Python
PROJECT 1.4.1
Change colors
Part 1
For our projects we will use Microsoft Visual Studio application. It allows to create projects in different programming languages and on different platforms. Download and install Visual Studio on your Personal Compiuter.
Download Visual Studio >>>
Open Visual Studio. Click Create a new project
From The first Lists choose Python . From the second All platforms , from the third All project types.
Click Python Application
In the first text line give the name of your project. We called our project MyFirstPythonApplication. You can choose the project adress on your PC from the secund line. Click Create.
Now we are in Visual Studio programming environment.
Initially, we have to create an App interface and add programming code. But we can not do this in Python as in VB.Net or C#, because we can not use the drag-and-drop method to create the App interface. For the interface, we have to work with the programming code.
To create an App interface we will use Tkinter library. Tkinter is the most commonly used library for developing GUI (Graphical User Interface) in Python.
Paste the next code to import Tkinter and create the App Form.
In Python for the comments symbol # is used.
import tkinter as tk
# Create the main window (Form)
window = tk.Tk()
# Here we can change Form size
window.geometry("300x200")
# Run the application
window.mainloop()
Run the application using the green triangle button on the meniu panel. We will see empty form.
Now lets put on the form 3 buttons and define theyr functions. We will have 3 functions for changing the background color and 3 buttons with specific name (btn1, btn2 and btn3),
text (Red, Blue, and Black), width (15), and function (fun1, fun2, and fun3).
Copy and paste the next code in the place you see on the next image.
Shift all window.configure() to the right.
# Functions for changing the background color
def fun1():
window.configure(bg='red')
def fun2():
window.configure(bg='blue')
def fun3():
window.configure(bg='black')
# creating buttons with specific name (btn1, btn2 and btn3),
# text (Red, Blue, and Black), width (15), and function (fun1, fun2, and fun3)
btn1 = tk.Button(window, text = 'Red', width=15,
command = fun1)
btn2 = tk.Button(window, text = 'Blue', width=15,
command = fun2)
btn3 = tk.Button(window, text = 'Black', width=15,
command = fun3)
# Place buttons on the Form
btn1.pack()
btn2.pack()
btn3.pack()
Run the application using the green triangle button on the meniu panel. Click the buttons. WOW! it works. Background color was changed to the red, blue and black!
Part 2
Now let's make our app more diinamic. We want to change the screen color based on text we will write in the textbox. If we will write "Red" Color must change to the red, If the "Blue" color must be blue and if "black" the screen must became black.
For this we have to learn most important operator of all programming languages.
if opeartor
Here is the Python syntax for the if operator:
--------------------------
if condition :
operation(s)
--------------------------
In the Python code, condition is not inside parentheses () and ends with :
operation(s) are not inside curly braces {}.
Operation (s) are not ending with the ; symbol.
Let's look on this picture. here condition is the rain and operation - taking umbrella.
:
Now let's put a textbox on the Window and define its function. In the Tkinter textbox will be Entry.
Using the if let's define what will happen if the Entry text (new_value) changes:
def on_entry_change(*args):
new_value = entry_var.get()
if new_value=="red":
window.configure(bg='red')
if new_value=="blue":
window.configure(bg='blue')
if new_value=="black":
window.configure(bg='black')
Using the next code we will create variable entry_var which will get text results after the Entry text is changed. and create an Entry.
# Create a String Variable to track the Entry widget value
entry_var = tk.StringVar()
# Set the trace method to call on_entry_change() when the value changes
entry_var.trace("w", on_entry_change)
# Create an Entry widget
entry = tk.Entry(window, textvariable=entry_var)
The final stage is to put the Entry on the Window:
# place the Entry on the Window
entry.pack()
Copy and paste the next code in the place you see on the next image.
Shift all if to the right (one move) and all window.configure() to the right 2 move.
#--------part2------------------------
# Using the if let's define what will happen if the Entry text (new_value) changes:
def on_entry_change(*args):
new_value = entry_var.get()
if new_value=="red":
window.configure(bg='red')
if new_value=="blue":
window.configure(bg='blue')
if new_value=="black":
window.configure(bg='black')
# Create a String Variable to track the Entry widget value
entry_var = tk.StringVar()
# Set the trace method to call on_entry_change() when the value changes
entry_var.trace("w", on_entry_change)
# Create an Entry widget
entry = tk.Entry(window, textvariable=entry_var)
# Place Entry on the Form
entry.pack()
Run the application using the green triangle button on the meniu panel. Write in the text box "Red" or "Blue or "Black"
WOW! The application performs tasks!
Conclusion:
We have created an application in the Visual Studio environment. We wrote the programming code using the Pythonprogramming language.
Now let's see the difference between the first and second part of the project. In the first part, we have a linear algorithm, that is, the buttons always perform the same command. We need 3 buttons for three colors. For 100 colors we will need 100 buttons.
In the second part, we have only one text block and depending on what text we enter, the background color will change - the result depends on the input data.
As you see, we can not use the drag-and-drop method to create the App interface in Python. For the interface, we have to work with the programming code. To create an App interface we used the Tkinter library.
Tkinter is the most commonly used library for developing GUI (Graphical User Interface) in Python.