import wx
from math import *

class CalcFrame(wx.Frame):

    def __init__(self, title):
        super(CalcFrame, self).__init__(None, title=title, size=(300, 250))

        self.InitUI()
        self.Centre()
        self.Show()

    def InitUI(self):
        # 定义一个BoxSizer来放置TextCtrl文本框
        vbox = wx.BoxSizer(wx.VERTICAL)
        self.textprint = wx.TextCtrl(self, -1, '', style = wx.TE_RIGHT|wx.TE_READONLY)  # 不能让键盘输入, 只能点击按钮进行输入
        self.equation = ''
        vbox.Add(self.textprint, flag = wx.EXPAND|wx.TOP|wx.BOTTOM, border = 4)

        # 在放置一个 GridSizer 来防止按钮
        gridBox = wx.GridSizer(5, 4, 5, 5)
        labels = ['AC', 'DEL', 'pi', 'CLOSE', '7', '8', '9', '/', '4', '5', '6', '*', '1', '2', '3', '-', '0', '.', '=', '+']
        for label in labels:
            buttonItem = wx.Button(self, label = label)
            self.createHandler(buttonItem, label)   # 点击不同的按钮, 选择不同的回调
            gridBox.Add(buttonItem, 1, wx.EXPAND)

        vbox.Add(gridBox, proportion = 1, flag = wx.EXPAND)
        self.SetSizer(vbox)

    # 创建按钮处理方法
    def createHandler(self, button, labels):
        item = "DEL AC = CLOSE"
        if labels not in item:
            self.Bind(wx.EVT_BUTTON, self.OnAppend, button)
        elif labels == 'DEL':
            self.Bind(wx.EVT_BUTTON, self.OnDel, button)
        elif labels == 'AC':
            self.Bind(wx.EVT_BUTTON, self.OnAc, button)
        elif labels == '=':
            self.Bind(wx.EVT_BUTTON, self.OnTarget, button)
        elif labels == 'CLOSE':
            self.Bind(wx.EVT_BUTTON, self.OnExit, button)

    # 添加运算符和数字
    def OnAppend(self, event):
        eventbutton = event.GetEventObject()
        label = eventbutton.GetLabel()
        self.equation += label
        self.textprint.SetValue(self.equation)
    def OnDel(self, event):
        self.equation = self.equation[:-1]
        self.textprint.SetValue(self.equation)
    def OnAc(self, event):
        self.textprint.Clear()
        self.equation=""
    def OnTarget(self, event):
        string = self.equation
        try:
            target = eval(string)
            self.equation = str(target)
            self.textprint.SetValue(self.equation)
        except SyntaxError:
            dlg = wx.MessageDialog(self, u'格式错误, 请输入正确的等式!', u'请注意', wx.OK|wx.ICON_INFORMATION)
            dlg.ShowModal()
            dlg.Destroy()
    def OnExit(self, event):
        self.Close()


if __name__ == "__main__":
    app = wx.App()
    CalcFrame(title = '无敌计算器')
    app.MainLoop()