问题
I want to add a vertical line following the mouse_x position (working) and a horizontal line following the curve (and not mouse_y). In the pyqtgraph crosshair example, it shows how to add a crosshair following the mouse_x and mouse_y position. But that does not help that much. The following code sets the vertical line position to mouse_x postion. But i dont know how to set the horizontal line's postion to the curves current y position (depending on where the mouse x position is).
data1 = 10000 + 15000 * pg.gaussianFilter(np.random.random(size=10000), 10) + 3000 * np.random.random(size=10000)
def mouseMoved(evt):
pos = evt[0]
if p1.sceneBoundingRect().contains(pos):
mousePoint = vb.mapSceneToView(pos)
index = int(mousePoint.x())
if index > 0 and index < len(data1):
label.setText("<span style='font-size: 12pt'>x=%0.1f, <span style='color: red'>y1=%0.1f</span>, <span style='color: green'>y2=%0.1f</span>" % (mousePoint.x(), data1[index], data2[index]))
vLine.setPos(mousePoint.x()) # here i set the vertical line's position to mouse_x position
#hLinePos = vb.mapToView( vLine.pos() )
hLine.setPos(data1[mousePoint.x()]) # <-- how do i set this horizontal line so it is kind of snaped to the curve
回答1:
Maybe this crosshair widget can point you in the right direction
from PyQt4 import QtCore, QtGui
import sys
import numpy as np
import pyqtgraph as pg
import random
"""Crosshair Plot Widget Example"""
class CrosshairPlotWidget(QtGui.QWidget):
"""Scrolling plot with crosshair"""
def __init__(self, parent=None):
super(CrosshairPlotWidget, self).__init__(parent)
# Use for time.sleep (s)
self.FREQUENCY = .025
# Use for timer.timer (ms)
self.TIMER_FREQUENCY = self.FREQUENCY * 1000
self.LEFT_X = -10
self.RIGHT_X = 0
self.x_axis = np.arange(self.LEFT_X, self.RIGHT_X, self.FREQUENCY)
self.buffer = int((abs(self.LEFT_X) + abs(self.RIGHT_X))/self.FREQUENCY)
self.data = []
self.crosshair_plot_widget = pg.PlotWidget()
self.crosshair_plot_widget.setXRange(self.LEFT_X, self.RIGHT_X)
self.crosshair_plot_widget.setLabel('left', 'Value')
self.crosshair_plot_widget.setLabel('bottom', 'Time (s)')
self.crosshair_color = (196,220,255)
self.crosshair_plot = self.crosshair_plot_widget.plot()
self.layout = QtGui.QGridLayout()
self.layout.addWidget(self.crosshair_plot_widget)
self.crosshair_plot_widget.plotItem.setAutoVisible(y=True)
self.vertical_line = pg.InfiniteLine(angle=90)
self.horizontal_line = pg.InfiniteLine(angle=0, movable=False)
self.vertical_line.setPen(self.crosshair_color)
self.horizontal_line.setPen(self.crosshair_color)
self.crosshair_plot_widget.setAutoVisible(y=True)
self.crosshair_plot_widget.addItem(self.vertical_line, ignoreBounds=True)
self.crosshair_plot_widget.addItem(self.horizontal_line, ignoreBounds=True)
self.crosshair_update = pg.SignalProxy(self.crosshair_plot_widget.scene().sigMouseMoved, rateLimit=60, slot=self.update_crosshair)
self.start()
def plot_updater(self):
"""Updates data buffer with data value"""
self.data_point = random.randint(1,101)
if len(self.data) >= self.buffer:
del self.data[:1]
self.data.append(float(self.data_point))
self.crosshair_plot.setData(self.x_axis[len(self.x_axis) - len(self.data):], self.data)
def update_crosshair(self, event):
"""Paint crosshair on mouse"""
coordinates = event[0]
if self.crosshair_plot_widget.sceneBoundingRect().contains(coordinates):
mouse_point = self.crosshair_plot_widget.plotItem.vb.mapSceneToView(coordinates)
index = mouse_point.x()
if index > self.LEFT_X and index <= self.RIGHT_X:
self.crosshair_plot_widget.setTitle("<span style='font-size: 12pt'>x=%0.1f, <span style='color: red'>y=%0.1f</span>" % (mouse_point.x(), mouse_point.y()))
self.vertical_line.setPos(mouse_point.x())
self.horizontal_line.setPos(mouse_point.y())
def start(self):
self.timer = QtCore.QTimer()
self.timer.timeout.connect(self.plot_updater)
self.timer.start(self.get_timer_frequency())
def get_crosshair_plot_layout(self):
return self.layout
def get_timer_frequency(self):
return self.TIMER_FREQUENCY
if __name__ == '__main__':
# Create main application window
app = QtGui.QApplication([])
app.setStyle(QtGui.QStyleFactory.create("Cleanlooks"))
mw = QtGui.QMainWindow()
mw.setWindowTitle('Crosshair Plot Example')
# Create and set widget layout
# Main widget container
cw = QtGui.QWidget()
ml = QtGui.QGridLayout()
cw.setLayout(ml)
mw.setCentralWidget(cw)
# Create crosshair plot
crosshair_plot = CrosshairPlotWidget()
ml.addLayout(crosshair_plot.get_crosshair_plot_layout(),0,0)
mw.show()
## Start Qt event loop unless running in interactive mode or using pyside.
if (sys.flags.interactive != 1) or not hasattr(QtCore, 'PYQT_VERSION'):
QtGui.QApplication.instance().exec_()
来源：https://stackoverflow.com/questions/57359843/pyqtgraph-add-crosshair-on-mouse-x-graph-y