event(n)						       Tk Built-In Commands							  event(n)

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NAME

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

SYNOPSIS

       event option ?arg arg ...?
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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 <<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.

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 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 substitu-
	      tion 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 substitu-
	      tion 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 Noti-
	      fyNonlinear	  NotifyVirtual Valid for Enter, Leave, FocusIn and FocusOut events.  Corresponds to the %d substitution for bind-
	      ing 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.  Corre-
	      sponds 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, Button-
	      Release, Enter, Leave, and Motion events.  Corresponds to the %X substitution for binding scripts.

       -rooty coord
	      Coord  must be a screen distance;  it specifies th y_root field for the event.  Valid for KeyPress, KeyRelease, ButtonPress, Button-
	      Release, 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, Button-
	      Release, 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, ButtonRe-
	      lease, 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 bind-
	      ing scripts.

       -y coord
	      Coord must be a screen distance;	it specifies the y field for the event.  Valid for KeyPress,  KeyRelease,  ButtonPress,  ButtonRe-
	      lease,  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  bind-
	      ing 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  com-
       mand.  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>>  bind-
       ing.

SEE ALSO

       bind

KEYWORDS

       event, binding, define, handle, virtual event

Tk									8.3								  event(n)