title: How to add point to QChart when using QDateTimeAxis x-axis
body: <p>I modify code from <a href="https://stackoverflow.com/questions/57079698/qdatetimeaxis-series-are-not-displayed">here</a></p>
  
  <ol>
  <li><p>I try to use <code>datetime.timestamp()</code> as x-point , but it doesn't work.</p></li>
  <li><p>My totally hour is 5 hours and tickcount is 10, I expect every half hour to cut the time , but it is not.</p></li>
  <li><p>how to add candlestick at specific time(maybe 8:45) to this qchart ?</p></li>
  </ol>
  
  <pre><code>import random, datetime
  from PySide2 import QtCore, QtGui, QtWidgets
  from PySide2.QtCharts import QtCharts
  from PySide2.QtCore import QPointF, Qt
  class MainWindow(QtWidgets.QMainWindow):
      def __init__(self):
          super(MainWindow, self).__init__()
          self.plot = QtCharts.QChart()
          self.chart_view = QtCharts.QChartView(self.plot)
          self.setCentralWidget(self.chart_view)
  
          self.series = QtCharts.QLineSeries()
          self.candle_series = QtCharts.QCandlestickSeries()
          self.series.setName("Magnitude")
          self.plot.addSeries(self.series)
          self.plot.addSeries(self.candle_series)
          # self.plot.createDefaultAxes()
          # self.plot.legend().hide()
          self.candle_series.setDecreasingColor(Qt.green)
          self.candle_series.setIncreasingColor(Qt.red)
  
          # Setting X-axis
          self.axis_x = QtCharts.QDateTimeAxis()
          self.axis_x.setTickCount(11)
          self.axis_x.setLabelsAngle(70)
          self.axis_x.setFormat("h:mm")
          self.axis_x.setTitleText("Date")
          self.axis_x.setMax(datetime.datetime.strptime('202005071345','%Y%m%d%H%M'))
          self.axis_x.setMin(datetime.datetime.strptime('202005070845','%Y%m%d%H%M'))
          # Setting Y-axis
          self.axis_y = QtCharts.QValueAxis()
          self.axis_y.setTickCount(7)
          self.axis_y.setLabelFormat("%i")
          self.axis_y.setTitleText("Temperature [celcious]")
          self.axis_y.setMax(60)
          self.axis_y.setMin(10)
          self.plot.setAxisX(self.axis_x, self.series)
          self.plot.setAxisY(self.axis_y, self.series)
          self.plot.setAxisX(self.axis_x,self.candle_series)
          self.plot.setAxisY(self.axis_y,self.candle_series)      
          self.candle_series.append(QtCharts.QCandlestickSet(30,50,20,25))
  
          self.series.append(float(QtCore.QDateTime.fromString("202005070849", "yyyyMMddhhmm").toMSecsSinceEpoch()),22,)
          self.series.append(float(QtCore.QDateTime.fromString("202005070950", "yyyyMMddhhmm").toMSecsSinceEpoch()),20,)
          self.series.append(float(QtCore.QDateTime.fromString("202005071051", "yyyyMMddhhmm").toMSecsSinceEpoch()),58,)
  
  if __name__ == "__main__":
      import sys
  
      app = QtWidgets.QApplication(sys.argv)
      window = MainWindow()
      window.resize(640, 480)
      window.show()
      sys.exit(app.exec_())
  </code></pre>
  
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