path: root/doc/BindTable.3

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'\" Copyright (c) 1994 The Regents of the University of California.
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.TH Tk_CreateBindingTable 3 4.0 Tk "Tk Library Procedures"
.so man.macros
.BS
.SH NAME
Tk_CreateBindingTable, Tk_DeleteBindingTable, Tk_CreateBinding, Tk_DeleteBinding, Tk_GetBinding, Tk_GetAllBindings, Tk_DeleteAllBindings, Tk_BindEvent \- invoke scripts in response to X events
.SH SYNOPSIS
.nf
\fB#include <tk.h>\fR
.sp
Tk_BindingTable
\fBTk_CreateBindingTable(\fIinterp\fB)\fR
.sp
\fBTk_DeleteBindingTable(\fIbindingTable\fB)\fR
.sp
unsigned long
\fBTk_CreateBinding(\fIinterp, bindingTable, object, eventString, script, append\fB)\fR
.sp
int
\fBTk_DeleteBinding(\fIinterp, bindingTable, object, eventString\fB)\fR
.sp
const char *
\fBTk_GetBinding(\fIinterp, bindingTable, object, eventString\fB)\fR
.sp
\fBTk_GetAllBindings(\fIinterp, bindingTable, object\fB)\fR
.sp
\fBTk_DeleteAllBindings(\fIbindingTable, object\fB)\fR
.sp
\fBTk_BindEvent(\fIbindingTable, eventPtr, tkwin, numObjects, objectPtr\fB)\fR
.SH ARGUMENTS
.AS Tk_BindingTable bindingTable
.AP Tcl_Interp *interp in
Interpreter to use when invoking bindings in binding table.  Also
used for returning results and errors from binding procedures.
.AP Tk_BindingTable bindingTable in
Token for binding table;  must have been returned by some previous
call to \fBTk_CreateBindingTable\fR.
.AP "void *" object in
Identifies object with which binding is associated.
.AP "const char" *eventString in
String describing event sequence.
.AP "const char" *script in
Tcl script to invoke when binding triggers.
.AP int append in
Non-zero means append \fIscript\fR to existing script for binding,
if any; zero means replace existing script with new one.
.AP XEvent *eventPtr in
X event to match against bindings in \fIbindingTable\fR.
.AP 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.
.AP Tcl_Size numObjects in
Number of object identifiers pointed to by \fIobjectPtr\fR.
.AP "void **" objectPtr in
Points to an array of object identifiers:  bindings will be considered
for each of these objects in order from first to last.
.BE
.SH DESCRIPTION
.PP
These procedures provide a general-purpose mechanism for creating
and invoking bindings.
Bindings are organized in terms of \fIbinding tables\fR.
A binding table consists of a collection of bindings plus a history
of recent events.
Within a binding table, bindings are associated with \fIobjects\fR.
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 \fBbind\fR command.
For this table, objects are pointers to strings such as window names, class
names, or other binding tags such as \fBall\fR.
Tk also keeps a separate binding table for each canvas widget, which manages
bindings created by the canvas's \fBbind\fR 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.
.PP
The procedure \fBTk_CreateBindingTable\fR creates a new binding
table and associates \fIinterp\fR with it (when bindings in the
table are invoked, the scripts will be evaluated in \fIinterp\fR).
\fBTk_CreateBindingTable\fR returns a token for the table, which
must be used in calls to other procedures such as \fBTk_CreateBinding\fR
or \fBTk_BindEvent\fR.
.PP
\fBTk_DeleteBindingTable\fR frees all of the state associated
with a binding table.
Once it returns the caller should not use the \fIbindingTable\fR
token again.
.PP
\fBTk_CreateBinding\fR adds a new binding to an existing table.
The \fIobject\fR 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 \fIeventString\fR argument identifies the event or sequence
of events for the binding;  see the documentation for the
\fBbind\fR command for a description of its format.
\fIscript\fR is the Tcl script to be evaluated when the binding
triggers.
\fIappend\fR indicates what to do if there already
exists a binding for \fIobject\fR and \fIeventString\fR:  if \fIappend\fR
is zero then \fIscript\fR replaces the old script;  if \fIappend\fR
is non-zero then the new script is appended to the old one.
\fBTk_CreateBinding\fR returns an X event mask for all the events
associated with the bindings.
This information may be useful to invoke \fBXSelectInput\fR to
select relevant events, or to disallow the use of certain events
in bindings.
If an error occurred while creating the binding (e.g., \fIeventString\fR
refers to a non-existent event), then 0 is returned and an error
message is left as the result of interpreter \fIinterp\fR.
.PP
\fBTk_DeleteBinding\fR removes from \fIbindingTable\fR the
binding given by \fIobject\fR and \fIeventString\fR, if
such a binding exists.
\fBTk_DeleteBinding\fR always returns \fBTCL_OK\fR.
In some cases it may reset the interpreter result to the default
empty value.
.PP
\fBTk_GetBinding\fR returns a pointer to the script associated
with \fIeventString\fR and \fIobject\fR in \fIbindingTable\fR.
If no such binding exists then NULL is returned and an error
message is left as the result of interpreter \fIinterp\fR.
.PP
\fBTk_GetAllBindings\fR returns in \fIinterp\fR's result a list
of all the event strings for which there are bindings in
\fIbindingTable\fR associated with \fIobject\fR.
If there are no bindings for \fIobject\fR, the result will be an empty
string.
.PP
\fBTk_DeleteAllBindings\fR deletes all of the bindings in
\fIbindingTable\fR that are associated with \fIobject\fR.
.PP
\fBTk_BindEvent\fR 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.
\fBTk_BindEvent\fR processes each of the objects pointed to
by \fIobjectPtr\fR 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 \fBbind\fR,
and invokes the script for that binding.
If there are no matching bindings for a particular object, then
the object is skipped.
\fBTk_BindEvent\fR continues through all of the objects, handling
exceptions such as errors, \fBbreak\fR, and \fBcontinue\fR as
described in the documentation for \fBbind\fR.
.SH KEYWORDS
binding, event, object, script