1selection(n) Tk Built-In Commands selection(n)
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8 selection - Manipulate the X selection
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11 selection option ?arg arg ...?
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15 This command provides a Tcl interface to the X selection mechanism and
16 implements the full selection functionality described in the X Inter-
17 Client Communication Conventions Manual (ICCCM).
18 Note that for management of the CLIPBOARD selection (see below), the
20 clipboard command may also be used.
21 The first argument to selection determines the format of the rest of
23 the arguments and the behavior of the command. The following forms are
24 currently supported:
25 selection clear ?-displayof window? ?-selection selection?
27 If selection exists anywhere on window's display, clear it so
28 that no window owns the selection anymore. Selection specifies
29 the X selection that should be cleared, and should be an atom
30 name such as PRIMARY or CLIPBOARD; see the Inter-Client Communi‐
31 cation Conventions Manual for complete details. Selection
32 defaults to PRIMARY and window defaults to “.”. Returns an
33 empty string.
34 selection get ?-displayof window? ?-selection selection? ?-type type?
36 Retrieves the value of selection from window's display and
37 returns it as a result. Selection defaults to PRIMARY and win‐
38 dow defaults to “.”. Type specifies the form in which the
39 selection is to be returned (the desired “target” for conver‐
40 sion, in ICCCM terminology), and should be an atom name such as
41 STRING or FILE_NAME; see the Inter-Client Communication Conven‐
42 tions Manual for complete details. Type defaults to STRING.
43 The selection owner may choose to return the selection in any of
44 several different representation formats, such as STRING,
45 UTF8_STRING, ATOM, INTEGER, etc. (this format is different than
46 the selection type; see the ICCCM for all the confusing
47 details). If the selection is returned in a non-string format,
48 such as INTEGER or ATOM, the selection command converts it to
49 string format as a collection of fields separated by spaces:
50 atoms are converted to their textual names, and anything else is
51 converted to hexadecimal integers. Note that selection get does
52 not retrieve the selection in the UTF8_STRING format unless told
53 to.
54 selection handle ?-selection s? ?-type t? ?-format f? window command
56 Creates a handler for selection requests, such that command will
57 be executed whenever selection s is owned by window and someone
58 attempts to retrieve it in the form given by type t (e.g. t is
59 specified in the selection get command). S defaults to PRIMARY,
60 t defaults to STRING, and f defaults to STRING. If command is
61 an empty string then any existing handler for window, t, and s
62 is removed. Note that when the selection is handled as type
63 STRING it is also automatically handled as type UTF8_STRING as
64 well.
65 When selection is requested, window is the selection owner, and
67 type is the requested type, command will be executed as a Tcl
68 command with two additional numbers appended to it (with space
69 separators). The two additional numbers are offset and max‐
70 Chars: offset specifies a starting character position in the
71 selection and maxChars gives the maximum number of characters to
72 retrieve. The command should return a value consisting of at
73 most maxChars of the selection, starting at position offset.
74 For very large selections (larger than maxChars) the selection
75 will be retrieved using several invocations of command with
76 increasing offset values. If command returns a string whose
77 length is less than maxChars, the return value is assumed to
78 include all of the remainder of the selection; if the length of
79 command's result is equal to maxChars then command will be
80 invoked again, until it eventually returns a result shorter than
81 maxChars. The value of maxChars will always be relatively large
82 (thousands of characters).
83 If command returns an error then the selection retrieval is
85 rejected just as if the selection did not exist at all.
86 The format argument specifies the representation that should be
88 used to transmit the selection to the requester (the second col‐
89 umn of Table 2 of the ICCCM), and defaults to STRING. If format
90 is STRING, the selection is transmitted as 8-bit ASCII charac‐
91 ters (i.e. just in the form returned by command, in the system
92 encoding; the UTF8_STRING format always uses UTF-8 as its encod‐
93 ing). If format is ATOM, then the return value from command is
94 divided into fields separated by white space; each field is
95 converted to its atom value, and the 32-bit atom value is trans‐
96 mitted instead of the atom name. For any other format, the
97 return value from command is divided into fields separated by
98 white space and each field is converted to a 32-bit integer; an
99 array of integers is transmitted to the selection requester.
100 The format argument is needed only for compatibility with selec‐
102 tion requesters that do not use Tk. If Tk is being used to
103 retrieve the selection then the value is converted back to a
104 string at the requesting end, so format is irrelevant.
105 selection own ?-displayof window? ?-selection selection?
107 selection own ?-command command? ?-selection selection? window
109 The first form of selection own returns the path name of the
110 window in this application that owns selection on the display
111 containing window, or an empty string if no window in this
112 application owns the selection. Selection defaults to PRIMARY
113 and window defaults to “.”.
114 The second form of selection own causes window to become the new
116 owner of selection on window's display, returning an empty
117 string as result. The existing owner, if any, is notified that
118 it has lost the selection. If command is specified, it is a Tcl
119 script to execute when some other window claims ownership of the
120 selection away from window. Selection defaults to PRIMARY.
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123 On X11 platforms, one of the standard selections available is the SEC‐
124 ONDARY selection. Hardly anything uses it, but here is how to read it
125 using Tk:
126 set selContents [selection get -selection SECONDARY]
128 Many different types of data may be available for a selection; the spe‐
130 cial type TARGETS allows you to get a list of available types:
131 foreach type [selection get -type TARGETS] {
133 puts "Selection PRIMARY supports type $type"
134 }
135 To claim the selection, you must first set up a handler to supply the
137 data for the selection. Then you have to claim the selection...
138 # Set up the data handler ready for incoming requests
139 set foo "This is a string with some data in it... blah blah"
140 selection handle -selection SECONDARY . getData
141 proc getData {offset maxChars} {
142 puts "Retrieving selection starting at $offset"
143 return [string range $::foo $offset [expr {$offset+$maxChars-1}]]
144 }
145 # Now we grab the selection itself
147 puts "Claiming selection"
148 selection own -command lost -selection SECONDARY .
149 proc lost {} {
150 puts "Lost selection"
151 }
152
154 clipboard(n)
155
157 clear, format, handler, ICCCM, own, selection, target, type
158Tk 8.1 selection(n)