1Widget(3) User Contributed Perl Documentation Widget(3)
2
6 Tk::Widget - Base class of all widgets
7
9 package Tk::Whatever;
10 require Tk::Widget;
11 @ISA = qw(Tk::Widget);
12 Construct Tk::Widget 'Whatever';
13 sub Tk_cmd { \&Tk::whatever }
15 $widget->method(?arg, arg, ...?)
17
19 The Tk::Widget is an abstract base class for all Tk widgets.
20 Generic methods available to all widgets include the methods based on
22 core "winfo" mechanism and are used to retrieve information about
23 windows managed by Tk. They can take any of a number of different
24 forms, depending on the method. The legal forms are:
25 $widget->appname?(newName)?
27 If newName isn't specified, this method returns the name of the
28 application (the name that may be used in send commands to
29 communicate with the application). If newName is specified, then
30 the name of the application is changed to newName. If the given
31 name is already in use, then a suffix of the form `` #2'' or ``
32 #3'' is appended in order to make the name unique. The method's
33 result is the name actually chosen. newName should not start with
34 a capital letter. This will interfere with option processing,
35 since names starting with capitals are assumed to be classes; as a
36 result, Tk may not be able to find some options for the
37 application. If sends have been disabled by deleting the send
38 command, this command will reenable them and recreate the send
39 command.
40 $widget->atom(name)
42 Returns a decimal string giving the integer identifier for the atom
43 whose name is name. If no atom exists with the name name then a
44 new one is created.
45 $widget->atomname(id)
47 Returns the textual name for the atom whose integer identifier is
48 id. This command is the inverse of the $widget->atom command. It
49 generates an error if no such atom exists.
50 $widget->bell( ?-nice? );
52 This command rings the bell on the display for $widget and returns
53 an empty string. The command uses the current bell-related
54 settings for the display, which may be modified with programs such
55 as xset.
56 If -nice is not specified, this command also resets the screen
58 saver for the screen. Some screen savers will ignore this, but
59 others will reset so that the screen becomes visible again.
60 $widget->bindDump
62 This command returns a list of strings suitable for printing
63 detailing binding information for a widget. It prints a widget's
64 bindtags. For each binding tag it prints all the bindings,
65 comprised of the event descriptor and the callback. Callback
66 arguments are printed, and Tk::Ev objects are expanded.
67 $widget->Busy?(?-recurse => 1?,-option => value?)?
69 This method configures a -cursor option for $widget and (if
70 -recurse = 1> is specified) all its descendants. The cursor to be
71 set may be passed as -cursor = cursor> or defaults to 'watch'.
72 Additional configure options are applied to $widget only. It also
73 adds a special tag 'Busy' to the bindtags of the widgets so
74 configured so that KeyPress, KeyRelease, ButtonPress and
75 ButtonRelease events are ignored (with press events generating a
76 call to bell). It then acquires a local grab for $widget. The
77 state of the widgets and the grab is restored by a call to
78 $widget->Unbusy.
79 $widget->caret( ?-x => x?, ?-y => y?, ?-height => height? );
81 Sets and queries the caret location for the display of the
82 specified Tk window window. The caret is the per-display cursor
83 location used for indicating global focus (e.g. to comply with
84 Microsoft Accessibility guidelines), as well as for location of the
85 over-the-spot XIM (X Input Methods) or Windows IME windows. If no
86 options are specified, the last values used for setting the caret
87 are return in option-value pair format. -x and -y represent
88 window-relative coordinates, and -height is the height of the
89 current cursor location, or the height of the specified window if
90 none is given.
91 $widget->cells
93 Returns a decimal string giving the number of cells in the color
94 map for $widget.
95 $widget->children
97 $widget->children Returns a list containing all the children of
98 $widget. The list is in stacking order, with the lowest window
99 first. Top-level windows are returned as children of their logical
100 parents.
101 $widget->class
103 Returns the class name for $widget.
104 $widget->colormapfull
106 Returns 1 if the colormap for $widget is known to be full, 0
107 otherwise. The colormap for a window is ``known'' to be full if
108 the last attempt to allocate a new color on that window failed and
109 this application hasn't freed any colors in the colormap since the
110 failed allocation.
111 $widget->ConfigSpecs
113 Used to perform delegated option configuration for a mega-widget.
114 Returns, in Tk::Derived::ConfigSpecs notation (see
115 Tk::ConfigSpecs), all possible options for a widget. For example,
116 $s = $self->Scale;
118 $self->ConfigSpecs(
119 $s->ConfigSpecs,
120 .... more ConfigSpecs specifications
121 );
122 returns a hash of all Tk::Scale options, delegated to $s - e.g.
124 some representative examples:
125 -bigincrement => [$s, bigIncrement, BigIncrement, 0, 0]
127 -digits => [$s, digits, Digits, 0, 0]
128 -sliderlength => [$s, sliderLength, SliderLength, 10m, 30]
129 -troughcolor => [$s, troughColor, Background, #c3c3c3, #c3c3c3]
130 This provides an easy means of populating a mega-widget's
132 ConfigSpecs with initializers.
133 $widget->containing(rootX,rootY)
135 Returns the window containing the point given by rootX and rootY.
136 RootX and rootY are specified in screen units (i.e. any form
137 acceptable to Tk_GetPixels) in the coordinate system of the root
138 window (if a virtual-root window manager is in use then the
139 coordinate system of the virtual root window is used). If no
140 window in this application contains the point then an empty string
141 is returned. In selecting the containing window, children are
142 given higher priority than parents and among siblings the highest
143 one in the stacking order is chosen.
144 $widget->depth
146 Returns a decimal string giving the depth of $widget (number of
147 bits per pixel).
148 $widget->destroy
150 This command deletes the window related to $widget, plus all its
151 descendants. If all the MainWindows are deleted then the entire
152 application will be destroyed.
153 The perl object $widget continues to exist while references to it
155 still exist, e.g. until variable goes out of scope. However any
156 attempt to use Tk methods on the object will fail. Exists($widget)
157 will return false on such objects.
158 Note however that while a window exists for $widget the perl object
160 is maintained (due to "references" in perl/Tk internals) even
161 though original variables may have gone out of scope. (Normally
162 this is intuitive.)
163 Exists($widget)
165 Returns 1 if there exists a window for $widget, 0 if no such window
166 exists.
167 $widget->font(option?, arg, arg, ...?)
169 Create and inspect fonts. See Tk::Font for further details.
170 $widget->fpixels(number)
172 Returns a floating-point value giving the number of pixels in
173 $widget corresponding to the distance given by number. Number may
174 be specified in any of the forms acceptable to Tk_GetScreenMM, such
175 as ``2.0c'' or ``1i''. The return value may be fractional; for an
176 integer value, use $widget->pixels.
177 $widget->Getimage(name)
179 Given name, look for an image file with that base name and return a
180 Tk::Image. File extensions are tried in this order: xpm, gif, ppm,
181 xbm until a valid iamge is found. If no image is found, try a
182 builtin image with that name.
183 $widget->geometry
185 Returns the geometry for $widget, in the form widthxheight+x+y.
186 All dimensions are in pixels.
187 $widget->height
189 Returns a decimal string giving $widget's height in pixels. When a
190 window is first created its height will be 1 pixel; the height
191 will eventually be changed by a geometry manager to fulfill the
192 window's needs. If you need the true height immediately after
193 creating a widget, invoke update to force the geometry manager to
194 arrange it, or use $widget->reqheight to get the window's requested
195 height instead of its actual height.
196 $widget->id
198 Returns a hexadecimal string giving a low-level platform-specific
199 identifier for $widget. On Unix platforms, this is the X window
200 identifier. Under Windows, this is the Windows HWND. On the
201 Macintosh the value has no meaning outside Tk.
202 $widget->idletasks
204 One of two methods which are used to bring the application ``up to
205 date'' by entering the event loop repeated until all pending events
206 (including idle callbacks) have been processed.
207 If the idletasks method is specified, then no new events or errors
209 are processed; only idle callbacks are invoked. This causes
210 operations that are normally deferred, such as display updates and
211 window layout calculations, to be performed immediately.
212 The idletasks command is useful in scripts where changes have been
214 made to the application's state and you want those changes to
215 appear on the display immediately, rather than waiting for the
216 script to complete. Most display updates are performed as idle
217 callbacks, so idletasks will cause them to run. However, there are
218 some kinds of updates that only happen in response to events, such
219 as those triggered by window size changes; these updates will not
220 occur in idletasks.
221 $widget->interps
223 Returns a list whose members are the names of all Tcl interpreters
224 (e.g. all Tk-based applications) currently registered for a
225 particular display. The return value refers to the display of
226 $widget.
227 $widget->ismapped
229 Returns 1 if $widget is currently mapped, 0 otherwise.
230 $widget->lower(?belowThis?)
232 If the belowThis argument is omitted then the command lowers
233 $widget so that it is below all of its siblings in the stacking
234 order (it will be obscured by any siblings that overlap it and will
235 not obscure any siblings). If belowThis is specified then it must
236 be the path name of a window that is either a sibling of $widget or
237 the descendant of a sibling of $widget. In this case the lower
238 command will insert $widget into the stacking order just below
239 belowThis (or the ancestor of belowThis that is a sibling of
240 $widget); this could end up either raising or lowering $widget.
241 $widget->MapWindow
243 Cause $widget to be "mapped" i.e. made visible on the display. May
244 confuse the geometry manager (pack, grid, place, ...) that thinks
245 it is managing the widget.
246 $widget->manager
248 Returns the name of the geometry manager currently responsible for
249 $widget, or an empty string if $widget isn't managed by any
250 geometry manager. The name is usually the name of the method for
251 the geometry manager, such as pack or place. If the geometry
252 manager is a widget, such as canvases or text, the name is the
253 widget's class command, such as canvas.
254 $widget->name
256 Returns $widget's name (i.e. its name within its parent, as opposed
257 to its full path name). The command $mainwin->name will return the
258 name of the application.
259 $widget->OnDestroy(callback);
261 OnDestroy accepts a standard perl/Tk callback. When the window
262 associated with $widget is destroyed then the callback is invoked.
263 Unlike $widget->bind('<Destroy>',...) the widgets methods are
264 still available when callback is executed, so (for example) a Text
265 widget can save its contents to a file.
266 OnDestroy was required for new after mechanism.
268 $widget->parent
270 Returns $widget's parent, or an empty string if $widget is the main
271 window of the application.
272 $widget->PathName
274 Returns the Tk path name of $widget. This is the inverse of the
275 "Widget" method. (This is an import from the C interface.)
276 $widget->pathname(id)
278 Returns an object whose X identifier is id. The identifier is
279 looked up on the display of $widget. Id must be a decimal,
280 hexadecimal, or octal integer and must correspond to a window in
281 the invoking application, or an error occurs which can be trapped
282 with "eval { }" or "Tk::catch { }". If the window belongs to the
283 application, but is not an object (for example wrapper windows,
284 HList header, etc.) then "undef" is returned.
285 $widget->pixels(number)
287 Returns the number of pixels in $widget corresponding to the
288 distance given by number. Number may be specified in any of the
289 forms acceptable to Tk_GetPixels, such as ``2.0c'' or ``1i''. The
290 result is rounded to the nearest integer value; for a fractional
291 result, use $widget->fpixels.
292 $widget->pointerx
294 If the mouse pointer is on the same screen as $widget, returns the
295 pointer's x coordinate, measured in pixels in the screen's root
296 window. If a virtual root window is in use on the screen, the
297 position is measured in the virtual root. If the mouse pointer
298 isn't on the same screen as $widget then -1 is returned.
299 $widget->pointerxy
301 If the mouse pointer is on the same screen as $widget, returns a
302 list with two elements, which are the pointer's x and y coordinates
303 measured in pixels in the screen's root window. If a virtual root
304 window is in use on the screen, the position is computed in the
305 virtual root. If the mouse pointer isn't on the same screen as
306 $widget then both of the returned coordinates are -1.
307 $widget->pointery
309 If the mouse pointer is on the same screen as $widget, returns the
310 pointer's y coordinate, measured in pixels in the screen's root
311 window. If a virtual root window is in use on the screen, the
312 position is computed in the virtual root. If the mouse pointer
313 isn't on the same screen as $widget then -1 is returned.
314 $widget->raise(?aboveThis?)
316 If the aboveThis argument is omitted then the command raises
317 $widget so that it is above all of its siblings in the stacking
318 order (it will not be obscured by any siblings and will obscure any
319 siblings that overlap it). If aboveThis is specified then it must
320 be the path name of a window that is either a sibling of $widget or
321 the descendant of a sibling of $widget. In this case the raise
322 command will insert $widget into the stacking order just above
323 aboveThis (or the ancestor of aboveThis that is a sibling of
324 $widget); this could end up either raising or lowering $widget.
325 $widget->reqheight
327 Returns a decimal string giving $widget's requested height, in
328 pixels. This is the value used by $widget's geometry manager to
329 compute its geometry.
330 $widget->reqwidth
332 Returns a decimal string giving $widget's requested width, in
333 pixels. This is the value used by $widget's geometry manager to
334 compute its geometry.
335 $widget->rgb(color)
337 Returns a list containing three decimal values, which are the red,
338 green, and blue intensities that correspond to color in the window
339 given by $widget. Color may be specified in any of the forms
340 acceptable for a color option.
341 $widget->rootx
343 Returns a decimal string giving the x-coordinate, in the root
344 window of the screen, of the upper-left corner of $widget's border
345 (or $widget if it has no border).
346 $widget->rooty
348 Returns a decimal string giving the y-coordinate, in the root
349 window of the screen, of the upper-left corner of $widget's border
350 (or $widget if it has no border).
351 $widget->scaling?(number)?
353 Sets and queries the current scaling factor used by Tk to convert
354 between physical units (for example, points, inches, or
355 millimeters) and pixels. The number argument is a floating point
356 number that specifies the number of pixels per point on $widget's
357 display. If the number argument is omitted, the current value of
358 the scaling factor is returned.
359 A ``point'' is a unit of measurement equal to 1/72 inch. A scaling
361 factor of 1.0 corresponds to 1 pixel per point, which is equivalent
362 to a standard 72 dpi monitor. A scaling factor of 1.25 would mean
363 1.25 pixels per point, which is the setting for a 90 dpi monitor;
364 setting the scaling factor to 1.25 on a 72 dpi monitor would cause
365 everything in the application to be displayed 1.25 times as large
366 as normal. The initial value for the scaling factor is set when
367 the application starts, based on properties of the installed
368 monitor (as reported via the window system), but it can be changed
369 at any time. Measurements made after the scaling factor is changed
370 will use the new scaling factor, but it is undefined whether
371 existing widgets will resize themselves dynamically to accomodate
372 the new scaling factor.
373 $widget->screen
375 Returns the name of the screen associated with $widget, in the form
376 displayName.screenIndex.
377 $widget->screencells
379 Returns a decimal string giving the number of cells in the default
380 color map for $widget's screen.
381 $widget->screendepth
383 Returns a decimal string giving the depth of the root window of
384 $widget's screen (number of bits per pixel).
385 $widget->screenheight
387 Returns a decimal string giving the height of $widget's screen, in
388 pixels.
389 $widget->screenmmheight
391 Returns a decimal string giving the height of $widget's screen, in
392 millimeters.
393 $widget->screenmmwidth
395 Returns a decimal string giving the width of $widget's screen, in
396 millimeters.
397 $widget->screenvisual
399 Returns one of the following strings to indicate the default visual
400 class for $widget's screen: directcolor, grayscale, pseudocolor,
401 staticcolor, staticgray, or truecolor.
402 $widget->screenwidth
404 Returns a decimal string giving the width of $widget's screen, in
405 pixels.
406 $widget->server
408 Returns a string containing information about the server for
409 $widget's display. The exact format of this string may vary from
410 platform to platform. For X servers the string has the form
411 ``XmajorRminor vendor vendorVersion'' where major and minor are the
412 version and revision numbers provided by the server (e.g., X11R5),
413 vendor is the name of the vendor for the server, and vendorRelease
414 is an integer release number provided by the server.
415 $widget->toplevel
417 Returns the reference of the top-level window containing $widget.
418 $widget->Unbusy
420 Restores widget state after a call to $widget->Busy.
421 $widget->UnmapWindow
423 Cause $widget to be "unmapped" i.e. removed from the display. This
424 does for any widget what $widget->withdraw does for toplevel
425 widgets. May confuse the geometry manager (pack, grid, place, ...)
426 that thinks it is managing the widget.
427 $widget->update
429 One of two methods which are used to bring the application ``up to
430 date'' by entering the event loop repeated until all pending events
431 (including idle callbacks) have been processed.
432 The update method is useful in scripts where you are performing a
434 long-running computation but you still want the application to
435 respond to events such as user interactions; if you occasionally
436 call update then user input will be processed during the next call
437 to update.
438 $widget->useinputmethods( ?boolean? )
440 Sets and queries the state of whether Tk should use XIM (X Input
441 Methods) for filtering events. The resulting state is returned.
442 XIM is used in some locales (ie: Japanese, Korean), to handle
443 special input devices. This feature is only significant on X.
444 If XIM support is not available, this will always return 0. If
445 the boolean argument is omitted, the current state is
446 returned. This is turned on by default for the main display.
447 $widget->viewable
449 Returns 1 if $widget and all of its ancestors up through the
450 nearest toplevel window are mapped. Returns 0 if any of these
451 windows are not mapped.
452 $widget->visual
454 Returns one of the following strings to indicate the visual class
455 for $widget: directcolor, grayscale, pseudocolor, staticcolor,
456 staticgray, or truecolor.
457 $widget->visualid
459 Returns the X identifier for the visual for $widget.
460 $widget->visualsavailable(?includeids?)
462 Returns a list whose elements describe the visuals available for
463 $widget's screen. Each element consists of a visual class followed
464 by an integer depth. The class has the same form as returned by
465 $widget->visual. The depth gives the number of bits per pixel in
466 the visual. In addition, if the includeids argument is provided,
467 then the depth is followed by the X identifier for the visual.
468 $widget->vrootheight
470 Returns the height of the virtual root window associated with
471 $widget if there is one; otherwise returns the height of $widget's
472 screen.
473 $widget->vrootwidth
475 Returns the width of the virtual root window associated with
476 $widget if there is one; otherwise returns the width of $widget's
477 screen.
478 $widget->vrootx
480 Returns the x-offset of the virtual root window associated with
481 $widget, relative to the root window of its screen. This is
482 normally either zero or negative. Returns 0 if there is no virtual
483 root window for $widget.
484 $widget->vrooty
486 Returns the y-offset of the virtual root window associated with
487 $widget, relative to the root window of its screen. This is
488 normally either zero or negative. Returns 0 if there is no virtual
489 root window for $widget.
490 $widget->waitVariable(\$name)
492 $widget->waitVisibility
493 $widget->waitWindow
494 The tk wait methods wait for one of several things to happen, then
495 it returns without taking any other actions. The return value is
496 always an empty string. waitVariable expects a reference to a perl
497 variable and the command waits for that variable to be modified.
498 This form is typically used to wait for a user to finish
499 interacting with a dialog which sets the variable as part (possibly
500 final) part of the interaction. waitVisibility waits for a change
501 in $widget's visibility state (as indicated by the arrival of a
502 VisibilityNotify event). This form is typically used to wait for a
503 newly-created window to appear on the screen before taking some
504 action. waitWindow waits for $widget to be destroyed. This form
505 is typically used to wait for a user to finish interacting with a
506 dialog box before using the result of that interaction. Note that
507 creating and destroying the window each time a dialog is required
508 makes code modular but imposes overhead which can be avoided by
509 withdrawing the window instead and using waitVisibility.
510 While the tk wait methods are waiting they processes events in the
512 normal fashion, so the application will continue to respond to user
513 interactions. If an event handler invokes tkwait again, the nested
514 call to tkwait must complete before the outer call can complete.
515 $widget->Walk(proc?, arg, ...?)
517 Traverse a widget hierarchy starting at $widget while executing the
518 subroutine proc to every visited widget. The arguments arg, ...
519 are supplied to the subroutine.
520 $widget->Widget(pathname)
522 Returns the widget reference for the given Tk path name, or "undef"
523 if the path name does not match a Tk widget. This is the inverse of
524 the "PathName" method. (This is an import from the C interface.)
525 $widget->width
527 Returns a decimal string giving $widget's width in pixels. When a
528 window is first created its width will be 1 pixel; the width will
529 eventually be changed by a geometry manager to fulfill the window's
530 needs. If you need the true width immediately after creating a
531 widget, invoke update to force the geometry manager to arrange it,
532 or use $widget->reqwidth to get the window's requested width
533 instead of its actual width.
534 $widget->windowingsystem
536 Returns the current Tk windowing system, one of x11 (X11-based),
537 win32 (MS Windows), classic (Mac OS Classic), or aqua (Mac OS X
538 Aqua).
539 $widget->x
541 Returns a decimal string giving the x-coordinate, in $widget's
542 parent, of the upper-left corner of $widget's border (or $widget if
543 it has no border).
544 $widget->y
546 Returns a decimal string giving the y-coordinate, in $widget's
547 parent, of the upper-left corner of $widget's border (or $widget if
548 it has no border).
549
551 The above documentaion on generic methods is incomplete.
552
554 atom, children, class, geometry, height, identifier, information,
555 interpreters, mapped, parent, path name, screen, virtual root, width,
556 window
557perl v5.32.0 2020-07-28 Widget(3)