Mailman 3 November 2012 - Tkinter-discuss

Control position of Tkinter common dialogs?
by python＠bdurham.com Dec. 9, 2016

Dec. 9, 2016

Python 2.7 under Windows: How can we control the position of Tkinter's common dialogs? Here's what we've discovered: * Certain common dialogs always open up relative to their parent window * Certain common dialogs always open up centered on the user's desktop * All common dialogs appear to ignore the optional parent= parameter Questions: * How can we force a dialog to open up relative to its parent window? * How can we force a dialog to open up centered on the user's desktop? Background: import tkColorChooser as colorchooser import tkFileDialog as filedialog import tkMessageBox as messagebox # always open up relative to parent windows fileOpen = filedialog.askopenfilename() fileOpens = filedialog.askopenfilenames() fileSaveAs = filedialog.asksaveasfilename() color = colorchooser.askcolor() # always open up centered on desktop folderOpen = filedialog.askdirectory() messagebox.askquestion() Malcolm

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Proposal to use dynamic proxy with tkinter to communicate with background thread
by Andreas Ostermann Nov. 30, 2012

Nov. 30, 2012

Hi! I was currently searching for the possibility to communicate between tkinter and a python background thread. I hoped for something like java's invokeLater mechanism. I found a lot of ideas, using a Queue for the communication and then poll in Tkinter on the Queue, raising the question which interval should be used. Then there was mentioned to use the after_idle() method to pass something into the Tk loop, but the method is not thread_safe as it seems. And then there was the idea of binding events to methods and to raise the event so that method will be called. It seems, that this is still a valid question, so I would like to share my solution and open it for discussion and hope you would review it and show me problems if there are any. First I want something like the invokeLater call from java, so I created to classes which will be "listener", one for the tk loop and one as a background thread: class BackgroundListener (threading.Thread) : def __init__(self): threading.Thread.__init__(self) self.queue = Queue.Queue() self.cancel = threading.Event() def invokeLater(self, delegate): self.queue.put(delegate) def interrupt(self) : self.cancel.set() def run(self): while not self.cancel.isSet() : try : delegate = self.queue.get(timeout=0.5) if not self.cancel.isSet() : # don't call if already finished ! delegate() except Queue.Empty : pass class TkListener : def __init__(self, tk) : self.queue = Queue.Queue() self.tk = tk self.event = "<<%s>>" % uuid.uuid1() tk.bind(self.event, self.invoke) def invokeLater(self, delegate) : self.queue.put(delegate) self.tk.event_generate(self.event, when='tail') def invoke(self, event) : try : while True : delegate = self.queue.get(block=False) delegate() except Queue.Empty : pass So, what happens here? The Background thread will store the delegate object (see below) into a Queue and the background thread is reading from this Queue, as Queue is threadsafe everything is fine. (I misuse the Event to create something like the interrupt() call from java) The TkListener will get a reference to the tk object and binds a event to it which calls a the invoke method. Therefore it is similar to the other listener. The invokeLater call adds the delegate to the Queue, then raise the event. The tkloop will then handle the event by calling the invoke method, where all waiting delegates are removed from the queue and called. So whats with the delegate class? Its part of a dynamic proxy implementation which can be used for any other purpose as long as the listener you provide has an invokeLater method. And that's what they look like: class Delegate : def __init__(self, real, name, args, kwargs) : self.real = real self.name = name self.args = args self.kwargs = kwargs def __call__(self) : method = getattr(self.real, self.name) apply(method, self.args, self.kwargs) class Delegator : def __init__(self, listener, real, name) : self.listener = listener self.real = real self.name = name def __call__(self, *args, **kwargs) : delegate = Delegate(self.real, self.name, args, kwargs) self.listener.invokeLater(delegate) class Proxy : def __init__(self, listener, real) : self.listener = listener self.real = real self.cache = {} def __getattr__(self, name) : try : delegator = self.cache[name] except KeyError : delegator = Delegator(self.listener, self.real, name) self.cache[name] = delegator return delegator The Proxy class will hold the listener and the real object. When you call a method on the proxy a delegator object for the method name is generated and cached. Then the delegator is returned and the caller call will be handled in the delegator. The delegator then creates a delegate object holding all the informations and the attributes of the call and the delegate object will be hand over to the listener via the invokeLater method. As you have seen above the listener will then get the delegate object from the Queue and call it, which leads to a call to the real object in the context of the listener. And at last, so that you have something to play around with, some test classes showing different ways on how to use the proxy object, even for callbacks over thread boundaries: import Tkinter import Queue import uuid import threading import thread class MyTkinterObject: def __init__(self, tk): frame = Tkinter.Frame(tk) self.quitButton = Tkinter.Button(frame, text="QUIT", fg="red", command=frame.quit) self.quitButton.pack(side=Tkinter.LEFT) self.helloButton = Tkinter.Button(frame, text="Hello") self.helloButton.pack(side=Tkinter.LEFT) self.hello2Button = Tkinter.Button(frame, text="Hello2", command=self.trigger2) self.hello2Button.pack(side=Tkinter.LEFT) frame.pack() def register(self, myBackgroundObject) : self.helloButton.bind("<Button-1>", myBackgroundObject.trigger) def trigger(self, callback) : print "%s - Front hello" % thread.get_ident() callback() def trigger2(self) : print "%s - Front hello" % thread.get_ident() class MyBackgroundObject : def __init__(self, listener): self.proxy = Proxy(listener, self) def register(self, myTkinterObject) : self.myTkinterObject = myTkinterObject def trigger(self, event) : print "%s - Back hello - %s" % (thread.get_ident(), event) self.myTkinterObject.trigger(self.proxy.callback) def callback(self) : print "%s - Back bye" % thread.get_ident() def main() : root = Tkinter.Tk() tkListener = TkListener(root) backgroundListener = BackgroundListener() myTkinterObject = MyTkinterObject(root) myBackgroundObject = MyBackgroundObject(backgroundListener) myTkinterObject.register(myBackgroundObject.proxy) myBackgroundObject.register(Proxy(tkListener, myTkinterObject)) backgroundListener.start() root.mainloop() backgroundListener.interrupt() if __name__ == "__main__": main() I would like to hear your comments! thanks, AO

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Can't configure ttk.Entry font
by John W. Shipman Nov. 28, 2012

Nov. 28, 2012

Below my signature is a trivial ttk script with two widgets: an Entry and a quit button. Styling the font on the quit button works great. But styling the font on the Entry widget does not; I always get the default font, which is a bit small for many people over the age of 40. I've tried a number of things, but either I'm missing something really stupid in my code, or there is a defect in the ttk.Entry code that it does not pick up a font. Here's our version: >>> tk.__version__ '$Revision: 81008 $' >>> ttk.__version__ '0.3.1' I would appreciate any suggestions. Best regards, John Shipman (john(a)nmt.edu), Applications Specialist New Mexico Tech Computer Center, Speare 146, Socorro, NM 87801 (575) 835-5735, http://www.nmt.edu/~john ``Let's go outside and commiserate with nature.'' --Dave Farber ================================================================ #!/usr/bin/env python # wtfentry: Why can't I specify a font on a ttk.Entry? # Submitted by John W. Shipman, john(a)nmt.edu import sys import ttk import Tkinter as tk import tkFont class App(ttk.Frame): def __init__(self): ttk.Frame.__init__(self, None) self.grid() self._styling() self._createWidgets() def _styling(self): self._mainFont = tkFont.Font(family='Helvetica', size=20, slant='italic') self._entryFont = tkFont.Font(family='Helvetica', size=36) self._entryStyle = ttk.Style() self._entryStyle.configure('My.TEntry', font=self._entryFont) self._buttonStyle = ttk.Style() self._buttonStyle.configure('My.TButton', font=self._mainFont) def _createWidgets(self): self._entryVar = tk.StringVar() self._entryVar.set('initial value') self._entry = ttk.Entry(self, style='My.TEntry', textvariable=self._entryVar) self._entry.grid() self._quitButton = ttk.Button(self, text='Quit', style='My.TButton', command=self.quit) self._quitButton.grid() app = App() app.mainloop()

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Re: [Tkinter-discuss] Segfault in Image.PhotoImage on OS X
by Kevin Walzer Nov. 14, 2012

Nov. 14, 2012

On 11/14/12 1:51 PM, mohsen jadidi wrote: > Can you explain in more detail? what is wrong with my install_name_tool? > what do you mean by offending library? > > > On Wed, Nov 14, 2012 at 7:48 PM, Kevin Walzer <kw(a)codebykevin.com > <mailto:kw@codebykevin.com>> wrote: > > It's likely that a Tk or Python library is linking against one > framework and Tk itself links against another. You'll have to run > install_name_tool on the offending library. Rather than running otool -L against the Python and Tk frameworks, run it against tkinter.so, and whatever shared objects/dylibs are part of the Imaging extension. They should be linked against the same framework as tkinter.so. The install_name_tool CLI program can fix this. See man install_name_tool for more information. --Kevin -- Kevin Walzer Code by Kevin http://www.codebykevin.com

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Segfault in Image.PhotoImage on OS X
by Marc Culler Nov. 14, 2012

Nov. 14, 2012

This was reported here in February, but no debugging information was provided by the reporter: http://stackoverflow.com/questions/9142786/python-imagetk-photoimage-segfau… <view-source:http://stackoverflow.com/questions/9142786/python-imagetk-photo…> I can explain the nature of the problem, but I don't know how to fix it correctly. I am using the standard x86_64 Python 2.7.2 package from python.org and I have installed Active State Tcl/Tk 8.11. When I tried using easy_install to install PIL it would not load, claiming that _imaging.so did not exist. In fact, it existed but was only a thin i386 executable. So I compiled Imaging-1.1.7 with export CFLAGS='-arch i386 -arch x86_64' and export TCL_ROOT=/Library/Frameworks/Tcl.framework/Versions/8.5/Tcl I was then able to load the module. However, the following code produced a segfault: import Image import ImageTk import Tkinter W = Tkinter.Tk() Im = Image.open('test_image.jpg') x = ImageTk.PhotoImage(Im) The crash occurs in Tk_GetImageMasterData. More importantly, though, the crash was preceded by the following messages: objc[36554]: Class TKApplication is implemented in both /Library/Frameworks/Tk.framework/Versions/8.5/Tk and /System/Library/Frameworks/Tk.framework/Versions/8.5/Tk. One of the two will be used. Which one is undefined. objc[36554]: Class TKMenu is implemented in both /Library/Frameworks/Tk.framework/Versions/8.5/Tk and /System/Library/Frameworks/Tk.framework/Versions/8.5/Tk. One of the two will be used. Which one is undefined. objc[36554]: Class TKContentView is implemented in both /Library/Frameworks/Tk.framework/Versions/8.5/Tk and /System/Library/Frameworks/Tk.framework/Versions/8.5/Tk. One of the two will be used. Which one is undefined. objc[36554]: Class TKWindow is implemented in both /Library/Frameworks/Tk.framework/Versions/8.5/Tk and /System/Library/Frameworks/Tk.framework/Versions/8.5/Tk. One of the two will be used. Which one is undefined. Guessing that PIL was finding the System/Library/Frameworks/Tk.Framework instead of /Library/Frameworks/Tk.Framework, I tried hiding the system Tcl and Tk frameworks by renaming them. I was then able to create the PhotoImage and display it. I don't know where those messages come from, and I have never encountered them before. But I am guessing they are from OS X, since they are generated by an objective C program. Evidently _tkinter.so is able to specify which Tk.Framework to use. I don't know its mechanism for doing that. But, somehow, PIL is not doing it, and it ends up using the wrong one. A stack trace of the crash is below. - Marc 0x000000011517bccd in Tk_GetImageMasterData () (gdb) bt #0 0x000000011517bccd in Tk_GetImageMasterData () #1 0x0000000115183d9f in Tk_FindPhoto () #2 0x00000001014fbadc in PyImagingPhotoPut () #3 0x000000011502a05b in TclInvokeStringCommand () #4 0x000000010102142a in TclEvalObjvInternal () #5 0x000000010102261c in Tcl_EvalObjv () #6 0x000000010100646d in Tkapp_Call () #7 0x00000001000c102d in PyEval_EvalFrameEx () #8 0x00000001000c2d29 in PyEval_EvalCodeEx () #9 0x00000001000c0b6a in PyEval_EvalFrameEx () #10 0x00000001000c2d29 in PyEval_EvalCodeEx () #11 0x000000010003da80 in function_call () #12 0x000000010000c5e2 in PyObject_Call () #13 0x000000010001ebcb in instancemethod_call () #14 0x000000010000c5e2 in PyObject_Call () #15 0x00000001000ba5f7 in PyEval_CallObjectWithKeywords () #16 0x0000000100021e5e in PyInstance_New () #17 0x000000010000c5e2 in PyObject_Call () #18 0x00000001000be5f3 in PyEval_EvalFrameEx () #19 0x00000001000c2d29 in PyEval_EvalCodeEx () #20 0x00000001000c2e46 in PyEval_EvalCode () #21 0x00000001000e769c in PyRun_InteractiveOneFlags () #22 0x00000001000e78fe in PyRun_InteractiveLoopFlags () #23 0x00000001000e80e1 in PyRun_AnyFileExFlags () #24 0x00000001000fe77c in Py_Main () #25 0x0000000100000f14 in dyld_stub_strlen ()

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Attaching Widget Var to Widget?
by Lion Kimbro Nov. 5, 2012

Nov. 5, 2012

I'm trying to minimize maintenance of Var values. It is irritating that there is no method to get the check state of a Checkbutton, like there is to get the content of an Entry (.get). There is much out there on using the variable= parameter out there, but little on strategies for maintaining the variables. Are there any known problems with simply attaching a StringVar or IntVar to the Python widget it comes with? Ex: var=IntVar() chk=Checkbutton(frame, text="label", variable=var) chk.var=var Will there be any allocation/deal location problems with this? If the widget is destroyed via a grandparent or something, will any resources be left dangling? Anyone have any experience with this? I notice in the tk docs that a default variable is created if you don't make one yourself, and I am considering creating a StringVar using the name parameter such that it matches by querying the full path from the ID of the widget.

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Multiple images on a ttk widget?
by John W. Shipman Nov. 5, 2012

Nov. 5, 2012

I'm currently attempting to learn the ttk widgets in the process of updating our locally written Tkinter reference manual. However, I am unable to reproduce the behavior described in this paragraph from the Python 2.7.3 library reference. This is from http://docs.python.org/2.7/library/ttk.html, in the section on the ttk.Widget class, the table of "Label Options": image: Specifies an image to display. This is a list of 1 or more elements. The first element is the default image name. The rest of the list is a sequence of statespec/value pairs as defined by Style.map(), specifying different images to use when the widget is in a particular state or a combination of states. All images in the list should have the same size. First of all, image names don't work. I was able to get a ttk.Label to display an image by using image=t, where t is an instance of ImageTk.PhotoImage. For the rest of it, after an hour of trying I was unable to get the state-dependent image changing to work. If anyone has a working example of this, I would greatly appreciate it! Best regards, John Shipman (john(a)nmt.edu), Applications Specialist New Mexico Tech Computer Center, Speare 146, Socorro, NM 87801 (575) 835-5735, http://www.nmt.edu/~john ``Let's go outside and commiserate with nature.'' --Dave Farber P.S. Here's a preview of the new stuff. This is the section on the Treeview widget, which I think I understand now:

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Multiple images on a ttk widget? (correction)
by John W. Shipman Nov. 4, 2012

Nov. 4, 2012

Oops, the URL somehow got cut off after this: +-- | P.S. Here's a preview of the new stuff. This is the section on | the Treeview widget, which I think I understand now: +-- http://www.nmt.edu/tcc/help/pubs/tkinter85/web/ttk-Treeview.html John Shipman (john(a)nmt.edu), Applications Specialist New Mexico Tech Computer Center, Speare 146, Socorro, NM 87801 (575) 835-5735, http://www.nmt.edu/~john ``Let's go outside and commiserate with nature.'' --Dave Farber

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question on horizontal scrolling with ttk.Treeview
by Lynn Oliver Nov. 4, 2012

Nov. 4, 2012

When using a horizontal scrollbar with the ttk.Treeview widget, xscrollcommand returns last = 1.0 unless the window is resized to less than the value for minwidth. So even if there is text displayed that is wider than minwidth you can't scroll to the portion that is beyond minwidth. Is there any way to change this behavior? BTW, if you insert a value into a Treeview widget that contains nulls, you get some very strange output displayed (characters mirrored across baseline):

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