Python-Programs/program_18_Tk_States.py at master · SoftwareLiteracyFoundation/Python-Programs · GitHub

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#----------------------------------------------------------
# These websites are a good reference for Tk
# http://www.tkdocs.com/tutorial/index.html
# http://www.pythonware.com/library/tkinter/introduction/
#----------------------------------------------------------

from tkinter import *
from tkinter import ttk

#----------------------------------------------------------------
# This program will use the database (dictionary) of US States
# from program_12_States.py to allow the user to select a state
# from a Tk Listbox. When a state is selected, it's database
# information is displayed in a Label widget.
#----------------------------------------------------------------

# Create a UnitedStates object from program_12_States
import program_12_States
US = program_12_States.UnitedStates()

# Fill in the database from the file with the US.ReadDataFile() method
US.ReadDataFile( 'US_States.csv' )

# Get a list of the state names from the US_database
# We will show this list in the Listbox
stateNames = list( US.US_database.keys() )

# Since this list is from dictionary keys, the order is random
# sort them alphabetically
stateNames.sort()

# Initialize Tk, must be prior to creation of StringVar()
root = Tk()
root.title('US States Database')

# Tk I/O variables
# valid types are BooleanVar, DoubleVar, IntVar, StringVar
outputMessage = StringVar()

#----------------------------------------------------------------
# When the user selects an item from the Listbox, this callback
# function process the selected state by extracting the stored
# information from the US_database and updating the message
# text in outputMessage. The outputMessage is then displayed
# in the Label widget.
#----------------------------------------------------------------
def ProcessListbox(*args):
    # Get the index of the state selected in the ListBox
    i_selected = lbox.curselection() # tuple of indices as text

    # Just process the first selection (i_selected[0])
    # and output all the info for this single selection
    if len( i_selected ) > 0:

        i = int(i_selected[0]) # have to convert the text to an int

        # we assume that the i corresponds to the index in stateNames
        # get the data from the database into local variables
        dateFounded = US.US_database[ stateNames[i] ].dateFounded
        USPS        = US.US_database[ stateNames[i] ].USPS
        capital     = US.US_database[ stateNames[i] ].capital
        population  = US.US_database[ stateNames[i] ].population
        area        = US.US_database[ stateNames[i] ].area
        biggestCity = US.US_database[ stateNames[i] ].biggestCity

        # Create an output message from the data
        msg = stateNames[i] + ' was founded ' + dateFounded + '\n'
        msg = msg + 'The capital is ' + capital + '\n'
        msg = msg + 'The largest city is ' + biggestCity + '\n'
        msg = msg + 'The population is ' + population + '\n'
        msg = msg + 'The area is ' + area  + '\n'

        outputMessage.set(msg)

#----------------------------------------------------------------
# Create and grid the outer content frame
mainFrame = ttk.Frame( root, padding = (5, 5, 12, 0) )
mainFrame.grid( column = 0, row = 0, sticky = (N,W,E,S) )

# These grid_*configure functions make the widgets in the
# rows and columns expand as the root window is resized
# if weight = 0, there is no resize, if weight = 1, then
# resize to fill the whole window
root.grid_columnconfigure(0, weight = 1)
root.grid_rowconfigure   (0, weight = 1)

# Create the Listbox to hold the state names
lbox = Listbox( mainFrame, height = 10 )

# Insert the state names into the Listbox
# The listvariable = [] option won't work if
# there is whitespace in a name, so insert them manually
for i in range( len(stateNames) ) :
    lbox.insert( i, stateNames[i] )

# Create a Label to hold the outputMessage
stateInfo = ttk.Label( mainFrame, textvariable = outputMessage, anchor = E )

# Create a vertical scroll bar for the Listbox
# Tell the scrollbar that it will call the Listbox yview function
# when the user moves the scrollbar
scrollBar = ttk.Scrollbar( mainFrame, orient = VERTICAL, command = lbox.yview )

# Tell the Listbox that it will scroll according to the scrollBar
lbox.configure( yscrollcommand = scrollBar.set )

# Grid all the widgets - This is the layout of the window
# This application has 2 columns and 1 row
# The Listbox and scrollbar are in column 0,
# The outputMessage Label is in column 1
# Both the Listbox and outputMessage Label are in row 0
# padx = 23 prevents overlap with the scrollbar
lbox.grid( column = 0, row = 0, padx = 23, sticky=(N,S,E,W) )

scrollBar.grid( column = 0, row = 0, sticky = (W,N,S) )

stateInfo.grid( column = 1, row = 0, sticky=(W,E) )

# Don't resize the column 0 - the width of the Listbox
mainFrame.grid_columnconfigure(0, weight = 0)

# Resize the column 1 and row 0 as the window is resized
mainFrame.grid_columnconfigure(1, weight = 1)
mainFrame.grid_rowconfigure   (0, weight = 1)

# This tells the Listbox to call the functin ProcessListbox()
# when the selection in the listbox changes
lbox.bind('<<ListboxSelect>>', ProcessListbox)

# Colorize alternating lines of the listbox
for i in range( 0, len(stateNames), 2 ):
    lbox.itemconfigure( i, background = '#f0f0ff' )

# Set the starting state of the interface by selecting
# the first state in the list and calling ProcessListbox()
lbox.selection_set(0)
ProcessListbox()

# Enter the main event loop
root.mainloop()