event(3)

NAME

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

SYNOPSIS

$widget->eventAction(?arg, arg, ...?);

DESCRIPTION

The eventAction methods provides several facilities for dealing with window system events, such as defining vir
tual events and synthesizing events. Virtual events are
shared by all widgets of the same MainWindow. Different MainWindows can have different virtual event.

The following methods are currently supported:

$widget->eventAdd('<<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 method. If vir_ tual is already defined, the new physical event
sequences add to the existing sequences for the event.
$widget->eventDelete('<<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 method. 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.
$widget->eventGenerate(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 sys
tem. $window is a reference to the window for which the event will be generated. 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 method 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 eventGenerate method returns. If the -when option is specified then it determines when
the event is processed.
$widget->eventInfo(?'<<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 undef
is returned.

EVENT FIELDS

The following options are supported for the eventGenerate method. These correspond to the ``%'' expansions allowed
in binding callback for the bind method.

-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 bor_ der_width field for the event. Valid for Configure events. Corresponds to the %B substitution for bind
ing 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
binding scripts.
-count => number: Number must be an integer; it specifies the count field for the event. Valid for Expose events. Corre
sponds to the %c 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 bind
ing 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 bind
ing scripts.
-keycode number: Number must be an integer; it specifies the keycode field for the event. Valid for KeyPress and KeyRe lease 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 substitu tion 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, Button Press, 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. Corre
sponds 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 Visi bilityUnobscured, VisibilityPartiallyObscured, or Vis ibilityFullyObscured. This option overrides any modi fiers 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, KeyRe lease, 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.
-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 bind
ing 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 com
mand returns. This also happens if the -when
option is omitted.
tail Place the event on perl/Tk's event queue: behind any events already queued for this
application.
head Place the event at the front of perl/Tk's: event queue, so that it will be handled before
any other events already queued.
mark Place the event at the front of perl/Tk'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. Cor responds to the the %x substitution for binding
scripts. If Window is empty the coordinate is rela
tive 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. Cor responds to the the %y substitution for binding
scripts. If Window is empty the coordinate is rela
tive 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.

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 eventAdd method. Second, a binding must be created for the virtual event with the bind method.
Consider the following virtual event definitions:: $widget->eventAdd('<<Paste>>' => '<Control-y>');
$widget->eventAdd('<<Paste>>' => '<Button-2>');
$widget->eventAdd('<<Save>>' => '<Control-X><Control; S>');
$widget->eventAdd('<<Save>>' => '<Shift-F12>');
In the bind method, a virtual event can be bound like any
other builtin event type as follows:: $entry->bind('Tk::Entry', '<<Paste>>' => sub {
$entry->Insert($entry->selectionGet) });
The double angle brackets are used to specify that a vir
tual event is being bound. If the user types Control-y or
presses button 2, or if a <<Paste>> virtual event is syn thesized with eventGenerate, then the <<Paste>> binding will be invoked.
If a virtual binding has the exact same sequence as a sep arate physical binding, then the physical binding will take precedence. Consider the following example:: $mw->eventAdd('<<Paste>>' => '<Control-y>','<Meta-Con; trol-y>');
$mw->bind('Tk::Entry', '<Control-y>' => sub{print 'Con; trol-y'});
$mw->bind('Tk::Entry', '<<Paste>>' => sub{print; '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 modi fier 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 vir tual event exists. Indeed, the virtual event never actu ally needs to be defined, for instance, on platforms where the specific virtual event would meaningless or ungenerat able.
When a definition of a virtual event changes at run time, all windows will respond immediately to the new defini tion. Starting from the preceding example, if the follow ing code is executed:: $entry->bind(ref($entry), '<Control-y>' => undef);
$entry->eventAdd('<<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.

KEYWORDS

event, binding, define, handle, virtual event

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