Pyqt5 中QComboBox控件的currentIndexChanged无法正确重写

想重写currentIndexChanged函数，实现在输出选择的内容时同时输出控件在屏幕上的坐标。但尝试了很久还是没实现。请指点下应怎么搞？

from PyQt5.Qt import *
class banrd_combobox(QComboBox):
   # 如何实现对 brand_comboBox控件桌面坐标的输出？
    pass
class Window(QWidget):
    def __init__(self):
        super().__init__()
        self.setWindowTitle('主页面')
        self.resize(500,500)
        self.setup_ui()
    def setup_ui(self):
        self.product_row_frame = QFrame(self)
        self.product_row_frame.setGeometry(QRect(0, 0, 500, 40))
        self.product_row_frame.setStyleSheet("QWidget:hover{"
                                             "background-color:rgb(0, 202, 202);}")
        self.brand_comboBox = banrd_combobox(self.product_row_frame)
        self.brand_comboBox.setGeometry(QRect(0,0,80,40))
        self.brand_comboBox.addItems(['乔丹','周杰伦','刘翔','泰森'])
        self.brand_comboBox.setCurrentIndex(-1)
        self.brand_comboBox.currentIndexChanged[str].connect(self.brand_comboBox_changed)
    def brand_comboBox_changed(self,x,y,name):
        print('brand_comboBox横坐标：',x)
        print('brand_comboBox纵坐标：',y)
        print(name)
if __name__ == '__main__':
    import sys
    app = QApplication(sys.argv)
    window = Window()

    window.show()

    sys.exit(app.exec_())

    def brand_comboBox_changed(self, index):
        print(index)
        print(self.brand_comboBox.geometry())  # 控件相对于主窗口的坐标
        print(self.geometry())  # 主窗口的屏幕坐标

可以利用相对坐标计算出控件的屏幕坐标

    self.brand_comboBox.currentIndexChanged.connect(self.brand_comboBox_changed)

str是个啥，哪冒出来的