How to update layers of tkinter widgets dynamically? - python

Tkinter Requirements
So I am relatively new to using tkinter and I am struggling with a very specific doubt here. I tried finding solutions to this but as much as I find it obvious, the solution to this doesn't seem to be easy to understand. So if you can see the image above, I am trying to create a GUI for a particular project which requires multi-layer (I am calling it 3D array based) widgets.
Let's say the variables used for this pointer system are i, j, and k.
I am creating individual layer widgets using for loop:
for n in range(i):
frame_x[i] = Frame(root).grid(row = 1, column = i)
entry_x[i] = Entry(frame_x[i]).grid(row = 2, column = i)
button_x[i] = Button(frame_x[i]).grid(row=3, column = i)
Please note this is not a functional code, I have tried to keep it to the point just to give an idea of the method I am using. (Let me know if you want a more detailed code block.)
Now coming to the problem. I am able to do the basic part of this. But the problem is that I want it to work dynamically.
Let's say if the user enters j = 4 first. 4 blocks will be created.
Later if he changes the value to j = 2 and the presses the button, ideally it should make the widgets at block j= 3 and 4 disappear. But I guess tkinter works on overlapping basis and doesn't change a grid element until something is specifically overlapped over it. How do I do that. I tried destroying the entire frame just after entering the for loop, but that doesn't work as for the first time no widget is created before destroying and python throws NameError saying I can't use a variable before assignment.
Anyways, please let me know how do I do this efficiently.
And also in general, if there is a better way to go about the whole thing. Please refer the image above and let me know if it doesn't make sense.
I am not very comfortable with classes in general. I prefer the inefficient way by only using functions to do everything I have to. So it would be great if you can share me a framework without using classes. But its okay if you use them. I know I should start working with classes at some point.

First off, I want to address this part of the question:
I guess tkinter works on overlapping basis and doesn't change a grid element until something is specifically overlapped over it.
I'm not entirely sure what you mean by that, but if it means what I think it means, it is a false statement. tkinter doesn't "work on an overlapping basis". If you destroy a widget, it is destroyed. It doesn't matter if it's overlapped or not.
Based on the tiny bit of code you posted, the main problem is that you aren't putting the entry and button in the frame. Because of that, they are not destroyed when you destroy the frame.
The reason you aren't putting the widgets into the frame is because of this line:
frame_x[i] = Frame(root).grid(row = 1, column = i)
In python, when you do x=y().z(), x has the value of z(). Thus, when you do frame_x[i] = Frame(...).grid(...), frame_x[i] has the value of .grid(...), and .grid(...) always returns None. Thus, frame_x[i] will be None.
When you next do entry_x[i] = Entry(frame_x[i]).grid(...), it's the same as doing entry_x[i] = Entry(None).grid(...). Because the master of the Entry is None, it becomes a child of the root window.
So, the first step is to separate the creation of the widget from the layout of the widget.
frame_x[i] = Frame(root)
frame_x[i].grid(row = 1, column = i)
Once you do that, the Entry and Button widgets will become a child of the frame, and you can remove widgets you don't want by destroying the frame (eg: frame_x[i].destroy()), since destroying a widget will also cause all children of the widget to be destroyed.
Once you have that in place, you can destroy unwanted widgets by simply calling .destroy() on the frame. For example, if you have previously created 10 groups and now need only 5, you can destroy the others and then remove them from the list like this:
# assume 'num' contains the number of frames that we want,
# and that it is smaller than the number of items in frames_x
for frame in frames_x[num:]:
frame.destroy()
frames_x = frames_x[:num]
Here is a complete working program to illustrate. Enter a number and click the button. It will create that many frame+entry+button combinations. Enter a new number that is larger or smaller and it will either add or remove widgets.
This would be easier if you used classes, but you specifically asked for a solution that doesn't use classes. In your real code you probably need to also save the entry widgets in an array so that you can reference them later, but this example is focuses on the creation of the widgets rather than writing your whole program for you.
import tkinter as tk
frames_x = [] def create_widgets():
global frames_x
num = int(num_widgets.get())
# if the number is less than the previous number of
# widgets, delete the widgets we no longer want
for frame in frames_x[num:]:
frame.destroy()
frames_x = frames_x[:num]
# if the number is greater than the previous number of
# widgets, create additional widgets
for i in range(len(frames_x), num):
# create new widget
frame = tk.Frame(root, bd=1, relief="raised")
entry = tk.Entry(frame)
button = tk.Button(frame, text="click me")
# pack entry and button in frame
button.pack(side="right")
entry.pack(side="left", fill="x", expand=True)
# grid the frame in the parent
frame.grid(row=i+1, column=0, columnspan=2)
# save the new frame in the array
frames_x.append(frame)
root = tk.Tk() num_widgets = tk.Entry(root) button = tk.Button(root, text="Create widgets", command=create_widgets)
button.grid(row=0, column=1) num_widgets.grid(row=0, column=0, sticky="ew")
root.mainloop()

Related

Can't understand pack and grid geometry with tkinter

Hi I didn't really understand how furas made the below code work. Why didn't he get an error message about grid and pack on the same root when he added a box? In the addbox function he sets a frame to the root which is pack already and even uses the pack inside the function and then uses the grid.
Can someone please explain to me how this "magic" works?
a link to the his answer:
Creating new entry boxes with button Tkinter
from Tkinter import *
#------------------------------------
def addBox():
print "ADD"
frame = Frame(root)
frame.pack()
Label(frame, text='From').grid(row=0, column=0)
ent1 = Entry(frame)
ent1.grid(row=1, column=0)
Label(frame, text='To').grid(row=0, column=1)
ent2 = Entry(frame)
ent2.grid(row=1, column=1)
all_entries.append( (ent1, ent2) )
#------------------------------------
def showEntries():
for number, (ent1, ent2) in enumerate(all_entries):
print number, ent1.get(), ent2.get()
#------------------------------------
all_entries = []
root = Tk()
showButton = Button(root, text='Show all text', command=showEntries)
showButton.pack()
Thanks
There's no magic, it's just working as designed. The code uses pack in the root window, and uses grid inside a frame. Each widget that acts as a container for other widgets can use either grid or pack. You just can't use both grid and pack together for widgets that have the same master.
not really an answer but I think you will be helped by the link.
tkinter and it's layout is indeed a bit hard to understand.
I never understood how to deal with it until I stumbled over this presentation which explained the layout particulars in a way where I finally could get the hang of it.
Just putting it out there for others to find as well.
tkinter tutorial by beazley
I think you miss out on what pack and grid actually are. Consider such code:
import tkinter as tk
root = tk.Tk()
myFrame = tk.Frame(root)
myFrame.pack()
myButton1 = tk.Button(myFrame, text='This is button 1')
myButton2 = tk.Button(myFrame, text='This is button 2')
myButton1.grid(row=0, column=0)
myButton2.grid(row=1, column=0)
root.mainloop()
By creating root we create a new window. In this window we will put everything else. Then we create myFrame. Note, that the actual "thing" (in more adequate terms - widget) is created in line myFrame = tk.Frame(root). Note, that we have to specify where we are going to put this widget in brackets and we've written that it is going to be root - our main window. Blank frame probably isn't the best example since you can not see it being placed (not unless you use some more specifications at least), but still. We have created it, but not placed it in our user interface. The we use .pack() to place it. Now you refer to widgets as being used as packs or grids. That is not true though. Pack and grid are just the set of rules, on which the widgets are being placed inside some kind of window. Because of that, if you want to add something more to the root in our case, you will have to use .pack() again. Why? If you will give two sets of rules on how to place things on the screen for your computer - they will most likely conflict with each other. However, if we go one more level down and now want to place something inside our myFrame, we can again choose which set of rules to use. It is because it does not matter, where our frame is going to end up inside root, we now just want to specify where our Buttons 1 and 2 are going to end up inside the frame. Therefore we can again use .pack() or switch to .grid().
To conclude: .pack(), .grid() and .place() are sets of rules on how place widgets inside other widgets. In more general terms though these are rules on how place boxes in other boxes. One boxes in which we arrange other boxes can only have one set of rules.
I hope this example helps.

Python Tkinter :removing widgets that were created using a for loop

I'm currently learning how to use the Tkinter library on python to create a GUI that takes in longitude and latitude points and outputing that into a file. Basically I'm trying to automate the process of having to copy the correct format of line of points to another file.
So I created a Entry and button field to see how many long/lat points are needed to generate a 'shape'. Using this integer input from user, I have a for loop to populate the GUI with multiple widgets asking for the long/lat points. I have that working properly, but now I am trying to have a clear button, which would allow the user to clear all these long/lat points and give them the ability to repopulate the field with the amount of points the other shape requires.
So far I have:
def clearGrid():
coordAmount = int(pointText.get())
latLabel.grid_forget()
longLabel.grid_forget()
.....(contains code that populates the GUI)
#creating clear site Button
clearButton = Button(main_gui, text="Clear Sites!",command=clearGrid)
clearButton.grid(row=lastRow+1, column=5, pady=10)
However, the problem that I am running into is that when the clear button is clicked, it only clears the latest instance of the widgets not all of them. So in a for loop that creates 5 instances/iteration of widgets, it will remove only the 5th instance/iteration of widgets.
I'm trying to have the clear button functionality be able to delete all 5 instances of these widgets.
So here is a shortened code of how I am populating the GUI with widgets
def generatePoints():
for x in range(0,3):
degLong_label = Label(main_gui, text="Degree:", height=2)
degLong_label.grid(row=y,column=6,sticky=E)
degLong = Entry(main_gui, width=4)
degLong.grid(row=y,column=7,sticky=W)
#minute
minLong_Label = Label(main_gui,text="Minutes:", height=2)
minLong_Label.grid(row=y,column=8,sticky=W)
minLong = Entry(main_gui,width=3)
minLong.grid(row=y,column=8,sticky=E)
#seconds
secLong_Label= Label(main_gui,text="Sec:",height=2)
secLong_Label.grid(row=y,column=9,sticky=W,padx=20)
secLong = Entry(main_gui,width=3)
secLong.grid(row=y,column=9,sticky=E,padx=20)
#direction
dirLong_Label = Label(main_gui,text="Direction:",padx=5,height=2)
dirLong_Label.grid(row=y,column=12,sticky=W)
dirLong = Entry(main_gui,width=3)
dirLong.grid(row=y,column=13)
You need to hold on to references to all those widgets, usually via a list. Try initializing a list (list_of_widgets) before your loop, then every time you create a widget, append it to that list. When you clear, you can iterate through that list of widgets and destroy each one. Once you're done clearing them, you can clear the list so you don't try to destroy a widget twice (Tkinter will error at that point).
def generatePoints():
list_of_widgets = [] # or take the list as a parameter
for x in range(3):
degLong_label = Label(...)
degLong_label.grid(...)
list_of_widgets.append(degLong_label)
degLong = Entry(...)
degLong.grid(...)
list_of_widgets.append(degLong)
# et al.
def clearGrid(list_of_widgets):
for widget in list_of_widgets:
widget.destroy()
Note that you probably want to actually destroy the widgets if you aren't planning on showing that specific widget again (initializing a new one doesn't count).

Tkinter Listbox and Checkboxes on same height

I have 2 Listboxes next to each other and I try to create a checkbox for each entry of these Listboxes. Unfortunately, I do not manage to make the checkboxes and listbox elements have the same height/be on the same position, as you can see in the screenshot below.
Do you have any idea how i can modify it to have something similar to checkboxes in a list(which is not possible in Tkinter afaik)?
For my Listboxes, I use a customized version of this snippet:
https://stackoverflow.com/a/16056555/3429131
I hope I explained my problem in an understandable way.
Thanks for your help.
If it's not 100% necessary to have everything in a listbox then you could try and display the data using grid or pack which would make them line up properly, grid would probably be better.
Just declare it as something like:
master = Tk()
Model1 = Label(master, text="F45")
Part1 = Label(master, text="AUFN-BUCHSE")
Active1 = Checkbutton(master, variable=Var)
Model1.grid(row=0,column=0)
Part1.grid(row=0, column=1)
Active1.grid(row=0, column=2)
And if you wanted to repeat this you could pull the Model and Part sections out of a file and then create a for loop that creates a list containing the Labels.
You could then use a for loop to grid the labels, something like this:
for Counter1 in range(0, NumberOfRows)
Model[Counter1].grid(row=Counter1, column=0)
Part[Counter1].grid(row=Counter1, column=1)
Checkbutton.grid(row=Counter1, column=2)
Something along the lines of this, with a few tweaks, where Model[] would be something like [F45, F46, F47...] and Part[] would be [AUFN-BUCHSE, AUFN-BUCHSE-BOLZEN...]
Again you may have to tweak my code a little, not sure if it's spot on what you wanted but all of this depends on whether list boxes are completely necessary or not.
If you want to read up some more on gird method, check this out:
http://effbot.org/tkinterbook/grid.htm

how to use text box in tkinter and use the values? python 3

How to create multi-lines in an entry widget in tkinter and use those inputs to create something?
For example, I want a textbox widget to come up and ask the user:
How many squares do you want? (ex: 4x4, 5x5)
What color do you want them?
And with the users input, I would like to create that many x-amount of squares in that specific height/width and specify the colors etc.
I am totally new to tkinter and I'm not really sure how to approach this.
I tried using this, but i'm not really sure how to add more lines and to use the values inputted.
import tkinter
from tkinter import *
class Squares:
root = Tk()
root.title('Random')
x = Label(text='How many squares? (ex: 4x4, 5x3)').pack(side=TOP,padx=10,pady=10)
Entry(root, width=10).pack(side=TOP,padx=10,pady=10)
Button(root, text='OK').pack(side= LEFT)
Button(root, text='CLOSE').pack(side= RIGHT)
You have a number of problems here.
I'm not sure what the Squares class is supposed to be doing, but it's basically not doing anything. You have a bunch of code that runs when you define the class, creating a few variables (which will end up as class attributes, shared by all instances of the class), and… that's it. Rather than try to figure out what you're intending here, I'm just going to scrap the class and make it all module-level code.
You never call root.mainloop(), so your program will just define a GUI and then never run it.
You don't bind your buttons to anything, so there's no way they can have any effect. You need to create some kind of function that does something, then pass it as the command argument, or .bind it later.
You don't store references for any of your controls, so there's no way to access them later. If you want to get the value out of the entry, you need some way to refer to it. (The exception is your x variable, but that's going to be None, because you're setting it to the result of calling pack on the Label, not the Label itself.)
Once you've done that, you just need to parse the value, which is pretty easy.
Putting it all together:
import tkinter
from tkinter import *
root = Tk()
root.title('Random')
Label(text='How many squares? (ex: 4x4, 5x3)').pack(side=TOP,padx=10,pady=10)
entry = Entry(root, width=10)
entry.pack(side=TOP,padx=10,pady=10)
def onok():
x, y = entry.get().split('x')
for row in range(int(y)):
for col in range(int(x)):
print((col, row))
Button(root, text='OK', command=onok).pack(side=LEFT)
Button(root, text='CLOSE').pack(side= RIGHT)
root.mainloop()
You just have to change that print to do something useful, like creating the squares.
If you don't need an outline for the text box, create_text would be the easiest thing, even though it doesn't have a wrap text feature(at least, in python 3 you can do this):
from tkinter import *
tk = Tk()
canvas = Canvas(tk, 1000, 1000)
canvas.pack()
canvas.create_text(200, 200, text="Example Text")
Try it!

How do you create a LabelFrame with a scrollbar in Tkinter?

I'm using Python and Tkinter to create a GUI for a program I'm writing, and I'm having a couple of problems.
I have three objects descended from LabelFrame in an object descended from Frame. One of the LabelFrame descendants is two columns of corresponding Label and Entry objects.
The problem is that there are a varying number of Label and Entry pairs, and there can be more than fit on the screen. I need a way to make a scrollbar for this LabelFrame so that everything fits on the screen. I've tried various ways of making a Scrollbar object, but nothing seems to work. How can I bind a scrollbar to this frame?
Also, I need to be able to refresh or reload this LabelFrame when the load_message() method is called, but it just redisplays the new pairs on top of the old ones (so when there are less pairs in the new set, the old set is still visible at the bottom). I've tried using grid_forget() but either nothing changes or the whole frame doesn't display. How can I forget this display and then redisplay it?
Here is the code for this class:
class freq_frame(LabelFrame):
def __init__(self, master = None, text = 'Substitutions'):
LabelFrame.__init__(self, master, text = text)
self.grid()
def load_message(self):
self.frequency = get_freq(message)
self.create_widgets()
def create_widgets(self):
self.label_list = [Label(self, text = get_label(char, self.frequency[char]), justify = LEFT) for char in self.frequency.keys()]
self.entry_list = [Entry(self, width = 1) for char in self.frequency.keys()]
for n in range(len(self.label_list)):
self.label_list[n].grid(column = 0, row = n)
for n in range(len(self.entry_list)):
self.entry_list[n].grid(column = 1, row = n)
If anyone can help with either of these problems, I'd appreciate it.
Also, this question seems like it might be a little thin, but I don't know what to add. Don't hesitate to ask for more information (but be specific).
Thanks!
Labelframes don't support scrolling. So the short answer to your question is "you can't". It sounds obvious, but if the documentation for a widget doesn't say it supports scrolling, it doesn't support scrolling.
However, there is a simple solution. First, add a canvas as a child to the labelframe and pack it so that it fills the labelframe. Attach scrollbars to the canvas and add them to the labelframe too. Then embed a frame within the canvas, add your widgets to that inner frame, and then adjust the scrollregion of the canvas to match the size of the frame after you've added all the inner labels and entries.
It sounds complicated, but it's really very straight-forward.
As for re-creating the widgets when you call load_message, calling grid_forget only removes them from view, it doesn't actually destroy the widgets. Over time you could potentially end up with hundreds of non-visible widgets which is almost certainly not what you want.
Instead, you want to first destroy all the existing widgets. That's pretty easy if they all are in the same parent, since you can ask the parent for a list of all its children. Just iterate over that list to delete each child, then add any new children. An even easier solution is to destroy and recreate that inner frame that contains the labels and entries. When you delete a widget, all child widgets get automatically destroyed. So, delete that inner frame, create a new one, and add your labels and entries again.

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