I want to create a client frontend in pygtk for my Django project. My general idea is to have one main window, and everytime the user has an action that must change the screen to unload previous widgets and load the new ones. E.g if i have a login page, after user logs in he is presented with a customer screen. I want the new screen to be placed on the same main window, kinda like a page stack, but without the "back" functionality. My first thought was to create a function for every screen, a show_login, a show_customers_screen, etc. Is this a good choice or should i try a better one. And a second question, related to the first. Can i create callbacks inside a function?
e.g
This would be a method of MainWindow
def create_login(self):
....creating widgets here
#UnboundLocalError: local variable 'clear_clb' referenced before assignment
btnlogin.connect('clicked', clear_clb, data=None)
def clear_clb(widget, data=None):
..log in process
I know why i get the error. The thing is that the fields i want this func to clear are local in create_login. Is this the right approach?
Define the clear_clb symbol before referencing it:
def create_login(self):
# create widgets
def clear_clb(widget, data=None):
# log in process
btnlogin.connect('clicked', clear_clb, data=None)
However, the more usual, and in my opinion more readable, way of doing this is to save references to your widgets as attributes of self:
def create_login(self):
# create widgets
self.btnlogin = gtk.Button(...
self.btnlogin.connect('clicked', clear_clb)
def clear_clb(self, widget, data=None):
# log in process
Related
for a python program I created a gui with QtDesigner. Inside my program the gui is initiated and calls the .ui-file to implement content.
The gui class object is than given to a Controller, and here it gets tricky:
Instead of one Controller, there are a main controller and some sub-controller for different parts of the gui. The main Controller does one or two general things and than hands over different parts of the gui to different sub controller.
See the following example for better understanding:
import Controller # import the folder with the controller
def __init__(self, window):
self.window = window # self.window is the handed over gui
self.sub_controls()
def sub_controls(self):
Controller.Sub_Controller_1(window = self.window.part_1)
Controller.Sub_Controller_2(window = self.window.part_2)
Controller.Sub_Controller_3(window = self.window.part_3)
...
The sub-Controller is set up like this:
def __init__(self, window):
self.window = window
... # do stuff:
-----------------------------------------
by trying to call a widget in this Sub-Controller (lets say its a label called timmy), i get an error:
self.window.timmy.setVisible(False)
AttributeError: 'QWidget' object has no attribute 'timmy'
but by using the children()-Method, which returns a list of all children in the gui, I may access this label:
self.window.children()[1].setVisible(False)
This works well and hides timmy.
By trying to do this in the main Controller, it works fine as usual:
self.window.timmy.setVisible(False) # works fine here
I also tried to save the sub-controller object like this:
def sub_controls(self):
self.save_part_1 = Controller.Sub_Controller_1(window = self.window.part_1)
but this doesn't work.
Does any one have a suggestion, how I could solve this Problem?
Sure, I couldt access just all widgets with the children()-method-list, but this is laborious because of the great amount of widgets. Same thing applies to reassigning every child.
PS:
Unfortunately I cannot show you the original Code due to company guidelines.
Ok so I figured out, that the tree Structure of in each other nested widgets has nothing to do with the naming of the widgets. For example:
MainWindow
->centralWidget
->otherWidget
->Button
In this you can address "Button" with self.Button, because (how I believe) the name is saved in MainWindow-Level. If you cut out "otherWidget", the QPushButton in it still exists, but cannot addressed by name.
So it's not possible to just hand over a part of your Gui to a Handler, at least if it's build with QtDesigner.
My Solution for me to the original Problem is to hand over the complete Gui to every sub handler:
def __init__(self, window):
self.window = window # self.window is the handed over gui
self.sub_controls()
def sub_controls(self):
Controller.Sub_Controller_1(window = self.window)
Controller.Sub_Controller_2(window = self.window)
# Controller.Sub_Controller_3(window = self.window.part_3) # before
I know this is a super vague question, but I'm just getting into GUI development using wxPython and could use some guidance. I have a program that:
opens a modal dialog box where the user is to select a .csv file containing data to be analyzed
stores the data as a pandas DataFrame object
does some formatting, cleaning up, and calculation on the data
generates a new dataframe with the results of the calculations
plots the results (linear regressions) and displays the results tables, as well as saving both the plots and new tables to .png and .csv files, respectively.
I want a GUI such that, when launched, a simple window appears with some text and a single button in the middle "import csv to begin" or something (I was able to create this first window by subclassing wx.Frame, but the button currently doesn't do anything). On clicking the button, the modal dialog will open so the user can select the .csv data file. On clicking OK/Open/whatever the button is (long day, memory no work), the window/frame will change to a different layout (again, was able to piece together a class for this frame). My question is mainly how I should go about getting the data between frames WHILE ALSO changing the frame.
The method for switching between frames I found was to include, in the class definition, the method
def _NextFrame(self, event):
self.frame.Show()
self.Hide()
and then in the body of main() call it as
app = wx.App(redirect=True)
f1 = Frame("Frame1")
f2 = Frame("Frame2")
f1.frame = f2
f2.frame = f1
f1.Show()
app.MainLoop()
But this was for just switching between two instances of the same frame, not two different frames with different functions. Additionally, I think that this way will instantiate the frames all before running the app, so if I have the self.getcsv() function called in the __init__() of my second frame, the user will be prompted to open a file before they even click the button on the first frame (even though the second frame is as-yet invisible).
Can I use the code for the CLI version, build in the classes for the GUI, and handle all the calculations etc. outside of wxPython, using wx only to display what I want to display? I'm just pretty lost in general. Again, sorry for the vague question, but I didn't know where else to turn.
Finished the app. For other green GUI programmers, the way I handled this was to instantiate the next frame in an event handler bound to a logical button/control (such as a "Start" button, "Analyze" button, etc.). For example, after creating all the classes for the different frames, data handlers, and so on, I start the app with
def main():
app = wx.App()
frm = StartFrame(None)
frm.Show()
app.MainLoop()
if __name__ == "__main__":
main()
Within the StartFrame instance, there's a "Start" button bound to the handler:
def _OnStart(self,event):
frm2 = ParaFrame(None)
frm2.Show()
self.Destroy()
The ParaFrame frame has an "analyze" button which is a little more complex: it instantiates a (non-wx, custom) class DataHandler, sets various attributes according to user input in the ParaFrame instance, calls a DataHandler method which analyzes the data, then instantiates the result frame (which takes some of the results from DataHandler's analysis as __init__() parameters), shows it, deletes the DataHandler, and destroys itself:
def _analyze(self, event):
dhandler = DataHandler(self)
dhandler.path = self.path
dhandler.logconv = self.logbtn.GetValue()
dhandler.numTar = int(self.inputNum.GetValue())
dhandler.conc = self.inputcb.GetValue()
for idx, tar in enumerate(self.tarcbs):
dhandler.targets.append(self.tarcbs[idx].GetValue())
dhandler._analyzeData()
resfrm = ResultFrame(None, dhandler.targets, dhandler.dftables)
resfrm.Show()
del dhandler
self.Destroy()
From the ResultFrame instance, aside from just displaying the results, there are controls to either exit the app (bound to _OnExit, below) or restart the app from the beginning to run a new analysis (bound to _OnRestart):
def _OnExit(self, event):
"""Close frame & terminate app"""
self.Close(True)
def _OnRestart(self, event):
frm = StartFrame(None)
frm.Show()
self.Destroy()
This method also helped get around the problem with the example of switching frames I found; that example was suited to switching back and forth between two persistent frames, whereas I wanted a linear A --> B --> C approach, where once a frame was displayed, the previous frame should be destroyed.
Hopefully this will help someone in the future :)
I'm creating a GUI to run a fatigue analysis program in Python using PyQt. When the user clicks 'Start' in the main window to start the analysis a function in another file is called, which then chugs away (potentially for hours) until complete.
I'd like to find a way to update the status bar in the main window from within the separate fatigue analysis file. I don't care how I achieve this, but I'd really rather not just copy and paste everything from the fatigue analysis file into the GUI file (in which case I'd know how to update the status bar).
So far I've tried starting the GUI using the code below which is global (MainWindow is a class with all the stuff to set up the GUI, and updateStatus is a method within that class to update the status bar of the GUI):
app = QtGui.QApplication(sys.argv)
TopWindow = MainWindow(LastData)
TopWindow.show()
sys.exit(app.exec_())
In the Fatigue Analysis file I have the following code, which is called within a loop:
TopWindow.updateStatus(PercentComplete)
This throws the error below:
NameError: global name 'TopWindow' is not defined
I don't understand why this doesn't work, but it definitely doesn't! Any ideas for a workaround?
Thanks,
Pete
I believe you misunderstood the scope of a variable. Let me explain.
When you write the following code,
def myfunction():
a = 5
print(a) # OK
b = a # This line fails
you will get a failure, because a is local to myfunction, that is to say it only exists inside that function, and the last statement refers to a variable that is not known to python. The same holds for modules. Variables defined in one module are not accessible to the other modules... Unless you really want to do crappy things.
A nice solution is to think your modules as a main one, calling functionalities from the other ones. These functionalities can be classes or functions, in other words, you will pass the reference to your main window as an argument.
Main module
import fatigue_analysis
class MainWindow(QtGui.Window):
# ....
def start_file_compute(self, path_to_file):
# Pass a reference to self (MainWindow instance) to the helper function
fatigue_analysis.start(path_to_file, self)
# ....
fatigue_analysis.py
def start(path_to_file, top_window):
# ....
top_window.updateStatus(PercentComplete)
# ....
That said, you may consider using QtCore.QThread to run your long computation while leaving the GUI responsive. In this case, beware that Qt do not like very much that one thread tries to modify a member of another thread (i.e. you main window). You should use signals to pass information from on thread to another.
You can do the following:
In the MainWindow class, you should first create a statusbar: self.statusbar = self.statusBar()
Then, from the analysis code, pass a reference to the MainWindow object and from there you can update the statusbar as you wish using this:
main_window_object.statusbar.showMessage(PercentComplete)
EDIT: I do not know what the LastData is, but you would need to inherit from the QtGui.QMainWindow ideally.
I'm writing a 'wizard' type Python Tkinter GUI that collects information from the user and then performs several actions based on the user's entries: file copying, DB updates, etc. The processing normally takes 30-60 seconds and during that time, I want to:
Provide the user with text updates on the activity and progress
Prevent the user from closing the app until it's finished what it's doing
I started on the route of having the text updates appear in a child window that's configured to be trainsient and using wait_window to pause the main loop until the activities are done. This worked fine for other custom dialog boxes I created which have OK/cancel buttons that call the window's destroy method. The basic approach is:
def myCustomDialog(parent,*args):
winCDLG = _cdlgWin(parent,*args)
winCDLG.showWin()
winCDLG.dlgWin.focus_set()
winCDLG.dlgWin.grab_set()
winCDLG.dlgWin.transient(parent)
winCDLG.dlgWin.wait_window(winCDLG.dlgWin)
return winCDLG.userResponse
class _cdlgWin():
def __init__(self,parent,*args):
self.parent = parent
self.dlgWin = tk.Toplevel()
self.userResponse = ''
def showWin(self):
#Tkinter widgets and geometry defined here
def _btnOKClick(self):
#self.userResponse assigned from user entry/entries on dialog
self.dlgWin.destroy()
def _btnCancelClick(self):
self.dlgWin.destroy()
However this approach isn't working for the new monitor-and-update dialog I want to create.
First, because there's no user-initiated action to trigger the copy/update activities and then the destroy, I have to put them either in showWin, or in another method. I've tried both ways but I'm stuck between a race condition (the code completes the copy/update stuff but then tries to destroy the window before it's there), and never executing the copy/update stuff in the first place because it hits the wait_window before I can activate the other method.
If I could figure out a way past that, then the secondary problem (preventing the user from closing the child window before the work's done) is covered by the answers below.
So... is there any kind of bandaid I could apply to make this approach work the way I want? Or do I need to just scrap this because it can't work? (And if it's the latter, is there any way I can accomplish the original goal?)
self.dlgWin.overrideredirect(1) will remove all of the buttons (make a borderless window). Is that what you're looking for?
As far as I know, window control buttons are implemented by the window manager, so I think it is not possible to just remove one of them with Tkinter (I am not 100% sure though). The common solution for this problem is to set a callback to the protocol WM_DELETE_WINDOW and use it to control the behaviour of the window:
class _cdlgWin():
def __init__(self,parent,*args):
self.parent = parent
self.dlgWin = tk.Toplevel()
self.dlgWin.protocol('WM_DELETE_WINDOW', self.close)
self.userResponse = ''
def close(self):
tkMessageBox.showwarning('Warning!',
'The pending action has not finished yet')
# ...
Hopefully this doesn't fall under "general discussion topic", since I'd like it to be more about resolving these issues in an efficient manner than a giant debate about which general approach to GUI programming is the absolute best.
So I've started some GUI programming with tkinter and long story short my code is getting pretty ugly pretty quickly. I'm trying to create a tile-based map editor for a video game. My main issues seem to be:
the inability of callbacks to return values.
the inability to transfer data between windows easily.
I assume that the reason I see these as issues is because I'm using functions a lot more than I'm using classes. For instance, my "load tileset" window is handled entirely functionally: Clicking the menu option in the main window calls the function that loads the new window. From within that window, I create an open file dialog when looking for the image, and modify the canvas displaying the image when I press the enter key (so that it draws the appropriate grid over the image). function function function.
What looks like really bad practice to me is the inclusion of extra arguments to compensate. For example, when I create a tileset, the instance of the TileSet class created should be sent back to the main window where the appropriate information can be displayed. I have a list of loaded tilesets as a global variable (even more bad practice: Everything dealing with my root window is in the global scope! yay!), and because callback functions don't return values, I pass that list as an argument to my "load tileset window" function, which then passes the argument to the create tileset function (called when you click the appropriate button in the window), where it's actually needed so that I can add my newly created tileset to the list. Passing arguments through a function 'hierarchy' like that seems like a horrible idea. It gets confusing, it's horrible for writing modular code, and just generally seems unnecessary.
My attempt at fixing the problem would be to write a class representing the whole GUI, and custom made window classes (that the GUI class can create and reference) that can actually store relevant data. That should take care of issues with transferring data between windows. Hopefully it would cut down on my gratuitous use of lambda functions in callbacks as well.
But I'm wondering: is this the best way? Or at least close? I'd rather not start rewriting and then end up with another system that's just sloppy and confusing in a different way. I know my methods are bad, but I don't really know what the best approach would be. I'm getting a lot of advice on how to do specific things, but none on how to structure the program as a whole. Any help would be greatly appreciated.
It sounds like you're trying to create a GUI that acts procedurally, which won't work. GUIs aren't procedural, their code doesn't run linearly where functions call callbacks which return values. What you're asking isn't unique to tkinter. This is the nature of event based GUI programming -- callbacks can't return anything because the caller is an event rather than a function.
Roughly speaking, you must use a global object of some sort to store your data. Typically this is called the "Model". It can be a global variable, or it might be a database, or it can be an object of some sort. In any case, it must exist "globally"; that is, it must be accessible to the whole GUI.
Often, this access is provided by a third component called a "Controller". It is the interface between the GUI (the "View") and the data (the "Model"). These three components make up what is called the model-view-controller pattern, or MVC.
The model, view and controller don't have to be three different objects. Often, the GUI and the controller are the same object. For small programs this works quite well -- the GUI components talk directly to your data model.
For example, you could have a class that represents a window which inherits from Tkinter.Toplevel. It can have an attribute that represents the data being edited. When the user selects "New" from a main window, it does something like self.tileset = TileSet(filename). That is, it sets the attribute named tileset of the GUI object named self to be an instance of the TileSet class specific to the given filename. Later functions that manipulate the data use self.tileset to access the object. For functions that live outside the main window object (for example, a "save all" function from the main window) you can either pass this object as an argument, or use the window object as the controller, asking it to do something to its tileset.
Here's a brief example:
import Tkinter as tk
import tkFileDialog
import datetime
class SampleApp(tk.Tk):
def __init__(self, *args, **kwargs):
tk.Tk.__init__(self, *args, **kwargs)
self.windows = []
menubar = tk.Menu(self)
self.configure(menu=menubar)
fileMenu = tk.Menu(self)
fileMenu.add_command(label="New...", command=self.new_window)
fileMenu.add_command(label="Save All", command=self.save_all)
menubar.add_cascade(label="Window", menu=fileMenu)
label = tk.Label(self, text="Select 'New' from the window menu")
label.pack(padx=20, pady=40)
def save_all(self):
# ask each window object, which is acting both as
# the view and controller, to save it's data
for window in self.windows:
window.save()
def new_window(self):
filename = tkFileDialog.askopenfilename()
if filename is not None:
self.windows.append(TileWindow(self, filename))
class TileWindow(tk.Toplevel):
def __init__(self, master, filename):
tk.Toplevel.__init__(self, master)
self.title("%s - Tile Editor" % filename)
self.filename = filename
# create an instance of a TileSet; all other
# methods in this class can reference this
# tile set
self.tileset = TileSet(filename)
label = tk.Label(self, text="My filename is %s" % filename)
label.pack(padx=20, pady=40)
self.status = tk.Label(self, text="", anchor="w")
self.status.pack(side="bottom", fill="x")
def save(self):
# this method acts as a controller for the data,
# allowing other objects to request that the
# data be saved
now = datetime.datetime.now()
self.status.configure(text="saved %s" % str(now))
class TileSet(object):
def __init__(self, filename):
self.data = "..."
if __name__ == "__main__":
app = SampleApp()
app.mainloop()