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event(n) - event, event - Miscellaneous event facilities: define virtual events and generate events - man n event

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



NAME
       event  - Miscellaneous event facilities: define virtual(5,8) events and gen-
       erate events

SYNOPSIS
       event option ?arg arg ...?


DESCRIPTION
       The event command provides several facilities for dealing  with  window
       system events, such as defining virtual(5,8) events and synthesizing events.
       The command has several different forms, determined by the first  argu-
       ment.  The following forms are currently supported:

       event add <<virtual(5,8)>> sequence ?sequence ...?
              Associates  the  virtual(5,8)  event  virtual(5,8) with the physical event
              sequence(s) given by the sequence arguments, so that the virtual(5,8)
              event  will  trigger  whenever  any one of the sequences occurs.
              Virtual may be any string(3,n) value and sequence may have any of the
              values  allowed  for  the sequence argument to the bind(2,n,1 builtins) command.
              If virtual(5,8) is already defined, the new physical event  sequences
              add to the existing sequences for the event.

       event delete <<virtual(5,8)>> ?sequence sequence ...?
              Deletes  each  of  the  sequences from those associated with the
              virtual(5,8) event given by virtual(5,8).  Virtual may be any string(3,n) value
              and sequence may have any of the values allowed for the sequence
              argument to the bind(2,n,1 builtins) command.  Any sequences not currently asso-
              ciated  with  virtual(5,8)  are  ignored.  If no sequence argument is
              provided, all physical event sequences are removed for  virtual(5,8),
              so that the virtual(5,8) 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(3,n) 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(1,8) the current application.  Event
              provides a basic description of the event, such  as  <Shift-But-
              ton-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(2,n,1 builtins) command except that it must consist of a single event  pat-
              tern, 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  han-
              dlers for the event will complete before the event generate com-
              mand returns.  If the -when option is specified then  it  deter-
              mines  when the event is processed.  Certain events, such as key
              events, require that the window has focus to receive  the  event
              properly.

       event info(1,5,n) ?<<virtual(5,8)>>?
              Returns  information  about  virtual(5,8) events.  If the <<virtual(5,8)>>
              argument is omitted, the return value is a list of all the  vir-
              tual(5,8) events that are currently defined.  If <<virtual(5,8)>> is spec-
              ified then the return value is a list  whose  elements  are  the
              physical event sequences currently defined for the given virtual(5,8)
              event;  if(3,n) the virtual(5,8) event is not defined then an empty string(3,n)
              is returned.


EVENT FIELDS
       The  following  options  are  supported for the event generate command.
       These correspond to the ``%'' expansions allowed in(1,8) binding scripts for
       the bind(2,n,1 builtins) command.

       -above window
              Window specifies the above field for the event, either as a win-
              dow 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  num-
              ber provided in(1,8) 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  substi-
              tution 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  magni-
              tude  the  mouse  wheel  was  rotated.   Note the value is not a
              screen distance but are units(1,7) of  motion  in(1,8)  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     NotifyDetail-
              None        NotifyPointer NotifyInferior          NotifyPointer-
              Root  NotifyNonlinear         NotifyVirtual  Valid  for   Enter,
              Leave,  FocusIn and FocusOut events.  Corresponds to the %d sub-
              stitution 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.  Corre-
              sponds 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(1,8)  the  base
              event argument.  Valid for KeyPress and KeyRelease events.  Cor-
              responds 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.   Corre-
              sponds to the %m substitution for binding scripts.

       -override boolean
              Boolean  must be a boolean value;  it specifies the override_re-
              direct field for the event.  Valid for Map, Reparent,  and  Con-
              figure  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 th 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 %# substi-
              tution 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,  VisibilityPartiallyOb-
              scured, or VisibilityFullyObscured.  This option  overrides  any
              modifiers  such  as Meta or Control specified in(1,8) 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(1,2,n)  field
              for  the  event.   Valid  for KeyPress, KeyRelease, ButtonPress,
              ButtonRelease, Enter, Leave, Motion, and Property events.   Cor-
              responds 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(3,n) 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(3,n)  the  -when  option  is
                        omitted.

              tail      Place the event on Tcl's event queue(1,3) behind any events
                        already queued for this application.

              head      Place the event at the front of Tcl's event queue(1,3),  so
                        that  it  will  be  handled  before  any  other events
                        already queued.

              mark      Place the event at the front of Tcl's event queue(1,3)  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(1,8) 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, Button-
              Release, 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 substitu-
              tion for binding scripts.

       -y coord
              Coord must be a screen distance;  it specifies the y  field  for
              the event.  Valid for KeyPress, KeyRelease, ButtonPress, Button-
              Release, 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 substitu-
              tion 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(5,8) event binding to trigger, two things  must  hap-
       pen.   First, the virtual(5,8) event must be defined with the event add com-
       mand.  Second, a binding must be created for the virtual(5,8) event with the
       bind(2,n,1 builtins)  command.  Consider the following virtual(5,8) 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(2,n,1 builtins) command, a virtual(5,8) event can be bound like any other builtin event
       type  as  follows: bind(2,n,1 builtins) Entry <<Paste>> {%W insert [selection get]} The
       double angle brackets are used to specify that a virtual(5,8) event is being
       bound.   If  the  user  types  Control-y  or  presses button 2, or if(3,n) a
       <<Paste>> virtual(5,8) event is synthesized with event  generate,  then  the
       <<Paste>> binding will be invoked.

       If a virtual(5,8) 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(2,n,1 builtins) Entry <Control-y> {puts(3,n)  Control-y}  bind(2,n,1 builtins)  Entry  <<Paste>>  {puts(3,n)
       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(5,8)  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(1,8) the physical pattern associated with the virtual(5,8) bind-
       ing is more specific than the <Control-y>  sequence  for  the  physical
       event.

       Bindings  on  a  virtual(5,8)  event may be created before the virtual(5,8) event
       exists.  Indeed, the virtual(5,8) event never actually needs to be  defined,
       for instance, on platforms where the specific virtual(5,8) event would mean-
       ingless or ungeneratable.

       When a definition of a virtual(5,8) event changes at run time(1,2,n),  all  windows
       will respond immediately to the new definition.  Starting from the pre-
       ceding example, if(3,n) the following code is executed: bind(2,n,1 builtins)  <Entry>  <Con-
       trol-y>  {}  event add <<Paste>> <Key-F6> the behavior will change such
       in(1,8) two ways.  First, the shadowed <<Paste>> binding will emerge.   Typ-
       ing  Control-y  will  no  longer  invoke  the  <Control-y> binding, but
       instead invoke the virtual(5,8) event <<Paste>>.  Second,  pressing  the  F6
       key will now also invoke the <<Paste>> binding.


SEE ALSO
       bind(2,n,1 builtins)


KEYWORDS
       event, binding, define, handle, virtual(5,8) event



Tk                                    8.3                             event(n)

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