Matplotlib嵌入PyQt5里以后重新绘制的时间比单独用Matplotlib长，是为什么？

# coding=utf-8



import numpy as np

import matplotlib

# Make sure that we are using QT5

matplotlib.use('Qt5Agg')

from matplotlib.figure import Figure

from matplotlib.animation import TimedAnimation, FuncAnimation

from matplotlib.lines import Line2D

from PyQt5 import QtGui, QtWidgets, QtCore

import time



from matplotlib.backends.backend_qt5agg import FigureCanvasQTAgg as FigureCanvas

from matplotlib.backends.backend_qt5agg import NavigationToolbar2QT as NavigationToolbar





class CustomFigCanvas(FigureCanvas, FuncAnimation):



    def __init__(self):



        # The data

        self.xdata = []

        self.ydata = []

        self.end = float()

        self.start = float()



        # The window

        self.fig = Figure()

        self.ax = self.fig.add_subplot(111)

        self.line, = self.ax.plot([], [], lw=2)

        self.ax.grid()

        # ax1 settings

        self.ax.set_xlabel('time')

        self.ax.set_ylabel('raw data')



        FigureCanvas.__init__(self, self.fig)

        FuncAnimation.__init__(self, self.fig, self.Update, self.data_gen,  blit=False,

                               interval=40, repeat=False, init_func=self.init)

        FigureCanvas.setSizePolicy(self, QtWidgets.QSizePolicy.Expanding,

                                   QtWidgets.QSizePolicy.Expanding)



    def data_gen(self):



        self.cnt = 0

        self.t = 0

        while self.cnt <1000:

            print(self.cnt)

            self.cnt += 1

            self.t += 0.1

            self.y = np.sin(2 * np.pi * self.t) * np.exp(-self.t / 10.)

            yield self.t, self.y



    def init(self):

        self.ax.set_ylim(-1.1, 1.1)

        self.ax.set_xlim(0, 10)

        del self.xdata[:]

        del self.ydata[:]

        self.line.set_data(self.xdata, self.ydata)

        return self.line,



    def Update(self, data):

        # update the data

        self.end = time.time()

        print(self.end - self.start)

        t, y = data

        self.xdata.append(t)

        self.ydata.append(y)

        xmin, xmax = self.ax.get_xlim()



        if t >= xmax:

            self.ax.set_xlim(xmin, 2 * xmax)

            self.ax.figure.canvas.draw()

            self.line.set_data(self.xdata, self.ydata)

        self.start = time.time()

        print('---------')

        return self.line,





class MplCanvasWrapper(QtWidgets.QDialog):



    def __init__(self, parent=None):

        QtWidgets.QDialog.__init__(self, parent)

        self.canvas = CustomFigCanvas()

        self.vbl = QtWidgets.QVBoxLayout()

        self.ntb = NavigationToolbar(self.canvas, parent)

        self.btnStart = QtWidgets.QPushButton()

        self.btnStart.setText('开始')

        self.btnPause = QtWidgets.QPushButton()

        self.btnPause.setText('结束')



        self.vbl.addWidget(self.ntb)

        self.vbl.addWidget(self.canvas)

        self.vbl.addWidget(self.btnStart)

        self.vbl.addWidget(self.btnPause)



        self.setLayout(self.vbl)



        self.btnStart.clicked.connect(self.startPlot)

        self.btnPause.clicked.connect(self.pausePlot)



        self.dataX = []

        self.dataY = []



    def startPlot(self):

        pass



    def pausePlot(self):

        pass





if __name__ == "__main__":

    import sys

    app = QtWidgets.QApplication(sys.argv)

    test_widget = MplCanvasWrapper()

    test_widget.show()

    sys.exit(app.exec_())