Provided by: perl-tk_804.036+dfsg1-1ubuntu3_amd64 
NAME
Tk::Widget - Base class of all widgets
SYNOPSIS
package Tk::Whatever;
require Tk::Widget;
@ISA = qw(Tk::Widget);
Construct Tk::Widget 'Whatever';
sub Tk_cmd { \&Tk::whatever }
$widget->method(?arg, arg, ...?)
DESCRIPTION
The Tk::Widget is an abstract base class for all Tk widgets.
Generic methods available to all widgets include the methods based on core "winfo" mechanism and are used
to retrieve information about windows managed by Tk. They can take any of a number of different forms,
depending on the method. The legal forms are:
$widget->appname?(newName)?
If newName isn't specified, this method returns the name of the application (the name that may be
used in send commands to communicate with the application). If newName is specified, then the name
of the application is changed to newName. If the given name is already in use, then a suffix of the
form `` #2'' or `` #3'' is appended in order to make the name unique. The method's result is the
name actually chosen. newName should not start with a capital letter. This will interfere with
option processing, since names starting with capitals are assumed to be classes; as a result, Tk may
not be able to find some options for the application. If sends have been disabled by deleting the
send command, this command will re-enable them and recreate the send command.
$widget->atom(name)
Returns a decimal string giving the integer identifier for the atom whose name is name. If no atom
exists with the name name then a new one is created.
$widget->atomname(id)
Returns the textual name for the atom whose integer identifier is id. This command is the inverse of
the $widget->atom command. It generates an error if no such atom exists.
$widget->bell( ?-nice? );
This command rings the bell on the display for $widget and returns an empty string. The command uses
the current bell-related settings for the display, which may be modified with programs such as xset.
If -nice is not specified, this command also resets the screen saver for the screen. Some screen
savers will ignore this, but others will reset so that the screen becomes visible again.
$widget->bindDump
This command returns a list of strings suitable for printing detailing binding information for a
widget. It prints a widget's bindtags. For each binding tag it prints all the bindings, comprised
of the event descriptor and the callback. Callback arguments are printed, and Tk::Ev objects are
expanded.
$widget->Busy?(?-recurse => 1?,-option => value?)?
This method configures a -cursor option for $widget and (if -recurse = 1> is specified) all its
descendants. The cursor to be set may be passed as -cursor = cursor> or defaults to 'watch'.
Additional configure options are applied to $widget only. It also adds a special tag 'Busy' to the
bindtags of the widgets so configured so that KeyPress, KeyRelease, ButtonPress and ButtonRelease
events are ignored (with press events generating a call to bell). It then acquires a local grab for
$widget. The state of the widgets and the grab is restored by a call to $widget->Unbusy.
$widget->caret( ?-x => x?, ?-y => y?, ?-height => height? );
Sets and queries the caret location for the display of the specified Tk window window. The caret is
the per-display cursor location used for indicating global focus (e.g. to comply with Microsoft
Accessibility guidelines), as well as for location of the over-the-spot XIM (X Input Methods) or
Windows IME windows. If no options are specified, the last values used for setting the caret are
return in option-value pair format. -x and -y represent window-relative coordinates, and -height is
the height of the current cursor location, or the height of the specified window if none is given.
$widget->cells
Returns a decimal string giving the number of cells in the color map for $widget.
$widget->children
$widget->children Returns a list containing all the children of $widget. The list is in stacking
order, with the lowest window first. Top-level windows are returned as children of their logical
parents.
$widget->class
Returns the class name for $widget.
$widget->colormapfull
Returns 1 if the colormap for $widget is known to be full, 0 otherwise. The colormap for a window is
``known'' to be full if the last attempt to allocate a new color on that window failed and this
application hasn't freed any colors in the colormap since the failed allocation.
$widget->ConfigSpecs
Used to perform delegated option configuration for a mega-widget. Returns, in
Tk::Derived::ConfigSpecs notation (see Tk::ConfigSpecs), all possible options for a widget. For
example,
$s = $self->Scale;
$self->ConfigSpecs(
$s->ConfigSpecs,
.... more ConfigSpecs specifications
);
returns a hash of all Tk::Scale options, delegated to $s - e.g. some representative examples:
-bigincrement => [$s, bigIncrement, BigIncrement, 0, 0]
-digits => [$s, digits, Digits, 0, 0]
-sliderlength => [$s, sliderLength, SliderLength, 10m, 30]
-troughcolor => [$s, troughColor, Background, #c3c3c3, #c3c3c3]
This provides an easy means of populating a mega-widget's ConfigSpecs with initializers.
$widget->containing(rootX,rootY)
Returns the window containing the point given by rootX and rootY. RootX and rootY are specified in
screen units (i.e. any form acceptable to Tk_GetPixels) in the coordinate system of the root window
(if a virtual-root window manager is in use then the coordinate system of the virtual root window is
used). If no window in this application contains the point then an empty string is returned. In
selecting the containing window, children are given higher priority than parents and among siblings
the highest one in the stacking order is chosen.
$widget->depth
Returns a decimal string giving the depth of $widget (number of bits per pixel).
$widget->destroy
This command deletes the window related to $widget, plus all its descendants. If all the MainWindows
are deleted then the entire application will be destroyed.
The perl object $widget continues to exist while references to it still exist, e.g. until variable
goes out of scope. However any attempt to use Tk methods on the object will fail. Exists($widget)
will return false on such objects.
Note however that while a window exists for $widget the perl object is maintained (due to
"references" in perl/Tk internals) even though original variables may have gone out of scope.
(Normally this is intuitive.)
Exists($widget)
Returns 1 if there exists a window for $widget, 0 if no such window exists.
$widget->font(option?, arg, arg, ...?)
Create and inspect fonts. See Tk::Font for further details.
$widget->fpixels(number)
Returns a floating-point value giving the number of pixels in $widget corresponding to the distance
given by number. Number may be specified in any of the forms acceptable to Tk_GetScreenMM, such as
``2.0c'' or ``1i''. The return value may be fractional; for an integer value, use $widget->pixels.
$widget->Getimage(name)
Given name, look for an image file with that base name and return a Tk::Image. File extensions are
tried in this order: xpm, gif, ppm, xbm until a valid iamge is found. If no image is found, try a
builtin image with that name.
$widget->geometry
Returns the geometry for $widget, in the form widthxheight+x+y. All dimensions are in pixels.
$widget->height
Returns a decimal string giving $widget's height in pixels. When a window is first created its
height will be 1 pixel; the height will eventually be changed by a geometry manager to fulfill the
window's needs. If you need the true height immediately after creating a widget, invoke update to
force the geometry manager to arrange it, or use $widget->reqheight to get the window's requested
height instead of its actual height.
$widget->id
Returns a hexadecimal string giving a low-level platform-specific identifier for $widget. On Unix
platforms, this is the X window identifier. Under Windows, this is the Windows HWND. On the
Macintosh the value has no meaning outside Tk.
$widget->idletasks
One of two methods which are used to bring the application ``up to date'' by entering the event loop
repeated until all pending events (including idle callbacks) have been processed.
If the idletasks method is specified, then no new events or errors are processed; only idle callbacks
are invoked. This causes operations that are normally deferred, such as display updates and window
layout calculations, to be performed immediately.
The idletasks command is useful in scripts where changes have been made to the application's state
and you want those changes to appear on the display immediately, rather than waiting for the script
to complete. Most display updates are performed as idle callbacks, so idletasks will cause them to
run. However, there are some kinds of updates that only happen in response to events, such as those
triggered by window size changes; these updates will not occur in idletasks.
$widget->interps
Returns a list whose members are the names of all Tcl interpreters (e.g. all Tk-based applications)
currently registered for a particular display. The return value refers to the display of $widget.
$widget->ismapped
Returns 1 if $widget is currently mapped, 0 otherwise.
$widget->lower(?belowThis?)
If the belowThis argument is omitted then the command lowers $widget so that it is below all of its
siblings in the stacking order (it will be obscured by any siblings that overlap it and will not
obscure any siblings). If belowThis is specified then it must be the path name of a window that is
either a sibling of $widget or the descendant of a sibling of $widget. In this case the lower
command will insert $widget into the stacking order just below belowThis (or the ancestor of
belowThis that is a sibling of $widget); this could end up either raising or lowering $widget.
$widget->MapWindow
Cause $widget to be "mapped" i.e. made visible on the display. May confuse the geometry manager
(pack, grid, place, ...) that thinks it is managing the widget.
$widget->manager
Returns the name of the geometry manager currently responsible for $widget, or an empty string if
$widget isn't managed by any geometry manager. The name is usually the name of the method for the
geometry manager, such as pack or place. If the geometry manager is a widget, such as canvases or
text, the name is the widget's class command, such as canvas.
$widget->name
Returns $widget's name (i.e. its name within its parent, as opposed to its full path name). The
command $mainwin->name will return the name of the application.
$widget->OnDestroy(callback);
OnDestroy accepts a standard perl/Tk callback. When the window associated with $widget is destroyed
then the callback is invoked. Unlike $widget->bind('<Destroy>',...) the widgets methods are still
available when callback is executed, so (for example) a Text widget can save its contents to a file.
OnDestroy was required for new after mechanism.
$widget->parent
Returns $widget's parent, or an empty string if $widget is the main window of the application.
$widget->PathName
Returns the Tk path name of $widget. This is the inverse of the "Widget" method. (This is an import
from the C interface.)
$widget->pathname(id)
Returns an object whose X identifier is id. The identifier is looked up on the display of $widget.
Id must be a decimal, hexadecimal, or octal integer and must correspond to a window in the invoking
application, or an error occurs which can be trapped with "eval { }" or "Tk::catch { }". If the
window belongs to the application, but is not an object (for example wrapper windows, HList header,
etc.) then "undef" is returned.
$widget->pixels(number)
Returns the number of pixels in $widget corresponding to the distance given by number. Number may be
specified in any of the forms acceptable to Tk_GetPixels, such as ``2.0c'' or ``1i''. The result is
rounded to the nearest integer value; for a fractional result, use $widget->fpixels.
$widget->pointerx
If the mouse pointer is on the same screen as $widget, returns the pointer's x coordinate, measured
in pixels in the screen's root window. If a virtual root window is in use on the screen, the
position is measured in the virtual root. If the mouse pointer isn't on the same screen as $widget
then -1 is returned.
$widget->pointerxy
If the mouse pointer is on the same screen as $widget, returns a list with two elements, which are
the pointer's x and y coordinates measured in pixels in the screen's root window. If a virtual root
window is in use on the screen, the position is computed in the virtual root. If the mouse pointer
isn't on the same screen as $widget then both of the returned coordinates are -1.
$widget->pointery
If the mouse pointer is on the same screen as $widget, returns the pointer's y coordinate, measured
in pixels in the screen's root window. If a virtual root window is in use on the screen, the
position is computed in the virtual root. If the mouse pointer isn't on the same screen as $widget
then -1 is returned.
$widget->raise(?aboveThis?)
If the aboveThis argument is omitted then the command raises $widget so that it is above all of its
siblings in the stacking order (it will not be obscured by any siblings and will obscure any siblings
that overlap it). If aboveThis is specified then it must be the path name of a window that is either
a sibling of $widget or the descendant of a sibling of $widget. In this case the raise command will
insert $widget into the stacking order just above aboveThis (or the ancestor of aboveThis that is a
sibling of $widget); this could end up either raising or lowering $widget.
$widget->reqheight
Returns a decimal string giving $widget's requested height, in pixels. This is the value used by
$widget's geometry manager to compute its geometry.
$widget->reqwidth
Returns a decimal string giving $widget's requested width, in pixels. This is the value used by
$widget's geometry manager to compute its geometry.
$widget->rgb(color)
Returns a list containing three decimal values, which are the red, green, and blue intensities that
correspond to color in the window given by $widget. Color may be specified in any of the forms
acceptable for a color option.
$widget->rootx
Returns a decimal string giving the x-coordinate, in the root window of the screen, of the upper-left
corner of $widget's border (or $widget if it has no border).
$widget->rooty
Returns a decimal string giving the y-coordinate, in the root window of the screen, of the upper-left
corner of $widget's border (or $widget if it has no border).
$widget->scaling?(number)?
Sets and queries the current scaling factor used by Tk to convert between physical units (for
example, points, inches, or millimeters) and pixels. The number argument is a floating point number
that specifies the number of pixels per point on $widget's display. If the number argument is
omitted, the current value of the scaling factor is returned.
A ``point'' is a unit of measurement equal to 1/72 inch. A scaling factor of 1.0 corresponds to 1
pixel per point, which is equivalent to a standard 72 dpi monitor. A scaling factor of 1.25 would
mean 1.25 pixels per point, which is the setting for a 90 dpi monitor; setting the scaling factor to
1.25 on a 72 dpi monitor would cause everything in the application to be displayed 1.25 times as
large as normal. The initial value for the scaling factor is set when the application starts, based
on properties of the installed monitor (as reported via the window system), but it can be changed at
any time. Measurements made after the scaling factor is changed will use the new scaling factor, but
it is undefined whether existing widgets will resize themselves dynamically to accommodate the new
scaling factor.
$widget->screen
Returns the name of the screen associated with $widget, in the form displayName.screenIndex.
$widget->screencells
Returns a decimal string giving the number of cells in the default color map for $widget's screen.
$widget->screendepth
Returns a decimal string giving the depth of the root window of $widget's screen (number of bits per
pixel).
$widget->screenheight
Returns a decimal string giving the height of $widget's screen, in pixels.
$widget->screenmmheight
Returns a decimal string giving the height of $widget's screen, in millimeters.
$widget->screenmmwidth
Returns a decimal string giving the width of $widget's screen, in millimeters.
$widget->screenvisual
Returns one of the following strings to indicate the default visual class for $widget's screen:
directcolor, grayscale, pseudocolor, staticcolor, staticgray, or truecolor.
$widget->screenwidth
Returns a decimal string giving the width of $widget's screen, in pixels.
$widget->server
Returns a string containing information about the server for $widget's display. The exact format of
this string may vary from platform to platform. For X servers the string has the form ``XmajorRminor
vendor vendorVersion'' where major and minor are the version and revision numbers provided by the
server (e.g., X11R5), vendor is the name of the vendor for the server, and vendorRelease is an
integer release number provided by the server.
$widget->toplevel
Returns the reference of the top-level window containing $widget.
$widget->Unbusy
Restores widget state after a call to $widget->Busy.
$widget->UnmapWindow
Cause $widget to be "unmapped" i.e. removed from the display. This does for any widget what
$widget->withdraw does for toplevel widgets. May confuse the geometry manager (pack, grid, place,
...) that thinks it is managing the widget.
$widget->update
One of two methods which are used to bring the application ``up to date'' by entering the event loop
repeated until all pending events (including idle callbacks) have been processed.
The update method is useful in scripts where you are performing a long-running computation but you
still want the application to respond to events such as user interactions; if you occasionally call
update then user input will be processed during the next call to update.
$widget->useinputmethods( ?boolean? )
Sets and queries the state of whether Tk should use XIM (X Input Methods) for filtering events. The
resulting state is returned. XIM is used in some locales (ie: Japanese, Korean), to handle
special input devices. This feature is only significant on X. If XIM support is not available,
this will always return 0. If the boolean argument is omitted, the current state is
returned. This is turned on by default for the main display.
$widget->viewable
Returns 1 if $widget and all of its ancestors up through the nearest toplevel window are mapped.
Returns 0 if any of these windows are not mapped.
$widget->visual
Returns one of the following strings to indicate the visual class for $widget: directcolor,
grayscale, pseudocolor, staticcolor, staticgray, or truecolor.
$widget->visualid
Returns the X identifier for the visual for $widget.
$widget->visualsavailable(?includeids?)
Returns a list whose elements describe the visuals available for $widget's screen. Each element
consists of a visual class followed by an integer depth. The class has the same form as returned by
$widget->visual. The depth gives the number of bits per pixel in the visual. In addition, if the
includeids argument is provided, then the depth is followed by the X identifier for the visual.
$widget->vrootheight
Returns the height of the virtual root window associated with $widget if there is one; otherwise
returns the height of $widget's screen.
$widget->vrootwidth
Returns the width of the virtual root window associated with $widget if there is one; otherwise
returns the width of $widget's screen.
$widget->vrootx
Returns the x-offset of the virtual root window associated with $widget, relative to the root window
of its screen. This is normally either zero or negative. Returns 0 if there is no virtual root
window for $widget.
$widget->vrooty
Returns the y-offset of the virtual root window associated with $widget, relative to the root window
of its screen. This is normally either zero or negative. Returns 0 if there is no virtual root
window for $widget.
$widget->waitVariable(\$name)
$widget->waitVisibility
$widget->waitWindow
The tk wait methods wait for one of several things to happen, then it returns without taking any
other actions. The return value is always an empty string. waitVariable expects a reference to a
perl variable and the command waits for that variable to be modified. This form is typically used to
wait for a user to finish interacting with a dialog which sets the variable as part (possibly final)
part of the interaction. waitVisibility waits for a change in $widget's visibility state (as
indicated by the arrival of a VisibilityNotify event). This form is typically used to wait for a
newly-created window to appear on the screen before taking some action. waitWindow waits for $widget
to be destroyed. This form is typically used to wait for a user to finish interacting with a dialog
box before using the result of that interaction. Note that creating and destroying the window each
time a dialog is required makes code modular but imposes overhead which can be avoided by withdrawing
the window instead and using waitVisibility.
While the tk wait methods are waiting they processes events in the normal fashion, so the application
will continue to respond to user interactions. If an event handler invokes tkwait again, the nested
call to tkwait must complete before the outer call can complete.
$widget->Walk(proc?, arg, ...?)
Traverse a widget hierarchy starting at $widget while executing the subroutine proc to every visited
widget. The arguments arg, ... are supplied to the subroutine.
$widget->Widget(pathname)
Returns the widget reference for the given Tk path name, or "undef" if the path name does not match a
Tk widget. This is the inverse of the "PathName" method. (This is an import from the C interface.)
$widget->width
Returns a decimal string giving $widget's width in pixels. When a window is first created its width
will be 1 pixel; the width will eventually be changed by a geometry manager to fulfill the window's
needs. If you need the true width immediately after creating a widget, invoke update to force the
geometry manager to arrange it, or use $widget->reqwidth to get the window's requested width instead
of its actual width.
$widget->windowingsystem
Returns the current Tk windowing system, one of x11 (X11-based), win32 (MS Windows), classic (Mac OS
Classic), or aqua (Mac OS X Aqua).
$widget->x
Returns a decimal string giving the x-coordinate, in $widget's parent, of the upper-left corner of
$widget's border (or $widget if it has no border).
$widget->y
Returns a decimal string giving the y-coordinate, in $widget's parent, of the upper-left corner of
$widget's border (or $widget if it has no border).
CAVEATS
The above documentation on generic methods is incomplete.
KEYWORDS
atom, children, class, geometry, height, identifier, information, interpreters, mapped, parent, path
name, screen, virtual root, width, window
perl v5.38.2 2024-04-01 Widget(3pm)