event(n) manual page
Table of Contents
event - Miscellaneous event facilities: define
virtual events and generate events
event option ?arg arg ...?
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 <<virtual>> 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 <<virtual>> ?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 provided, 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 processed 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 <Shift-Button-2> or <<Paste>>. 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. 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 ?<<virtual>>?
- Returns information about virtual events. If the <<virtual>> argument is omitted,
the return value is a list of all the virtual events that are currently
defined. If <<virtual>> 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.
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 substitution for binding scripts.
- -borderwidth size
- Size must be a screen distance; it specifies the border_width
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, overriding any
button number provided in the base event argument. Corresponds to the %b
substitution for binding 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 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
- -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 NotifyWhileGrabbed. Valid for Enter, Leave,
FocusIn, and FocusOut events. Corresponds to the %m substitution for binding
scripts.
- -override boolean
- Boolean must be a boolean value; it specifies
the override_redirect 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 Circulate 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 x_root 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 y_root 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 send_event 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 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 application.
- 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 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 substitution
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 substitution 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.
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 <<Paste>> <Control-y>
event add <<Paste>> <Button-2>
event add <<Save>> <Control-X><Control-S>
event add <<Save>> <Shift-F12>
In the bind command, a virtual event can be bound like any other builtin
event type as follows:
bind Entry <<Paste>> {%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 <<Paste>> virtual
event is synthesized with event generate, then the <<Paste>> 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 <<Paste>> <Control-y> <Meta-Control-y>
bind Entry <Control-y> {puts Control-y}
bind Entry <<Paste>> {puts Paste}
When the user types Control-y the <Control-y> 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
<<Paste>> binding will be invoked, because the Meta modifier in the physical
pattern associated with the virtual binding is more specific than the
<Control-y> sequence for the physical event.
Bindings on a virtual event may
be created before the virtual 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 <Entry> <Control-y> {}
event add <<Paste>> <Key-F6>
the behavior will change such in two ways. First, the shadowed <<Paste>> binding
will emerge. Typing Control-y will no longer invoke the <Control-y> binding,
but instead invoke the virtual event <<Paste>>. Second, pressing the F6 key
will now also invoke the <<Paste>> binding.
bind(n)
event,
binding, define, handle, virtual event
Table of Contents
![[Go to CFHT Home Page]](/images/cfht-icon.gif){kind=icon}
Man Pages 
Back to Software Index 
Manpage Top Level