1event(n) Tk Built-In Commands event(n)
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8 event - Miscellaneous event facilities: define virtual events and gen‐
9 erate events
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12 event option ?arg arg ...?
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16 The event command provides several facilities for dealing with window
17 system events, such as defining virtual events and synthesizing events.
18 The command has several different forms, determined by the first argu‐
19 ment. The following forms are currently supported:
20 event add <<virtual>> sequence ?sequence ...?
22 Associates the virtual event virtual with the physical event
23 sequence(s) given by the sequence arguments, so that the virtual
24 event will trigger whenever any one of the sequences occurs.
25 Virtual may be any string value and sequence may have any of the
26 values allowed for the sequence argument to the bind command.
27 If virtual is already defined, the new physical event sequences
28 add to the existing sequences for the event.
29 event delete <<virtual>> ?sequence sequence ...?
31 Deletes each of the sequences from those associated with the
32 virtual event given by virtual. Virtual may be any string value
33 and sequence may have any of the values allowed for the sequence
34 argument to the bind command. Any sequences not currently asso‐
35 ciated with virtual are ignored. If no sequence argument is
36 provided, all physical event sequences are removed for virtual,
37 so that the virtual event will not trigger anymore.
38 event generate window event ?option value option value ...?
40 Generates a window event and arranges for it to be processed
41 just as if it had come from the window system. Window gives the
42 path name of the window for which the event will be generated;
43 it may also be an identifier (such as returned by winfo id) as
44 long as it is for a window in the current application. Event
45 provides a basic description of the event, such as <Shift-But‐
46 ton-2> or <<Paste>>. If Window is empty the whole screen is
47 meant, and coordinates are relative to the screen. Event may
48 have any of the forms allowed for the sequence argument of the
49 bind command except that it must consist of a single event pat‐
50 tern, not a sequence. Option-value pairs may be used to specify
51 additional attributes of the event, such as the x and y mouse
52 position; see EVENT FIELDS below. If the -when option is not
53 specified, the event is processed immediately: all of the han‐
54 dlers for the event will complete before the event generate com‐
55 mand returns. If the -when option is specified then it deter‐
56 mines when the event is processed. Certain events, such as key
57 events, require that the window has focus to receive the event
58 properly.
59 event info ?<<virtual>>?
61 Returns information about virtual events. If the <<virtual>>
62 argument is omitted, the return value is a list of all the vir‐
63 tual events that are currently defined. If <<virtual>> is spec‐
64 ified then the return value is a list whose elements are the
65 physical event sequences currently defined for the given virtual
66 event; if the virtual event is not defined then an empty string
67 is returned.
68 Note that virtual events that are not bound to physical event
70 sequences are not returned by event info.
71
73 The following options are supported for the event generate command.
74 These correspond to the “%” expansions allowed in binding scripts for
75 the bind command.
76 -above window
78 Window specifies the above field for the event, either as a win‐
79 dow path name or as an integer window id. Valid for Configure
80 events. Corresponds to the %a substitution for binding scripts.
81 -borderwidth size
83 Size must be a screen distance; it specifies the border_width
84 field for the event. Valid for Configure events. Corresponds
85 to the %B substitution for binding scripts.
86 -button number
88 Number must be an integer; it specifies the detail field for a
89 ButtonPress or ButtonRelease event, overriding any button num‐
90 ber provided in the base event argument. Corresponds to the %b
91 substitution for binding scripts.
92 -count number
94 Number must be an integer; it specifies the count field for the
95 event. Valid for Expose events. Corresponds to the %c substi‐
96 tution for binding scripts.
97 -data string
99 String may be any value; it specifies the user_data field for
100 the event. Only valid for virtual events. Corresponds to the
101 %d substitution for virtual events in binding scripts.
102 -delta number
104 Number must be an integer; it specifies the delta field for the
105 MouseWheel event. The delta refers to the direction and magni‐
106 tude the mouse wheel was rotated. Note the value is not a
107 screen distance but are units of motion in the mouse wheel.
108 Typically these values are multiples of 120. For example, 120
109 should scroll the text widget up 4 lines and -240 would scroll
110 the text widget down 8 lines. Of course, other widgets may
111 define different behaviors for mouse wheel motion. This field
112 corresponds to the %D substitution for binding scripts.
113 -detail detail
115 Detail specifies the detail field for the event and must be one
116 of the following:
117 NotifyAncestor NotifyNonlinearVirtual
119 NotifyDetailNone NotifyPointer
120 NotifyInferior NotifyPointerRoot
121 NotifyNonlinear NotifyVirtual
122 Valid for Enter, Leave, FocusIn and FocusOut events. Corre‐
124 sponds to the %d substitution for binding scripts.
125 -focus boolean
127 Boolean must be a boolean value; it specifies the focus field
128 for the event. Valid for Enter and Leave events. Corresponds
129 to the %f substitution for binding scripts.
130 -height size
132 Size must be a screen distance; it specifies the height field
133 for the event. Valid for Configure events. Corresponds to the
134 %h substitution for binding scripts.
135 -keycode number
137 Number must be an integer; it specifies the keycode field for
138 the event. Valid for KeyPress and KeyRelease events. Corre‐
139 sponds to the %k substitution for binding scripts.
140 -keysym name
142 Name must be the name of a valid keysym, such as g, space, or
143 Return; its corresponding keycode value is used as the keycode
144 field for event, overriding any detail specified in the base
145 event argument. Valid for KeyPress and KeyRelease events. Cor‐
146 responds to the %K substitution for binding scripts.
147 -mode notify
149 Notify specifies the mode field for the event and must be one of
150 NotifyNormal, NotifyGrab, NotifyUngrab, or NotifyWhileGrabbed.
151 Valid for Enter, Leave, FocusIn, and FocusOut events. Corre‐
152 sponds to the %m substitution for binding scripts.
153 -override boolean
155 Boolean must be a boolean value; it specifies the override_re‐
156 direct field for the event. Valid for Map, Reparent, and Con‐
157 figure events. Corresponds to the %o substitution for binding
158 scripts.
159 -place where
161 Where specifies the place field for the event; it must be
162 either PlaceOnTop or PlaceOnBottom. Valid for Circulate events.
163 Corresponds to the %p substitution for binding scripts.
164 -root window
166 Window must be either a window path name or an integer window
167 identifier; it specifies the root field for the event. Valid
168 for KeyPress, KeyRelease, ButtonPress, ButtonRelease, Enter,
169 Leave, and Motion events. Corresponds to the %R substitution
170 for binding scripts.
171 -rootx coord
173 Coord must be a screen distance; it specifies the x_root field
174 for the event. Valid for KeyPress, KeyRelease, ButtonPress,
175 ButtonRelease, Enter, Leave, and Motion events. Corresponds to
176 the %X substitution for binding scripts.
177 -rooty coord
179 Coord must be a screen distance; it specifies the y_root field
180 for the event. Valid for KeyPress, KeyRelease, ButtonPress,
181 ButtonRelease, Enter, Leave, and Motion events. Corresponds to
182 the %Y substitution for binding scripts.
183 -sendevent boolean
185 Boolean must be a boolean value; it specifies the send_event
186 field for the event. Valid for all events. Corresponds to the
187 %E substitution for binding scripts.
188 -serial number
190 Number must be an integer; it specifies the serial field for
191 the event. Valid for all events. Corresponds to the %# substi‐
192 tution for binding scripts.
193 -state state
195 State specifies the state field for the event. For KeyPress,
196 KeyRelease, ButtonPress, ButtonRelease, Enter, Leave, and Motion
197 events it must be an integer value. For Visibility events it
198 must be one of VisibilityUnobscured, VisibilityPartiallyOb‐
199 scured, or VisibilityFullyObscured. This option overrides any
200 modifiers such as Meta or Control specified in the base event.
201 Corresponds to the %s substitution for binding scripts.
202 -subwindow window
204 Window specifies the subwindow field for the event, either as a
205 path name for a Tk widget or as an integer window identifier.
206 Valid for KeyPress, KeyRelease, ButtonPress, ButtonRelease,
207 Enter, Leave, and Motion events. Similar to %S substitution for
208 binding scripts.
209 -time integer
211 Integer must be an integer value; it specifies the time field
212 for the event. Additonally the special value current is allowed,
213 this value will be substituted by the current event time. Valid
214 for KeyPress, KeyRelease, ButtonPress, ButtonRelease, Enter,
215 Leave, Motion, and Property events. Corresponds to the %t sub‐
216 stitution for binding scripts.
217 -warp boolean
219 boolean must be a boolean value; it specifies whether the
220 screen pointer should be warped as well. Valid for KeyPress,
221 KeyRelease, ButtonPress, ButtonRelease, and Motion events. The
222 pointer will only warp to a window if it is mapped.
223 -width size
225 Size must be a screen distance; it specifies the width field
226 for the event. Valid for Configure events. Corresponds to the
227 %w substitution for binding scripts.
228 -when when
230 When determines when the event will be processed; it must have
231 one of the following values:
232 now Process the event immediately, before the command
234 returns. This also happens if the -when option is
235 omitted.
236 tail Place the event on Tcl's event queue behind any events
238 already queued for this application.
239 head Place the event at the front of Tcl's event queue, so
241 that it will be handled before any other events
242 already queued.
243 mark Place the event at the front of Tcl's event queue but
245 behind any other events already queued with -when
246 mark. This option is useful when generating a series
247 of events that should be processed in order but at the
248 front of the queue.
249 -x coord
251 Coord must be a screen distance; it specifies the x field for
252 the event. Valid for KeyPress, KeyRelease, ButtonPress, Button‐
253 Release, Motion, Enter, Leave, Expose, Configure, Gravity, and
254 Reparent events. Corresponds to the %x substitution for binding
255 scripts. If Window is empty the coordinate is relative to the
256 screen, and this option corresponds to the %X substitution for
257 binding scripts.
258 -y coord
260 Coord must be a screen distance; it specifies the y field for
261 the event. Valid for KeyPress, KeyRelease, ButtonPress, Button‐
262 Release, Motion, Enter, Leave, Expose, Configure, Gravity, and
263 Reparent events. Corresponds to the %y substitution for binding
264 scripts. If Window is empty the coordinate is relative to the
265 screen, and this option corresponds to the %Y substitution for
266 binding scripts.
267 Any options that are not specified when generating an event are filled
269 with the value 0, except for serial, which is filled with the next X
270 event serial number.
271
273 Tk defines the following virtual events for the purposes of notifica‐
274 tion:
275 <<AltUnderlined>>
277 This is sent to widget to notify it that the letter it has
278 underlined (as an accelerator indicator) with the -underline
279 option has been pressed in combination with the Alt key. The
280 usual response to this is to either focus into the widget (or
281 some related widget) or to invoke the widget.
282 <<Invoke>>
284 This can be sent to some widgets (e.g. button, listbox, menu) as
285 an alternative to <space>.
286 <<ListboxSelect>>
288 This is sent to a listbox when the set of selected item(s) in
289 the listbox is updated.
290 <<MenuSelect>>
292 This is sent to a menu when the currently selected item in the
293 menu changes. It is intended for use with context-sensitive help
294 systems.
295 <<Modified>>
297 This is sent to a text widget when the contents of the widget
298 are changed.
299 <<Selection>>
301 This is sent to a text widget when the selection in the widget
302 is changed.
303 <<ThemeChanged>>
305 This is sent to all widgets when the ttk theme changed. The ttk
306 widgets listen to this event and redisplay themselves when it
307 fires. The legacy widgets ignore this event.
308 <<TraverseIn>>
310 This is sent to a widget when the focus enters the widget
311 because of a user-driven “tab to widget” action.
312 <<TraverseOut>>
314 This is sent to a widget when the focus leaves the widget
315 because of a user-driven “tab to widget” action.
316 <<UndoStack>>
318 This is sent to a text widget when its undo stack or redo stack
319 becomes empty or unempty.
320 <<WidgetViewSync>>
322 This is sent to a text widget when its internal data become
323 obsolete, and again when these internal data are back in sync
324 with the widget view. The detail field (%d substitution) is
325 either true (when the widget is in sync) or false (when it is
326 not).
327 Tk defines the following virtual events for the purposes of unifying
329 bindings across multiple platforms. Users expect them to behave in the
330 following way:
331 <<Clear>>
333 Delete the currently selected widget contents.
334 <<Copy>>
336 Copy the currently selected widget contents to the clipboard.
337 <<Cut>>
339 Move the currently selected widget contents to the clipboard.
340 <<LineEnd>>
342 Move to the end of the line in the current widget while dese‐
343 lecting any selected contents.
344 <<LineStart>>
346 Move to the start of the line in the current widget while dese‐
347 lecting any selected contents.
348 <<NextChar>>
350 Move to the next item (i.e., visible character) in the current
351 widget while deselecting any selected contents.
352 <<NextLine>>
354 Move to the next line in the current widget while deselecting
355 any selected contents.
356 <<NextPara>>
358 Move to the next paragraph in the current widget while deselect‐
359 ing any selected contents.
360 <<NextWord>>
362 Move to the next group of items (i.e., visible word) in the cur‐
363 rent widget while deselecting any selected contents.
364 <<Paste>>
366 Replace the currently selected widget contents with the contents
367 of the clipboard.
368 <<PasteSelection>>
370 Insert the contents of the selection at the mouse location.
371 (This event has meaningful %x and %y substitutions).
372 <<PrevChar>>
374 Move to the previous item (i.e., visible character) in the cur‐
375 rent widget while deselecting any selected contents.
376 <<PrevLine>>
378 Move to the previous line in the current widget while deselect‐
379 ing any selected contents.
380 <<PrevPara>>
382 Move to the previous paragraph in the current widget while dese‐
383 lecting any selected contents.
384 <<PrevWindow>>
386 Traverse to the previous window.
387 <<PrevWord>>
389 Move to the previous group of items (i.e., visible word) in the
390 current widget while deselecting any selected contents.
391 <<Redo>>
393 Redo one undone action.
394 <<SelectAll>>
396 Set the range of selected contents to the complete widget.
397 <<SelectLineEnd>>
399 Move to the end of the line in the current widget while extend‐
400 ing the range of selected contents.
401 <<SelectLineStart>>
403 Move to the start of the line in the current widget while
404 extending the range of selected contents.
405 <<SelectNextChar>>
407 Move to the next item (i.e., visible character) in the current
408 widget while extending the range of selected contents.
409 <<SelectNextLine>>
411 Move to the next line in the current widget while extending the
412 range of selected contents.
413 <<SelectNextPara>>
415 Move to the next paragraph in the current widget while extending
416 the range of selected contents.
417 <<SelectNextWord>>
419 Move to the next group of items (i.e., visible word) in the cur‐
420 rent widget while extending the range of selected contents.
421 <<SelectNone>>
423 Reset the range of selected contents to be empty.
424 <<SelectPrevChar>>
426 Move to the previous item (i.e., visible character) in the cur‐
427 rent widget while extending the range of selected contents.
428 <<SelectPrevLine>>
430 Move to the previous line in the current widget while extending
431 the range of selected contents.
432 <<SelectPrevPara>>
434 Move to the previous paragraph in the current widget while
435 extending the range of selected contents.
436 <<SelectPrevWord>>
438 Move to the previous group of items (i.e., visible word) in the
439 current widget while extending the range of selected contents.
440 <<ToggleSelection>>
442 Toggle the selection.
443 <<Undo>>
445 Undo the last action.
446
448 MAPPING KEYS TO VIRTUAL EVENTS
449 In order for a virtual event binding to trigger, two things must hap‐
450 pen. First, the virtual event must be defined with the event add com‐
451 mand. Second, a binding must be created for the virtual event with the
452 bind command. Consider the following virtual event definitions:
453 event add <<Paste>> <Control-y>
455 event add <<Paste>> <Button-2>
456 event add <<Save>> <Control-X><Control-S>
457 event add <<Save>> <Shift-F12>
458 if {[tk windowingsystem] eq "aqua"} {
459 event add <<Save>> <Command-s>
460 }
461 In the bind command, a virtual event can be bound like any other
463 builtin event type as follows:
464 bind Entry <<Paste>> {%W insert [selection get]}
466 The double angle brackets are used to specify that a virtual event is
468 being bound. If the user types Control-y or presses button 2, or if a
469 <<Paste>> virtual event is synthesized with event generate, then the
470 <<Paste>> binding will be invoked.
471 If a virtual binding has the exact same sequence as a separate physical
473 binding, then the physical binding will take precedence. Consider the
474 following example:
475 event add <<Paste>> <Control-y> <Meta-Control-y>
477 bind Entry <Control-y> {puts Control-y}
478 bind Entry <<Paste>> {puts Paste}
479 When the user types Control-y the <Control-y> binding will be invoked,
481 because a physical event is considered more specific than a virtual
482 event, all other things being equal. However, when the user types
483 Meta-Control-y the <<Paste>> binding will be invoked, because the Meta
484 modifier in the physical pattern associated with the virtual binding is
485 more specific than the <Control-y> sequence for the physical event.
486 Bindings on a virtual event may be created before the virtual event
488 exists. Indeed, the virtual event never actually needs to be defined,
489 for instance, on platforms where the specific virtual event would be
490 meaningless or ungeneratable.
491 When a definition of a virtual event changes at run time, all windows
493 will respond immediately to the new definition. Starting from the pre‐
494 ceding example, if the following code is executed:
495 bind Entry <Control-y> {}
497 event add <<Paste>> <Key-F6>
498 the behavior will change such in two ways. First, the shadowed
500 <<Paste>> binding will emerge. Typing Control-y will no longer invoke
501 the <Control-y> binding, but instead invoke the virtual event
502 <<Paste>>. Second, pressing the F6 key will now also invoke the
503 <<Paste>> binding.
504 MOVING THE MOUSE POINTER
506 Sometimes it is useful to be able to really move the mouse pointer. For
507 example, if you have some software that is capable of demonstrating
508 directly to the user how to use the program. To do this, you need to
509 “warp” the mouse around by using event generate, like this:
510 for {set xy 0} {$xy < 200} {incr xy} {
512 event generate . <Motion> -x $xy -y $xy -warp 1
513 update
514 after 50
515 }
516 Note that it is usually considered bad style to move the mouse pointer
518 for the user because it removes control from them. Therefore this tech‐
519 nique should be used with caution. Also note that it is not guaranteed
520 to function on all platforms.
521
523 bind(n)
524
526 event, binding, define, handle, virtual event
527Tk 8.3 event(n)