Tk::event - Miscellaneous event facilities: define virtual events and generate events
$widget
->eventAction(?arg,
arg, ...?);
The eventAction methods provides several facilities for dealing with window system events, such as defining virtual events and synthesizing events. Virtual events are shared by all widgets of the same MainWindow. Different MainWindows can have different virtual event.
The following methods are currently supported:
Associates the virtual event virtual with the physical event sequence(s) given by the sequence arguments, so that the virtual event will trigger whenever any one of the sequences occurs. Virtual may be any string value and sequence may have any of the values allowed for the sequence argument to the bind method. If virtual is already defined, the new physical event sequences add to the existing sequences for the event.
Deletes each of the sequences from those associated with the virtual event given by virtual. Virtual may be any string value and sequence may have any of the values allowed for the sequence argument to the bind method. Any sequences not currently associated with virtual are ignored. If no sequence argument is provided, all physical event sequences are removed for virtual, so that the virtual event will not trigger anymore.
Generates a window event and arranges for it to be processed just as
if it had come from the window system. $window
is
a reference to the window for which the event will be generated.
Event provides a basic description of the event, such as
<Shift-Button-2> or
<<Paste>>. If Window is empty the
whole screen is meant, and coordinates are relative to the screen.
Event may have any of the forms allowed for the
sequence argument of the bind method except that it must
consist of a single event pattern, not a sequence. Option-value
pairs may be used to specify additional attributes of the event, such as
the x and y mouse position; see EVENT FIELDS below. If the
-when option is not specified, the event is processed
immediately: all of the handlers for the event will complete before the
eventGenerate method returns. If the
-when option is specified then it determines when the
event is processed.
Returns information about virtual events. If the <<virtual>> argument is omitted, the return value is a list of all the virtual events that are currently defined. If <<virtual>> is specified then the return value is a list whose elements are the physical event sequences currently defined for the given virtual event; if the virtual event is not defined then undef is returned.
The following options are supported for the eventGenerate method. These correspond to the ``%'' expansions allowed in binding callback for the bind method.
Window specifies the above field for the event,
either as a window path name or as an integer window id. Valid for
Configure events. Corresponds to the %a
substitution for binding scripts.
Size must be a screen distance; it specifies the
border_width field for the event. Valid for
Configure events. Corresponds to the %B
substitution for binding scripts.
Number must be an integer; it specifies the detail
field for a ButtonPress or
ButtonRelease event, overriding any button number
provided in the base event argument. Corresponds to the
%b
substitution for binding scripts.
Number must be an integer; it specifies the count
field for the event. Valid for Expose events.
Corresponds to the %c
substitution for binding scripts.
number must be an integer; it specifies the
delta field for the MouseWheel event.
The delta refers to the direction and magnitude the mouse wheel was
rotated. Note the value is not a screen distance but are units of motion
in the mouse wheel. Typically these values are multiples of 120. For
example, 120 should scroll the text widget up 4 lines and -240 would
scroll the text widget down 8 lines. Of course, other widgets may define
different behaviors for mouse wheel motion. This field corresponds to
the %D
substitution for binding scripts.
Detail specifies the detail field for the event and must be one of the following:
NotifyAncestor NotifyNonlinearVirtual NotifyDetailNone NotifyPointer NotifyInferior NotifyPointerRoot NotifyNonlinear NotifyVirtual
Valid for Enter, Leave,
FocusIn and FocusOut events.
Corresponds to the %d
substitution for binding scripts.
Boolean must be a boolean value; it specifies the
focus field for the event. Valid for Enter and
Leave events. Corresponds to the %f
substitution for binding scripts.
Size must be a screen distance; it specifies the
height field for the event. Valid for
Configure events. Corresponds to the %h
substitution for binding scripts.
Number must be an integer; it specifies the keycode
field for the event. Valid for KeyPress and
KeyRelease events. Corresponds to the %k
substitution for binding scripts.
Name must be the name of a valid keysym, such as
g, space, or Return;
its corresponding keycode value is used as the keycode field
for event, overriding any detail specified in the base event
argument. Valid for KeyPress and
KeyRelease events. Corresponds to the %K
substitution for binding scripts.
Notify specifies the mode field for the event and
must be one of NotifyNormal,
NotifyGrab, NotifyUngrab, or
NotifyWhileGrabbed. Valid for Enter,
Leave, FocusIn, and
FocusOut events. Corresponds to the %m
substitution for binding scripts.
Boolean must be a boolean value; it specifies the
override_redirect field for the event. Valid for
Map, Reparent, and
Configure events. Corresponds to the %o
substitution for binding scripts.
Where specifies the place field for the event; it
must be either PlaceOnTop or
PlaceOnBottom. Valid for Circulate
events. Corresponds to the %p
substitution for binding
scripts.
Window must be either a window path name or an integer
window identifier; it specifies the root field for the event.
Valid for KeyPress, KeyRelease,
ButtonPress, ButtonRelease,
Enter, Leave, and
Motion events. Corresponds to the %R
substitution for binding scripts.
Coord must be a screen distance; it specifies the
x_root field for the event. Valid for
KeyPress, KeyRelease,
ButtonPress, ButtonRelease,
Enter, Leave, and
Motion events. Corresponds to the %X
substitution for binding scripts.
Coord must be a screen distance; it specifies the
y_root field for the event. Valid for
KeyPress, KeyRelease,
ButtonPress, ButtonRelease,
Enter, Leave, and
Motion events. Corresponds to the %Y
substitution for binding scripts.
Boolean must be a boolean value; it specifies the
send_event field for the event. Valid for all events.
Corresponds to the %E
substitution for binding scripts.
Number must be an integer; it specifies the serial field for the event. Valid for all events. Corresponds to the %# substitution for binding scripts.
State specifies the state field for the event. For
KeyPress, KeyRelease,
ButtonPress, ButtonRelease,
Enter, Leave, and
Motion events it must be an integer value. For
Visibility events it must be one of
VisibilityUnobscured,
VisibilityPartiallyObscured, or
VisibilityFullyObscured. This option overrides any
modifiers such as Meta or Control
specified in the base event. Corresponds to the %s
substitution for binding scripts.
Window specifies the subwindow field for the event,
either as a path name for a Tk widget or as an integer window
identifier. Valid for KeyPress,
KeyRelease, ButtonPress,
ButtonRelease, Enter,
Leave, and Motion events. Similar to
%S
substitution for binding scripts.
Integer must be an integer value; it specifies the
time field for the event. Valid for KeyPress,
KeyRelease, ButtonPress,
ButtonRelease, Enter,
Leave, Motion, and
Property events. Corresponds to the %t
substitution for binding scripts.
boolean must be a boolean value; it specifies whether the screen pointer should be warped as well. Valid for KeyPress, KeyRelease, ButtonPress, ButtonRelease, and Motion events.
Size must be a screen distance; it specifies the
width field for the event. Valid for Configure
events. Corresponds to the %w
substitution for binding
scripts.
When determines when the event will be processed; it must have one of the following values:
Process the event immediately, before the command returns. This also happens if the -when option is omitted.
Place the event on perl/Tk's event queue behind any events already queued for this application.
Place the event at the front of perl/Tk's event queue, so that it will be handled before any other events already queued.
Place the event at the front of perl/Tk's event queue but behind any other events already queued with -when mark. This option is useful when generating a series of events that should be processed in order but at the front of the queue.
Coord must be a screen distance; it specifies the x
field for the event. Valid for KeyPress,
KeyRelease, ButtonPress,
ButtonRelease, Motion,
Enter, Leave, Expose,
Configure, Gravity, and
Reparent events. Corresponds to the the %x
substitution for binding scripts. If Window is empty the
coordinate is relative to the screen, and this option corresponds to the
%X
substitution for binding scripts.
Coord must be a screen distance; it specifies the y
field for the event. Valid for KeyPress,
KeyRelease, ButtonPress,
ButtonRelease, Motion,
Enter, Leave, Expose,
Configure, Gravity, and
Reparent events. Corresponds to the the %y
substitution for binding scripts. If Window is empty the
coordinate is relative to the screen, and this option corresponds to the
%Y
substitution for binding scripts. Any options that are
not specified when generating an event are filled with the value 0,
except for serial, which is filled with the next X event serial
number.
In order for a virtual event binding to trigger, two things must happen. First, the virtual event must be defined with the eventAdd method. Second, a binding must be created for the virtual event with the bind method. Consider the following virtual event definitions:
$widget->eventAdd(<<Paste>> => <Control-y>); $widget->eventAdd(<<Paste>> => <Button-2>); $widget->eventAdd(<<Save>> => <Control-X><Control-S>); $widget->eventAdd(<<Save>> => <Shift-F12>);
In the bind method, a virtual event can be bound like any other builtin event type as follows:
$entry->bind(Tk::Entry, <<Paste>> => sub { $entry->Insert($entry->selectionGet) });
The double angle brackets are used to specify that a virtual event is being bound. If the user types Control-y or presses button 2, or if a <<Paste>> virtual event is synthesized with eventGenerate, then the <<Paste>> binding will be invoked.
If a virtual binding has the exact same sequence as a separate physical binding, then the physical binding will take precedence. Consider the following example:
$mw->eventAdd(<<Paste>> => <Control-y>,<Meta-Control-y>); $mw->bind(Tk::Entry, <Control-y> => sub{print Control-y}); $mw->bind(Tk::Entry, <<Paste>> => sub{print Paste});
When the user types Control-y the <Control-y> binding will be invoked, because a physical event is considered more specific than a virtual event, all other things being equal. However, when the user types Meta-Control-y the <<Paste>> binding will be invoked, because the Meta modifier in the physical pattern associated with the virtual binding is more specific than the <Control-y> sequence for the physical event.
Bindings on a virtual event may be created before the virtual event exists. Indeed, the virtual event never actually needs to be defined, for instance, on platforms where the specific virtual event would meaningless or ungeneratable.
When a definition of a virtual event changes at run time, all windows will respond immediately to the new definition. Starting from the preceding example, if the following code is executed:
$entry->bind(ref($entry), <Control-y> => undef); $entry->eventAdd(<<Paste>> => <Key-F6>);
the behavior will change such in two ways. First, the shadowed <<Paste>> binding will emerge. Typing Control-y will no longer invoke the <Control-y> binding, but instead invoke the virtual event <<Paste>>. Second, pressing the F6 key will now also invoke the <<Paste>> binding.
Tk::bind Tk::callbacks
event, binding, define, handle, virtual event