# Really simple demo

    import numpy as np

    from qtpy.QtCore import Qt
    import qwt

    class SimplePlot(qwt.QwtPlot):
        def __init__(self):
            qwt.QwtPlot.__init__(self)
            self.setTitle("Really simple demo")
            self.insertLegend(qwt.QwtLegend(), qwt.QwtPlot.RightLegend)
            self.setAxisTitle(qwt.QwtPlot.xBottom, "X-axis")
            self.setAxisTitle(qwt.QwtPlot.yLeft, "Y-axis")
            self.enableAxis(self.xBottom)
            self.setCanvasBackground(Qt.white)

            qwt.QwtPlotGrid.make(self, color=Qt.lightGray, width=0, style=Qt.DotLine)

            # insert a few curves
            x = np.arange(0.0, 10.0, 0.1)
            qwt.QwtPlotCurve.make(x, np.sin(x), "y = sin(x)", self, linecolor="red")
            qwt.QwtPlotCurve.make(x, np.cos(x), "y = cos(x)", self, linecolor="blue")

            # insert a horizontal marker at y = 0
            qwt.QwtPlotMarker.make(
                label="y = 0",
                align=Qt.AlignRight | Qt.AlignTop,
                linestyle=qwt.QwtPlotMarker.HLine,
                color="darkGreen",
                plot=self,
            )

            # insert a vertical marker at x = 2 pi
            qwt.QwtPlotMarker.make(
                xvalue=2 * np.pi,
                label="x = 2 pi",
                align=Qt.AlignRight | Qt.AlignTop,
                linestyle=qwt.QwtPlotMarker.VLine,
                color="darkGreen",
                plot=self,
            )

    if __name__ == "__main__":
        from qwt import tests

        tests.test_widget(SimplePlot, size=(600, 400))