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 Communication 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 window defaults to ``.''.  Type specifies the form in which the selection
              is to be returned (the desired ``target'' for conversion, in ICCCM terminology), and should be  an
              atom  name  such as STRING or FILE_NAME; see the Inter-Client Communication Conventions 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 textual names, and anything else is converted to hexadecimal integers.

       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
              window, 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 maxChars:   offset  specifies  a  starting 2
              character  position  in  the  selection  and  maxChars  gives  the maximum number of characters to 2
              retrieve.  The command should return a value consisting of at  most  maxChars  of  the  selection, 2
              starting  at position offset.  For very large selections (larger than maxChars) the selection will 2
              be retrieved using several invocations of command  with  increasing  offset  values.   If  command 2
              returns a string whose length is less than maxChars, the return value is assumed to include all of 2
              the  remainder  of  the  selection;   if  the length of command's result is equal to maxChars then 2
              command will be invoked again, until it eventually returns a result shorter  than  maxChars.   The 2
              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 column of Table 2 of the ICCCM), and defaults to STRING.  If format is
              STRING, the selection is transmitted as 8-bit ASCII characters (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 selection 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 SECONDARY 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 special 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(3tk)

KEYWORDS

       clear, format, handler, ICCCM, own, selection, target, type

Tk                                                     8.1                                        selection(3tk)