Tk_BindEvent(3tk)
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NAME
Tk_CreateBindingTable, Tk_DeleteBindingTable, Tk_CreateBinding,
Tk_DeleteBinding, Tk_GetBinding, Tk_GetAllBindings, Tk_DeleteAllBind-
ings, 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 binding
table. Also used for
returning results and errors
from binding 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
binding is associated.
CONST char *eventString (in) String describing event
sequence.
char *script (in) Tcl script to invoke when
binding triggers.
int append (in) Non-zero means append script
to existing script for bind-
ing, 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 dis-
play-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.
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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 collection of bindings plus a history of
recent events. Within a binding table, bindings are associated with
objects. The 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 can-
vas 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 as-
sociates 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 associ-
ated, and it may be any one-word value. Typically it is a pointer to a
string or data structure. 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 useful to invoke XSelectIn-
put 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_GetAllBindings returns in interp->result a list of all the event
strings for which there are bindings in bindingTable 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 bindingTable 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 pro-
cesses 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 particular
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 4.0 Tk_CreateBindingTable(3)
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