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selection(3)		       User Contributed Perl Documentation		     selection(3)

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

perl v5.16.3				    2014-06-10				     selection(3)
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