import tkinter as tk

#定义空函数，在没有赋值的时候输出为text
def create_button(text, col, row, cs, rs, print='', px=(1, 1), py=(1, 1)):  #创建函数生成按钮
    if print == '':
        t = text
    else:
        t = print
    a = tk.Button(window, text=text , width=4, command=lambda:(text_print(t)))    #输入内容
    a.grid(column=col, row=row, columnspan=cs, rowspan=rs, padx=px, pady=py, sticky='nswe')
    return (a)

#定义函数自动填充行和列
def grid_rowconfigure(*rows):        #函数填充行。 *rows:允许接收多个参数
    for i in rows:
        window.grid_rowconfigure(i, weight=1)

def grid_columnconfigure(*cols):        #函数填充列。 *cols:允许接收多个参数
    for i in cols:
        window.grid_columnconfigure(i, weight=1)

#绑定键盘事件
def bind_print(event):                              #函数键盘事件输入算式
    global textchange, equal_is
    if event.keysym != 'Return':
        if event.keysym == 'BackSpace':             #如果按键名为backspace，那就退格
            a = str(textchange)[0:-1]
            textchange = a
        elif event.keysym == 'Delete':              #清空
            textchange = ''
        else:
            textchange = str(textchange) + str(event.char)  #输入按键内容，char不会获得Ctrl，Shift等特殊按键的文本
        printf.configure(text=textchange)           #显示内容
        show_is()                                   #判断是否错误
        equal_is = False
    else:
        text_equal()

#定义输入和计算函数
def text_print(x):          #函数按钮输入算式
    global textchange,equal_is
    if x != '=':
        if x == '←':
            a = str(textchange)[0:-1]
            textchange = a              #退格
        elif x == 'C':
            textchange = ''             #清空
        else:
            textchange = str(textchange) + str(x)   #输入
        printf.configure(text=textchange)
        show_is()
        equal_is=False                  #判断格式有无错误
    if x == '=':
        text_equal()                    #计算结果

#计算结果
def text_equal(event=None):                         #函数计算结果并显示在输入框
    global textchange, equal_is                     #声明全局变量
    if displayf['text'] != '错误' and equal_is == False:
        textchange = displayf['text']               #无格式错误时，计算结果
        printf.configure(text=textchange)           #输入框显示结果
        displayf.configure(text='')                 #清空显示框
        equal_is = True

def show_is():                          #显示框内容
    global textchange                   #声明全局变量
    if textchange != '':
        try:
            textshow = eval(textchange)
        except(SyntaxError, TypeError, NameError):
            displayf.configure(text='错误')           #出错显示
        else:
            displayf.configure(text=textshow)       #没出错显示结果
    else:
        displayf.configure(text='')                 #输入框为空就清空显示框

#创建窗体
window = tk.Tk()
window.geometry('250x350')
window.title('简易计算器')
#绑定键盘事件
window.bind('<Key>', bind_print)                    #当键盘按下任意键，执行bind_print

equal_is = False
txtchange=''        #设置输入框的内容

#生成输入框
printf=tk.Label(window, text='', bg='white', fg='black', font=('宋体',24), anchor='w', relief='flat')
printf.grid(column=0, row=0, columnspan=5, rowspan=1, sticky='we')
#生成显示框
displayf=tk.Label(window, bg='white', fg='grey', height=1, font=('宋体',22), anchor='w', relief='flat')
displayf.grid(column=0, row=1, columnspan=5, rowspan=1, sticky='we')

#生成按钮
button = {}
button['1'] = create_button('1', 0, 4, 1, 1)
button['2'] = create_button('2', 1, 4, 1, 1)
button['3'] = create_button('3', 2, 4, 1, 1)
button['4'] = create_button('4', 0, 3, 1, 1)
button['5'] = create_button('5', 1, 3, 1, 1)
button['6'] = create_button('6', 2, 3, 1, 1)
button['7'] = create_button('7', 0, 2, 1, 1)
button['8'] = create_button('8', 1, 2, 1, 1)
button['9'] = create_button('9', 2, 2, 1, 1)
button['0'] = create_button('0', 0, 5, 1, 1)

button['.'] = create_button('.', 1, 5, 1, 1)
button['='] = create_button('=', 4, 5, 1, 1)
button['+'] = create_button('+', 3, 3, 1, 1)
button['-'] = create_button('-', 3, 4, 1, 1)
button['*'] = create_button('×', 3, 5, 1, 1, print='*')
button['/'] = create_button('÷', 4, 4, 1, 1, print='/')
button['←'] = create_button('←', 4, 3, 1, 1)

button['C'] = create_button('C', 2, 5, 1, 1)
button['('] = create_button('(', 3, 2, 1, 1)
button[')'] = create_button(')', 4, 2, 1, 1)

grid_rowconfigure(2, 3, 4, 5)
grid_columnconfigure(0, 1, 2, 3, 4)

#进行事件循环
window.mainloop()