Tk_CreateBindingTable(3) Tk Library Procedures Tk_CreateBindingTable(3)

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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
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.

const char *script (in) Tcl script to invoke when
binding 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.
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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 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 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 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 as the result
of interpreter interp.

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 the interpreter
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 as the result of
interpreter interp.

Tk_GetAllBindings returns in interp's 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, the result will be an
empty string.

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
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
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)