pyqtgraph选择图形的2D区域作为阈值来重绘图形

我希望添加功能，以便用户可以在选择的线条上绘制一个矩形，并且图形将刷新，以便矩形内的线条保持各自的颜色，而外部的任何线条都变成灰色？

我的代码如下，当前在线条上缩放用户定义的矩形的绘图（对于 3 行，我的实际代码将绘制更多）：

from pyqtgraph.Qt import QtGui, QtCore
import numpy as np
import pyqtgraph as pg

pg.setConfigOption('background', 'w')
pg.setConfigOption('foreground', 'k')

from random import randint

class CustomViewBox(pg.ViewBox):
    def __init__(self, *args, **kwds):
    pg.ViewBox.__init__(self, *args, **kwds)
    self.setMouseMode(self.RectMode)

    ## reimplement right-click to zoom out
    def mouseClickEvent(self, ev):
    if ev.button() == QtCore.Qt.RightButton:
        #self.autoRange()
        self.setXRange(0,5)
        self.setYRange(0,10)

    def mouseDragEvent(self, ev):
    if ev.button() == QtCore.Qt.RightButton:
        ev.ignore()
    else:
        pg.ViewBox.mouseDragEvent(self, ev)


app = pg.mkQApp()

vb = CustomViewBox()

graph = pg.PlotWidget(viewBox=vb, enableMenu=False)

colour = []

for i in range(0,3):
    colourvalue = [randint(0,255), randint(0,255), randint(0,255)]
    tuple(colourvalue)
    colour.append(colourvalue)

y_data = [ 
     [['a',0],['b',1],['c',None],['d',6],['e',7]],
     [['a',5],['b',2],['c',1],['d',None],['e',1]],
     [['a',3],['b',None],['c',4],['d',9],['e',None]],
     ]

x_data = [0, 1, 2, 3, 4]

for i in range(3):
    xv = []
    yv = []
    for j, v in enumerate(row[i][1] for row in y_data):
    if v is not None:
        xv.append(int(j))
        yv.append(float(v))
    graph.plot(xv, yv, pen = colour[i], name=y_data[0][i][0])

graph.show()
graph.setWindowTitle('Hourly Frequency Graph')
graph.setXRange(0,5)
graph.setYRange(0,10)

graph.setLabel('left', "Frequency", units='%')
graph.setLabel('bottom', "Hour")
graph.showGrid(x=True, y=True)

if __name__ == '__main__':
    import sys
    if (sys.flags.interactive != 1) or not hasattr(QtCore, 'PYQT_VERSION'):
        QtGui.QApplication.instance().exec_()

预先感谢您的任何帮助和建议！

顺便说一句，我还想知道为什么当我关闭窗口时，这段代码总是给出分段错误：11。