wxpython设置背景图片

我使用wxpython设计了一个界面，我现在希望为他添加一个背景图片，但不是图片显示不出来，就是图片把按键盖住了。
我在网上找到一段代码如下：

import wx
 
class Frame(wx.Frame):
    def __init__(self):
        wx.Frame.__init__(self,None,-1,"My Frame",size=(400,300),
                          style = wx.DEFAULT_FRAME_STYLE)
        self.panel = wx.Panel(self)
        self.panel.Bind(wx.EVT_ERASE_BACKGROUND,self.OnEraseBack)
    def OnEraseBack(self,event):
        dc = event.GetDC()
        if not dc:
            dc = wx.ClientDC(self)
            rect = self.GetUpdateRegion().GetBox()
            dc.SetClippingRect(rect)
        dc.Clear()
        bmp = wx.Bitmap(r'C:\Users\gztsrayz\PycharmProjects\flask-test\img\爬 - 副本.jfif')
        dc.DrawBitmap(bmp, 0, 0)
if __name__ == '__main__':
    app = wx.App()
    frame = Frame()
    frame.Show()
    app.MainLoop()

这段代码是可以正确运行的，以下是我的代码：

import wx
import random
# from wx import MessageBox
class Frame(wx.Frame):
    def __init__(self):
          # Create a new app, don't redirect stdout/stderr to a window.
        wx.Frame.__init__(self,None,-1,title="酒泉",size=(500,600),style = wx.DEFAULT_FRAME_STYLE)

        self.panel = wx.Panel(self)
        self.panel.Bind(wx.EVT_ERASE_BACKGROUND,self.OnEraseBack)
        
#         image_file = r'C:\Users\gztsrayz\PycharmProjects\flask-test\img\爬 - 副本.jfif'
#         to_bmp_image = wx.Image(image_file, wx.BITMAP_TYPE_ANY).ConvertToBitmap()
        
#         self.bitmap = wx.StaticBitmap(frame, -1, to_bmp_image, (0, 0))
        
        bt1=wx.Button(frame,label='拳头',pos=(100,50),size=(300,100))
        bt2=wx.Button(frame,label='剪刀',pos=(100,200),size=(300,100))
        bt3=wx.Button(frame,label='布',pos=(100,350),size=(300,100))

        bt1.Bind(wx.EVT_BUTTON,self.quantou)
        bt2.Bind(wx.EVT_BUTTON,self.jiandao)
        bt3.Bind(wx.EVT_BUTTON,self.bu)

#         frame.Show()     
#         app.MainLoop()

        
    def OnEraseBack(self,event):
        dc = event.GetDC()
        if not dc:
            dc = wx.ClientDC(self)
            rect = self.GetUpdateRegion().GetBox()
            dc.SetClippingRect(rect)
        dc.Clear()
        bmp = wx.Bitmap(r'C:\Users\gztsrayz\PycharmProjects\flask-test\img\爬 - 副本.jfif')
        dc.DrawBitmap(bmp, 0, 0)

    def quantou(self,event):
        a=random.choice(['拳头','剪刀','布'])
        if a=='拳头':
            wx.MessageBox('平手了，但是'+random.choice(['你的拳头更大','你的拳头被打穿了']))
        elif a=='剪刀':
            wx.MessageBox('you win !')
        else:
            wx.MessageBox('you lose !')
        
    def jiandao(self,event):
        a=random.choice(['拳头','剪刀','布'])
        if a=='拳头':
            wx.MessageBox('you lose !')
        elif a=='剪刀':
            wx.MessageBox('平手了，但是'+random.choice(['你的剪刀更锐利','你的剪刀不得劲']))
        else:
            wx.MessageBox('you win !')
    
    def bu(self,event):
        a=random.choice(['拳头','剪刀','布'])
        if a=='拳头':
            wx.MessageBox('you win !')
        elif a=='剪刀':
            wx.MessageBox('you lose !')
        else:
            wx.MessageBox('平手了，但是'+random.choice(['你的布更大','你被包住了']))

if __name__ == '__main__':
    app = wx.App()
    frame = Frame()
    frame.Show()
    app.MainLoop()

报错：PyNoAppError: The wx.App object must be created first!

当我将按键删除后则没有报错，请问这是什么原因，我应该如何设置背景图片？

改了一下， 你把图片文件改为你的图片即可


import wx
import random

class MyPanel(wx.Panel):
    def __init__(self, parent, id):
        wx.Panel.__init__(self, parent, id)
        try:
            image_file = 'bg.png'
            to_bmp_image = wx.Image(image_file, wx.BITMAP_TYPE_ANY).ConvertToBitmap()
            self.bitmap = wx.StaticBitmap(self, -1, to_bmp_image, (0, 0))
            # image_width = to_bmp_image.GetWidth()
            # image_height = to_bmp_image.GetHeight()
            # set_title = '%s %d x %d' % (image_file, to_bmp_image.GetWidth(), to_bmp_image.GetHeight())
            parent.SetTitle("酒泉")
        except IOError:
            # print('Image file %s not found' % image_file)
            raise SystemExit
        # 创建按钮
        self.bt1 = wx.Button(self.bitmap, label='拳头', pos=(100, 50), size=(300, 100))
        self.bt2 = wx.Button(self.bitmap,label='剪刀', pos=(100, 200), size=(300, 100))
        self.bt3 = wx.Button(self.bitmap,label='布', pos=(100, 350), size=(300, 100))

        self.bt1.Bind(wx.EVT_BUTTON, self.quantou)
        self.bt2.Bind(wx.EVT_BUTTON, self.jiandao)
        self.bt3.Bind(wx.EVT_BUTTON, self.bu)

    def quantou(self, event):
        a = random.choice(['拳头', '剪刀', '布'])
        if a == '拳头':
            wx.MessageBox('平手了，但是' + random.choice(['你的拳头更大', '你的拳头被打穿了']))
        elif a == '剪刀':
            wx.MessageBox('you win !')
        else:
            wx.MessageBox('you lose !')

    def jiandao(self, event):
        a = random.choice(['拳头', '剪刀', '布'])
        if a == '拳头':
            wx.MessageBox('you lose !')
        elif a == '剪刀':
            wx.MessageBox('平手了，但是' + random.choice(['你的剪刀更锐利', '你的剪刀不得劲']))
        else:
            wx.MessageBox('you win !')

    def bu(self, event):
        a = random.choice(['拳头', '剪刀', '布'])
        if a == '拳头':
            wx.MessageBox('you win !')
        elif a == '剪刀':
            wx.MessageBox('you lose !')
        else:
            wx.MessageBox('平手了，但是' + random.choice(['你的布更大', '你被包住了']))


if __name__ == '__main__':
    app = wx.App()
    frame = wx.Frame(None, -1, '游戏', size=(500, 600))
    my_panel = MyPanel(frame, -1)
    frame.Show()
    app.MainLoop()

img