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Tk_CreateBinding(3tk)





Tk_CreateBindingTable(3Tk Library ProcedureTk_CreateBindingTable(3)


_________________________________________________________________


NAME

     Tk_CreateBindingTable,                Tk_DeleteBindingTable,
     Tk_CreateBinding,      Tk_DeleteBinding,      Tk_GetBinding,
     Tk_GetAllBindings,  Tk_DeleteAllBindings,   Tk_BindEvent   -
     invoke scripts in response to X events


SYNOPSIS

     #include <tk.h>

     Tk_BindingTable
     Tk_CreateBindingTable(interp)

     Tk_DeleteBindingTable(bindingTable)

     unsigned long
     Tk_CreateBinding(interp, bindingTable, object, eventString, script, append)

     int
     Tk_DeleteBinding(interp, bindingTable, object, eventString)

     const char *
     Tk_GetBinding(interp, bindingTable, object, eventString)

     Tk_GetAllBindings(interp, bindingTable, object)

     Tk_DeleteAllBindings(bindingTable, object)

     Tk_BindEvent(bindingTable, eventPtr, tkwin, numObjects, objectPtr)


ARGUMENTS

     Tcl_Interp *interp (in)                    Interpreter    to
                                                use when invoking
                                                bindings in bind-
                                                ing  table.  Also
                                                used for  return-
                                                ing  results  and
                                                errors from bind-
                                                ing procedures.

     Tk_BindingTable bindingTable (in)          Token for binding
                                                table;  must have
                                                been returned  by
                                                some     previous
                                                call           to
                                                Tk_CreateBindingTable.

     ClientData object (in)                     Identifies object
                                                with  which bind-
                                                ing  is   associ-
                                                ated.

Tk                      Last change: 4.0                        1


Tk_CreateBindingTable(3Tk Library ProcedureTk_CreateBindingTable(3)


     const char *eventString (in)               String describing
                                                event sequence.

     char *script (in)                          Tcl   script   to
                                                invoke when bind-
                                                ing triggers.

     int append (in)                            Non-zero    means
                                                append  script to
                                                existing   script
                                                for  binding,  if
                                                any;  zero  means
                                                replace  existing
                                                script  with  new
                                                one.

     XEvent *eventPtr (in)                      X event to  match
                                                against  bindings
                                                in bindingTable.

     Tk_Window tkwin (in)                       Identifier    for
                                                any window on the
                                                display where the
                                                event   occurred.
                                                Used   to    find
                                                display-related
                                                information  such
                                                as key maps.

     int numObjects (in)                        Number of  object
                                                identifiers
                                                pointed   to   by
                                                objectPtr.

     ClientData *objectPtr (in)                 Points   to    an
                                                array  of  object
                                                identifiers:
                                                bindings  will be
                                                considered    for
                                                each   of   these
                                                objects in  order
                                                from   first   to
                                                last.
_________________________________________________________________


DESCRIPTION

     These procedures provide  a  general-purpose  mechanism  for
     creating  and  invoking bindings.  Bindings are organized in
     terms of binding tables.  A binding table consists of a col-
     lection of bindings plus a history of recent events.  Within
     a binding table, bindings are associated with objects.   The

Tk                      Last change: 4.0                        2


Tk_CreateBindingTable(3Tk Library ProcedureTk_CreateBindingTable(3)


     meaning  of  an  object is defined by clients of the binding
     package.  For example, Tk keeps uses one  binding  table  to
     hold  all  of the bindings created by the bind command.  For
     this table, objects are pointers to strings such  as  window
     names,  class  names, or other binding tags such as all.  Tk
     also keeps a separate binding table for each canvas  widget,
     which  manages  bindings created by the canvas's bind widget
     command;  within this table, an object is either  a  pointer
     to  the  internal  structure  for  a canvas item or a Tk_Uid
     identifying a tag.

     The procedure Tk_CreateBindingTable creates  a  new  binding
     table  and  associates  interp with it (when bindings in the
     table are invoked, the scripts will be evaluated in interp).
     Tk_CreateBindingTable  returns  a token for the table, which
     must  be  used  in  calls  to  other  procedures   such   as
     Tk_CreateBinding or Tk_BindEvent.

     Tk_DeleteBindingTable frees all of the state associated with
     a  binding table.  Once it returns the caller should not use
     the bindingTable token again.

     Tk_CreateBinding adds a new binding to  an  existing  table.
     The  object  argument  identifies  the object with which the
     binding is to be associated, and  it  may  be  any  one-word
     value.  Typically it is a pointer to a string or data struc-
     ture.  The eventString  argument  identifies  the  event  or
     sequence  of  events for the binding;  see the documentation
     for the bind  command  for  a  description  of  its  format.
     script  is  the  Tcl script to be evaluated when the binding
     triggers.  append indicates what  to  do  if  there  already
     exists  a  binding for object and eventString:  if append is
     zero then script replaces the  old  script;   if  append  is
     non-zero  then  the  new  script is appended to the old one.
     Tk_CreateBinding returns an X event mask for all the  events
     associated  with the bindings.  This information may be use-
     ful to invoke XSelectInput to select relevant events, or  to
     disallow the use of certain events in bindings.  If an error
     occurred  while  creating  the  binding  (e.g.,  eventString
     refers  to  a non-existent event), then 0 is returned and an
     error message is left in interp->result.

     Tk_DeleteBinding removes from bindingTable the binding given
     by  object  and  eventString,  if  such  a  binding  exists.
     Tk_DeleteBinding always returns TCL_OK.  In  some  cases  it
     may reset interp->result to the default empty value.

     Tk_GetBinding returns a pointer  to  the  script  associated
     with  eventString  and  object  in bindingTable.  If no such
     binding exists then NULL is returned and an error message is
     left in interp->result.

Tk                      Last change: 4.0                        3


Tk_CreateBindingTable(3Tk Library ProcedureTk_CreateBindingTable(3)


     Tk_GetAllBindings returns in interp->result a  list  of  all
     the  event strings for which there are bindings in bindingT-
     able associated with object.  If there are no  bindings  for
     object then an empty string is returned in interp->result.

     Tk_DeleteAllBindings deletes all of  the  bindings  in  bin-
     dingTable that are associated with object.

     Tk_BindEvent is called to process an event.  It makes a copy
     of the event in an internal history list associated with the
     binding table, then it checks for bindings  that  match  the
     event.   Tk_BindEvent  processes each of the objects pointed
     to by objectPtr in turn.  For each object, it finds all  the
     bindings  that  match the current event history, selects the
     most specific binding using the priority mechanism described
     in  the  documentation  for bind, and invokes the script for
     that binding.  If there are no matching bindings for a  par-
     ticular  object,  then  the object is skipped.  Tk_BindEvent
     continues through all of the  objects,  handling  exceptions
     such  as  errors,  break,  and  continue as described in the
     documentation for bind.


KEYWORDS

     binding, event, object, script

Tk                      Last change: 4.0                        4


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