关于python：如何在pyqtgraph中绘制十字准线并绘制鼠标位置？

How to draw crosshair and plot mouse position in pyqtgraph?

我是Python和pyqtgraph的新手。我正在为各种信号的查看器工作。目前，当我想在鼠标位置添加十字准线和文本标签时，我陷入了困境。我正在使用GridLayout，因为以后图形将与其他几个元素组合在一起。

我试图改写pyqtgraph示例十字线/鼠标交互，但是除了pyqtgraph中的许多其他事情之外，我不了解在mousemoved()之前vb = signalgraph.vb的含义，并且脚本引发了NameError

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

#QtGui.QApplication.setGraphicsSystem('raster')
app = QtGui.QApplication([])
mainwindow = QtGui.QMainWindow()
mainwindow.setWindowTitle('pyqtgraph example: PlotWidget')
mainwindow.resize(1000,800)
cw = QtGui.QWidget()
mainwindow.setCentralWidget(cw)

gridlayout = QtGui.QGridLayout()
cw.setLayout(gridlayout)

# define plot windows
signalgraph = pg.PlotWidget(name='Signalgraph')

# set position and size of plot windows
gridlayout.addWidget(signalgraph,0,0)

mainwindow.show()

# sample data
x = [0,1,2,3,4,5,6,7,8,9,10]
y = [0,0,0,8,8,8,9,9,9,0,0]

# plot 1
curve = pg.PlotCurveItem(x,y[:-1],pen='w',stepMode=True)
signalgraph.addItem(curve)

#cross hair in signalgraph
vLine = pg.InfiniteLine(angle=90, movable=False)
hLine = pg.InfiniteLine(angle=0, movable=False)
signalgraph.addItem(vLine, ignoreBounds=True)
signalgraph.addItem(hLine, ignoreBounds=True)

# Here I am not sure what to do ...
vb = signalgraph.vb
##vb = pg.ViewBox()

def mouseMoved(evt):
pos = evt[0]
if signalgraph.sceneBoundingRect().contains(pos):
mousePoint = vb.mapSceneToView(pos)
index = int(mousePoint.x())
if index > 0 and index < len(x):
label.setText("<span style='font-size: 12pt'>x=%0.1f, <span style='color: red'>y1=%0.1f</span>" % (mousePoint.x(), y[index], data2[index]))
vLine.setPos(mousePoint.x())
hLine.setPos(mousePoint.y())

proxy = pg.SignalProxy(signalgraph.scene().sigMouseMoved, rateLimit=60, slot=mouseMoved)
signalgraph.scene().sigMouseMoved.connect(mouseMoved)

# Start Qt event loop unless running in interactive mode or using pyside.
if __name__ == '__main__':
import sys
if (sys.flags.interactive != 1) or not hasattr(QtCore, 'PYQT_VERSION'):
QtGui.QApplication.instance().exec_()

非常感谢
问候
迈克尔

" vb"是PlotItem类的属性。由于signalgraph是PlotWidget，因此您可能不希望它具有相同的属性(尽管它确实包装了其内部PlotItem中的某些方法)。因此，您需要的代码是：

1	vb = signalgraph.plotItem.vb

如果您对PlotWidget和PlotItem之间的区别感到困惑，请继续阅读QGraphicsView和QGraphicsItem类(均在Qt文档中)。 PlotWidget只是一个QGraphicsView，内部显示了一个PlotItem。