NAME
       selection - Manipulate the X selection

SYNOPSIS
       selection option ?arg arg ...?


DESCRIPTION
       This  command provides a Tcl interface to the X selection mechanism and
       implements the full selection functionality described in the  X  Inter-
       Client Communication Conventions Manual (ICCCM).

       Note  that  for  management of the CLIPBOARD selection (see below), the
       clipboard command may also be used.

       The first argument to selection determines the format of  the  rest  of
       the arguments and the behavior of the command.  The following forms are
       currently supported:


       selection clear ?-displayof window? ?-selection selection?
              If selection exists anywhere on window's display,  clear  it  so
              that  no window owns the selection anymore.  Selection specifies
              the X selection that should be cleared, and should  be  an  atom
              name such as PRIMARY or CLIPBOARD; see the Inter-Client Communi-
              cation  Conventions  Manual  for  complete  details.   Selection
              defaults  to  PRIMARY  and window defaults to ``.''.  Returns an
              empty string.

       selection get ?-displayof window? ?-selection selection? ?-type type?
              Retrieves the value  of  selection  from  window's  display  and
              returns  it as a result.  Selection defaults to PRIMARY and win-
              dow defaults to ``.''.  Type specifies the  form  in  which  the
              selection  is to be returned (the desired ``target'' for conver-
              sion, in ICCCM terminology), and should be an atom name such  as
              STRING  or FILE_NAME; see the Inter-Client Communication Conven-
              tions Manual for complete details.   Type  defaults  to  STRING.
              The selection owner may choose to return the selection in any of
              several different representation formats, such as STRING,  ATOM,
              INTEGER, etc. (this format is different than the selection type;
              see the ICCCM for all the confusing details).  If the  selection
              is returned in a non-string format, such as INTEGER or ATOM, the
              selection command converts it to string format as  a  collection
              of fields separated by spaces: atoms are converted to their tex-
              tual names, and anything else is converted to hexadecimal  inte-
              gers.

       selection  handle  ?-selection selection? ?-type type? ?-format format?
       window command
              Creates a handler for selection requests, such that command will
              be executed whenever selection is owned by  window  and  someone
              attempts  to retrieve it in the form given by type (e.g. type is
              specified in the selection get command).  Selection defaults  to
              PRIMARY, type defaults to STRING, and format defaults to STRING.
              If command is an empty string then any existing handler for win-
              dow, type, and selection is removed.

              When  selection is requested, window is the selection owner, and
              type is the requested type, command will be executed  as  a  Tcl
              command  with  two additional numbers appended to it (with space
              separators).  The two additional numbers  are  offset  and  max-
              Chars:   offset  specifies  a starting character position in the
              selection and maxChars gives the maximum number of characters to
              retrieve.   The  command  should return a value consisting of at
              most maxChars of the selection,  starting  at  position  offset.
              For  very  large selections (larger than maxChars) the selection
              will be retrieved using  several  invocations  of  command  with
              increasing  offset  values.   If  command returns a string whose
              length is less than maxChars, the return  value  is  assumed  to
              include all of the remainder of the selection;  if the length of
              command's result is equal  to  maxChars  then  command  will  be
              invoked again, until it eventually returns a result shorter than
              maxChars.  The value of maxChars will always be relatively large
              (thousands of characters).

              If  command  returns  an  error  then the selection retrieval is
              rejected just as if the selection didn't exist at all.

              The format argument specifies the representation that should  be
              used to transmit the selection to the requester (the second col-
              umn of Table 2 of the ICCCM), and defaults to STRING.  If format
              is  STRING,  the selection is transmitted as 8-bit ASCII charac-
              ters (i.e.  just in the form returned by command).  If format is
              ATOM,  then the return value from command is divided into fields
              separated by white space;  each field is converted to  its  atom
              value,  and  the 32-bit atom value is transmitted instead of the
              atom name.  For any other format, the return value from  command
              is  divided  into fields separated by white space and each field
              is converted to a 32-bit  integer;   an  array  of  integers  is
              transmitted to the selection requester.

              The format argument is needed only for compatibility with selec-
              tion requesters that don't use Tk.   If  Tk  is  being  used  to
              retrieve  the  selection  then  the value is converted back to a
              string at the requesting end, so format is irrelevant.

       selection own ?-displayof window? ?-selection selection?

       selection own ?-command command? ?-selection selection? window
              The first form of selection own returns the  path  name  of  the
              window  in  this  application that owns selection on the display
              containing window, or an empty  string  if  no  window  in  this
              application  owns  the selection.  Selection defaults to PRIMARY
              and window defaults to ``.''.

       The second form of selection own causes window to become the new  owner
       of  selection on window's display, returning an empty string as result.
       The existing owner, if any, is notified that it has lost the selection.
       If  command is specified, it is a Tcl script to execute when some other
       window claims ownership of the selection away from  window.   Selection
       defaults to PRIMARY.

EXAMPLES
       On  X11 platforms, one of the standard selections available is the SEC-
       ONDARY selection. Hardly anything uses it, but here is how to  read  it
       using Tk:
              set selContents [selection get -selection SECONDARY]

       Many different types of data may be available for a selection; the spe-
       cial type TARGETS allows you to get a list of available types:
              foreach type [selection get -type TARGETS] {
                 puts "Selection PRIMARY supports type $type"
              }

       To claim the selection, you must first set up a handler to  supply  the
       data for the selection.  Then you have to claim the selection...
              # Set up the data handler ready for incoming requests
              set foo "This is a string with some data in it... blah blah"
              selection handle -selection SECONDARY . getData
              proc getData {offset maxChars} {
                 puts "Retrieving selection starting at $offset"
                 return [string range $::foo $offset [expr {$offset+$maxChars}]]
              }

              # Now we grab the selection itself
              puts "Claiming selection"
              selection own -command lost -selection SECONDARY .
              proc lost {} {
                 puts "Lost selection"
              }


SEE ALSO
       clipboard(n)


KEYWORDS
