add calculator app tutorial

Author: x4nth055

README.md

@@ -214,5 +214,6 @@ This is a repository of all the tutorials of [The Python Code](https://www.thepy
     - [How to Make a Button using PyGame in Python](https://www.thepythoncode.com/article/make-a-button-using-pygame-in-python). ([code](gui-programming/button-in-pygame))
     - [How to Make a Drawing Program in Python](https://www.thepythoncode.com/article/make-a-drawing-program-with-python). ([code](gui-programming/drawing-tool-in-pygame))
     - [How to Make a File Explorer using Tkinter in Python](https://www.thepythoncode.com/article/create-a-simple-file-explorer-using-tkinter-in-python). ([code](gui-programming/file-explorer))
+    - [How to Make a Calculator with Tkinter in Python](https://www.thepythoncode.com/article/make-a-calculator-app-using-tkinter-in-python). ([code](gui-programming/calculator-app))
 
 For any feedback, please consider pulling requests.

gui-programming/calculator-app/README.md

@@ -0,0 +1,2 @@
+# [How to Make a Calculator with Tkinter in Python](https://www.thepythoncode.com/article/make-a-calculator-app-using-tkinter-in-python)
+You can get the original version of the calculator [here](https://github.com/Maximinodotpy/calculator).

gui-programming/calculator-app/calculator.py

@@ -0,0 +1,197 @@
+from tkinter import *
+import tkinter.font as font
+from functools import partial
+import ctypes
+import json
+import re
+
+# so the functions can be used from the math module can be used in the lineedit.
+import math
+
+ctypes.windll.shcore.SetProcessDpiAwareness(1)
+
+# Colors
+buttonColor = (255, 255, 255)
+historyPanelBackground = (255, 255, 255)
+
+# Tkinter Setup
+root = Tk()
+root.geometry("550x270")
+root.title("Calculator")
+
+# Setting icon for the Application
+photo = PhotoImage(file = "icon.png")
+root.iconphoto(False, photo)
+
+# Loading Font from font name
+myFont = font.Font(family='Consolas', size=12)
+
+# Formula Templates
+formulas = [
+    ['Pythagoras->c', '(({a}**2)+({b}**2))**0.5 ? a=5 & b=5'],
+    ['Pythagoras->c**2', '({a}**2)+({b}**2) ? a=5 & b=5'],
+    ['pq->(x1, x2)', '-({p}/2) + sqrt(({p}/2)**2 - ({q})), -({p}/2) - sqrt(({p}/2)**2 - ({q})) ? p=-1 & q=-12'],
+    ['abc->(x1, x2)', 'quadratic_formula({a}, {b}, {c}) ? a=1 & b=5 & c=6'],
+    ['Incline->y', '{m}*{x} + {q} ? m=4 & x=5 & q=6'],
+]
+
+# All the history equations are in this list.
+history = []
+# Where the history file is located.
+historyFilePath = 'history.json'
+print("Reading history from:", historyFilePath)
+# Creating History file if it does not exist.
+try:
+    with open(historyFilePath, 'x') as fp:
+        pass
+    print("Created file at:", historyFilePath)
+except:
+    print('File already exists')
+
+# converting RGB values to HEX
+def rgb_to_hex(rgb):
+    return "#%02x%02x%02x" % rgb
+
+# Add something to the current calculation
+def addSymbol(event=None, symbol=None):
+
+    if symbol == '<':
+        entryVariable.set(entryVariable.get()[:-1])
+    else:
+        entryVariable.set(entryVariable.get()+symbol)
+
+def varChange(*args):
+    evaluationString = entryVariable.get().replace(' ', '').split('?')[0]
+
+    print('Before insertion: ',evaluationString)
+
+    if len(entryVariable.get().split('?')) == 2:
+
+        parameters = entryVariable.get().replace(' ', '').split('?')[1]
+
+        for param in parameters.split('&'):
+            where, what = param.split('=')
+            evaluationString = re.sub('{'+where+'}', what, evaluationString)
+
+    try:
+        print('After insertion: ', evaluationString)
+        resultLabel.config(text=str(eval(evaluationString)))
+    except:
+        resultLabel.config(text='Invalid Input')
+
+def saveCurrentInputToHistory(event=None):
+    if entryVariable.get() in history:
+        return
+
+    history.append(entryVariable.get())
+
+    with open(historyFilePath, 'w') as file:
+        file.write(json.dumps(history))
+
+    updateListBox()
+
+def updateListBox(event=None):
+    global history
+
+    historyList.delete(0, END)
+
+    try:
+        with open(historyFilePath, 'r') as file:
+            history = json.loads(file.read())
+    except json.decoder.JSONDecodeError:
+        print('File does not contain JSON')
+
+    for index, item in enumerate(history):
+        historyList.insert(index, item)
+
+def setEntryFromHistory(event=None):
+    historyItem = historyList.get(historyList.curselection()[0])
+    entryVariable.set(historyItem)
+
+def addFormula(formula=''):
+    saveCurrentInputToHistory()
+    entryVariable.set(formula)
+
+def quadratic_formula(a, b, c):
+
+    disc = b**2 - 4 * a * c
+
+    x1 = (-b - math.sqrt(disc)) / (2 * a)
+    x2 = (-b + math.sqrt(disc)) / (2 * a)
+
+    return(x1, x2)
+
+# Work with Frames to split the window in two parts: the calculator and the History Panel.
+
+# Calculation Panel
+calcSide = Frame(root)
+calcSide.pack(side=LEFT, fill=BOTH, expand=1)
+
+# Entry Variable for the calculations
+entryVariable = StringVar(root, '4/2**2')
+entryVariable.trace('w', varChange)
+
+Entry(calcSide, textvariable=entryVariable, font=myFont, borderwidth=0).pack(fill=X, ipady=10, ipadx=10)
+resultLabel = Label(calcSide, text='Result', font=myFont, borderwidth=0,anchor="e")
+resultLabel.pack(fill=X, ipady=10)
+
+# History Panel
+historySide = Frame(root, bg=rgb_to_hex(historyPanelBackground))
+historySide.pack(side=LEFT, fill=BOTH, expand=1)
+
+historyTopBar = Frame(historySide)
+historyTopBar.pack(fill=X)
+Label(historyTopBar, text='History').pack(side=LEFT)
+Button(historyTopBar, text='Save Current Input', bg=rgb_to_hex(buttonColor), borderwidth=0, command=saveCurrentInputToHistory).pack(side=RIGHT)
+
+historyList = Listbox(historySide, borderwidth=0)
+historyList.pack(fill=BOTH, expand=True)
+historyList.bind("<Double-Button-1>", setEntryFromHistory)
+
+# Insert stuff into the history
+updateListBox()
+
+# Button Symbols (and their position)
+symbols = [
+    ['1', '2', '3', '+'],
+    ['4', '5', '6', '-'],
+    ['7', '8', '9', '/'],
+    ['0', '.', '<', '*'],
+]
+
+for rowList in symbols:
+    # Make a row
+    row = Frame(calcSide)
+    row.pack(fill=BOTH, expand=True)
+    for symbol in rowList:
+        # Making and packing the Button
+        Button(
+            row, text=symbol, command=partial(addSymbol, symbol=symbol),
+            font=myFont, bg=rgb_to_hex(buttonColor), borderwidth=0) \
+        .pack(side=LEFT, fill=BOTH, expand=1)
+        # Change button color each iteration for gradient.
+        buttonColor = (buttonColor[0] - 10, buttonColor[1] - 10, buttonColor[1] - 2)
+
+
+menubar = Menu(root)
+
+filemenu = Menu(menubar, tearoff=0)
+
+# Add all Formulas to the dropdown menu.
+for formula in formulas:
+    filemenu.add_command(label=formula[0], command=partial(addFormula, formula[1]))
+
+filemenu.add_separator()
+
+# Quit command
+filemenu.add_command(label="Exit", command=root.quit)
+
+menubar.add_cascade(menu=filemenu, label='Formulas')
+
+root.config(menu=menubar)
+
+
+# Call the var change once so it is evaluated withhout actual change.
+varChange('foo')
+
+root.mainloop()

gui-programming/calculator-app/history.json

@@ -0,0 +1 @@
+["4/2**2", "4/2**3", "{a} ? a = 6", "", "-({p}/2) + sqrt( ({p}/2) - {q}) ? p=10 & q=5", "0", "({a}**2)+({b}**2) ? a=5 & b=5", "2+3/2*2-4", "(({a}**2)+({b}**2))**0.5 ? a=1 & b=7", "quadratic_formula({a}, {b}, {c}) ? a=1 & b=5 & c=6", "2-1/8*55", " {a} + 1 ? a=14"]