Mailman 3 October 2008 - Tkinter-discuss

Possibly n00bish question about ImageTk
by Barnesdesdes Feb. 10, 2009

Feb. 10, 2009

I've been trying to make a program which will import a png file and display it inside a frame. It actually works when I just run the code, but if I try to abstract the exact same code into a function, it fails. In the code below, if I just run it, it works. However, if I comment out the lines between "root=Tkinter.Tk()" and "moo(root)" and comment in "moo(root)", it no longer works. Instead of displaying the image, it just displays a gray frame of the correct size. Does anyone have any insights about what I'm doing wrong? import Image, ImageTk, Tkinter def moo(master): img = Image.open('plotfig.png') f = Tkinter.Frame(master, width=800, height=600) pi = ImageTk.PhotoImage(img) t = Tkinter.Label(f, image=pi) f.pack() t.place(x=0, y=0, width=800, height=600) t.pack() root = Tkinter.Tk() img = Image.open('plotfig.png') f = Tkinter.Frame(root, width=800, height=600) pi = ImageTk.PhotoImage(img) t = Tkinter.Label(f, image=pi) f.pack() t.place(x=0, y=0, width=800, height=600) t.pack() #moo(root) root.mainloop() Thanks very much. Alan -- View this message in context: http://www.nabble.com/Possibly-n00bish-question-about-ImageTk-tf3990201.htm… Sent from the Python - tkinter-discuss mailing list archive at Nabble.com.

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mtTkinter version 0.2 uploaded
by Allen Taylor Nov. 30, 2008

Nov. 30, 2008

Fixed some fairly major bugs and uploaded to http://tkinter.unpythonic.net/wiki/mtTkinter. Allen

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Fwd: WxPython -> Tkinter
by Guilherme Polo Nov. 2, 2008

Nov. 2, 2008

---------- Forwarded message ---------- From: Guilherme Polo <ggpolo(a)gmail.com> Date: Oct 29, 2008 9:16 AM Subject: Re: [Tkinter-discuss] WxPython -> Tkinter To: Olrik Lenstra <o.lenstra(a)gmail.com> Cc: python-list(a)python.org On 10/29/08, Olrik Lenstra <o.lenstra(a)gmail.com> wrote: > Hello everyone, > > A while ago I joined the Tutor mailing list, and they helped me out with a > question regarding wxPython. > Now however, I have tried a program in Tkinter and I would like to see if > there is a similar command to "wx.SafeYield(self, True)". It will be a combination of commands, not a single one. Initially I considered this as "probably without solution", since tcl acquired a yield command just in the 8.6a3 release, but then I looked at wx.SafeYield code and apparently it is possible to replicate it. Here is an initial cut, it is very possible to contain something not equivalent to wx.SafeYield (besides it could be improved): import ttk inside_tkyield = False disabled_wins = {} def safe_yield(window, only_if_needed=False): window_disabler(window) try: return tk_yield(window, only_if_needed) finally: for widget, flags in disabled_wins.iteritems(): ttk.Widget.state(widget, flags) disabled_wins.clear() def window_disabler(window): widgets = window.children.values() widgets.append(window) for widget in widgets: if widget.instate(['!disabled']): prev_flags = widget.state(['disabled']) disabled_wins[widget] = prev_flags def tk_yield(window, only_if_needed=False): # wx implements this differently based on the backend it is using global inside_tkyield if inside_tkyield: if not only_if_needed: raise RuntimeError("safe_yield called recursively") return False inside_tkyield = True; window.update() window.update_idletasks() inside_tkyield = False; return True Note that this depends on ttk widgets (http://pypi.python.org/pypi/pyttk) since it uses widget.state to disable and reenable the widgets. On windows the "wm" command supports disabling the entire window, so it is easier if you can use it. [Forwarded because I sent to the wrong list first time] > Below is a copy of the message to the tutor list. > > > Dear Mailing list, > > > > a while ago a few of you helped me solve an issue I had with a GUI / scan > > program that I made. > > The problem was that when I tried to move the frame it would hang until > the > > scan was finished. > > To solve this I had to add "wx.SafeYield(self, True)" to the scan and the > > GUI wouldn't hang any more. > > Now I have redone the program and have written it with Tkinter instead of > > WxPython. > > > > So is there a similar command for Tkinter as there is for WxPython? > > > > Thanks in advance. > > Regards, > > Olrik > > > > _______________________________________________ > Tkinter-discuss mailing list > Tkinter-discuss(a)python.org > http://mail.python.org/mailman/listinfo/tkinter-discuss > > -- -- Guilherme H. Polo Goncalves -- -- Guilherme H. Polo Goncalves

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WxPython -> Tkinter
by Olrik Lenstra Oct. 29, 2008

Oct. 29, 2008

Hello everyone, A while ago I joined the Tutor mailing list, and they helped me out with a question regarding wxPython. Now however, I have tried a program in Tkinter and I would like to see if there is a similar command to "wx.SafeYield(self, True)". Below is a copy of the message to the tutor list. Dear Mailing list, > > a while ago a few of you helped me solve an issue I had with a GUI / scan > program that I made. > The problem was that when I tried to move the frame it would hang until the > scan was finished. > To solve this I had to add "wx.SafeYield(self, True)" to the scan and the > GUI wouldn't hang any more. > Now I have redone the program and have written it with Tkinter instead of > WxPython. > > So is there a similar command for Tkinter as there is for WxPython? > > Thanks in advance. > Regards, > Olrik >

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Re: [Tkinter-discuss] Proposal for thread-safe Tkinter
by Allen Taylor Oct. 28, 2008

Oct. 28, 2008

All, After a very helpful discussion with "Guilherme Polo <ggpolo(a)gmail.com>", we have come to the following conclusion regarding multithreaded applications and Tkinter. Although Tk is technically thread-safe (if built with --enable-threads), practically speaking it still has problems when used in multithreaded applications. The problem stems from the fact that _tkinter attempts to gain control of the main thread via a polling technique. If it succeeds, all is well. If it fails, however, the application receives an exception with the message "RuntimeError: main thread is not in main loop". There is no way to tell when this might happen, so calling Tk routines from multiple threads seems to be problematic at best. The mtTkinter module I published last week (http://tkinter.unpythonic.net/wiki/mtTkinter) solves this problem by marshaling calls coming from multiple threads through a queue which is read by an 'after' event running periodically in the main loop. This is similar to the technique used in many other platforms (e.g., .NET's InvokeRequired/Invoke mechanism). The technique used in mtTkinter is exception-safe as well, marshaling exceptions through a response queue back to the caller's thread. If a similar technique were employed in _tkinter instead of the polling technique, that would be a preferable solution. In the meantime, mtTkinter will work as a good stop-gap measure. Allen B. Taylor

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Re: [Tkinter-discuss] Proposal for thread-safe Tkinter
by Guilherme Polo Oct. 28, 2008

Oct. 28, 2008

On Thu, Oct 23, 2008 at 5:49 PM, Allen Taylor <Allen.Taylor(a)mdacorporation.com> wrote: > I was given the task of upgrading a Python/Tkinter GUI application to the > latest versions of Python and Tk. After a while, I realized that the > application had not been written in a thread-safe manner. Multiple threads > would simply use the Tk object directly. The application apparently ran fine > (i.e., didn't crash!) using older versions of Python (2.2) and Tk (8.3), but > it started to have serious problems (i.e., crashing) after using the latest > versions. Did you compile these new tcl/tk versions with --enable-threads ? That is where the problem lies in _tkinter currently. In a tk.call it checks if python was compiled with threads, but if tcl wasn't compiled with threads support too, _tkinter acts like single threaded and then you get these crashes (this happens in other places there too). > > The problem is that there isn't enough budget to fix the whole application. > So, I invested a bit of time to develop mtTkinter, a thread-safe version of > Tkinter. Importing mtTkinter actually modifies the original Tkinter in such > a way to make it thread-safe, recognizing and diverting out-of-thread calls > to the Tk object creation thread via a queue and an 'after' event. I think > it works quite well, requiring basically no changes to the application other > than to import mtTkinter instead of (or in addition to) Tkinter. Even > packages that use Tkinter (e.g., Pmw) benefit. > > I would like to contribute this module (single file, about 160 lines) to the > Python community, but I don't know how. I'm new to Python and am not > initiated in the deep Pythonic developer world. Can someone give me some > pointers? Many thanks. > I have read your other email where you posted the code for this module but let me comment on it here too. It is nice that it fixes the problem mentioned above ;) And I believe _tkinter deserves a fix in this respect, I don't think it was intended to not work correctly when python has thread support and tcl/tk doesn't. > Allen B. Taylor > MDA > 9445 Airport Road > Brampton, ON L6S 4J3 > 905-790-2800 ext. 4350 > allen.taylor(a)mdacorporation.com > -- > http://mail.python.org/mailman/listinfo/python-list > > -- -- Guilherme H. Polo Goncalves

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Proposal for thread-safe Tkinter
by Allen Taylor Oct. 24, 2008

Oct. 24, 2008

I was given the task of upgrading a Python/Tkinter GUI application to the latest versions of Python and Tk. After a while, I realized that the application had not been written in a thread-safe manner. Multiple threads would simply use the Tk object directly. The application apparently ran fine (i.e., didn't crash!) using older versions of Python (2.2) and Tk (8.3), but it started to have serious problems (i.e., crashing) after using the latest versions. The problem is that there isn't enough budget to fix the whole application. So, I invested a bit of time to develop mtTkinter, a thread-safe version of Tkinter. Importing mtTkinter actually modifies the original Tkinter in such a way to make it thread-safe, recognizing and diverting out-of-thread calls to the Tk object creation thread via a queue and an 'after' event. I think it works quite well, requiring basically no changes to the application other than to import mtTkinter instead of (or in addition to) Tkinter. Even packages that use Tkinter (e.g., Pmw) benefit. I would like to contribute this module (single file, about 160 lines) to the Python community, but I don't know how. I'm new to Python and am not initiated in the deep Pythonic developer world. Can someone give me some pointers? Many thanks. Allen B. Taylor MDA 9445 Airport Road Brampton, ON L6S 4J3 905-790-2800 ext. 4350 allen.taylor(a)mdacorporation.com

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Unicode on Mac (yet again)
by Fred Mailhot Oct. 9, 2008

Oct. 9, 2008

Greetings, I've followed some of the discussion on the list concerning the problem of getting some Unicode characters to display properly. As suggested in a few messages, I've recompiled my python to link to Tcl/Tk8.5. I know this has succeeded, as running Tkinter._test() pops up a dialog confirming that I'm using 8.5. Unfortunately, there still seem to be problems displaying Unicode characters properly. The following snippet demonstrates (disclaimer: I'm not a Tkinter guru by any means)... import Tkinter root = Tkinter.Tk() w1 = Tkinter.Button(root, text=u"\u026E", font=("Lucida Grande",24)) w2 = Tkinter.Label(root, text=u"\u026E", font=("Lucida Grande",24)) w1.pack() w2.pack The Button displays the correct character (a digraph from the International Phonetic Alphabet), whereas the Label displays what looks like a Chinese kanji character...the same problem as in 8.4. Is there something I'm doing wrong? For the record, I'm running OSX 10.4.11 on a PPC Mac. Thanks for any advice or pointers, Fred.

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validation woes
by Jeff Cagle Oct. 6, 2008

Oct. 6, 2008

I want an Entry widget to accept a single digit only. Here's the attempt: --- import Tkinter as Tk class MyEntry(Tk.Entry): def __init__(self, parent, **kwargs): kwargs['validate']='key' # could also be 'all' -- has the same result kwargs['vcmd']=self.validate Tk.Entry.__init__(self, parent, **kwargs) def validate(self): print self.get() # diagnostic only if self.get() in [''] + list("123456789"): return True else: self.bell() return False if __name__=="__main__": main = Tk.Tk() main.e = MyEntry(main) main.e.grid() main.mainloop() --- I'd like to think this is straightforward, but No. I type in MyEntry: 1 printed value: (empty string) contents of MyEntry: 1 I type in MyEntry: 11 printed value: 1 contents of MyEntry: 11 I type in MyEntry: 111 (bell rings) printed value: 11 contents of MyEntry: 11 I type in MyEntry: a printed value: (empty string) contents of MyEntry: a I type in MyEntry: a1 (bell rings) printed value: a contents of MyEntry: a Near as I can tell, validate() is called after a key is pressed and displayed in the Entry widget, but *before* the pressed key has been added to MyEntry's contents. Hence, validate() has no way of knowing what the new keypress is -- it can only validate the past entry. Once it does so, the new key is added to MyEntry's contents. How can validate() discover the new keypress in order to validate it prior to addition to the Entry widget? Yikes! Thanks in advance, Jeff Cagle

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Python + Tk/Tcl building
by Алексей Макаров Oct. 1, 2008

Oct. 1, 2008

Hello! I want to build python with Tk/Tcl by mysel. When writing coomand ¨import Tkinter¨ tehere is an error >>> import Tkinter Traceback (most recent call last): File "<stdin>", line 1, in <module> File "/usr/local/Py/lib/python2.5/lib-tk/Tkinter.py", line 38, in <module> import _tkinter # If this fails your Python may not be configured for Tk ImportError: No module named _tkinter >>> I don understand, how should i buld python for it work correctly. Is there some options in ./configure command for this? -- Best regards, Makarov Alexey

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