- NAME
- selection - Manipulate the X selection
- SYNOPSIS
- DESCRIPTION
- selection clear ?-displayof window? ?-selection selection?
- selection get ?-displayof window? ?-selection selection? ?-type type?
- selection handle ?-selection s? ?-type t? ?-format f? window command
- selection own ?-displayof window? ?-selection selection?
- selection own ?-command command? ?-selection selection? window
- EXAMPLES
- SEE ALSO
- KEYWORDS
selection - Manipulate the X selection
selection option ?
arg arg ...?
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, UTF8_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.
Note that selection get does not retrieve the selection in the
UTF8_STRING format unless told to.
- selection handle ?-selection s? ?-type t? ?-format f? window command
-
Creates a handler for selection requests, such that command will
be executed whenever selection s is owned by window and
someone attempts to retrieve it in the form given by type t
(e.g. t is specified in the selection get command).
S defaults to PRIMARY, t defaults to STRING, and
f defaults to STRING. If command is an empty string
then any existing handler for window, t, and
s is removed.
Note that when the selection is handled as type STRING it is also
automatically handled as type UTF8_STRING as well.
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
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 did not 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, in the system encoding;
the UTF8_STRING format always uses UTF-8 as its encoding).
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 do not 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.
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"
}
clipboard
clear,
format,
handler,
ICCCM,
own,
selection,
target,
type
Copyright © 1995-1997 Roger E. Critchlow Jr.
Copyright © 1990-1994 The Regents of the University of California.
Copyright © 1994-1996 Sun Microsystems, Inc.
