BIND(9) BIND(9)
NAME
bind - Arrange for events to invoke Tk scripts
SYNOPSIS
bind tag sequence script
bind tag sequence +script
INTRODUCTION
The bind command associates Tk scripts with window events.
If all three arguments are specified, bind will arrange for
script (a Tk script) to be evaluated whenever the event(s)
given by sequence occur in the window(s) identified by tag.
If script is prefixed with a ``+'', then it is appended to
any existing binding for sequence; otherwise script
replaces any existing binding. If script is an empty string
then the current binding for sequence is destroyed, leaving
sequence unbound. In all of the cases where a script
argument is provided, bind returns an empty string. If
script is prefixed with a ``-'', then any existing binding
for sequence, whose script is exactly the same as script, is
removed. The tag argument gives the pathname of the window
to which sequence is bound.
EVENT PATTERNS
The sequence argument specifies a sequence of one or more
event patterns, with optional white space between the
patterns. Each event pattern may take one of two forms. In
the simplest case it is a single printing ASCII character,
such as a or [. The character may not be a space character
or the character <. This form of pattern matches a KeyPress
event for the particular character. The second form of
pattern is longer but more general. It has the following
syntax:
<event-event-...-event>
The following events are accepted:
Key or Keypress
This represents the press of the character in the fol-
lowing event. If there is no following event, this rep-
resents the press of any key. The key letter may be
escaped with a backslash (\) to prevent any character
(e.g. >) from being treated specially.
Configure
This event occurs whenever the widget is configured
such that its requested size changes.
Control
This represents the press of the character in the
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following event with the Control key pressed. The char-
acter may be quoted as for Key.
ButtonPress or Button
This represents the pressed state of the mouse button
given by the following event, which should be 1, 2, or
3. If there is no following event, this represents the
press of any button. If the mouse is moved with a but-
ton pressed, the Button event is delivered in combina-
tion with a Motion event so long as the button remains
pressed.
ButtonRelease
Like ButtonPress, but represents the release of any
button.
Motion
Mouse movement.
Double
Any events in the sequence representing button presses
must be double-clicked for the sequence to match.
Map The event that a toplevel widget is mapped onto the
screen.
Unmap
The event that a toplevel widget is unmapped from the
screen.
Enter
The event of the mouse entering the widget from out-
side.
Leave
The event of the mouse leaving the boundaries of the
widget.
FocusIn
The event of the widget getting the keyboard focus.
FocusOut
The event of the widget losing the keyboard focus.
The event sequence can contain any combination of the above
events. They are treated independently, and if any of the
events occur, the sequence matches. You cannot combine key
presses of more than one key. Events will not be combined on
delivery, except that Motion events may be combined with
button presses (possibly doubled).
BINDING SCRIPTS AND SUBSTITUTIONS
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The script argument to bind is a Tk script, which will be
executed whenever the given event sequence occurs. If
script contains any % characters, then the script will not
be executed directly. Instead, a new script will be gener-
ated by replacing each %, and the character following it,
with information from the current event. The replacement
depends on the character following the %, as defined in the
list below. Unless otherwise indicated, the replacement
string is the decimal value of the given field from the cur-
rent event. Some of the substitutions are only valid for
certain types of events; if they are used for other types
of events the value substituted is undefined.
%% Replaced with a single percent.
%b The number of the button that was pressed or released.
Valid only for ButtonPress and ButtonRelease events.
%h For Configure events, this is the old requested height
of the widget.
%s For mouse events, this is the logical OR of the mouse
buttons; for keyboard events, it is the decimal value
of the pressed character.
%w For Configure events, this is the old requested width
of the widget.
%x The x coordinate from the event, relative to the origin
of the toplevel window. Valid only for Enter, Leave,
and mouse events.
%y The y coordinate from the event, relative to the origin
of the toplevel window. Valid only for Enter, Leave,
and mouse events.
%A The ASCII character corresponding to a Key event.
%K The pressed character for the event, as four hexadeci-
mal digits. Valid only for Key events.
%W The path name of the window to which the event was
reported (the window field from the event). Valid for
all event types.
%X Same as %x except that the screen coordinate system is
used.
%Y Same as %y except that the screen coordinate system is
used.
The replacement string for a %-replacement is formatted as a
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proper Tk list element. This means that it will be sur-
rounded with braces if it contains spaces, or special char-
acters such as $ and { may be preceded by backslashes. This
guarantees that the string will be passed through the Tk
parser when the binding script is evaluated.
BUGS
The above scheme is not ideal, and will probably be fixed in
the future. Quoting is a mess - in particular, the quoting
provided for the %A substitution does not work correctly
when a quoted character is re-interpreted by Tk.
The length of binding scripts is limited to 128 characters.
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