Create resizable/multiline Tkinter/ttk Labels with word wrap

Is it possible to create a multi-line label with word wrap that resizes in sync with the width of its parent? In other words the wordwrap behavior of Notepad as you change the width of the NotePad window.

The use case is a dialog that needs to present a block of multi-line text (instructions) in its entirety without having the text clipped or resorting to scrollbars. The parent container will have enough vertical space to accomodate narrow widths.

I've been experimenting with Tkinter Label and Message widgets and the ttk Label widget without success. It seems that I need to hard code a pixel wraplength value vs. have these controls auto wordwrap when 开发者_StackOverflow社区their text reaches the right edge of their containers. Certainly Tkinters geometry managers can help me auto-resize my labels and update their wraplength values accordingly?

Should I be looking at the Text widget instead? If so, is it possible to hide the border of a Text widget so I can use it as a multi-line label with wordwrap?

Here's a prototype of how one might do what I described above. It was inspired by Bryan Oakley's tip to use the Text widget and the following post on Stackoverflow: In python's tkinter, how can I make a Label such that you can select the text with the mouse?

from Tkinter import *
master = Tk()

text = """
If tkinter is 8.5 or above you'll want the selection background to appear like it does when the widget is activated. Comment this out for older versions of Tkinter.

This is even more text.

The final line of our auto-wrapping label that supports clipboard copy.
""".strip()

frameLabel = Frame( master, padx=20, pady=20 )
frameLabel.pack()
w = Text( frameLabel, wrap='word', font='Arial 12 italic' )
w.insert( 1.0, text )
w.pack()

# - have selection background appear like it does when the widget is activated (Tkinter 8.5+)
# - have label background color match its parent background color via .cget('bg')
# - set relief='flat' to hide Text control borders
# - set state='disabled' to block changes to text (while still allowing selection/clipboard copy)
w.configure( bg=master.cget('bg'), relief='flat', state='disabled' )

mainloop()

Use Message widget:

The Message widget is a variant of the Label, designed to display multiline messages. The message widget can wrap text, and adjust its width to maintain a given aspect ratio.

No, there is no feature built-in to Tk to auto-word-wrap labels. However, it's doable by binding to the <Configure> event of the label and adjusting the wrap length then. This binding will fire every time the label widget is resized.

The other option, as you suggest, is to use a text widget. It is possible to entirely turn off the border if you so desire. This has always been my choice when I want word-wrapped instructional text.

Here is the code:

entry = Label(self, text=text,
    anchor=NW, justify=LEFT,
    relief=RIDGE, bd=2)
def y(event, entry=entry):
  # FIXME: make this a global method, to prevent function object creation
  # for every label.
  pad = 0
  pad += int(str(entry['bd']))
  pad += int(str(entry['padx']))
  pad *= 2
  entry.configure(wraplength = event.width - pad)
entry.bind("<Configure>", y )

The tkinter.Message widget suggested by some people does NOT use TTK styling, which means that it's gonna look like garbage inside a TTK (themed) interface.

You could manually apply the background and foreground colors from your TTK theme to the tkinter.Message (by instantiating ttk.Style() and requesting the active themes' TLabel foreground and background colors from that style object), but it's not worth it... because the ancient Message widget has ZERO advantages over TTK's regular ttk.Label.

The tkinter.Message widget has an "aspect ratio" property that defines how many pixels until it wraps.

The ttk.Label instead has a wraplength= property which determines how many pixels until the words wrap. You should also use its anchor= and justify= properties to customize it to your exact desires. With these properties you can make your Label behave as the old Message widget did.

Example: ttk.Label(root, text="foo", wraplength=220, anchor=tkinter.NW, justify=tkinter.LEFT). Creates a beautifully styled label which permanently wraps its text after 220 pixels wide.

As for automatically updating the wraplength? Well, you should attach to the <Configure> event as people have said... However, if you have a completely fluid window (which resizes itself to fit all content), or a grid/frame that is fluid and contains the label, then you can't automatically calculate it that way, because the parent WINDOW/CONTAINER itself will EXPAND whenever the label grows too wide. Which means that the label will always resize itself to the maximum width it would need to fit all text. So, updating wraplength automatically is only possible if the label itself has some constraints on how wide it can grow (either via its parent container being a fixed size/maxsize, or itself being a fixed size/maxsize). In that case, sure, you can use configure to calculate new wrapping numbers to make sure the text always wraps... However, the example code by t7ko is broken and not valid anymore, just fyi.