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_CreateBind-
ingTable.
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 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 asso-
ciated 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 asso-
ciated, 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 XSe-
lectInput 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 con-
tinue as described in the documentation for bind.
KEYWORDS
binding, event, object, script
Tk 4.0 Tk_CreateBindingTable(3)