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CentOS 7.0 - man page for tk::event (centos section 3)

event(3)		       User Contributed Perl Documentation			 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 virtual 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 virtual 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 provided, 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 system.  $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 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

	   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 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.

       -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 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.  Corresponds to the 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 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.

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 virtual event is being bound.  If the
       user types Control-y or presses button 2, or if a <<Paste>> virtual event is synthesized
       with eventGenerate, 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:

	$mw->eventAdd('<<Paste>>' => '<Control-y>','<Meta-Control-y>');
	$mw->bind('Tk::Entry', '<Control-y>' => sub{print 'Control-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 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:

	$entry->bind(ref($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.

SEE ALSO
       Tk::bind Tk::callbacks

KEYWORDS
       event, binding, define, handle, virtual event

perl v5.16.3				    2014-06-10					 event(3)


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