The following line creates a frame widget, which in this case will contain a label and a button we’ll create next. The frame is fit inside the root window.
The next line creates a label widget holding a static text string. The
grid()
method is used to specify the relative layout (position) of the label within its containing frame widget, similar to how tables in HTML work.
A button widget is then created, and placed to the right of the label. When pressed, it will call the
destroy()
method of the root window.
Important Tk Concepts
¶
Even this simple program illustrates the following key Tk concepts:
-
widgets
-
A Tkinter user interface is made up of individual
widgets
. Each widget is represented as a Python object, instantiated from classes like
ttk.Frame
,
ttk.Label
，和
ttk.Button
.
-
widget hierarchy
-
Widgets are arranged in a
hierarchy
. The label and button were contained within a frame, which in turn was contained within the root window. When creating each
child
widget, its
parent
widget is passed as the first argument to the widget constructor.
-
configuration options
-
Widgets have
configuration options
, which modify their appearance and behavior, such as the text to display in a label or button. Different classes of widgets will have different sets of options.
-
geometry management
-
Widgets aren’t automatically added to the user interface when they are created. A
geometry manager
like
grid
controls where in the user interface they are placed.
-
事件循环
-
Tkinter reacts to user input, changes from your program, and even refreshes the display only when actively running an
事件循环
. If your program isn’t running the event loop, your user interface won’t update.
Understanding How Tkinter Wraps Tcl/Tk
¶
When your application uses Tkinter’s classes and methods, internally Tkinter is assembling strings representing Tcl/Tk commands, and executing those commands in the Tcl interpreter attached to your application’s
Tk
实例。
Whether it’s trying to navigate reference documentation, trying to find the right method or option, adapting some existing code, or debugging your Tkinter application, there are times that it will be useful to understand what those underlying Tcl/Tk commands look like.
To illustrate, here is the Tcl/Tk equivalent of the main part of the Tkinter script above.
ttk::frame .frm -padding 10
grid .frm
grid [ttk::label .frm.lbl -text "Hello World!"] -column 0 -row 0
grid [ttk::button .frm.btn -text "Quit" -command "destroy ."] -column 1 -row 0
Tcl’s syntax is similar to many shell languages, where the first word is the command to be executed, with arguments to that command following it, separated by spaces. Without getting into too many details, notice the following:
-
The commands used to create widgets (like
ttk::frame
) correspond to widget classes in Tkinter.
-
Tcl widget options (like
-text
) correspond to keyword arguments in Tkinter.
-
Widgets are referred to by a
pathname
in Tcl (like
.frm.btn
), whereas Tkinter doesn’t use names but object references.
-
A widget’s place in the widget hierarchy is encoded in its (hierarchical) pathname, which uses a
.
(dot) as a path separator. The pathname for the root window is just
.
(dot). In Tkinter, the hierarchy is defined not by pathname but by specifying the parent widget when creating each child widget.
-
Operations which are implemented as separate
命令
in Tcl (like
grid
or
destroy
) are represented as
方法
on Tkinter widget objects. As you’ll see shortly, at other times Tcl uses what appear to be method calls on widget objects, which more closely mirror what would is used in Tkinter.
How do I…? What option does…?
¶
If you’re not sure how to do something in Tkinter, and you can’t immediately find it in the tutorial or reference documentation you’re using, there are a few strategies that can be helpful.
First, remember that the details of how individual widgets work may vary across different versions of both Tkinter and Tcl/Tk. If you’re searching documentation, make sure it corresponds to the Python and Tcl/Tk versions installed on your system.
When searching for how to use an API, it helps to know the exact name of the class, option, or method that you’re using. Introspection, either in an interactive Python shell or with
print()
, can help you identify what you need.
To find out what configuration options are available on any widget, call its
configure()
method, which returns a dictionary containing a variety of information about each object, including its default and current values. Use
keys()
to get just the names of each option.
btn = ttk.Button(frm, ...)
print(btn.configure().keys())
As most widgets have many configuration options in common, it can be useful to find out which are specific to a particular widget class. Comparing the list of options to that of a simpler widget, like a frame, is one way to do that.
print(set(btn.configure().keys()) - set(frm.configure().keys()))
Similarly, you can find the available methods for a widget object using the standard
dir()
function. If you try it, you’ll see there are over 200 common widget methods, so again identifying those specific to a widget class is helpful.
print(dir(btn))
print(set(dir(btn)) - set(dir(frm)))
Navigating the Tcl/Tk Reference Manual
¶
As noted, the official
Tk commands
reference manual (man pages) is often the most accurate description of what specific operations on widgets do. Even when you know the name of the option or method that you need, you may still have a few places to look.
While all operations in Tkinter are implemented as method calls on widget objects, you’ve seen that many Tcl/Tk operations appear as commands that take a widget pathname as its first parameter, followed by optional parameters, e.g.
destroy .
grid .frm.btn -column 0 -row 0
Others, however, look more like methods called on a widget object (in fact, when you create a widget in Tcl/Tk, it creates a Tcl command with the name of the widget pathname, with the first parameter to that command being the name of a method to call).
.frm.btn invoke
.frm.lbl configure -text "Goodbye"
In the official Tcl/Tk reference documentation, you’ll find most operations that look like method calls on the man page for a specific widget (e.g., you’ll find the
invoke()
method on the
ttk::button
man page), while functions that take a widget as a parameter often have their own man page (e.g.,
grid
).
You’ll find many common options and methods in the
选项
or
ttk::widget
man pages, while others are found in the man page for a specific widget class.
You’ll also find that many Tkinter methods have compound names, e.g.,
winfo_x()
,
winfo_height()
,
winfo_viewable()
. You’d find documentation for all of these in the
winfo
man page.
注意
Somewhat confusingly, there are also methods on all Tkinter widgets that don’t actually operate on the widget, but operate at a global scope, independent of any widget. Examples are methods for accessing the clipboard or the system bell. (They happen to be implemented as methods in the base
Widget
class that all Tkinter widgets inherit from).
Threading model
¶
Python and Tcl/Tk have very different threading models, which
tkinter
tries to bridge. If you use threads, you may need to be aware of this.
A Python interpreter may have many threads associated with it. In Tcl, multiple threads can be created, but each thread has a separate Tcl interpreter instance associated with it. Threads can also create more than one interpreter instance, though each interpreter instance can be used only by the one thread that created it.
每个
Tk
object created by
tkinter
contains a Tcl interpreter. It also keeps track of which thread created that interpreter. Calls to
tkinter
can be made from any Python thread. Internally, if a call comes from a thread other than the one that created the
Tk
object, an event is posted to the interpreter’s event queue, and when executed, the result is returned to the calling Python thread.
Tcl/Tk applications are normally event-driven, meaning that after initialization, the interpreter runs an event loop (i.e.
Tk.mainloop()
) and responds to events. Because it is single-threaded, event handlers must respond quickly, otherwise they will block other events from being processed. To avoid this, any long-running computations should not run in an event handler, but are either broken into smaller pieces using timers, or run in another thread. This is different from many GUI toolkits where the GUI runs in a completely separate thread from all application code including event handlers.
If the Tcl interpreter is not running the event loop and processing events, any
tkinter
calls made from threads other than the one running the Tcl interpreter will fail.
A number of special cases exist:
-
Tcl/Tk libraries can be built so they are not thread-aware. In this case,
tkinter
calls the library from the originating Python thread, even if this is different than the thread that created the Tcl interpreter. A global lock ensures only one call occurs at a time.
-
While
tkinter
allows you to create more than one instance of a
Tk
object (with its own interpreter), all interpreters that are part of the same thread share a common event queue, which gets ugly fast. In practice, don’t create more than one instance of
Tk
at a time. Otherwise, it’s best to create them in separate threads and ensure you’re running a thread-aware Tcl/Tk build.
-
Blocking event handlers are not the only way to prevent the Tcl interpreter from reentering the event loop. It is even possible to run multiple nested event loops or abandon the event loop entirely. If you’re doing anything tricky when it comes to events or threads, be aware of these possibilities.
-
There are a few select
tkinter
functions that presently work only when called from the thread that created the Tcl interpreter.
Handy Reference
¶
设置选项
¶
Options control things like the color and border width of a widget. Options can be set in three ways:
-
At object creation time, using keyword arguments
-
fred = Button(self, fg="red", bg="blue")
-
After object creation, treating the option name like a dictionary index
-
fred["fg"] = "red"
fred["bg"] = "blue"
-
Use the config() method to update multiple attrs subsequent to object creation
-
fred.config(fg="red", bg="blue")
For a complete explanation of a given option and its behavior, see the Tk man pages for the widget in question.
Note that the man pages list “STANDARD OPTIONS” and “WIDGET SPECIFIC OPTIONS” for each widget. The former is a list of options that are common to many widgets, the latter are the options that are idiosyncratic to that particular widget. The Standard Options are documented on the
options(3)
man page.
No distinction between standard and widget-specific options is made in this document. Some options don’t apply to some kinds of widgets. Whether a given widget responds to a particular option depends on the class of the widget; buttons have a
command
option, labels do not.
The options supported by a given widget are listed in that widget’s man page, or can be queried at runtime by calling the
config()
method without arguments, or by calling the
keys()
method on that widget. The return value of these calls is a dictionary whose key is the name of the option as a string (for example,
'relief'
) and whose values are 5-tuples.
Some options, like
bg
are synonyms for common options with long names (
bg
is shorthand for “background”). Passing the
config()
method the name of a shorthand option will return a 2-tuple, not 5-tuple. The 2-tuple passed back will contain the name of the synonym and the “real” option (such as
('bg', 'background')
).
|
索引
|
含义
|
范例
|
|
0
|
option name
|
'relief'
|
|
1
|
option name for database lookup
|
'relief'
|
|
2
|
option class for database lookup
|
'Relief'
|
|
3
|
default value
|
'raised'
|
|
4
|
current value
|
'groove'
|
范例：
>>> print(fred.config())
{'relief': ('relief', 'relief', 'Relief', 'raised', 'groove')}
Of course, the dictionary printed will include all the options available and their values. This is meant only as an example.
The Packer
¶
The packer is one of Tk’s geometry-management mechanisms. Geometry managers are used to specify the relative positioning of widgets within their container - their mutual
master
. In contrast to the more cumbersome
placer
(which is used less commonly, and we do not cover here), the packer takes qualitative relationship specification -
above
,
to the left of
,
filling
, etc - and works everything out to determine the exact placement coordinates for you.
The size of any
master
widget is determined by the size of the “slave widgets” inside. The packer is used to control where slave widgets appear inside the master into which they are packed. You can pack widgets into frames, and frames into other frames, in order to achieve the kind of layout you desire. Additionally, the arrangement is dynamically adjusted to accommodate incremental changes to the configuration, once it is packed.
Note that widgets do not appear until they have had their geometry specified with a geometry manager. It’s a common early mistake to leave out the geometry specification, and then be surprised when the widget is created but nothing appears. A widget will appear only after it has had, for example, the packer’s
pack()
method applied to it.
The pack() method can be called with keyword-option/value pairs that control where the widget is to appear within its container, and how it is to behave when the main application window is resized. Here are some examples:
fred.pack() # defaults to side = "top"
fred.pack(side="left")
fred.pack(expand=1)
Packer Options
¶
For more extensive information on the packer and the options that it can take, see the man pages and page 183 of John Ousterhout’s book.
-
anchor
-
Anchor type. Denotes where the packer is to place each slave in its parcel.
-
expand
-
Boolean,
0
or
1
.
-
fill
-
Legal values:
'x'
,
'y'
,
'both'
,
'none'
.
-
ipadx and ipady
-
A distance - designating internal padding on each side of the slave widget.
-
padx and pady
-
A distance - designating external padding on each side of the slave widget.
-
side
-
Legal values are:
'left'
,
'right'
,
'top'
,
'bottom'
.
The Window Manager
¶
In Tk, there is a utility command,
wm
, for interacting with the window manager. Options to the
wm
command allow you to control things like titles, placement, icon bitmaps, and the like. In
tkinter
, these commands have been implemented as methods on the
Wm
class. Toplevel widgets are subclassed from the
Wm
class, and so can call the
Wm
methods directly.
To get at the toplevel window that contains a given widget, you can often just refer to the widget’s master. Of course if the widget has been packed inside of a frame, the master won’t represent a toplevel window. To get at the toplevel window that contains an arbitrary widget, you can call the
_root()
method. This method begins with an underscore to denote the fact that this function is part of the implementation, and not an interface to Tk functionality.
Here are some examples of typical usage:
import tkinter as tk
class App(tk.Frame):
def __init__(self, master=None):
super().__init__(master)
self.pack()
# create the application
myapp = App()
#
# here are method calls to the window manager class
#
myapp.master.title("My Do-Nothing Application")
myapp.master.maxsize(1000, 400)
# start the program
myapp.mainloop()
Tk Option Data Types
¶
-
anchor
-
Legal values are points of the compass:
"n"
,
"ne"
,
"e"
,
"se"
,
"s"
,
"sw"
,
"w"
,
"nw"
, and also
"center"
.
-
bitmap
-
There are eight built-in, named bitmaps:
'error'
,
'gray25'
,
'gray50'
,
'hourglass'
,
'info'
,
'questhead'
,
'question'
,
'warning'
. To specify an X bitmap filename, give the full path to the file, preceded with an
@
, as in
"@/usr/contrib/bitmap/gumby.bit"
.
-
boolean
-
You can pass integers 0 or 1 or the strings
"yes"
or
"no"
.
-
callback
-
This is any Python function that takes no arguments. For example:
def print_it():
print("hi there")
fred["command"] = print_it
-
color
-
Colors can be given as the names of X colors in the rgb.txt file, or as strings representing RGB values in 4 bit:
"#RGB"
, 8 bit:
"#RRGGBB"
, 12 bit:
"#RRRGGGBBB"
, or 16 bit:
"#RRRRGGGGBBBB"
ranges, where R,G,B here represent any legal hex digit. See page 160 of Ousterhout’s book for details.
-
cursor
-
The standard X cursor names from
cursorfont.h
can be used, without the
XC_
prefix. For example to get a hand cursor (
XC_hand2
), use the string
"hand2"
. You can also specify a bitmap and mask file of your own. See page 179 of Ousterhout’s book.
-
distance
-
Screen distances can be specified in either pixels or absolute distances. Pixels are given as numbers and absolute distances as strings, with the trailing character denoting units:
c
for centimetres,
i
for inches,
m
for millimetres,
p
for printer’s points. For example, 3.5 inches is expressed as
"3.5i"
.
-
font
-
Tk uses a list font name format, such as
{courier 10 bold}
. Font sizes with positive numbers are measured in points; sizes with negative numbers are measured in pixels.
-
geometry
-
This is a string of the form
widthxheight
, where width and height are measured in pixels for most widgets (in characters for widgets displaying text). For example:
fred["geometry"] = "200x100"
.
-
justify
-
Legal values are the strings:
"left"
,
"center"
,
"right"
，和
"fill"
.
-
region
-
This is a string with four space-delimited elements, each of which is a legal distance (see above). For example:
"2 3 4 5"
and
"3i 2i 4.5i 2i"
and
"3c 2c 4c 10.43c"
are all legal regions.
-
relief
-
Determines what the border style of a widget will be. Legal values are:
"raised"
,
"sunken"
,
"flat"
,
"groove"
，和
"ridge"
.
-
scrollcommand
-
This is almost always the
set()
method of some scrollbar widget, but can be any widget method that takes a single argument.
-
wrap
-
Must be one of:
"none"
,
"char"
，或
"word"
.
Bindings and Events
¶
The bind method from the widget command allows you to watch for certain events and to have a callback function trigger when that event type occurs. The form of the bind method is:
def bind(self, sequence, func, add=''):
其中：
-
sequence
-
is a string that denotes the target kind of event. (See the
bind(3tk)
man page, and page 201 of John Ousterhout’s book,
Tcl and the Tk Toolkit (2nd edition)
, for details).
-
func
-
is a Python function, taking one argument, to be invoked when the event occurs. An Event instance will be passed as the argument. (Functions deployed this way are commonly known as
callbacks
)。
-
add
-
is optional, either
''
or
'+'
. Passing an empty string denotes that this binding is to replace any other bindings that this event is associated with. Passing a
'+'
means that this function is to be added to the list of functions bound to this event type.
例如：
def turn_red(self, event):
event.widget["activeforeground"] = "red"
self.button.bind("<Enter>", self.turn_red)
Notice how the widget field of the event is being accessed in the
turn_red()
callback. This field contains the widget that caught the X event. The following table lists the other event fields you can access, and how they are denoted in Tk, which can be useful when referring to the Tk man pages.
|
Tk
|
Tkinter Event Field
|
Tk
|
Tkinter Event Field
|
|
%f
|
focus
|
%A
|
char
|
|
%h
|
height
|
%E
|
send_event
|
|
%k
|
keycode
|
%K
|
keysym
|
|
%s
|
state
|
%N
|
keysym_num
|
|
%t
|
time
|
%T
|
type
|
|
%w
|
width
|
%W
|
widget
|
|
%x
|
x
|
%X
|
x_root
|
|
%y
|
y
|
%Y
|
y_root
|
The index Parameter
¶
A number of widgets require “index” parameters to be passed. These are used to point at a specific place in a Text widget, or to particular characters in an Entry widget, or to particular menu items in a Menu widget.
-
Entry widget indexes (index, view index, etc.)
-
Entry widgets have options that refer to character positions in the text being displayed. You can use these
tkinter
functions to access these special points in text widgets:
-
Text widget indexes
-
The index notation for Text widgets is very rich and is best described in the Tk man pages.
-
Menu indexes (menu.invoke(), menu.entryconfig(), etc.)
-
Some options and methods for menus manipulate specific menu entries. Anytime a menu index is needed for an option or a parameter, you may pass in:
-
an integer which refers to the numeric position of the entry in the widget, counted from the top, starting with 0;
-
the string
"active"
, which refers to the menu position that is currently under the cursor;
-
the string
"last"
which refers to the last menu item;
-
An integer preceded by
@
, as in
@6
, where the integer is interpreted as a y pixel coordinate in the menu’s coordinate system;
-
the string
"none"
, which indicates no menu entry at all, most often used with menu.activate() to deactivate all entries, and finally,
-
a text string that is pattern matched against the label of the menu entry, as scanned from the top of the menu to the bottom. Note that this index type is considered after all the others, which means that matches for menu items labelled
last
,
active
，或
none
may be interpreted as the above literals, instead.
图像
¶
Images of different formats can be created through the corresponding subclass of
tkinter.Image
:
-
BitmapImage
for images in XBM format.
-
PhotoImage
for images in PGM, PPM, GIF and PNG formats. The latter is supported starting with Tk 8.6.
Either type of image is created through either the
file
或
data
option (other options are available as well).
Changed in version 3.13:
添加
PhotoImage
方法
copy_replace()
to copy a region from one image to other image, possibly with pixel zooming and/or subsampling. Add
from_coords
参数用于
PhotoImage
方法
copy()
,
zoom()
and
subsample()
. Add
zoom
and
subsample
parameters to
PhotoImage
方法
copy()
.
The image object can then be used wherever an
image
option is supported by some widget (e.g. labels, buttons, menus). In these cases, Tk will not keep a reference to the image. When the last Python reference to the image object is deleted, the image data is deleted as well, and Tk will display an empty box wherever the image was used.
另请参阅
The
Pillow
package adds support for formats such as BMP, JPEG, TIFF, and WebP, among others.
File Handlers
¶
Tk allows you to register and unregister a callback function which will be called from the Tk mainloop when I/O is possible on a file descriptor. Only one handler may be registered per file descriptor. Example code:
import tkinter
widget = tkinter.Tk()
mask = tkinter.READABLE | tkinter.WRITABLE
widget.tk.createfilehandler(file, mask, callback)
...
widget.tk.deletefilehandler(file)
This feature is not available on Windows.
Since you don’t know how many bytes are available for reading, you may not want to use the
BufferedIOBase
or
TextIOBase
read()
or
readline()
methods, since these will insist on reading a predefined number of bytes. For sockets, the
recv()
or
recvfrom()
methods will work fine; for other files, use raw reads or
os.read(file.fileno(), maxbytecount)
.
-
Widget.tk.
createfilehandler
(
file
,
mask
,
func
)
¶
-
Registers the file handler callback function
func
。
file
argument may either be an object with a
fileno()
method (such as a file or socket object), or an integer file descriptor. The
mask
argument is an ORed combination of any of the three constants below. The callback is called as follows:
callback(file, mask)
-
Widget.tk.
deletefilehandler
(
file
)
¶
-
Unregisters a file handler.
-
_tkinter.
READABLE
¶
-
_tkinter.
WRITABLE
¶
-
_tkinter.
EXCEPTION
¶
-
Constants used in the
mask
自变量。
