP)     move cursor to row, column
    CSI J (ED)      erase display
    CSI K (EL)      erase line
    CSI L (IL)      insert blank lines
    CSI M (DL)      delete lines
    CSI P (DCH)     delete characters on current line
    CSI X (ECH)     erase characters on current line
    CSI a (HPR)     move cursor right
    CSI c (DA)      return ESC [ ? 6 c (VT102)
    CSI d (VPA)     move to row (current column)
    CSI e (VPR)     move cursor down
    CSI f (HVP)     move cursor to row, column
    CSI m (SGR)     set graphic rendition
    CSI n (DSR)     device status report
    CSI r (DECSTBM) set scrolling region to (top, bottom) rows
    CSI s (CUPSV)   save cursor position
    CSI u (CUPRS)   restore cursor position
    CSI ` (HPA)     move cursor to column in current row
 
 

LIMITATIONS

Unknown escape sequences and control characters are ignored. All escape sequences pertaining to character sets are ignored.

The following known control characters / sequences are ignored:

    005 (ENQ)   trigger answerback message
    016 (SO)    activate G1 charset, carriage return
    017 (SI)    activate G0 charset
 
 

The following known escape sequences are ignored:

    ESC %@ (CSDFL)    select default charset (ISO646/8859-1)
    ESC %G (CSUTF8)   select UTF-8
    ESC %8 (CSUTF8)   select UTF-8 (obsolete)
    ESC (8 (G0DFL)    G0 charset = default mapping (ISO8859-1)
    ESC (0 (G0GFX)    G0 charset = VT100 graphics mapping
    ESC (U (G0ROM)    G0 charset = null mapping (straight to ROM)
    ESC (K (G0USR)    G0 charset = user defined mapping
    ESC (B (G0TXT)    G0 charset = ASCII mapping
    ESC )8 (G1DFL)    G1 charset = default mapping (ISO8859-1)
    ESC )0 (G1GFX)    G1 charset = VT100 graphics mapping
    ESC )U (G1ROM)    G1 charset = null mapping (straight to ROM)
    ESC )K (G1USR)    G1 charset = user defined mapping
    ESC )B (G1TXT)    G1 charset = ASCII mapping
    ESC *8 (G2DFL)    G2 charset = default mapping (ISO8859-1)
    ESC *0 (G2GFX)    G2 charset = VT100 graphics mapping
    ESC *U (G2ROM)    G2 charset = null mapping (straight to ROM)
    ESC *K (G2USR)    G2 charset = user defined mapping
    ESC +8 (G3DFL)    G3 charset = default mapping (ISO8859-1)
    ESC +0 (G3GFX)    G3 charset = VT100 graphics mapping
    ESC +U (G3ROM)    G3 charset = null mapping (straight to ROM)
    ESC +K (G3USR)    G3 charset = user defined mapping
    ESC >  (DECPNM)   set numeric keypad mode
    ESC =  (DECPAM)   set application keypad mode
    ESC H  (HTS)      set tab stop at current column
    ESC N  (SS2)      select G2 charset for next char only
    ESC O  (SS3)      select G3 charset for next char only
    ESC P  (DCS)      device control string (ended by ST)
    ESC X  (SOS)      start of string
    ESC ^  (PM)       privacy message (ended by ST)
    ESC \  (ST)       string terminator
    ESC n  (LS2)      invoke G2 charset
    ESC o  (LS3)      invoke G3 charset
    ESC |  (LS3R)     invoke G3 charset as GR
    ESC }  (LS2R)     invoke G2 charset as GR
    ESC ~  (LS1R)     invoke G1 charset as GR
 
 

The following known CSI (ESC [) sequences are ignored:

    CSI g (TBC)     clear tab stop (CSI 3 g = clear all stops)
    CSI q (DECLL)   set keyboard LEDs
 
 

The following known CSI (ESC [) sequences are only partially supported:

    CSI h (SM)      set mode (only support CSI ? 25 h, cursor on/off)
    CSI l (RM)      reset mode (as above)
 
 

EXAMPLES

For some examples, including how to interface Term::VT102 with Net::Telnet or a command such as SSH, please see the examples/ directory in the distribution.

AUTHORS

Copyright (C) 2003 Andrew Wood "<andrew dot wood at ivarch dot com>". Distributed under the terms of the Artistic License.

Credit is also due to:

   Charles Harker <CHarker at interland.com>
     - reported and helped to diagnose a bug in the handling of TABs
 
 

   Steve van der Burg <steve.vanderburg at lhsc.on.ca>
     - supplied basis for an example script using Net::Telnet
 
 

   Chris R. Donnelly <cdonnelly at digitalmotorworks.com>
     - added support for DECTCEM, partial support for SM/RM
 
 

   Paul L. Stoddard
     - reported a possible bug in cursor movement handling
 
 

THINGS TO WATCH OUT FOR

Make sure that your code understands NULL (\000) - you will get this in strings where nothing has been printed on the screen. For instance, the sequence ``12\e[C34'' (``12'', ``CUF (move right)'', ``34'') you might think would yield the string ``12 34'', but in fact it can also yield ``12\00034'' - that is, ``12'' followed by a zero byte followed by ``34''. This is because the screen's contents defaults to zeroes, not spaces.

SEE ALSO

console_codes(4), IO::Pty(3)