Provided by: perl-tk_804.031-1build1_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