Class myApp

projects/Calculator-GUI-With-Python/app.py:8–63

class myApp(App):
    def build(self):
        root_widget = BoxLayout(orientation="vertical")
        output_label = Label(size_hint_y=0.75, font_size=50)
        button_symbols = (
            "1",
            "2",
            "3",
            "+",
            "4",
            "5",
            "6",
            "-",
            "7",
            "8",
            "9",
            ".",
            "0",
            "*",
            "/",
            "=",
        )
        button_grid = GridLayout(cols=4, size_hint_y=2)
        for symbol in button_symbols:
            button_grid.add_widget(Button(text=symbol))

        clear_button = Button(text="Clear", size_hint_y=None, height=100)

        def print_button_text(instance):
            output_label.text += instance.text

        for button in button_grid.children[1:]:
            button.bind(on_press=print_button_text)

        def resize_label_text(label, new_height):
            label.fontsize = 0.5 * label.height

        output_label.bind(height=resize_label_text)

        def evaluate_result(instance):
            try:
                output_label.text = str(eval(output_label.text))
            except SyntaxError:
                output_label.text = "Python Syntax error!"

        button_grid.children[0].bind(on_press=evaluate_result)

        def clear_label(instance):
            output_label.text = " "

        clear_button.bind(on_press=clear_label)

        root_widget.add_widget(output_label)
        root_widget.add_widget(button_grid)
        root_widget.add_widget(clear_button)
        return root_widget