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'\"

'\" Copyright (c) 1996 Sun Microsystems, Inc.

'\" Copyright (c) 1998 by Scriptics Corporation.

'\"

'\" See the file "license.terms" for information on usage and redistribution

'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.

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'\" RCS: @(#) $Id: event.n,v 1.1.1.1 2002-01-16 10:25:48 markom Exp $

'\"

.so man.macros

.TH event n 8.0 Tk "Tk Built-In Commands"

.BS

'\" Note:  do not modify the .SH NAME line immediately below!

.SH NAME

event \- Miscellaneous event facilities: define virtual events and generate events

.SH SYNOPSIS

\fBevent\fI option \fR?\fIarg arg ...\fR?

.BE

.SH DESCRIPTION

.PP

The \fBevent\fR 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:

.TP

\fBevent add <<\fIvirtual\fB>>\fI sequence \fR?\fIsequence ...\fR?

Associates the virtual event \fIvirtual\fR with the physical

event sequence(s) given by the \fIsequence\fR arguments, so that

the virtual event will trigger whenever any one of the \fIsequence\fRs

occurs.

\fIVirtual\fR may be any string value and \fIsequence\fR may have

any of the values allowed for the \fIsequence\fR argument to the

\fBbind\fR command.

If \fIvirtual\fR is already defined, the new physical event sequences

add to the existing sequences for the event.

.TP

\fBevent delete <<\fIvirtual\fB>> \fR?\fIsequence\fR \fIsequence ...\fR?

Deletes each of the \fIsequence\fRs from those associated with

the virtual event given by \fIvirtual\fR.

\fIVirtual\fR may be any string value and \fIsequence\fR may have

any of the values allowed for the \fIsequence\fR argument to the

\fBbind\fR command.

Any \fIsequence\fRs not currently associated with \fIvirtual\fR

are ignored.

If no \fIsequence\fR argument is provided, all physical event sequences

are removed for \fIvirtual\fR, so that the virtual event will not

trigger anymore.

.TP

\fBevent generate \fIwindow event \fR?\fIoption value option value ...\fR?

Generates a window event and arranges for it to be processed just as if

it had come from the window system.

\fIWindow\fR gives the path name of the window for which the event

.VS

will be generated; it may also be an identifier (such as returned by

\fBwinfo id\fR) as long as it is for a window in the current application.

.VE

\fIEvent\fR provides a basic description of

the event, such as \fB\fR or \fB<>\fR.

\fIEvent\fR may have any of the forms allowed for the \fIsequence\fR

argument of the \fBbind\fR command except that it must consist

of a single event pattern, not a sequence.

\fIOption-value\fR 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 \fB\-when\fR option is not specified, the

event is processed immediately:  all of the handlers for the event

will complete before the \fBevent generate\fR command returns.

If the \fB\-when\fR option is specified then it determines when the

event is processed.

.TP

\fBevent info \fR?<<\fIvirtual\fB>>\fR?

Returns information about virtual events.

If the \fB<<\fIvirtual\fB>>\fR argument is omitted, the return value

is a list of all the virtual events that are currently defined.

If \fB<<\fIvirtual\fB>>\fR 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.

.SH "EVENT FIELDS"

.PP

The following options are supported for the \fBevent generate\fR

command.  These correspond to the ``%'' expansions

allowed in binding scripts for the \fBbind\fR command.

.TP

\fB\-above\fI window\fR

\fIWindow\fR specifies the \fIabove\fR field for the event,

either as a window path name or as an integer window id.

Valid for \fBConfigure\fR events.

Corresponds to the \fB%a\fR substitution for binding scripts.

.TP

\fB\-borderwidth\fI size\fR

\fISize\fR must be a screen distance;  it specifies the

\fIborder_width\fR field for the event.

Valid for \fBConfigure\fR events.

Corresponds to the \fB%B\fR substitution for binding scripts.

.TP

\fB\-button\fI number\fR

\fINumber\fR must be an integer;  it specifies the \fIdetail\fR field

for a \fBButtonPress\fR or \fBButtonRelease\fR event, overriding

any button  number provided in the base \fIevent\fR argument.

Corresponds to the \fB%b\fR substitution for binding scripts.

.TP

\fB\-count\fI number\fR

\fINumber\fR must be an integer;  it specifies the \fIcount\fR field

for the event.  Valid for \fBExpose\fR events.

Corresponds to the \fB%c\fR substitution for binding scripts.

.TP

\fB\-delta\fI number\fR

.VS

\fINumber\fR must be an integer;  it specifies the \fIdelta\fR field

for the \fBMouseWheel\fR event.  The \fIdelta\fR 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

\fB%D\fR substitution for binding scripts.

.VE

.TP

\fB\-detail\fI detail\fR

\fIDetail\fR specifies the \fIdetail\fR field for the event

and must be one of the following:

.RS

.DS

.ta 6c

\fBNotifyAncestor       NotifyNonlinearVirtual

NotifyDetailNone        NotifyPointer

NotifyInferior  NotifyPointerRoot

NotifyNonlinear NotifyVirtual\fR

.DE

Valid for \fBEnter\fR, \fBLeave\fR, \fBFocusIn\fR and

\fBFocusOut\fR events.

Corresponds to the \fB%d\fR substitution for binding scripts.

.RE

.TP

\fB\-focus\fI boolean\fR

\fIBoolean\fR must be a boolean value;  it specifies the \fIfocus\fR

field for the event.

Valid for \fBEnter\fR and \fBLeave\fR events.

Corresponds to the \fB%f\fR substitution for binding scripts.

.TP

\fB\-height\fI size\fR

\fISize\fR must be a screen distance;  it specifies the \fIheight\fR

field for the event.  Valid for \fBConfigure\fR events.

Corresponds to the \fB%h\fR substitution for binding scripts.

.TP

\fB\-keycode\fI number\fR

\fINumber\fR  must be an integer;  it specifies the \fIkeycode\fR

field for the event.

Valid for \fBKeyPress\fR and \fBKeyRelease\fR events.

Corresponds to the \fB%k\fR substitution for binding scripts.

.TP

\fB\-keysym\fI name\fR

\fIName\fR must be the name of a valid keysym, such as \fBg\fR,

\fBspace\fR, or \fBReturn\fR;  its corresponding

keycode value is used as the \fIkeycode\fR field for event, overriding

any detail specified in the base \fIevent\fR argument.

Valid for \fBKeyPress\fR and \fBKeyRelease\fR events.

Corresponds to the \fB%K\fR substitution for binding scripts.

.TP

\fB\-mode\fI notify\fR

\fINotify\fR specifies the \fImode\fR field for the event and must be

one of \fBNotifyNormal\fR, \fBNotifyGrab\fR, \fBNotifyUngrab\fR, or

\fBNotifyWhileGrabbed\fR.

Valid for \fBEnter\fR, \fBLeave\fR, \fBFocusIn\fR, and

\fBFocusOut\fR events.

Corresponds to the \fB%m\fR substitution for binding scripts.

.TP

\fB\-override\fI boolean\fR

\fIBoolean\fR must be a boolean value;  it specifies the

\fIoverride_redirect\fR field for the event.

Valid for \fBMap\fR, \fBReparent\fR, and \fBConfigure\fR events.

Corresponds to the \fB%o\fR substitution for binding scripts.

.TP

\fB\-place\fI where\fR

\fIWhere\fR specifies the \fIplace\fR field for the event;  it must be

either \fBPlaceOnTop\fR or \fBPlaceOnBottom\fR.

Valid for \fBCirculate\fR events.

Corresponds to the \fB%p\fR substitution for binding scripts.

.TP

\fB\-root\fI window\fR

\fIWindow\fR must be either a window path name or an integer window

identifier;  it specifies the \fIroot\fR field for the event.

Valid for \fBKeyPress\fR, \fBKeyRelease\fR, \fBButtonPress\fR,

\fBButtonRelease\fR, \fBEnter\fR, \fBLeave\fR, and \fBMotion\fR

events.

Corresponds to the \fB%R\fR substitution for binding scripts.

.TP

\fB\-rootx\fI coord\fR

\fICoord\fR must be a screen distance;  it specifies the \fIx_root\fR

field for the event.

Valid for \fBKeyPress\fR, \fBKeyRelease\fR, \fBButtonPress\fR,

\fBButtonRelease\fR, \fBEnter\fR, \fBLeave\fR, and \fBMotion\fR

events.  Corresponds to the \fB%X\fR substitution for binding scripts.

.TP

\fB\-rooty\fI coord\fR

\fICoord\fR must be a screen distance;  it specifies th \fIy_root\fR

field for the event.

Valid for \fBKeyPress\fR, \fBKeyRelease\fR, \fBButtonPress\fR,

\fBButtonRelease\fR, \fBEnter\fR, \fBLeave\fR, and \fBMotion\fR

events.

Corresponds to the \fB%Y\fR substitution for binding scripts.

.TP

\fB\-sendevent\fI boolean\fR

\fBBoolean\fR must be a boolean value;  it specifies the \fIsend_event\fR

field for the event.  Valid for all events.  Corresponds to the

\fB%E\fR substitution for binding scripts.

.TP

\fB\-serial\fI number\fR

\fINumber\fR must be an integer;  it specifies the \fIserial\fR field

for the event.  Valid for all events.

Corresponds to the \fB%#\fR substitution for binding scripts.

.TP

\fB\-state\fI state\fR

\fIState\fR specifies the \fIstate\fR field for the event.

For \fBKeyPress\fR, \fBKeyRelease\fR, \fBButtonPress\fR,

\fBButtonRelease\fR, \fBEnter\fR, \fBLeave\fR, and \fBMotion\fR events

it must be an integer value.

For \fBVisibility\fR events it must be one of \fBVisibilityUnobscured\fR,

\fBVisibilityPartiallyObscured\fR, or \fBVisibilityFullyObscured\fR.

This option overrides any modifiers such as \fBMeta\fR or \fBControl\fR

specified in the base \fIevent\fR.

Corresponds to the \fB%s\fR substitution for binding scripts.

.TP

\fB\-subwindow\fI window\fR

\fIWindow\fR specifies the \fIsubwindow\fR field for the event, either

as a path name for a Tk widget or as an integer window identifier.

Valid for \fBKeyPress\fR, \fBKeyRelease\fR, \fBButtonPress\fR,

\fBButtonRelease\fR, \fBEnter\fR, \fBLeave\fR, and \fBMotion\fR events.

Similar to \fB%S\fR substitution for binding scripts.

.TP

\fB\-time\fI integer\fR

\fIInteger\fR must be an integer value;  it specifies the \fItime\fR field

for the event.

Valid for \fBKeyPress\fR, \fBKeyRelease\fR, \fBButtonPress\fR,

\fBButtonRelease\fR, \fBEnter\fR, \fBLeave\fR, \fBMotion\fR,

and \fBProperty\fR events.

Corresponds to the \fB%t\fR substitution for binding scripts.

.TP

\fB\-width\fI size\fR

\fISize\fR must be a screen distance;  it specifies the \fIwidth\fR field

for the event.

Valid for \fBConfigure\fR events.

Corresponds to the \fB%w\fR substitution for binding scripts.

.TP

\fB\-when\fI when\fR

\fIWhen\fR determines when the event will be processed;  it must have one

of the following values:

.RS

.IP \fBnow\fR 10

Process the event immediately, before the command returns.

This also happens if the \fB\-when\fR option is omitted.

.IP \fBtail\fR 10

Place the event on Tcl's event queue behind any events already

queued for this application.

.IP \fBhead\fR 10

Place the event at the front of Tcl's event queue, so that it

will be handled before any other events already queued.

.IP \fBmark\fR 10

Place the event at the front of Tcl's event queue but behind any

other events already queued with \fB\-when mark\fR.

This option is useful when generating a series of events that should

be processed in order but at the front of the queue.

.RE

.TP

\fB\-x\fI coord\fR

\fICoord\fR must be a screen distance;  it specifies the \fIx\fR field

for the event.

Valid for \fBKeyPress\fR, \fBKeyRelease\fR, \fBButtonPress\fR,

\fBButtonRelease\fR, \fBMotion\fR, \fBEnter\fR, \fBLeave\fR,

\fBExpose\fR, \fBConfigure\fR, \fBGravity\fR, and \fBReparent\fR

events.

Corresponds to the the \fB%x\fR substitution for binding scripts.

.TP

\fB\-y\fI coord\fR

\fICoord\fR must be a screen distance;  it specifies the \fIy\fR

field for the event.

Valid for \fBKeyPress\fR, \fBKeyRelease\fR, \fBButtonPress\fR,

\fBButtonRelease\fR, \fBMotion\fR, \fBEnter\fR, \fBLeave\fR,

\fBExpose\fR, \fBConfigure\fR, \fBGravity\fR, and \fBReparent\fR

events.

Corresponds to the the \fB%y\fR substitution for binding scripts.

.PP

Any options that are not specified when generating an event are filled

with the value 0, except for \fIserial\fR, which is filled with the

next X event serial number.

.SH "VIRTUAL EVENT EXAMPLES"

.PP

In order for a virtual event binding to trigger, two things must

happen.  First, the virtual event must be defined with the

\fBevent add\fR command.  Second, a binding must be created for

the virtual event with the \fBbind\fR command.

Consider the following virtual event definitions:

.CS

event add <> 

event add <> 

event add <> 

event add <> 

.CE

In the \fBbind\fR command, a virtual event can be bound like any other

builtin event type as follows:

.CS

bind Entry <> {%W insert [selection get]}

.CE

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 \fB<>\fR virtual event is synthesized with \fBevent generate\fR,

then the \fB<>\fR binding will be invoked.

.PP

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:

.CS

event add <>  

bind Entry  {puts Control-y}

bind Entry <> {puts Paste}

.CE

When the user types Control-y the \fB\fR 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

\fB<>\fR binding will be invoked, because the

\fBMeta\fR modifier in the physical pattern associated with the

virtual binding is more specific than the \fB sequence for

the physical event.

.PP

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.

.PP

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:

.CS

bind   {}

event add <> 

.CE

the behavior will change such in two ways.  First, the shadowed

\fB<>\fR binding will emerge.

Typing Control-y will no longer invoke the \fB\fR binding,

but instead invoke the virtual event \fB<>\fR.  Second,

pressing the F6 key will now also invoke the \fB<>\fR binding.

.SH "SEE ALSO"

bind

.SH KEYWORDS

event, binding, define, handle, virtual event