Tk_CreateBindingTable(3Tk)Tk_CreateBindingTable(3Tk)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)
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.
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
binding, if any; zero means
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Tk_CreateBindingTable(3Tk)Tk_CreateBindingTable(3Tk)
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 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
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Tk_CreateBindingTable(3Tk)Tk_CreateBindingTable(3Tk)
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 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 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
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