selection(n)                 Tk Built-In Commands                 selection(n)



NAME
       selection - Manipulate the X selection

SYNOPSIS
       (selection option ?arg arg ...?)


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

       The first argument to selection determines the format of the rest of
       the arguments and the behavior of the procedure.  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 list.

       (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 ``*root*''.  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 procedure 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 procedure)
              Creates a handler for selection requests, such that procedure
              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 procedure).  Selection
              defaults to PRIMARY, type defaults to STRING, and format
              defaults to STRING.  If procedure 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, procedure will be applied as a STk
              procedure with a list of two numbers.  The two additional
              numbers are offset and maxBytes:  offset specifies a starting
              character position in the selection and maxBytes gives the
              maximum number of bytes to retrieve.  The procedure should
              return a value consisting of at most maxBytes of the selection,
              starting at position offset.  For very large selections (larger
              than maxBytes) the selection will be retrieved using several
              invocations of procedure with increasing offset values.  If
              procedure returns a string whose length is less than maxBytes,
              the return value is assumed to include all of the remainder of
              the selection;  if the length of procedure's result is equal to
              maxBytes then procedure will be invoked again, until it
              eventually returns a result shorter than maxBytes.  The value of
              maxBytes will always be relatively large (thousands of bytes).

              If procedure 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 procedure).  If
              format is ATOM, then the return value from procedure 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 procedure 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 ?:procedure procedure? ?: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 #f if no window in this application owns
              the selection.  Selection defaults to "PRIMARY" and window
              defaults to ``*root*''.
              The second form of selection own causes window to become the new
              owner of selection on window's display, returning an empty list
              as result. The existing owner, if any, is notified that it has
              lost the selection.  If procedure is specified, it is a STk
              script to execute when some other window claims ownership of the
              selection away from window. Selection defaults to "PRIMARY".




STk                                   3.1                         selection(n)
