Tk Built-In Commands bind(1T)
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NAME
bind - Arrange for X events to invoke Tcl scripts
SYNOPSIS
bind tag ?sequence? ?+??script?
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INTRODUCTIONThe 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 toany 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 argu-
ment 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 stringis 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 thereexist 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 oftags, and a binding applies to a particular window if its
tag is among those specified for the window. Although thebindtags command may be used to assign an arbitrary set of
binding tags to a window, the default binding tags provide
the following behavior:+o If a tag is the name of an internal window the binding
applies to that window.+o If the tag is the name of a toplevel window the binding
applies to the toplevel window and all its internal win-
dows. +o If the tag is the name of a class of widgets, such asButton, the binding applies to all widgets in that class;
+o If tag has the value all, the binding applies to all win-
dows in the application. Tk Last change: 8.0 1Tk Built-In Commands bind(1T)
EVENT PATTERNS The sequence argument specifies a sequence of one or moreevent patterns, with optional white space between the pat-
terns. 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 KeyPressevent for the particular character. The second form of pat-
tern is longer but more general. It has the following syn-
tax: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) iden-
tifying 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: | <> | 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. | Some widgets (e.g. menu and text) issue virtual events when | their internal state is updated in some ways. Please see | the manual page for each widget for details. MODIFIERS 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 Tk Last change: 8.0 2Tk Built-In Commands bind(1T)
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 inthe binding. For example, if button 1 is pressed while the
shift and control keys are down, the pattern
Button-1> will match the event, but
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 (keysymswill 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 thekeyboard (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 motionin between. For example,
is equivalent to ment. EVENT TYPES The type field may be any of the standard X event types, with a few extra abbreviations. The type field will also
with the extra time and space require- 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 Destroy Map ButtonPress, Button Enter MapRequest ButtonRelease Expose Motion Circulate FocusIn MouseWheel CirculateRequest FocusOut Property Colormap Gravity Reparent Configure KeyPress, Key ResizeRequest ConfigureRequest KeyRelease Unmap Create Leave Visibility Deactivate 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 | Tk Last change: 8.0 3Tk Built-In Commands bind(1T)
programming book. A couple of the events are extensions to |the X event system to support features unique to the Macin- |
tosh 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 plat- |
forms 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 dif- |
ferent 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 bind- |
ing 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 gen- |
erate MouseWheel events that the application can use to | scroll. On Windows, the event is always routed to the | window that currently has focus (like Key events.) On | Mac OS X, the event is routed to the window under the |pointer. When the event is received you can use the %D |
substitution to get the delta field for the event, | which is a integer value describing how 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. On Mac OS X, the value is not | scaled by 120, but a value of 1 corresponds to roughly | one text line. The sign of the value determines which | direction your widget should scroll. Positive values | should scroll up and negative values should scroll | down. KeyPress, KeyReleaseThe KeyPress and KeyRelease events are generated when-
ever a key is pressed or released. KeyPress and KeyRelease events are sent to the window which currently has the keyboard focus. ButtonPress, ButtonRelease, Motion The ButtonPress and ButtonRelease events are generated when the user presses or releases a mouse button. Motion events are generated whenever the pointer is Tk Last change: 8.0 4Tk Built-In Commands bind(1T)
moved. ButtonPress, ButtonRelease, and Motion events are normally sent to the window containing the pointer. When a mouse button is pressed, the window containing the pointer automatically obtains a temporary pointer grab. Subsequent ButtonPress, ButtonRelease, and Motion events will be sent to that window, regardless of which window contains the pointer, until all buttons have been released. Configure A Configure event is sent to a window whenever its size, position, or border width changes, and sometimes when it has changed position in the stacking order. Map, Unmap The Map and Unmap events are generated whenever the mapping state of a window changes.Windows are created in the unmapped state. Top-level
windows become mapped when they transition to the nor-
mal state, and are unmapped in the withdrawn and iconic states. Other windows become mapped when they are placed under control of a geometry manager (for example pack or grid).A window is viewable only if it and all of its ances-
tors are mapped. Note that geometry managers typically do not map their children until they have been mapped themselves, and unmap all children when they become unmapped; hence in Tk Map and Unmap events indicate whether or not a window is viewable. Visibility A window is said to be obscured when another windowabove it in the stacking order fully or partially over-
laps it. Visibility events are generated whenever awindow's obscurity state changes; the state field (%s)
specifies the new state. Expose An Expose event is generated whenever all or part of a window should be redrawn (for example, when a window isfirst mapped or if it becomes unobscured). It is nor-
mally not necessary for client applications to handle Expose events, since Tk handles them internally. Destroy A Destroy event is delivered to a window when it is destroyed. Tk Last change: 8.0 5Tk Built-In Commands bind(1T)
When the Destroy event is delivered to a widget, it isin a ``half-dead'' state: the widget still exists, but
most operations on it will fail. FocusIn, FocusOut The FocusIn and FocusOut events are generated whenever the keyboard focus changes. A FocusOut event is sent to the old focus window, and a FocusIn event is sent to the new one. In addition, if the old and new focus windows do not share a common parent, ``virtual crossing'' focus events are sent to the intermediate windows in the hierarchy. Thus a FocusIn event indicates that the target window or one of its descendants has acquired the focus, and a FocusOut event indicates that the focus has been changed to a window outside the target window's hierarchy. The keyboard focus may be changed explicitly by a call to focus, or implicitly by the window manager. Enter, Leave An Enter event is sent to a window when the pointer enters that window, and a Leave event is sent when the pointer leaves it. If there is a pointer grab in effect, Enter and Leave events are only delivered to the window owning the grab.In addition, when the pointer moves between two win-
dows, Enter and Leave ``virtual crossing'' events are sent to intermediate windows in the hierarchy in the same manner as for FocusIn and FocusOut events. PropertyA Property event is sent to a window whenever an X pro-
perty belonging to that window is changed or deleted.Property events are not normally delivered to Tk appli-
cations as they are handled by the Tk core. Colormap A Colormap event is generated whenever the colormap associated with a window has been changed, installed, or uninstalled.Widgets may be assigned a private colormap by specify-
ing a -colormap option; the window manager is responsi-
ble for installing and uninstalling colormaps as neces-
sary. Tk Last change: 8.0 6Tk Built-In Commands bind(1T)
Note that Tk provides no useful details for this event type. Create MapRequest, CirculateRequest, ResizeRequest, ConfigureRequest,These events are not normally delivered to Tk applica-
tions. They are included for completeness, to make it possible to write X11 window managers in Tk. (These events are only delivered when a client has selected SubstructureRedirectMask on a window; the Tk core does not use this mask.) Gravity, Reparent, Circulate The events Gravity and Reparent are not normally delivered to Tk applications. They are included for completeness. A Circulate event indicates that the window has moved to the top or to the bottom of the stacking order as a result of an XCirculateSubwindows protocol request. Note that the stacking order may be changed for other reasons which do not generate a Circulate event, and that Tk does not use XCirculateSubwindows() internally. This event type is included only for completeness; there is no reliable way to track changes to a window's position in the stacking order. EVENT DETAILS The last part of a long event specification is detail. In the case of a ButtonPress or ButtonRelease event, it is thenumber 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> isequivalent to
If the event type is KeyPress or KeyRelease, then detail may. be specified in the form of an X keysym. Keysyms are tex-
tual 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''), plusdescriptions for non-alphanumeric characters (``comma'' is
the keysym for the comma character), plus descriptions forall the non-ASCII keys on the keyboard (``Shift_L'' is the
keysym for the left shift key, and ``F1'' is the keysym for the F1 function key, if it exists). The complete list of Tk Last change: 8.0 7Tk Built-In Commands bind(1T)
keysyms is not presented here; it is available in other Xdocumentation and may vary from system to system. If neces-
sary, 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; itwill default to KeyPress. For example,
is equivalent to
BINDING SCRIPTS AND SUBSTITUTIONS. The script argument to bind is a Tcl script, which will be
executed whenever the given event sequence occurs. Commandwill be executed in the same interpreter that the bind com-
mand was executed in, and it will run at global level (only global variables will be accessible). If script containsany % characters, then the script will not be executed
directly. Instead, a new script will be generated byreplacing each %, and the character following it, with
information from the current event. The replacement dependson 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 hexade-
cimal number. Valid only for Configure events. Indi-
cates the sibling window immediately below the receiv-
ing window in the stacking order, or 0 if the receiving window is at the bottom.%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. Indicates that there are count pending Expose events which have not yet been delivered to the window.%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 Tk Last change: 8.0 8Tk Built-In Commands bind(1T)
NotifyNonlinear NotifyVirtual For ConfigureRequest events, the string will be one of: Above Opposite Below None BottomIf TopIf 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. 1 if the receiving windowis the focus window or a descendant of the focus win-
dow, 0 otherwise.%h The height field from the event. Valid for the Config- |
ure, ConfigureRequest, Create, ResizeRequest, and | Expose events. Indicates the new or requested height | of the window.%i The window field from the event, represented as a hexa-
decimal integer. Valid for all event types.%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 and CirculateRequest events.%s The state field from the event. For ButtonPress, But-
tonRelease, Enter, KeyPress, KeyRelease, Leave, and Motion events, a decimal string is substituted. For Visibility, one of the strings VisibilityUnobscured,VisibilityPartiallyObscured, and VisibilityFullyOb-
scured is substituted. For Property events, substi-
tuted with either the string NewValue (indicating that the property has been created or modified) or Delete (indicating that the property has been removed).%t The time field from the event. This is the X server
timestamp (typically the time since the last server reset) in milliseconds, when the event occurred. Valid Tk Last change: 8.0 9Tk Built-In Commands bind(1T)
for most events.%w The width field from the event. Indicates the new or
requested width of the window. Valid only for Config- |
ure, ConfigureRequest, Create, ResizeRequest, and | Expose events.%x, %y
The x and y fields from the event. For ButtonPress, ButtonRelease, Motion, KeyPress, KeyRelease, andMouseWheel events, %x and %y indicate the position of
the mouse pointer relative to the receiving window. For Enter and Leave events, the position where the mouse pointer crossed the window, relative to the receiving window. For Configure and Create requests, the x and y coordinates of the window relative to its parent window.%A Substitutes the UNICODE character corresponding to the
event, or the empty string if the event doesn't correspond to a UNICODE character (e.g. the shift key was pressed). XmbLookupString (or XLookupString when input method support is turned off) does all the work of translating from the event to a UNICODE character. Valid only for KeyPress and KeyRelease events.%B The border_width field from the event. Valid only for
Configure, ConfigureRequest, and Create 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. 0 indicates that this is a ``normal'' event, 1 indicates that it is a ``synthetic'' event generated by SendEvent.%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.%P The name of the property being updated or deleted
(which may be converted to an XAtom using winfo atom.) Tk Last change: 8.0 10Tk Built-In Commands bind(1T)
Valid only for Property 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, format-
ted 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 valueis the corresponding x-coordinate in the virtual root.
Valid only for ButtonPress, ButtonRelease, KeyPress,KeyRelease, and Motion events. Same meaning as %x,
except relative to the (virtual) root window.%Y The y_root field from the event. If a virtual-root
window manager is being used then the substituted valueis the corresponding y-coordinate in the virtual root.
Valid only for ButtonPress, ButtonRelease, KeyPress,KeyRelease, and Motion events. Same meaning as %y,
except relative to the (virtual) root window.The replacement string for a %-replacement is formatted as a
proper Tcl 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 Tclparser when the binding script is evaluated. Most replace-
ments are numbers or well-defined strings such as Above;
for these replacements no special formatting is ever neces-
sary. The most common case where reformatting occurs is forthe %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 replace-
ment 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. MULTIPLE MATCHESIt is possible for several bindings to match a given X
event. If the bindings are associated with different tag's,
Tk Last change: 8.0 11Tk Built-In Commands bind(1T)
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 addi-
tional binding tags with the window.
The continue and break commands may be used inside a binding
script to control the processing of matching scripts. Ifcontinue is invoked, then the current binding script is ter-
minated but Tk will continue processing binding scripts
associated with other tag's. If the break command isinvoked 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 thanthe same physical pattern that is not associated with a vir-
tual 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, thentests (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 <
> event add <
> event add <
> bind Entry <
> {puts Paste} bind Entry <
> {puts Scroll} If the user types Control-y, the <
invoked, but if the user presses button 2 then one of either> binding will be the <
but exactly which one gets invoked is undefined. Tk Last change: 8.0 12> or the < > bindings will be invoked, Tk Built-In Commands bind(1T)
If an X event does not match any of the existing bindings,
then the event is ignored. An unbound event is not con-
sidered to be an error.MULTI-EVENT SEQUENCES AND IGNORED EVENTS
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 sequencefirst. 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
will match each button press but the events. For example,
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 ofwill match a matching binding sequences.
ERRORS
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).EXAMPLES
Arrange for a string describing the motion of the mouse tobe printed out when the mouse is double-clicked:
bind .
{ puts "hi from (%x,%y)"
} A little GUI that displays what the keysym name of the last key pressed is: set keysym "Press any key"pack [label .l -textvariable keysym -padx 2m -pady 1m]
bind .
{ set keysym "You pressed %K"
}SEE ALSO
bgerror(1T), bindtags(1T), event(1T), focus(1T), grab(1T),
keysyms(1T) Tk Last change: 8.0 13Tk Built-In Commands bind(1T)
KEYWORDSbinding, event
ATTRIBUTES
See attributes(5) for descriptions of the following attri-
butes:_______________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE|
|____________________|__________________|_
| Availability | runtime/tk-8 |
|____________________|__________________|_
| Interface Stability| Uncommitted ||____________________|_________________|
NOTES Source for Tk is available on http://opensolaris.org. Tk Last change: 8.0 14