Tkinter Python PDF

What's Tkinter? The Tkinter module ("Tk interface") is the standard Python interface to the Tk GUI toolkit from Scriptics (formerly developed by Sun Labs). Both Tk and Tkinter are available on most Unix platforms, as well as on Windows and Macintosh systems. Starting with the most recent...

What's Tkinter? The Tkinter module ("Tk interface") is the standard Python interface to the Tk GUI toolkit from Scriptics (formerly developed by Sun Labs). Both Tk and Tkinter are available on most Unix platforms, as well as on Windows and Macintosh systems. Starting with the most recent release (8.0), Tk also offers native look and feel on all platforms. Tkinter consists of a number of modules. The Tk interface is located in a binary module named _tkinter (this was tkinter in earlier versions). This module contains the low-level interface to Tk, and should never be used directly by application programmers. It is usually a shared library (or DLL), but might in some cases be statically linked with the Python interpreter. In addition to the Tk interface module, Tkinter includes a number of Python modules. The two most important modules are the Tkinter itself, and a module called Tkconstants. The former automatically imports the latter, so to use Tkinter, all you need to do is to import one module: import Tkinter Or, more often: from Tkinter import * 1 Application Windows Coming soon. Base Windows In the simple examples we've used this far, there's only one window on the screen; the root window. This is automatically created when you call the Tk constructor, and is of course very convenient for simple applications: from Tkinter import * root = Tk() # create window contents as children to root... root.mainloop() If you need to create additional windows, you can use the Toplevel widget. It simply creates a new window on the screen, a window that looks and behaves pretty much like the original root window: from Tkinter import * root = Tk() # create root window contents... top = Toplevel() # create top window contents... root.mainloop() There's no need to use pack to display the Toplevel, since it is automatically displayed by the window manager (in fact, you'll get an error message if you try to use pack or any other geometry manager with a Toplevel widget). The Work Area Menus Toolbars Status Bars Most applications sport a status bar at the bottom of each application window. Implementing a status bar with Tkinter is trivial: you can simply use a suitably configured Label widget, and reconfigure the text option now and then. Here's one way to do it: 23 Hello, Tkinter But enough talk. Time to look at some code instead. As you know, every serious tutorial should start with a "hello world"-type example. In this overview, we'll show you not only one such example, but two. First, let's look at a pretty minimal version: Example 1. File: hello1.py from Tkinter import * root = Tk() w = Label(root, text="Hello, world!") w.pack() root.mainloop() Running the Example To run the program, run the script as usual: $ python hello1.py The following window appears. Figure 1. Running the program To stop the program, just close the window. Details We start by importing the Tkinter module. It contains all classes, functions and other things needed to work with the Tk toolkit. In most cases, you can simply import everything from Tkinter into your module's namespace: from Tkinter import * To initialize Tkinter, we have to create a Tk root widget. This is an ordinary window, with a title bar and other decoration provided by your window manager. You should only create one root widget for each program, and it must be created before any other widgets. root = Tk() Next, we create a Label widget as a child to the root window: 2  Hello, Tkinter w = Label(root, text="Hello, world!") w.pack() A Label widget can display either text or an icon or other image. In this case, we use the text option to specify which text to display. Next, we call the pack method on this widget, which tells it to size itself to fit the given text, and make itself visible. But before this happens, we have to enter the Tkinter event loop: root.mainloop() The program will stay in the event loop until we close the window. The event loop doesn't only handle events from the user (such as mouse clicks and key presses) or the windowing system (such as redraw events and window configuration messages), it also handle operations queued by Tkinter itself. Among these operations are geometry management (queued by the pack method) and display updates. This also means that the application window will not appear before you enter the main loop. 3 Tkinter Classes Widget classes Tkinter support 15 core widgets: Table 1. Tkinter Widget Classes Widget Description Button A simple button, used to execute a command or other operation. Canvas Structured graphics. This widget can be used to draw graphs and plots, create graphics editors, and to implement custom widgets. Checkbutton Represents a variable that can have two distinct values. Clicking the button toggles between the values. Entry A text entry field. Frame A container widget. The frame can have a border and a background, and is used to group other widgets when creating an application or dialog layout. Label Displays a text or an image. Listbox Displays a list of alternatives. The listbox can be configured to get radiobutton or checklist behaviour. Menu A menu pane. Used to implement pulldown and popup menus. Menubutton A menubutton. Used to implement pulldown menus. Message Display a text. Similar to the label widget, but can automatically wrap text to a given width or aspect ratio. Radiobutton Represents one value of a variable that can have one of many values. Clicking the button sets the variable to that value, and clears all other radiobuttons associated with the same variable. Scale Allows you to set a numerical value by dragging a 'slider'. Scrollbar Standard scrollbars for use with canvas, entry, listbox, and text widgets. Text Formatted text display. Allows you to display and edit text with various styles and attributes. Also supports embedded images and windows. Toplevel A container widget displayed as a separate, top-level window. Also note that there's no widget class hierarchy in Tkinter; all widget classes are siblings in the inheritance tree. All these widgets provide the Misc and geometry management methods, the configuration management methods, and additional methods defined by the widget itself. In addition, the 8  Tkinter Classes Toplevel class also provides the window manager interface. This means that a typical widget class provides some 150 methods. Mixins The Tkinter module provides classes corresponding to the various widget types in Tk, and a number of mixin and other helper classes (a mixin is a class designed to be combined with other classes using multiple inheritance). When you use Tkinter, you should never access the mixin classes directly. Implementation mixins The Misc class is used as a mixin by the root window and widget classes. It provides a large number of Tk and window related services, which are thus available for all Tkinter core widgets. This is done by delegation; the widget simply forwards the request to the appropriate internal object. The W m class is used as a mixin by the root window and Toplevel widget classes. It provides window manager services, also by delegation. Using delegation like this simplifies your application code: once you have a widget, you can access all parts of Tkinter using methods on the widget instance. Geometry mixins The Grid , Pack, and Place classes are used as mixins by the widget classes. They provide access to the various geometry managers, also via delegation. Table 2. Geometry mixins Manager Description Grid The grid geometry manager allows you to create table-like layouts, by organizing the widgets in a 2-dimensional grid. To use this geometry manager, use the grid method. Pack The pack geometry manager lets you create a layout by "packing" the widgets into a parent widget, by treating them as rectangular blocks placed in a frame. To use this geometry manager for a widget, use the pack method on that widget to set things up. Place The place geometry manager lets you explicitly place a widget in a given position. To use this geometry manager, use the place method. Widget configuration management The Widget class mixes the Misc class with the geometry mixins, and adds configuration management through the cget and configure methods, as well as through a partial dictionary interface. The latter can be used to set and query individual options, and is explained in further detail in the next chapter. 9 The Grid Geometry Manager The Grid geometry manager puts the widgets in a 2-dimensional table. The master widget is split into a number of rows and columns, and each "cell" in the resulting table can hold a widget. When to use the Grid Manager The grid manager is the most flexible of the geometry managers in Tkinter. If you don't want to learn how and when to use all three managers, you should at least make sure to learn this one. The grid manager is especially convenient to use when designing dialog boxes. If you're using the packer for that purpose today, you'll be surprised how much easier it is to use the grid manager instead. Instead of using lots of extra frames to get the packing to work, you can in most cases simply pour all the widgets into a single container widget (I tend to use two; one for the dialog body, and one for the button box at the bottom), and use the grid manager to get them all where you want them. Consider the following example: Figure 1. Creating this layout using the pack manager is possible, but it takes a number of extra frame widgets, and a lot of work to make things look good. If you use the grid manager instead, you only need one call per widget to get everything laid out properly (see next section for the code needed to create this layout). WARNING: Never mix grid and pack in the same master window. Tkinter will happily spend the rest of your lifetime trying to negotiate a solution that both managers are happy with. Instead of waiting, kill the application, and take another look at your code. A common mistake is to use the wrong parent for some of the widgets. Patterns Using the grid manager is easy. Just create the widgets, and use the grid method to tell the manager in which row and column to place them. You don't have to specify the size of the grid beforehand; the manager automatically determines that from the widgets in it. Label(master, text="First").grid(row=0) Label(master, text="Second").grid(row=1) e1 = Entry(master) e2 = Entry(master) 82 The Pack Geometry Manager The Pack geometry manager packs widgets in rows or columns. You can use options like fill, expand, and side to control this geometry manager. When to use the Pack Manager To be added. Warning Don't mix grid and pack in the same master window. Tkinter will happily spend the rest of your lifetime trying to negotiate a solution that both managers are happy with. Instead of waiting, kill the application, and take another look at your code. A common mistake is to use the wrong parent for some of the widgets. Patterns To be added. Methods The following methods are available on widgets managed by the pack manager: Widget Methods The following methods are available on widgets managed by the pack manager: pack pack(option=value,...), pack_configure(option=value,...). Pack the widget as described by the options (see below). pack_forget pack_forget(). Remove the widget. The widget is not destroyed, and can be displayed again by pack or any other manager. pack_info() pack_info(). Return a dictionary containing the current options. Manager Methods The following methods are available on widgets that are used as pack managers (that is, the geometry masters for widgets managed by the pack manager). 104 The Place Geometry Manager The Place geometry manager is the simplest of the three general geometry managers provided in Tkinter. It allows you explicitly set the position and size of a window, either in absolute terms, or relative to another window. You can access the place manager through the place method which is available for all standard widgets. When to use place It is usually not a good idea to use place for ordinary window and dialog layouts; its simply to much work to get things working as they should. Use the pack or grid managers for such purposes. However, place has its uses in more specialized cases. Most importantly, it can be used by compound widget containers to implement various custom geometry managers. Another use is to position control buttons in dialogs. Patterns Let's look at some usage patterns. The following command centers a widget in its parent: w.place(relx=0.5, rely=0.5, anchor=CENTER) Here's another variant. It packs a Label widget in a frame widget, and then places a DrawnButton in the upper right corner of the frame. The button will overlap the label. pane = Frame(master) Label(pane, text="Pane Title").pack() b = DrawnButton(pane, (12, 12), launch_icon, command=self.launch) b.place(relx=1, x=-2, y=2, anchor=NE) The following excerpt from a Notepad widget implementation displays a notepad page (implemented as a Frame) in the notepad body frame. It first loops over the available pages, calling place_forget for each one of them. Note that it's not an error to "unplace" a widget that it's not placed in the first case: for w in self.__pages: w.place_forget() self.__pages[index].place(in_=self.__body, x=bd, y=bd) You can combine the absolute and relative options. In such cases, the relative option is applied first, and the absolute value is then added to that position. In the following example, the widget w is almost completely covers its parent, except for a 5 pixel border around the widget. w.place(x=5, y=5, relwidth=1, relheight=1, width=-10, height=-10) You can also place a widget outside another widget. For example, why not place two widgets on top of each other: w2.place(in_=w1, relx=0.5, y=-2, anchor=S, bordermode="outside") 109 The Label Widget The Label widget is a standard Tkinter widget used to display a text or image on the screen. The button can only display text in a single font, but the text may span more than one line. In addition, one of the characters can be underlined, for example to mark a keyboard shortcut. Patterns To use a label, you just have to specify what to display in it (this can be text, a bitmap, or an image): w = Label(master, text="Hello, world!") If you don't specify a size, the label is made just large enough to hold its contents. You can also use the height and width options to explicitly set the size. If you display text in the label, these options define the size of the label in text units. If you display bitmaps or images instead, they define the size in pixels (or other screen units). See the Button description for an example how to specify the size in pixels also for text labels. You can specify which color to use for the label with the foreground (or fg) and background (or bg) options. You can also choose which font to use in the label (the following example uses Tk 8.0 font descriptors). Use colors and fonts sparingly; unless you have a good reason to do otherwise, you should stick to the default values. w = Label(master, text="Rouge", fg="red") w = Label(master, text="Helvetica", font=("Helvetica", 16)) Labels can display multiple lines of text. You can use newlines or use the wraplength option to make the label wrap text by itself. When wrapping text, you might wish to use the anchor and justify options to make things look exactly as you wish. An example: w = Label(master, text=longtext, anchor=W, justify=LEFT) You can associate a variable with the label. When the contents of the variable changes, the label is automatically updated: v = StringVar() Label(master, textvariable=v).pack() v.set("New Text!") Methods The Label widget supports the standard Tkinter Widget interface. There are no additional methods. Options The following options can be used for the Label widget. 87 The Button Widget The Button widget is a standard Tkinter widget used to implement various kinds of buttons. Buttons can contain text or images, and you can associate a Python function or method with each button. When the button is pressed, Tkinter automatically calls that function or method. The button can only display text in a single font, but the text may span more than one line. In addition, one of the characters can be underlined, for example to mark a keyboard shortcut. By default, the Tab key can be used to move to a button widget. Button Patterns Plain buttons are pretty straightforward to use. Simply specify the button contents (text, bitmap, or image) and a callback to call when the button is pressed: b = Button(master, text="OK", command=self.ok) A button without a callback is pretty useless; it simply doesn't do anything when you press the button. You might wish to use such buttons anyway when developing an application. In that case, it is probably a good idea to disable the button to avoid confusing your beta testers: b = Button(master, text="Help", state=DISABLED) If you don't specify a size, the button is made just large enough to hold its contents. You can use the padx and pady option to add some extra space between the contents and the button border. You can also use the height and width options to explicitly set the size. If you display text in the button, these options define the size of the button in text units. If you display bitmaps or images instead, they define the size in pixels (or other screen units). You can actually specify the size in pixels even for text buttons, but it takes some magic. Here's one way to do it (there are others): f = Frame(master, height=32, width=32) f.pack_propagate(0) # don't shrink b = Button(f, text="Sure!") b.pack(fill=BOTH, expand=1) Buttons can display multiple lines of text (but only in one font). You can use newlines or the wraplength option to make the button wrap text by itself. When wrapping text, use the anchor, justify, and possibly padx options to make things look exactly as you wish. An example: b = Button(master, text=longtext, anchor=W, justify=LEFT, padx=2) To make an ordinary button look like it's held down, for example if you wish to implement a toolbox of some kind, you can simply change the relief from RAISED to SUNKEN: b.config(relief=SUNKEN) You might wish to change the background as well. Note that a possibly better solution is to use a Checkbutton or Radiobutton with the indicatoron option set to false: 41 The Entry Widget The Entry widget is a standard Tkinter widget used to enter or display a single line of text. Concepts Indexes The Entry widget allows you to specify character positions in a number of ways: Numerical indexes ANCHOR END INSERT Mouse coordinates Numerical indexes work just like Python list indexes. The characters in the string are numbered from 0 and upwards. You specify ranges just like you slice lists in Python; for example, (0, 5) corresponds to the first five characters in the entry widget. ANCHOR (or "anchor") corresponds to the start of the selection, if any. You can use the select_from method to change this from the program. END (or "end") corresponds to the position just after the last character in the entry widget. The range (0, END) corresponds to all characters in the widget. INSERT (or "insert") corresponds to the current position of the text cursor. You can use the icursor method to change this from the program. Finally, you can use the mouse position for the index, using the following syntax: "@%d" % x where x is given in pixels relative to the left edge of the entry widget. Patterns Methods The Entry widget support the standard Tkinter Widget interface, plus the following methods: insert insert(index, text). Insert text at the given index. Use insert(INSERT, text) to insert text at the cursor, insert(END, text) to append text to the widget. delete delete(index), delete(from, to). Delete the character at index, or within the given range. Use delete(0, END) to delete all text in the widget. 74 Standard Dialogs Before we look at what to put in that application work area, let's take a look at another important part of GUI programming: displaying dialogs and message boxes. Starting with Tk 4.2, the Tk library provides a set of standard dialogs that can be used to display message boxes, and to select files and colors. In addition, Tkinter provides some simple dialogs allowing you to ask the user for integers, floating point values, and strings. Where possible, these standard dialogs use platform-specific mechanisms, to get the right look and feel. Message Boxes The tkMessageBox module provides an interface to the message dialogs. The easiest way to use this module is to use one of the convenience functions: showinfo, showwarning , showerror, askquestion , askokcancel, askyesno, or askretryignore. They all have the same syntax: tkMessageBox.function(title, message [, options]). The title argument is shown in the window title, and the message in the dialog body. You can use newline characters ("\n") in the message to make it occupy multiple lines. The options can be used to modify the look; they are explained later in this section. The first group of standard dialogs is used to present information. You provide the title and the message, the function displays these using an appropriate icon, and returns when the user has pressed OK. The return value should be ignored. Here's an example: try: fp = open(filename) except: tkMessageBox.showwarning( "Open file", "Cannot open this file\n(%s)" % filename ) return Figure 1. showinfo, showwarning, showerror dialogs 25  Standard Dialogs The second group is used to ask questions. The askquestion function returns the strings "yes" or "no" (you can use options to modify the number and type of buttons shown), while the others return a true value of the user gave a positive answer (ok, yes, and retry, respectively). if tkMessageBox.askyesno("Print", "Print this report?"): report.print() Figure 2. askquestion dialog Figure 3. askokcancel, askyesno, askretryignore dialogs 26  Standard Dialogs [Screenshots made on a Swedish version of Windows 95. Hope you don't mind...] Message Box Options If the standard message boxes are not appropriate, you can pick the closest alternative (askquestion, in most cases), and use options to change it to exactly suit your needs. You can use the following options (note that message and title are usually given as arguments, not as options). Table 1. Message Box Options Option Type Description default constant Which button to make default: ABORT, RETRY , IGNORE, OK, CANCEL, YES, or NO (the constants are defined in the tkMessageBox module). icon constant Which icon to display: ERROR, INFO, QUESTION, or WARNING message string The message to display (the second argument to the convenience functions). May contain newlines. parent widget Which window to place the message box on top of. When the message box is closed, the focus is returned to the parent window. title string Message box title (the first argument to the convenience functions). type constant Message box type; that is, which buttons to display: ABORTRETRYIGNORE, OK, OKCANCEL, RETRYCANCEL, YESNO, or YESNOCANCEL. 27  The Grid Geometry Manager e1.grid(row=0, column=1) e2.grid(row=1, column=1) Note that the column number defaults to 0 if not given. Running the above example produces the following window: Figure 2. Figure: simple grid example Empty rows and columns are ignored. The result would have been the same if you had placed the widgets in row 10 and 20 instead. Note that the widgets are centered in their cells. You can use the sticky option to change this; this option takes one or more values from the set N, S, E, W. To align the labels to the left border, you could use W (west): Label(master, text="First").grid(row=0, sticky=W) Label(master, text="Second").grid(row=1, sticky=W) e1 = Entry(master) e2 = Entry(master) e1.grid(row=0, column=1) e2.grid(row=1, column=1) Figure 3. Figure: using the sticky option You can also have the widgets span more than one cell. The columnspan option is used to let a widget span more than one column, and the rowspan option lets it span more than one row. The following code creates the layout shown in the previous section: label1.grid(sticky=E) label2.grid(sticky=E) entry1.grid(row=0, column=1) entry2.grid(row=1, column=1) checkbutton.grid(columnspan=2, sticky=W) image.grid(row=0, column=2, columnspan=2, rowspan=2, sticky=W+E+N+S, padx=5, pady=5) button1.grid(row=2, column=2) button2.grid(row=2, column=3) 83 The Radiobutton Widget The Radiobutton is a standard Tkinter widget used to implement one-of-many selections. Radiobuttons can contain text or images, and you can associate a Python function or method with each button. When the button is pressed, Tkinter automatically calls that function or method. The button can only display text in a single font, but the text may span more than one line. In addition, one of the characters can be underlined, for example to mark a keyboard shortcut. By default, the Tab key can be used to move to a button widget. Each group of Radiobutton widgets should be associated with single variable. Each button then represents a single value for that variable. Radiobutton Patterns The Radiobutton widget is very similar to the check button. To get a proper radio behaviour, make sure to have all buttons in a group point to the same variable, and use the value option to specify what value each button represents: v = IntVar() Radiobutton(master, text="One", variable=v, value=1).pack(anchor=W) Radiobutton(master, text="Two", variable=v, value=2).pack(anchor=W) If you need to get notified when the value changes, attach a command callback to each button. To create a large number of buttons, use a loop: MODES = [ ("Monochrome", "1"), ("Grayscale", "L"), ("True color", "RGB"), ("Color separation", "CMYK"), ] v = StringVar() v.set("L") # initialize for text, mode in MODES: b = Radiobutton(master, text=text, variable=v, value=mode) b.pack(anchor=W) 112  The Radiobutton Widget Figure 1. Standard radiobuttons To turn the above example into a "button box" rather than a set of radio buttons, set the indicatoron option to 0. In this case, there's no separate radio button indicator, and the selected button is drawn as SUNKEN instead of RAISED: Figure 2. Using indicatoron=0 Methods The Radiobutton widget supports the standard Tkinter Widget interface, plus the following methods: deselect deselect(). Deselect the button. flash flash(). Redraw the button several times, alternating between active and normal appearance. invoke invoke(). Call the command associated with the button. select select(). Select the button. 113 Widget Styling All Tkinter standard widgets provide a basic set of "styling" options, which allow you to modify things like colors, fonts, and other visual aspects of each widget. Colors Most widgets allow you to specify the widget and text colors, using the background and foreground options. To specify a color, you can either use a color name, or explicitly specify the red, green, and blue (RGB) color components. Color Names Tkinter includes a color database which maps color names to the corresponding RGB values. This database includes common names like Red, Green, Blue, Yellow, and LightBlue, but also more exotic things like Moccasin, PeachPuff, etc. On an X window system, the color names are defined by the X server. You might be able to locate a file named xrgb.txt which contains a list of color names and the corresponding RGB values. On Windows and Macintosh systems, the color name table is built into Tk. Under Windows, you can also use the Windows system colors (these can be changed by the user via the control panel): SystemActiveBorder, SystemActiveCaption, SystemAppWorkspace, SystemBackground, SystemButtonFace, SystemButtonHighlight, SystemButtonShadow, SystemButtonText, SystemCaptionText, SystemDisabledText, SystemHighlight, SystemHighlightText, SystemInactiveBorder, SystemInactiveCaption, SystemInactiveCaptionText, SystemMenu, SystemMenuText, SystemScrollbar, SystemWindow, SystemWindowFrame, SystemWindowText. On the Macintosh, the following system colors are available: SystemButtonFace, SystemButtonFrame, SystemButtonText, SystemHighlight, SystemHighlightText, SystemMenu, SystemMenuActive, SystemMenuActiveText, SystemMenuDisabled, SystemMenuText, SystemWindowBody. Color names are case insensitive. Many (but not all) color names are also available with or without spaces between the words. For example, "lightblue", "light blue", and "Light Blue" all specify the same color. RGB Specifications If you need to explicitly specify a color, you can use a string with the following format: #RRGGBB RR, GG, BB are hexadecimal representations of the red, green and blue values, respectively. The following sample shows how you can convert a color 3-tuple to a Tk color specification: tk_rgb = "#%02x%02x%02x" % (128, 192, 200) Tk also supports the forms "#RGB" and "#RRRRGGGGBBBB" to specify each value with 16 and 65536 levels, respectively. 12  Widget Styling You can use the winfo_rgb widget method to translate a color string (either a name or an RGB specification) to a 3-tuple: rgb = widget.winfo_rgb("red") red, green, blue = rgb/256, rgb/256, rgb/256 Note that winfo_rgb returns 16-bit RGB values, ranging from 0 to 65535. To map them into the more common 0-255 range, you must divide each value by 256 (or shift them 8 bits to the right). Fonts Widgets that allow you to display text in one way or another also allows you to specify which font to use. All widgets provide reasonable default values, and you seldom have to specify the font for simpler elements like labels and buttons. Fonts are usually specifed using the font widget option. Tkinter supports a number of different font descriptor types: Font descriptors User-defined font names System fonts X font descriptors With Tk versions before 8.0, only X font descriptors are supported (see below). Font descriptors Starting with Tk 8.0, Tkinter supports platform independent font descriptors. You can specify a font as tuple containing a family name, a height in points, and optionally a string with one or more styles. Examples: ("Times", 10, "bold") ("Helvetica", 10, "bold italic") ("Symbol", 8) To get the default size and style, you can give the font name as a single string. If the family name doesn't include spaces, you can also add size and styles to the string itself: "Times 10 bold" "Helvetica 10 bold italic" "Symbol 8" Here are some families available on most Windows platforms: Arial (corresponds to Helvetica), Courier New (Courier), Comic Sans MS, Fixedsys, MS Sans Serif, MS Serif, Symbol, System, Times New Roman (Times), and Verdana: 13  Widget Styling Note that if the family name contains spaces, you must use the tuple syntax described above. The available styles are normal, bold, roman, italic, underline , and overstrike. Tk 8.0 automatically maps Courier, Helvetica, and Times to their corresponding native family names on all platforms. In addition, a font specification can never fail under Tk 8.0 - - if Tk cannot come up with an exact match, it tries to find a similar font. If that fails, Tk falls back to a platform-specific default font. Tk's idea of what is "similar enough" probably doesn't correspond to your own view, so you shouldn't rely too much on this feature. Tk 4.2 under Windows supports this kind of font descriptors as well. There are several restrictions, including that the family name must exist on the platform, and not all the above style names exist (or rather, some of them have different names). Font names In addition, Tk 8.0 allows you to create named fonts and use their names when specifying fonts to the widgets. The tkFont module provides a Font class which allows you to create font instances. You can use such an instance everywhere Tkinter accepts a font specifier. You can also use a font instance to get font metrics, including the size occupied by a given string written in that font. tkFont.Font(family="Times", size=10, weight=tkFont.BOLD) tkFont.Font(family="Helvetica", size=10, weight=tkFont.BOLD, slant=tkFont.ITALIC) tkFont.Font(family="Symbol", size=8) If you modify a named font (using the config method), the changes are automatically propagated to all widgets using the font. The Font constructor supports the following style options: Table 1. Option Type Description family string Font family. size integer Font size in points. To give the size in pixels, use a negative value. 14  Widget Styling weight constant Font thickness. Use one of NORMAL or BOLD. Default is NORMAL. slant constant Font slant. Use one of NORMAL or ITALIC. Default is NORMAL. underline flag Font underlining. If 1 (true), the font is underlined. Default is 0 (false). overstrike flag Font strikeout. If 1 (true), a line is drawn over text written with this font. Default is 0 (false). FIXME: add more information about the tkFont module, or at least a link to the reference page System fonts Tk also supports system specific font names. Under X, these are usually font aliases like fixed, 6x10, etc. Under Windows, these include ansi, ansifixed, device, oemfixed, system, and systemfixed: On the Macintosh, the system font names are application and system. Note that the system fonts are full font names, not family names, and they cannot be combined with size or style attributes. For portability reasons, avoid using these names wherever possible. X Font Descriptors X Font Descriptors are strings having the following format (the asterisks represent fields that are usually not relevant. For details, see the Tk documentation, or an X manual): -*-family-weight-slant-*--*-size-*-*-*-*-charset The font family is typically something like Times, Helvetica, Courier or Symbol. The weight is either Bold or Normal. Slant is either R for "roman" (normal), I for italic, or O for oblique (in practice, this is just another word for italic). Size is the height of the font in decipoints (that is, points multiplied by 10). There are usually 72 points per inch, but some low-resolution displays may use larger "logical" points to make sure that small fonts are still legible. The character set, finally, is usuallyISO8859- 1 (ISO Latin 1), but may have other values for some fonts. The following descriptor requests a 12-point boldface Times font, using the ISO Latin 1 character set: -*-Times-Bold-R-*--*-120-*-*-*-*-ISO8859-1 15