- NAME
- bind - Arrange for X events to invoke Tcl scripts
- SYNOPSIS
- bind tag
- bind tag sequence
- bind tag sequence script
- bind tag sequence +script
- INTRODUCTION
- EVENT PATTERNS
- MODIFIERS
- EVENT TYPES
- Activate
- Deactivate
- MouseWheel
- BINDING SCRIPTS AND SUBSTITUTIONS
- %%
- %#
- %a
- %b
- %c
- %d
- %f
- %h
- %k
- %m
- %o
- %p
- %s
- %t
- %w
- %x
- %y
- %A
- %B
- %D
- %E
- %K
- %N
- %R
- %S
- %T
- %W
- %X
- %Y
- MULTIPLE MATCHES
- MULTI-EVENT SEQUENCES AND IGNORED EVENTS
- ERRORS
- SEE ALSO
- KEYWORDS
bind - Arrange for X events to invoke Tcl scripts
bind tag
bind tag sequence
bind tag sequence script
bind tag sequence +script
The bind command associates Tcl scripts with X events.
If all three arguments are specified, bind will
arrange for script (a Tcl 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 sequence is specified without a script, then the
script currently bound to sequence is returned, or
an empty string is returned if there is no binding for sequence.
If neither sequence nor script is specified, then the
return value is a list whose elements are all the sequences
for which there exist bindings for tag.
The tag argument determines which window(s) the binding applies to.
If tag begins with a dot, as in .a.b.c, then it must
be the path name for a window; otherwise it may be an arbitrary
string.
Each window has an associated list of tags, and a binding applies
to a particular window if its tag is among those specified for
the window.
Although the bindtags command may be used to assign an
arbitrary set of binding tags to a window, the default binding
tags provide the following behavior:
-
If a tag is the name of an internal window the binding applies
to that window.
If the tag is the name of a toplevel window the binding applies
to the toplevel window and all its internal windows.
If the tag is the name of a class of widgets, such as Button,
the binding applies to all widgets in that class;
If tag has the value all,
the binding applies to all windows in the application.
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 three 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:
<modifier-modifier-type-detail>
The entire event pattern is surrounded by angle brackets.
Inside the angle brackets are zero or more modifiers, an event
type, and an extra piece of information (detail) identifying
a particular button or keysym. Any of the fields may be omitted,
as long as at least one of type and detail is present.
The fields must be separated by white space or dashes.
The third form of pattern is used to specify a user-defined, named virtual
event. It has the following syntax:
<<name>>
The entire virtual event pattern is surrounded by double angle brackets.
Inside the angle brackets is the user-defined name of the virtual event.
Modifiers, such as Shift or Control, may not be combined with a
virtual event to modify it. Bindings on a virtual event may be created
before the virtual event is defined, and if the definition of a virtual
event changes dynamically, all windows bound to that virtual event will
respond immediately to the new definition.
Modifiers consist of any of the following values:
Control Mod2, M2
Shift Mod3, M3
Lock Mod4, M4
Button1, B1 Mod5, M5
Button2, B2 Meta, M
Button3, B3 Alt
Button4, B4 Double
Button5, B5 Triple
Mod1, M1 Quadruple
Where more than one value is listed, separated by commas, the values
are equivalent.
Most of the modifiers have the obvious X meanings.
For example, Button1 requires that
button 1 be depressed when the event occurs.
For a binding to match a given event, the modifiers in the event
must include all of those specified in the event pattern.
An event may also contain additional modifiers not specified in
the binding.
For example, if button 1 is pressed while the shift and control keys
are down, the pattern <Control-Button-1> will match
the event, but <Mod1-Button-1> will not.
If no modifiers are specified, then any combination of modifiers may
be present in the event.
Meta and M refer to whichever of the
M1 through M5 modifiers is associated with the meta
key(s) on the keyboard (keysyms Meta_R and Meta_L).
If there are no meta keys, or if they are not associated with any
modifiers, then Meta and M will not match any events.
Similarly, the Alt modifier refers to whichever modifier
is associated with the alt key(s) on the keyboard (keysyms
Alt_L and Alt_R).
The Double, Triple and Quadruple modifiers are a
convenience for specifying double mouse clicks and other repeated
events. They cause a particular event pattern to be repeated 2, 3 or 4
times, and also place a time and space requirement on the sequence: for a
sequence of events to match a Double, Triple or Quadruple
pattern, all of the events must occur close together in time and without
substantial mouse motion in between. For example, <Double-Button-1>
is equivalent to <Button-1><Button-1> with the extra time and space
requirement.
The type field may be any of the standard X event types, with a
few extra abbreviations. The type field will also accept a
couple non-standard X event types that were added to better support
the Macintosh and Windows platforms. Below is a list of all the valid
types; where two names appear together, they are synonyms.
Activate Enter Map
ButtonPress, Button Expose Motion
ButtonRelease FocusIn MouseWheel
Circulate FocusOut Property
Colormap Gravity Reparent
Configure KeyPress, Key Unmap
Deactivate KeyRelease Visibility
Destroy Leave
Most of the above events have the same fields and behaviors as events
in the X Windowing system. You can find more detailed descriptions of
these events in any X window programming book. A couple of the events
are extensions to the X event system to support features unique to the
Macintosh and Windows platforms. We provide a little more detail on
these events here. These include:
- Activate
-
- Deactivate
-
These two events are sent to every sub-window of a toplevel when they
change state. In addition to the focus Window, the Macintosh platform
and Windows platforms have a notion of an active window (which often
has but is not required to have the focus). On the Macintosh, widgets
in the active window have a different appearance than widgets in
deactive windows. The Activate event is sent to all the
sub-windows in a toplevel when it changes from being deactive to
active. Likewise, the Deactive event is sent when the window's
state changes from active to deactive. There are no useful percent
substitutions you would make when binding to these events.
- MouseWheel
-
Some mice on the Windows platform support a mouse wheel which is used
for scrolling documents without using the scrollbars. By rolling the
wheel, the system will generate MouseWheel events that the
application can use to scroll. Like Key events the event is
always routed to the window that currently has focus. When the event
is received you can use the %D substitution to get the
delta field for the event which is a integer value of motion
that the mouse wheel has moved. The smallest value for which the
system will report is defined by the OS. On Windows 95 & 98 machines
this value is at least 120 before it is reported. However, higher
resolution devices may be available in the future. The sign of the
value determines which direction your widget should scroll. Positive
values should scroll up and negative values should scroll down.
The last part of a long event specification is detail. In the
case of a ButtonPress or ButtonRelease event, it is the
number of a button (1-5). If a button number is given, then only an
event on that particular button will match; if no button number is
given, then an event on any button will match. Note: giving a
specific button number is different than specifying a button modifier;
in the first case, it refers to a button being pressed or released,
while in the second it refers to some other button that is already
depressed when the matching event occurs. If a button
number is given then type may be omitted: if will default
to ButtonPress. For example, the specifier <1>
is equivalent to <ButtonPress-1>.
If the event type is KeyPress or KeyRelease, then
detail may be specified in the form of an X keysym. Keysyms
are textual specifications for particular keys on the keyboard;
they include all the alphanumeric ASCII characters (e.g. ``a'' is
the keysym for the ASCII character ``a''), plus descriptions for
non-alphanumeric characters (``comma'' is the keysym for the comma
character), plus descriptions for all the non-ASCII keys on the
keyboard (``Shift_L'' is the keysm for the left shift key, and
``F1'' is the keysym for the F1 function key, if it exists). The
complete list of keysyms is not presented here; it is
available in other X documentation and may vary from system to
system.
If necessary, you can use the %K notation described below
to print out the keysym name for a particular key.
If a keysym detail is given, then the
type field may be omitted; it will default to KeyPress.
For example, <Control-comma> is equivalent to
<Control-KeyPress-comma>.
The script argument to bind is a Tcl script,
which will be executed whenever the given event sequence occurs.
Command will be executed in the same interpreter that the
bind command was executed in, and it will run at global
level (only global variables will be accessible).
If script contains
any % characters, then the script will not be
executed directly. Instead, a new script will be
generated 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 current 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.
- %#
-
The number of the last client request processed by the server
(the serial field from the event). Valid for all event
types.
- %a
-
The above field from the event,
formatted as a hexadecimal number.
Valid only for Configure events.
- %b
-
The number of the button that was pressed or released. Valid only
for ButtonPress and ButtonRelease events.
- %c
-
The count field from the event. Valid only for Expose events.
- %d
-
The detail field from the event. The %d is replaced by
a string identifying the detail. For Enter,
Leave, FocusIn, and FocusOut events,
the string will be one of the following:
NotifyAncestor NotifyNonlinearVirtual
NotifyDetailNone NotifyPointer
NotifyInferior NotifyPointerRoot
NotifyNonlinear NotifyVirtual
For events other than these, the substituted string is undefined.
- %f
-
The focus field from the event (0 or 1). Valid only
for Enter and Leave events.
- %h
-
The height field from the event. Valid for the Configure and
Expose events.
- %k
-
The keycode field from the event. Valid only for KeyPress
and KeyRelease events.
- %m
-
The mode field from the event. The substituted string is one of
NotifyNormal, NotifyGrab, NotifyUngrab, or
NotifyWhileGrabbed. Valid only for Enter,
FocusIn, FocusOut, and Leave events.
- %o
-
The override_redirect field from the event. Valid only for
Map, Reparent, and Configure events.
- %p
-
The place field from the event, substituted as one of the
strings PlaceOnTop or PlaceOnBottom. Valid only
for Circulate events.
- %s
-
The state field from the event. For ButtonPress,
ButtonRelease, Enter, KeyPress, KeyRelease,
Leave, and Motion events, a decimal string
is substituted. For Visibility, one of the strings
VisibilityUnobscured, VisibilityPartiallyObscured,
and VisibilityFullyObscured is substituted.
- %t
-
The time field from the event. Valid only for events that
contain a time field.
- %w
-
The width field from the event. Valid only for
Configure and Expose events.
- %x
-
The x field from the event. Valid only for events containing
an x field.
- %y
-
The y field from the event. Valid only for events containing
a y field.
- %A
-
Substitutes the ASCII character corresponding to the event, or
the empty string if the event doesn't correspond to an ASCII character
(e.g. the shift key was pressed). XLookupString does all the
work of translating from the event to an ASCII character.
Valid only for KeyPress and KeyRelease events.
- %B
-
The border_width field from the event. Valid only for
Configure events.
- %D
-
This reports the delta value of a MouseWheel event. The
delta value represents the rotation units the mouse wheel has
been moved. On Windows 95 & 98 systems the smallest value for the
delta is 120. Future systems may support higher resolution values for
the delta. The sign of the value represents the direction the mouse
wheel was scrolled.
- %E
-
The send_event field from the event. Valid for all event types.
- %K
-
The keysym corresponding to the event, substituted as a textual
string. Valid only for KeyPress and KeyRelease events.
- %N
-
The keysym corresponding to the event, substituted as a decimal
number. Valid only for KeyPress and KeyRelease events.
- %R
-
The root window identifier from the event. Valid only for
events containing a root field.
- %S
-
The subwindow window identifier from the event,
formatted as a hexadecimal number.
Valid only for events containing a subwindow field.
- %T
-
The type field from the event. Valid for all event types.
- %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
-
The x_root field from the event.
If a virtual-root window manager is being used then the substituted
value is the corresponding x-coordinate in the virtual root.
Valid only for
ButtonPress, ButtonRelease, KeyPress, KeyRelease,
and Motion events.
- %Y
-
The y_root field from the event.
If a virtual-root window manager is being used then the substituted
value is the corresponding y-coordinate in the virtual root.
Valid only for
ButtonPress, ButtonRelease, KeyPress, KeyRelease,
and Motion events.
The replacement string for a %-replacement is formatted as a proper
Tcl list element.
This means that it will be surrounded with braces
if it contains spaces, or special characters such as $ and
{ may be preceded by backslashes.
This guarantees that the string will be passed through the Tcl
parser when the binding script is evaluated.
Most replacements are numbers or well-defined strings such
as Above; for these replacements no special formatting
is ever necessary.
The most common case where reformatting occurs is for the %A
substitution. For example, if script is
insert %A
and the character typed is an open square bracket, then the script
actually executed will be
insert \[
This will cause the insert to receive the original replacement
string (open square bracket) as its first argument.
If the extra backslash hadn't been added, Tcl would not have been
able to parse the script correctly.
It is possible for several bindings to match a given X event.
If the bindings are associated with different tag's,
then each of the bindings will be executed, in order.
By default, a binding for the widget will be executed first, followed
by a class binding, a binding for its toplevel, and
an all binding.
The bindtags command may be used to change this order for
a particular window or to associate additional binding tags with
the window.
The continue and break commands may be used inside a
binding script to control the processing of matching scripts.
If continue is invoked, then the current binding script
is terminated but Tk will continue processing binding scripts
associated with other tag's.
If the break command is invoked within a binding script,
then that script terminates and no other scripts will be invoked
for the event.
If more than one binding matches a particular event and they
have the same tag, then the most specific binding
is chosen and its script is evaluated.
The following tests are applied, in order, to determine which of
several matching sequences is more specific:
(a) an event pattern that specifies a specific button or key is more specific
than one that doesn't;
(b) a longer sequence (in terms of number
of events matched) is more specific than a shorter sequence;
(c) if the modifiers specified in one pattern are a subset of the
modifiers in another pattern, then the pattern with more modifiers
is more specific.
(d) a virtual event whose physical pattern matches the sequence is less
specific than the same physical pattern that is not associated with a
virtual event.
(e) given a sequence that matches two or more virtual events, one
of the virtual events will be chosen, but the order is undefined.
If the matching sequences contain more than one event, then tests
(c)-(e) are applied in order from the most recent event to the least recent
event in the sequences. If these tests fail to determine a winner, then the
most recently registered sequence is the winner.
If there are two (or more) virtual events that are both triggered by the
same sequence, and both of those virtual events are bound to the same window
tag, then only one of the virtual events will be triggered, and it will
be picked at random:
event add <<Paste>> <Control-y>
event add <<Paste>> <Button-2>
event add <<Scroll>> <Button-2>
bind Entry <<Paste>> {puts Paste}
bind Entry <<Scroll>> {puts Scroll}
If the user types Control-y, the <<Paste>> binding
will be invoked, but if the user presses button 2 then one of
either the <<Paste>> or the <<Scroll>> bindings will
be invoked, but exactly which one gets invoked is undefined.
If an X event does not match any of the existing bindings, then the
event is ignored.
An unbound event is not considered to be an error.
When a sequence specified in a bind command contains
more than one event pattern, then its script is executed whenever
the recent events (leading up to and including the current event)
match the given sequence. This means, for example, that if button 1 is
clicked repeatedly the sequence <Double-ButtonPress-1> will match
each button press but the first.
If extraneous events that would prevent a match occur in the middle
of an event sequence then the extraneous events are
ignored unless they are KeyPress or ButtonPress events.
For example, <Double-ButtonPress-1> will match a sequence of
presses of button 1, even though there will be ButtonRelease
events (and possibly Motion events) between the
ButtonPress events.
Furthermore, a KeyPress event may be preceded by any number
of other KeyPress events for modifier keys without the
modifier keys preventing a match.
For example, the event sequence aB will match a press of the
a key, a release of the a key, a press of the Shift
key, and a press of the b key: the press of Shift is
ignored because it is a modifier key.
Finally, if several Motion events occur in a row, only
the last one is used for purposes of matching binding sequences.
If an error occurs in executing the script for a binding then the
bgerror mechanism is used to report the error.
The bgerror command will be executed at global level
(outside the context of any Tcl procedure).
bgerror, keysyms
form, manual
Copyright © 1990 The Regents of the University of California.
Copyright © 1994-1996 Sun Microsystems, Inc.
Copyright © 1998 by Scriptics Corporation.
Copyright © 1995-1997 Roger E. Critchlow Jr.