Tk Built-In Commands selection(1T)
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 (ICM).
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 Conven-
tions Manual for complete details. Selection defaults
to PRIMARY and window defaults to ``.''. Returns an
empty string.
type?
selection get ?-displayof window? ?-selection selection? ?-type
Retrieves the value of selection from window's display
and returns it as a result. Selection defaults to PRI-
MARY and window defaults to ``.''. Type specifies the
form in which the selection is to be returned (the
desired ``target'' for conversion, in ICM terminol-
ogy), and should be an atom name such as STRING or
FILENAME; see the Inter-Client Communication Conven-
tions 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 for-
mat is different than the selection type; see the ICM
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 for-
mat as a collection of fields separated by spaces:
atoms are converted to their textual names, and
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Tk Built-In Commands selection(1T)
anything else is converted to hexadecimal integers.
format? window command
selection handle ?-selection selection? ?-type type? ?-format
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 addi-
tional numbers are offset and maxChars: offset speci-
fies 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 posi-
tion 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 didn't
exist at all.
The format argument specifies the representation that
should be used to transmit the selection to the reques-
ter (the second column of Table 2 of the ICM), and
defaults to STRING. If format is STRING, the selection
is transmitted as 8-bit ASCI 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 transmit-
ted 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.
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Tk Built-In Commands selection(1T)
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 noti-
fied that it has lost the selection. If command is speci-
fied, it is a Tcl script to execute when some other window
claims ownership of the selection away from window. Selec-
tion 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 selec-
tion; 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 {} {
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Tk Built-In Commands selection(1T)
puts "Lost selection"
}
SEE ALSO
clipboard(1T)
KEYWORDS
clear, format, handler, ICM, own, selection, target, type
ATRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
ATRIBUTE TYPE ATRIBUTE VALUE
Availability SUNWTk
Interface Stability Uncommitted
NOTES
Source for Tk is available on http:/opensolaris.org.
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