Calculator

This basic calculator UI demonstrates how to use different colors to differentiate button functions.

Style Summary

The theme used in this example is flatly.

Item	Class	Bootstyle
Digits	Button	primary
Operators	Button	secondary
Equals	Button	success

Example Code

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import ttkbootstrap as ttk
from ttkbootstrap.constants import *


class Calculator(ttk.Frame):
    def __init__(self, master, **kwargs):
        super().__init__(master, padding=10, **kwargs)
        ttk.Style().configure("TButton", font="TkFixedFont 12")
        self.pack(fill=BOTH, expand=YES)
        self.digitsvar = ttk.StringVar(value=0)
        self.xnum = ttk.DoubleVar()
        self.ynum = ttk.DoubleVar()
        self.operator = ttk.StringVar(value="+")

        if "bootstyle" in kwargs:
            self.bootstyle = kwargs.pop("bootstyle")
        else:
            self.bootstyle = None
        self.create_num_display()
        self.create_num_pad()

    def create_num_display(self):
        container = ttk.Frame(master=self, padding=2, bootstyle=self.bootstyle)
        container.pack(fill=X, pady=20)
        digits = ttk.Label(
            master=container,
            font="TkFixedFont 14",
            textvariable=self.digitsvar,
            anchor=E,
        )
        digits.pack(fill=X)

    def create_num_pad(self):
        container = ttk.Frame(master=self, padding=2, bootstyle=self.bootstyle)
        container.pack(fill=BOTH, expand=YES)
        matrix = [
            ("%", "C", "CE", "/"),
            (7, 8, 9, "*"),
            (4, 5, 6, "-"),
            (1, 2, 3, "+"),
            ("±", 0, ".", "="),
        ]
        for i, row in enumerate(matrix):
            container.rowconfigure(i, weight=1)
            for j, num_txt in enumerate(row):
                container.columnconfigure(j, weight=1)
                btn = self.create_button(master=container, text=num_txt)
                btn.grid(row=i, column=j, sticky=NSEW, padx=1, pady=1)

    def create_button(self, master, text):
        if text == "=":
            bootstyle = SUCCESS
        elif not isinstance(text, int):
            bootstyle = SECONDARY
        else:
            bootstyle = PRIMARY
        return ttk.Button(
            master=master,
            text=text,
            command=lambda x=text: self.on_button_pressed(x),
            bootstyle=bootstyle,
            width=2,
            padding=10,
        )

    def reset_variables(self):
        self.xnum.set(value=0)
        self.ynum.set(value=0)
        self.operator.set("+")

    def on_button_pressed(self, txt):
        """Handles and routes all button press events."""
        display = self.digitsvar.get()

        # remove operator from screen after button is pressed
        if len(display) > 0:
            if display[0] in ["/", "*", "-", "+"]:
                display = display[1:]

        if txt in ["CE", "C"]:
            self.digitsvar.set("")
            self.reset_variables()
        elif isinstance(txt, int):
            self.press_number(display, txt)
        elif txt == "." and "." not in display:
            self.digitsvar.set(f"{display}{txt}")
        elif txt == "±":
            self.press_inverse(display)
        elif txt in ["/", "*", "-", "+"]:
            self.press_operator(txt)
        elif txt == "=":
            self.press_equals(display)

    def press_number(self, display, txt):
        """A digit button is pressed"""
        if display == "0":
            self.digitsvar.set(txt)
        else:
            self.digitsvar.set(f"{display}{txt}")

    def press_inverse(self, display):
        """The inverse number button is pressed"""
        if display.startswith("-"):
            if len(display) > 1:
                self.digitsvar.set(display[1:])
            else:
                self.digitsvar.set("")
        else:
            self.digitsvar.set(f"-{display}")

    def press_operator(self, txt):
        """An operator button is pressed"""
        self.operator.set(txt)
        display = float(self.digitsvar.get())
        if self.xnum.get() != 0:
            self.ynum.set(display)
        else:
            self.xnum.set(display)
        self.digitsvar.set(txt)

    def press_equals(self, display):
        """The equals button is pressed."""
        if self.xnum.get() != 0:
            self.ynum.set(display)
        else:
            self.xnum.set(display)
        x = self.xnum.get()
        y = self.ynum.get()
        op = self.operator.get()
        if all([x, y, op]):
            result = eval(f"{x}{op}{y}")
            self.digitsvar.set(result)
            self.reset_variables()


if __name__ == "__main__":

    app = ttk.Window(
        title="Calculator",
        themename="flatly",
        size=(350, 450),
        resizable=(False, False),
    )
    Calculator(app)
    app.mainloop()