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
width xheight+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