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

Question

这个官网上的例子自己运行的时候，没什么问题，会按照设置的间隔刷新，可是把这个例子嵌入到PyQt5里以后，大概在ydata list里压了一百个数据才会绘制一次。以下是嵌入后的代码嵌入pyqt5的代码

# 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_())

有人玩过吗？是不是qt的刷新问题啊？还是qt把matplotlib的绘制线程阻塞住了？

Answer 1

额，自己发现了，把75行代码放在if外面。