python-gui-calculator/calculator.py at main · 1khaled-ctrl/python-gui-calculator · GitHub

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import tkinter as tk
from tkinter import ttk

class Calculator(tk.Tk):
    def __init__(self):
        super().__init__()
        self.title("Calculator")
        self.resizable(False, False)

        self.expr = ""
        self.result_var = tk.StringVar(value="0")

        self._build_ui()
        self._bind_keys()

    def _build_ui(self):
        # Display
        display = ttk.Entry(
            self,
            textvariable=self.result_var,
            font=("Segoe UI", 18),
            justify="right",
            state="readonly",
            width=18
        )
        display.grid(row=0, column=0, columnspan=4, padx=10, pady=(10, 6), ipady=10)

        # Buttons layout
        buttons = [
            ("C", 1, 0), ("⌫", 1, 1), ("(", 1, 2), (")", 1, 3),
            ("7", 2, 0), ("8", 2, 1), ("9", 2, 2), ("/", 2, 3),
            ("4", 3, 0), ("5", 3, 1), ("6", 3, 2), ("*", 3, 3),
            ("1", 4, 0), ("2", 4, 1), ("3", 4, 2), ("-", 4, 3),
            ("0", 5, 0), (".", 5, 1), ("=", 5, 2), ("+", 5, 3),
        ]

        # Style
        style = ttk.Style(self)
        style.configure("Calc.TButton", font=("Segoe UI", 14), padding=10)

        for (text, r, c) in buttons:
            btn = ttk.Button(self, text=text, style="Calc.TButton",
                             command=lambda t=text: self.on_press(t))
            btn.grid(row=r, column=c, padx=6, pady=6, sticky="nsew")

        # Make grid cells consistent size
        for i in range(4):
            self.grid_columnconfigure(i, minsize=70)
        for i in range(1, 6):
            self.grid_rowconfigure(i, minsize=60)

        # Small hint label
        hint = ttk.Label(self, text="Keyboard: Enter/=, Esc=C, Backspace=⌫", font=("Segoe UI", 9))
        hint.grid(row=6, column=0, columnspan=4, pady=(0, 10))

    def _bind_keys(self):
        self.bind("<Return>", lambda e: self.on_press("="))
        self.bind("<KP_Enter>", lambda e: self.on_press("="))
        self.bind("<Escape>", lambda e: self.on_press("C"))
        self.bind("<BackSpace>", lambda e: self.on_press("⌫"))

        allowed = "0123456789.+-*/()"
        for ch in allowed:
            self.bind(ch, lambda e, c=ch: self.on_press(c))

    def on_press(self, key):
        if key == "C":
            self.expr = ""
            self.result_var.set("0")
            return

        if key == "⌫":
            self.expr = self.expr[:-1]
            self.result_var.set(self.expr if self.expr else "0")
            return

        if key == "=":
            self._evaluate()
            return

        # Prevent starting with multiple operators (simple guard)
        if key in "+*/" and (not self.expr or self.expr[-1] in "+-*/.("):
            return

        # Append character
        self.expr += key
        self.result_var.set(self.expr)

    def _evaluate(self):
        if not self.expr.strip():
            self.result_var.set("0")
            return

        try:
            # Safer eval: allow only numbers and operators
            safe = "".join(ch for ch in self.expr if ch in "0123456789.+-*/() ")
            if safe != self.expr:
                raise ValueError("Invalid characters")

            # Evaluate
            value = eval(safe, {"__builtins__": {}})
            # Clean display (avoid 5.0 if it's an int)
            if isinstance(value, float) and value.is_integer():
                value = int(value)
            self.expr = str(value)
            self.result_var.set(self.expr)
        except Exception:
            self.expr = ""
            self.result_var.set("Error")

if __name__ == "__main__":
    app = Calculator()
    app.mainloop()