NAME

       Tk::Selection - Manipulate the X selection

SYNOPSIS

       $widget->SelectionOption?(args)?

DESCRIPTION

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

       The widget object used to invoke the methods below determines which display is used to access the
       selection.  In order to avoid conflicts with selection methods of widget classes (e.g. Text) this set of
       methods uses the prefix Selection.  The following methods are currently supported:

       $widget->SelectionClear?(-selection=>selection)?
           If selection exists anywhere on $widget'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.  Returns an empty string.

       $widget->SelectionGet?(?-selection=>selection?,?-type=>type?)?
           Retrieves the value of selection from $widget's display and returns it as a result.  Selection
           defaults to PRIMARY.

           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 format is not STRING then things get messy, the following description is from the Tcl/Tk man page
           as yet incompetely translated for the perl version - it is misleading at best.

           If the selection is returned in a non-string format, such as INTEGER or ATOM, the SelectionGet
           converts it to a list of perl values: atoms are converted to their textual names, and anything else
           is converted integers.

           A goal of the perl port is to provide better handling of different formats than Tcl/Tk does, which
           should be possible given perl's wider range of ``types''. Although some thought went into this in
           very early days of perl/Tk what exactly happens is still "not quite right" and subject to change.

       $widget->SelectionHandle(?-selection=>selection?,?-type=>type?,?-format=>format? callback)
           Creates a handler for selection requests, such that callback will be executed whenever selection is
           owned by $widget 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 callback is an empty string then any existing handler for $widget,
           type, and selection is removed.

           When selection is requested, $widget is the selection owner, and type is the requested type, callback
           will be executed with two additional arguments.  The two additional arguments are offset and
           maxBytes:  offset specifies a starting character position in the selection and maxBytes gives the
           maximum number of bytes to retrieve.  The command 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 callback with increasing
           offset values.  If callback 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 callback's result is
           equal to maxBytes then callback 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 callback returns an error (e.g. via die) 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 not STRING then things get messy, the following description is from the Tcl/Tk man page
           as yet untranslated for the perl version - it is misleading at best.

           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 many selection requesters, except Tcl/Tk.
           If Tcl/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.

           A goal of the perl port is to provide better handling of different formats than Tcl/Tk does, which
           should be possible given perl's wider range of ``types''. Although some thought went into this in
           very early days of perl/Tk what exactly happens is still "not quite right" and subject to change.

       $widget->SelectionOwner?(-selection=>selection)?
           SelectionOwner returns the window in this application that owns selection on the display containing
           $widget, or an empty string if no window in this application owns the selection.  Selection defaults
           to PRIMARY.

       $widget->SelectionOwn?(?-command=>callback?,?-selection=>selection?)?
           SelectionOwn causes $widget to become the new owner of selection on $widget's display, returning an
           empty string as result. The existing owner, if any, is notified that it has lost the selection.  If
           callback is specified, it will be executed when some other window claims ownership of the selection
           away from $widget.  Selection defaults to PRIMARY.

KEYWORDS

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