Tk Built-In Commands event(1T)
NAME
event - Miscellaneous event facilities: define virtual
events and generate events
SYNOPSIS
event option ?arg arg ...?
DESCRIPTION
The event command provides several facilities for dealing
with window system events, such as defining virtual events
and synthesizing events. The command has several different
forms, determined by the first argument. The following
forms are currently supported:
event add <> sequence ?sequence ...?
Associates the virtual event virtual with the physical
event sequence(s) given by the sequence arguments, so
that the virtual event will trigger whenever any one of
the sequences occurs. Virtual may be any string value
and sequence may have any of the values allowed for the
sequence argument to the bind command. If virtual is
already defined, the new physical event sequences add
to the existing sequences for the event.
event delete <> ?sequence sequence ...?
Deletes each of the sequences from those associated
with the virtual event given by virtual. Virtual may
be any string value and sequence may have any of the
values allowed for the sequence argument to the bind
command. Any sequences not currently associated with
virtual are ignored. If no sequence argument is pro-
vided, all physical event sequences are removed for
virtual, so that the virtual event will not trigger
anymore.
event generate window event ?option value option value ...?
Generates a window event and arranges for it to be pro-
cessed just as if it had come from the window system.
Window gives the path name of the window for which the
event will be generated; it may also be an identifier
(such as returned by winfo id) as long as it is for a
window in the current application. Event provides a
basic description of the event, such as or <>. If Window is empty the whole screen
is meant, and coordinates are relative to the screen.
Event may have any of the forms allowed for the
sequence argument of the bind command except that it
must consist of a single event pattern, not a sequence.
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Tk Built-In Commands event(1T)
Option-value pairs may be used to specify additional
attributes of the event, such as the x and y mouse
position; see EVENT FIELDS below. If the -when option
is not specified, the event is processed immediately:
all of the handlers for the event will complete before
the event generate command returns. If the -when
option is specified then it determines when the event
is processed. Certain events, such as key events,
require that the window has focus to receive the event
properly.
event info ?<>?
Returns information about virtual events. If the
<> argument is omitted, the return value is a
list of all the virtual events that are currently
defined. If <> is specified then the return
value is a list whose elements are the physical event
sequences currently defined for the given virtual
event; if the virtual event is not defined then an
empty string is returned.
EVENT FIELDS
The following options are supported for the event generate
command. These correspond to the ``%'' expansions allowed
in binding scripts for the bind command.
-above window
Window specifies the above field for the event, either
as a window path name or as an integer window id.
Valid for Configure events. Corresponds to the %a sub-
stitution for binding scripts.
-borderwidth size
Size must be a screen distance; it specifies the
borderwidth field for the event. Valid for Configure
events. Corresponds to the %B substitution for binding
scripts.
-button number
Number must be an integer; it specifies the detail
field for a ButtonPress or ButtonRelease event, over-
riding any button number provided in the base event
argument. Corresponds to the %b substitution for bind-
ing scripts.
-count number
Number must be an integer; it specifies the count
field for the event. Valid for Expose events.
Corresponds to the %c substitution for binding scripts.
-delta number
Number must be an integer; it specifies the delta
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Tk Built-In Commands event(1T)
field for the MouseWheel event. The delta refers to
the direction and magnitude the mouse wheel was
rotated. Note the value is not a screen distance but
are units of motion in the mouse wheel. Typically
these values are multiples of 120. For example, 120
should scroll the text widget up 4 lines and -240 would
scroll the text widget down 8 lines. Of course, other
widgets may define different behaviors for mouse wheel
motion. This field corresponds to the %D substitution
for binding scripts.
-detail detail
Detail specifies the detail field for the event and
must be one of the following:
NotifyAncestor NotifyNonlinearVirtual
NotifyDetailNone NotifyPointer
NotifyInferior NotifyPointerRoot
NotifyNonlinear NotifyVirtual
Valid for Enter, Leave, FocusIn and FocusOut events.
Corresponds to the %d substitution for binding scripts.
-focus boolean
Boolean must be a boolean value; it specifies the
focus field for the event. Valid for Enter and Leave
events. Corresponds to the %f substitution for binding
scripts.
-height size
Size must be a screen distance; it specifies the
height field for the event. Valid for Configure
events. Corresponds to the %h substitution for binding
scripts.
-keycode number
Number must be an integer; it specifies the keycode
field for the event. Valid for KeyPress and KeyRelease
events. Corresponds to the %k substitution for binding
scripts.
-keysym name
Name must be the name of a valid keysym, such as g,
space, or Return; its corresponding keycode value is
used as the keycode field for event, overriding any
detail specified in the base event argument. Valid for
KeyPress and KeyRelease events. Corresponds to the %K
substitution for binding scripts.
-mode notify
Notify specifies the mode field for the event and must
be one of NotifyNormal, NotifyGrab, NotifyUngrab, or
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Tk Built-In Commands event(1T)
NotifyWhileGrabbed. Valid for Enter, Leave, FocusIn,
and FocusOut events. Corresponds to the %m substitu-
tion for binding scripts.
-override boolean
Boolean must be a boolean value; it specifies the
overrideredirect field for the event. Valid for Map,
Reparent, and Configure events. Corresponds to the %o
substitution for binding scripts.
-place where
Where specifies the place field for the event; it must
be either PlaceOnTop or PlaceOnBottom. Valid for Cir-
culate events. Corresponds to the %p substitution for
binding scripts.
-root window
Window must be either a window path name or an integer
window identifier; it specifies the root field for the
event. Valid for KeyPress, KeyRelease, ButtonPress,
ButtonRelease, Enter, Leave, and Motion events.
Corresponds to the %R substitution for binding scripts.
-rootx coord
Coord must be a screen distance; it specifies the
xroot field for the event. Valid for KeyPress,
KeyRelease, ButtonPress, ButtonRelease, Enter, Leave,
and Motion events. Corresponds to the %X substitution
for binding scripts.
-rooty coord
Coord must be a screen distance; it specifies the
yroot field for the event. Valid for KeyPress,
KeyRelease, ButtonPress, ButtonRelease, Enter, Leave,
and Motion events. Corresponds to the %Y substitution
for binding scripts.
-sendevent boolean
Boolean must be a boolean value; it specifies the
sendevent field for the event. Valid for all events.
Corresponds to the %E substitution for binding scripts.
-serial number
Number must be an integer; it specifies the serial
field for the event. Valid for all events.
Corresponds to the %# substitution for binding scripts.
-state state
State specifies the state field for the event. For
KeyPress, KeyRelease, ButtonPress, ButtonRelease,
Enter, Leave, and Motion events it must be an integer
value. For Visibility events it must be one of
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Tk Built-In Commands event(1T)
VisibilityUnobscured, VisibilityPartiallyObscured, or
VisibilityFullyObscured. This option overrides any
modifiers such as Meta or Control specified in the base
event. Corresponds to the %s substitution for binding
scripts.
-subwindow window
Window specifies the subwindow field for the event,
either as a path name for a Tk widget or as an integer
window identifier. Valid for KeyPress, KeyRelease,
ButtonPress, ButtonRelease, Enter, Leave, and Motion
events. Similar to %S substitution for binding
scripts.
-time integer
Integer must be an integer value; it specifies the
time field for the event. Valid for KeyPress,
KeyRelease, ButtonPress, ButtonRelease, Enter, Leave,
Motion, and Property events. Corresponds to the %t
substitution for binding scripts.
-warp boolean
boolean must be a boolean value; it specifies whether
the screen pointer should be warped as well. Valid for
KeyPress, KeyRelease, ButtonPress, ButtonRelease, and
Motion events. The pointer will only warp to a window
if it is mapped.
-width size
Size must be a screen distance; it specifies the width
field for the event. Valid for Configure events.
Corresponds to the %w substitution for binding scripts.
-when when
When determines when the event will be processed; it
must have one of the following values:
now Process the event immediately, before the
command returns. This also happens if the
-when option is omitted.
tail Place the event on Tcl's event queue behind
any events already queued for this applica-
tion.
head Place the event at the front of Tcl's event
queue, so that it will be handled before any
other events already queued.
mark Place the event at the front of Tcl's event
queue but behind any other events already
queued with -when mark. This option is
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Tk Built-In Commands event(1T)
useful when generating a series of events
that should be processed in order but at the
front of the queue.
-x coord
Coord must be a screen distance; it specifies the x
field for the event. Valid for KeyPress, KeyRelease,
ButtonPress, ButtonRelease, Motion, Enter, Leave,
Expose, Configure, Gravity, and Reparent events.
Corresponds to the %x substitution for binding scripts.
If Window is empty the coordinate is relative to the
screen, and this option corresponds to the %X substitu-
tion for binding scripts.
-y coord
Coord must be a screen distance; it specifies the y
field for the event. Valid for KeyPress, KeyRelease,
ButtonPress, ButtonRelease, Motion, Enter, Leave,
Expose, Configure, Gravity, and Reparent events.
Corresponds to the %y substitution for binding scripts.
If Window is empty the coordinate is relative to the
screen, and this option corresponds to the %Y substitu-
tion for binding scripts.
Any options that are not specified when generating an event
are filled with the value 0, except for serial, which is
filled with the next X event serial number.
VIRTUAL EVENT EXAMPLES
In order for a virtual event binding to trigger, two things
must happen. First, the virtual event must be defined with
the event add command. Second, a binding must be created
for the virtual event with the bind command. Consider the
following virtual event definitions:
event add <>
event add <>
event add <>
event add <>
In the bind command, a virtual event can be bound like any
other builtin event type as follows:
bind Entry <> {%W insert [selection get]}
The double angle brackets are used to specify that a virtual
event is being bound. If the user types Control-y or
presses button 2, or if a <> virtual event is syn-
thesized with event generate, then the <> binding
will be invoked.
If a virtual binding has the exact same sequence as a
separate physical binding, then the physical binding will
take precedence. Consider the following example:
event add <>
bind Entry {puts Control-y}
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Tk Built-In Commands event(1T)
bind Entry <> {puts Paste}
When the user types Control-y the binding will
be invoked, because a physical event is considered more
specific than a virtual event, all other things being equal.
However, when the user types Meta-Control-y the <>
binding will be invoked, because the Meta modifier in the
physical pattern associated with the virtual binding is more
specific than the sequence for the physical
event.
Bindings on a virtual event may be created before the vir-
tual event exists. Indeed, the virtual event never actually
needs to be defined, for instance, on platforms where the
specific virtual event would meaningless or ungeneratable.
When a definition of a virtual event changes at run time,
all windows will respond immediately to the new definition.
Starting from the preceding example, if the following code
is executed:
bind {}
event add <>
the behavior will change such in two ways. First, the sha-
dowed <> binding will emerge. Typing Control-y will
no longer invoke the binding, but instead invoke
the virtual event <>. Second, pressing the F6 key
will now also invoke the <> binding.
SEE ALSO
bind(1T)
KEYWORDS
event, binding, define, handle, virtual event
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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