Develop Reference

How to shrink a frame in tkinter after removing contents?

Most of the topics I came across deals with how to not shrink the Frame with contents, but I'm interested in shrinking it back after the destruction of said contents. Here's an example:
import tkinter as tk
root = tk.Tk()
lbl1 = tk.Label(root, text='Hello!')
lbl1.pack()
frm = tk.Frame(root, bg='black')
frm.pack()
lbl3 = tk.Label(root, text='Bye!')
lbl3.pack()
lbl2 = tk.Label(frm, text='My name is Foo')
lbl2.pack()
So far I should see this in my window:
Hello!
My name is Foo
Bye!
That's great, but I want to keep the middle layer interchangeable and hidden based on needs. So if I destroy the lbl2 inside:
lbl2.destroy()
I want to see:
Hello!
Bye!
But what I see instead:
Hello!
███████
Bye!
I want to shrink frm back to basically non-existence because I want to keep the order of my main widgets intact. Ideally, I want to run frm.pack(fill=tk.BOTH, expand=True) so that my widgets inside can scale accordingly. However if this interferes with the shrinking, I can live without fill/expand.
I've tried the following:
pack_propagate(0): This actually doesn't expand the frame at all past pack().
Re-run frm.pack(): but this ruins the order of my main widgets.
.geometry(''): This only works on the root window - doesn't exist for Frames.
frm.config(height=0): Oddly, this doesn't seem to change anything at all.
frm.pack_forget(): From this answer, however it doesn't bring it back.
The only option it leaves me is using a grid manager, which works I suppose, but not exactly what I'm looking for... so I'm interested to know if there's another way to achieve this.

When you destroy the last widget within a frame, the frame size is no longer managed by pack or grid. Therefore, neither pack nor grid knows it is supposed to shrink the frame.
A simple workaround is to add a small 1 pixel by 1 pixel window in the frame so that pack still thinks it is responsible for the size of the frame.
Here's an example based off of the code in the question:
import tkinter as tk
root = tk.Tk()
lbl1 = tk.Label(root, text='Hello!')
lbl1.pack()
frm = tk.Frame(root, bg='black')
frm.pack()
lbl3 = tk.Label(root, text='Bye!')
lbl3.pack()
lbl2 = tk.Label(frm, text='My name is Foo')
lbl2.pack()
def delete_the_label():
lbl2.destroy()
if len(frm.winfo_children()) == 0:
tmp = tk.Frame(frm, width=1, height=1, borderwidth=0, highlightthickness=0)
tmp.pack()
root.update_idletasks()
tmp.destroy()
button = tk.Button(root, text="Delete the label", command=delete_the_label)
button.pack()
root.mainloop()

Question: Shrink a Frame after removing the last widget?
Bind to the <'Expose'> event and .configure(height=1) if no children.
Reference:
Expose
An Expose event is generated whenever all or part of a widget should be redrawn
import tkinter as tk
class App(tk.Tk):
def __init__(self):
super().__init__()
tk.Label(self, text='Hello!').pack()
self.frm = frm = tk.Frame(self, bg='black')
frm.pack()
tk.Label(self, text='Bye!').pack()
tk.Label(frm, text='My name is Foo').pack()
self.menubar = tk.Menu()
self.config(menu=self.menubar)
self.menubar.add_command(label='delete', command=self.do_destroy)
self.menubar.add_command(label='add', command=self.do_add)
frm.bind('<Expose>', self.on_expose)
def do_add(self):
tk.Label(self.frm, text='My name is Foo').pack()
def do_destroy(self):
w = self.frm
if w.children:
child = list(w.children).pop(0)
w.children[child].destroy()
def on_expose(self, event):
w = event.widget
if not w.children:
w.configure(height=1)
if __name__ == "__main__":
App().mainloop()
Question: Re-run frm.pack(): but this ruins the order of my main widgets.
frm.pack_forget(), however it doesn't bring it back.
Pack has the options before= and after. This allows to pack a widget relative to other widgets.
Reference:
-before
Use its master as the master for the slaves, and insert the slaves just before other in the packing order.
Example using before= and self.lbl3 as anchor. The Frame are removed using .pack_forget() if no children and get repacked at the same place in the packing order.
Note: I show only the relevant parts!
class App(tk.Tk):
def __init__(self):
...
self.frm = frm = tk.Frame(self, bg='black')
frm.pack()
self.lbl3 = tk.Label(self, text='Bye!')
self.lbl3.pack()
...
def on_add(self):
try:
self.frm.pack_info()
except:
self.frm.pack(before=self.lbl3, fill=tk.BOTH, expand=True)
tk.Label(self.frm, text='My name is Foo').pack()
def on_expose(self, event):
w = event.widget
if not w.children:
w.pack_forget()
Tested with Python: 3.5 - 'TclVersion': 8.6 'TkVersion': 8.6

Tkinter treeview widgets not properly aligned/added space between widgets

I am working on this table in tkinter made from a bunch of treeveiw widgets. The idea is to get a table where I can add lines, select lines and edit them. In the code below you can add lines to the table by pushing the button. I now want to control the height of each row by configuring the style. However, when I use style the alignment of the treeview widgets is messed up, see attached picture. Any suggestions how to fix this?
EDIT: The problem is the added space between the widgets.
The code for the table is:
from tkinter import *
from tkinter import ttk
class MyApp(Tk):
def __init__(self):
super(MyApp, self).__init__()
self.geometry('950x500+100+100')
self.NewTree = []
label = Label(self,text='Table with some data', font=("Arial Bold", 25))
label.pack()
self.addLine()
master_frame = Frame(self, bd=3, relief=RIDGE)
master_frame.pack(side=BOTTOM)
# Create a frame for the canvas and scrollbar(s).
frame2 = Frame(master_frame)
frame2.pack(side = BOTTOM)
# Add a canvas in that frame.
self.canvas = Canvas(frame2)
self.canvas.grid(row=0, column=0)
# Create a vertical scrollbar linked to the canvas.
vsbar = Scrollbar(frame2, orient=VERTICAL, command=self.canvas.yview)
vsbar.grid(row=0, column=1, sticky=NS)
self.canvas.configure(yscrollcommand=vsbar.set)
# Create a frame on the canvas to contain the buttons.
self.table_frame = Frame(self.canvas)
# Create canvas window to hold the buttons_frame.
self.canvas.create_window((0,0), window=self.table_frame, anchor=NW)
def addLine(self):
#Make button for adding step
bt = Button(self,text='Add Line',command=lambda: self.addLineMethod())
bt.config(width=9, height=1)
bt.pack()
def addLineMethod(self):
lineNumber = int(len(self.NewTree)/5)
for index in range(5):
s = ttk.Style()
s.configure('MyStyle.Treeview', rowheight=25)
self.NewTree.append(ttk.Treeview(self.table_frame, height=1,show="tree",columns=("0"),style='MyStyle.Treeview'))
#Works fine when using this line instead of those above
#self.NewTree.append(ttk.Treeview(self.table_frame, height=1,show="tree",columns=("0")))
self.NewTree[index+5*lineNumber].grid(row=lineNumber, column=index+1)
self.NewTree[index+5*lineNumber]['show'] = ''
item = str(index+5*lineNumber)
self.NewTree[index+5*lineNumber].column("0", width=180, anchor="w")
self.NewTree[index+5*lineNumber].insert("", "end",item,text=item,values=('"Text text text"'))
self.table_frame.update_idletasks() # Needed to make bbox info available.
bbox = self.canvas.bbox(ALL) # Get bounding box of canvas with Buttons.
# Define the scrollable region as entire canvas with only the desired
# number of rows and columns displayed.
self.canvas.configure(scrollregion=bbox, width=925, height=200)
app = MyApp()
app.mainloop()
Her is a picture of the table with some lines.

Put the style configuration in the __init__() function and the effect will go away. I'm not clear as to why this works.
def __init__(self):
...
s = ttk.Style()
s.configure('MyStyle.Treeview', rowheight=20)

TKInter Entry is not exapanding along with Main Window

I am using the following code, I am having 2 issues,
1. When I try to maximize the window, the Entry widget is not aligned/maximized along with main window and see a gap between scrolled text and Entry widget.
2. Second I am trying to set my cursor in Entry widget when I try to open or whenever my app is active but it's not working for some reason. Any Idea what am I making mistakes?
import tkinter as tk
from tkinter import scrolledtext
class Main:
def __init__(self, master):
self.master = master
master.title("Main")
width = master.winfo_screenwidth()
height = master.winfo_screenheight()
master.minsize(width=1066, height=766)
master.maxsize(width=width, height=height)
self.frame = tk.Frame(self.master)
text_area = scrolledtext.ScrolledText(self.master,width=75,height=35)
text_area.pack(side="top",fill='both',expand=True)
text_entry = tk.Entry(self.master,width=65)
text_entry.pack(side="top",fill=X, expand=True,ipady=3, ipadx=3)
text_entry.configure(foreground="blue",font=('Arial', 10, 'bold', 'italic'))
text_entry.focus()
self.frame.pack()
def initial(self):
print ("initializing")
def main():
root = tk.Tk()
app = Main(root)
root.mainloop()
if __name__ == '__main__':
main()

I can address the issue of your entry field not expanding properly.
That is because you have fill=X and this is not a valid input for fill. Instead use fill="x". I believe your 2nd issue with the entry field having a large gap is because you have set expand = True instead change that to expand = False.
That said I prefer to use the grid() geometry manager instead. Take a look at my below example of how to do this with grid and weights.
When using the grid() manager you can tell each widget exactly where you want it along a grid. The use of weights is for telling a row or column how much if any it should expand with the window. This combined with sticky="nsew" will help us control stuff expands within the window.
import tkinter as tk
from tkinter import scrolledtext
class Main(tk.Tk):
def __init__(self):
tk.Tk.__init__(self)
self.title("Main")
width = self.winfo_screenwidth()
height = self.winfo_screenheight()
self.minsize(width=1066, height=766)
self.maxsize(width=width, height=height)
self.rowconfigure(0, weight=1)
self.rowconfigure(1, weight=0)
self.columnconfigure(0, weight=1)
text_area = scrolledtext.ScrolledText(self,width=75,height=35)
text_area.grid(row=0, column=0, ipady=3, ipadx=3, sticky="nsew")
text_entry = tk.Entry(self,width=65)
text_entry.grid(row=1, column=0, ipady=3, ipadx=3, sticky="ew")
text_entry.configure(foreground="blue",font=('Arial', 10, 'bold', 'italic'))
text_entry.focus()
def initial(self):
print ("initializing")
if __name__ == '__main__':
root = Main()
root.mainloop()
Update:
To clarify on your issue with fill and expand I have updated your code with the correction so you can see it working.
import tkinter as tk
from tkinter import scrolledtext
class Main:
def __init__(self, master):
self.master = master
master.title("Main")
width = master.winfo_screenwidth()
height = master.winfo_screenheight()
master.minsize(width=1066, height=766)
master.maxsize(width=width, height=height)
self.frame = tk.Frame(self.master)
text_area = scrolledtext.ScrolledText(self.master,width=75,height=35)
text_area.pack(side="top",fill='both',expand=True)
text_entry = tk.Entry(self.master,width=65)
text_entry.pack(side="top",fill="x", expand=False, ipady=3, ipadx=3)
text_entry.configure(foreground="blue",font=('Arial', 10, 'bold', 'italic'))
text_entry.focus()
self.frame.pack()
def initial(self):
print ("initializing")
def main():
root = tk.Tk()
app = Main(root)
root.mainloop()
if __name__ == '__main__':
main()

How can I explicitly set the terminal size in python?

I would like to explicitly set the terminal size. Is there a cross-platform way to do this?
I want to make a game, showing fixed-sized art.

I used Tkinter (Thanks Steven Rumbalski!), because I don't mind using GUI if it's cross-platform. Basically, I set a window geometry and the size of my "art" label:
from Tkinter import *
#Assign a variable to the shown image to be able to change it
displayed_image = "test.gif"
class App:
def __init__(self, master):
#Make a frame to enclose the art with a relief
self.topframe = Frame(master, borderwidth=5, pady=5, relief=RIDGE)
#Pack the frame to draw it
self.topframe.pack()
#This frame will contain the prompt
self.frame = Frame(master)
self.frame.pack()
photo = PhotoImage(file="../Art/"+displayed_image)
art = Label(self.topframe, width=1280, height=720, image=photo)
art.photo = photo
art.pack()
prompt = Entry(self.frame, width=1280)
prompt.pack()
root = Tk()
root.wm_geometry("%dx%d" % (1300, 780))
app = App(root)
root.mainloop()
root.destroy()

tkinter canvas image is not displayed in class

I am trying to display an image in python using the tkinter canvas option. However, if I input it in a class, like below, it doesn't give an error but also doesn't show my image. The buttons are displayed correctly though. Also, if I take the code for generating this image out of the class it works correctly. I can't seem to find out what the problem is.
import Tkinter as tk
from Tkinter import *
class Board(tk.Frame):
def __init__(self,parent):
frame = Frame(parent)
frame.pack()
tk.Frame.__init__(self,parent)
frame2 = Frame(frame)
frame2.pack()
c=Canvas(frame2)
c.pack(expand=YES,fill=BOTH)
background=PhotoImage(file='Board.gif')
c.create_image(100,100,image=background,anchor='nw')
button = Button(frame, text="Next turn", command=self.next_turn)
button.pack()
button = Button(frame, text="Roll the dice", command=self.roll)
button.pack()
....
root = Tk()
board = Board(root)
board.pack()
root.mainloop()

You have to keep a reference to the PhotoImage. This is just and example (you can also use self.background instead of c.background):
c = Canvas(frame2)
c.pack(expand=YES,fill=BOTH)
c.background = PhotoImage(file='Board.gif')
c.create_image(100,100,image=c.background,anchor='nw')