试图在 PyQt5 中的 pyqtgraph plotwidget 中获取坐标显示的光标
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【中文标题】试图在 PyQt5 中的 pyqtgraph plotwidget 中获取坐标显示的光标【英文标题】：Trying to get cursor with coordinate display within a pyqtgraph plotwidget in PyQt5 【发布时间】：2020-11-20 20:41:24 【问题描述】：我正在尝试在 PyQt5 的 pqytplot plotwidget 中添加光标位置的读数。我发现这段代码可以满足我的要求，但在一个独立的窗口中，都在一个程序文件中：
import pyqtgraph as pg
from pyqtgraph.Qt import QtGui, QtCore
#generate layout
app = QtGui.QApplication([])
win = pg.GraphicsWindow()
label = pg.LabelItem(justify='right')
win.addItem(label)
p1 = win.addPlot(row=1, col=0)
data1 = [n**2 for n in range(100)]
p1.plot(data1, pen="r")
#cross hair
vLine = pg.InfiniteLine(angle=90, movable=False)
hLine = pg.InfiniteLine(angle=0, movable=False)
p1.addItem(vLine, ignoreBounds=True)
p1.addItem(hLine, ignoreBounds=True)
def mouseMoved(evt):
pos = evt[0] ## using signal proxy turns original arguments into a tuple
if p1.sceneBoundingRect().contains(pos):
mousePoint = p1.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>" % (mousePoint.x(), data1[index]))
vLine.setPos(mousePoint.x())
hLine.setPos(mousePoint.y())
proxy = pg.SignalProxy(p1.scene().sigMouseMoved, rateLimit=60, slot=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_()
我遇到的问题是弄清楚如何用我的 GUI 实现类似的东西——我必须将 plotwidget 的引用传递给 mouseMoved 函数。在上面的示例中，mousemoved 函数可以访问 hline、vline 和 p1，但在我的代码中它不会——我需要能够通过它们。但我不知道该怎么做。
我尝试用尽可能少的代码来重现这个问题。首先是一个简单的 GUI 用户界面文件，名为 CursorLayout.ui
<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
<class>MainWindow</class>
<widget class="QMainWindow" name="MainWindow">
<property name="geometry">
<rect>
<x>0</x>
<y>0</y>
<width>1167</width>
<height>443</height>
</rect>
</property>
<property name="windowTitle">
<string>MainWindow</string>
</property>
<widget class="QWidget" name="centralwidget">
<layout class="QGridLayout" name="gridLayout_2">
<item row="0" column="0">
<layout class="QVBoxLayout" name="verticalLayout_6">
<item>
<layout class="QHBoxLayout" name="horizontalLayout_16">
<property name="sizeConstraint">
<enum>QLayout::SetFixedSize</enum>
</property>
<item>
<layout class="QVBoxLayout" name="verticalLayout">
<item>
<layout class="QHBoxLayout" name="horizontalLayout_4">
<item>
<widget class="QPushButton" name="startbutton">
<property name="sizePolicy">
<sizepolicy hsizetype="Fixed" vsizetype="Fixed">
<horstretch>0</horstretch>
<verstretch>0</verstretch>
</sizepolicy>
</property>
<property name="text">
<string>Plot</string>
</property>
</widget>
</item>
</layout>
</item>
</layout>
</item>
</layout>
</item>
<item>
<layout class="QVBoxLayout" name="verticalLayout_5">
<item>
<widget class="PlotWidget" name="plotWidget" native="true">
<property name="sizePolicy">
<sizepolicy hsizetype="Expanding" vsizetype="Preferred">
<horstretch>0</horstretch>
<verstretch>0</verstretch>
</sizepolicy>
</property>
<property name="minimumSize">
<size>
<width>0</width>
<height>300</height>
</size>
</property>
</widget>
</item>
<item>
<layout class="QHBoxLayout" name="horizontalLayout_3"/>
</item>
<item>
<layout class="QHBoxLayout" name="horizontalLayout_17">
<property name="spacing">
<number>0</number>
</property>
<item>
<widget class="QPushButton" name="exitbutton">
<property name="sizePolicy">
<sizepolicy hsizetype="Fixed" vsizetype="Fixed">
<horstretch>0</horstretch>
<verstretch>0</verstretch>
</sizepolicy>
</property>
<property name="text">
<string>Exit</string>
</property>
</widget>
</item>
</layout>
</item>
</layout>
</item>
</layout>
</item>
</layout>
</widget>
</widget>
<customwidgets>
<customwidget>
<class>PlotWidget</class>
<extends>QWidget</extends>
<header location="global">pyqtgraph</header>
<container>1</container>
</customwidget>
</customwidgets>
<resources/>
<connections/>
</ui>
主程序是这样的：
from PyQt5 import uic
from PyQt5.QtWidgets import QApplication, QMainWindow
from initGUI import connecttolayout, setinitialview
class UI(QMainWindow):
def __init__(self):
super(UI, self).__init__()
uic.loadUi("CursorLayout.ui", self) #load GUI layout file created with QtDesigner
connecttolayout(self) # connect code to elements in UI file
setinitialview(self) # set initial view (button/label visibility, default values, etc)
self.show()
def clickedstartButton(self): #action if start button clicked
self.plotWidget.clear()
plotx = range(100)
ploty = [number**2 for number in plotx]
thisline = self.plotWidget.plot(plotx, ploty, pen='r')
QApplication.processEvents()
def clickedexitButton(self):
self.close()
app=QApplication([])
UIWindow=UI()
app.exec()
包含用于设置 gui 的代码的文件 initGUI.py（不一定要这样做，但这是为了模仿我较大程序的文件结构）：
from PyQt5.QtWidgets import QPushButton
import pyqtgraph as pg
def connecttolayout(self): #connect GUI elements to elements in UI file
self.startButton = self.findChild(QPushButton, "startbutton")
self.exitButton = self.findChild(QPushButton, "exitbutton")
self.startButton.clicked.connect(self.clickedstartButton)
self.exitButton.clicked.connect(self.clickedexitButton)
def mouseMoved(evt):
pos = evt[0] ## using signal proxy turns original arguments into a tuple
if self.plotWidget.sceneBoundingRect().contains(pos):
mousePoint = self.plotWidget.vb.mapSceneToView(pos)
index = int(mousePoint.x())
#if index > 0 and index < len(data1):
if index > 0 and index < self.MFmax:
self.cursorlabel.setText("<span style='font-size: 12pt'>x=%0.1f, <span style='color: red'>y=%0.1f</span>" % (
mousePoint.x(), mousePoint.y()))
self.vLine.setPos(mousePoint.x())
self.hLine.setPos(mousePoint.y())
def setinitialview(self): #set initial view to pvst view and clear plot window
#set plot initial configuration
self.plotWidget.setBackground('w')
self.plotWidget.setLabels(left=('Pressure', 'Torr'))
self.plotWidget.setLabel('left',color='black',size=30)
self.plotWidget.setLabels(bottom=('Time', 's'))
self.plotWidget.setLabel('bottom',color='black',size=30)
self.plotWidget.clear()
# cross hair
self.vLine = pg.InfiniteLine(angle=90, movable=False)
self.hLine = pg.InfiniteLine(angle=0, movable=False)
self.plotWidget.addItem(self.vLine, ignoreBounds=True)
self.plotWidget.addItem(self.hLine, ignoreBounds=True)
self.cursorlabel = pg.LabelItem(justify='right')
proxy = pg.SignalProxy(self.plotWidget.scene().sigMouseMoved, rateLimit=60, slot=mouseMoved)
我真的很惊讶我的尝试没有导致错误 - 按下绘图按钮确实会创建一个绘图，但它肯定不会在 GUI 的图形中创建光标。
如何将必要的信息传递给 mouseMoved 函数？
【问题讨论】：
【参考方案1】：有一些小错误会让你的程序失败：
mouseMoved() 函数必须在您的小部件类中，因为它需要在小部件中生成的 evt 参数。
self.MFmax 变量/常量不在任何地方创建
在这一行：
mousePoint = self.plotWidget.vb.mapSceneToView(pos)
PlotWidget 对象没有vb 属性。这是一个PlotItem 的属性，那么你应该把那行改成这样：
mousePoint = self.plotWidget.plotItem.vb.mapSceneToView(pos)
Pyqtgraph 建议 here 使用 TextItem 而不是 LabelItem 在缩放视图中显示文本，因为它的缩放大小。
现在，话虽如此，并重新组织您的代码以使其更清晰，这是我对您的代码的解决方案（您只需要 UI 文件和此脚本）：
import sys
import pyqtgraph as pg
from pyqtgraph.Qt import QtGui, uic
ui_file = uic.loadUiType("CursorLayout.ui")[0]
class UI(QtGui.QMainWindow, ui_file):
def __init__(self):
## Inherit the QMainWindow and ui_file classes
QtGui.QMainWindow.__init__(self)
ui_file.__init__(self)
self.setupUi(self)
## Create aditional widgets
self.plot_item = self.plotWidget.plot()
self.vLine = pg.InfiniteLine(angle=90, movable=False)
self.hLine = pg.InfiniteLine(angle=0, movable=False)
self.cursorlabel = pg.TextItem(anchor=(-1,10))
## Build the rest of the GUI
self.format_plot()
## data
self.plotx = range(100)
self.ploty = [number**2 for number in self.plotx]
## Connect signals to actions
self.startbutton.clicked.connect(self.clickedstartButton)
self.exitbutton.clicked.connect(self.clickedexitButton)
self.plotWidget.scene().sigMouseMoved.connect(self.mouseMoved)
## OVERWRITE the mouseMoved action:
def mouseMoved(self, evt):
pos = evt
if self.plotWidget.sceneBoundingRect().contains(pos):
mousePoint = self.plotWidget.plotItem.vb.mapSceneToView(pos)
index = int(mousePoint.x())
if index > 0 and index < len(self.plotx):
# if index > 0 and index < self.MFmax:
self.cursorlabel.sethtml(
"<span style='font-size: 12pt'>x=:0.1f, \
<span style='color: red'>y=:0.1f</span>".format(
mousePoint.x(), mousePoint.y()))
self.vLine.setPos(mousePoint.x())
self.hLine.setPos(mousePoint.y())
def clickedstartButton(self): #action if start button clicked
self.plot_item.setData(self.plotx, self.ploty, pen='r')
self.plotWidget.addItem(self.cursorlabel)
def clickedexitButton(self):
self.close()
def format_plot(self):
self.plotWidget.setBackground('w')
self.plotWidget.setLabels(left=('Pressure', 'Torr'))
self.plotWidget.setLabel('left',color='black',size=30)
self.plotWidget.setLabels(bottom=('Time', 's'))
self.plotWidget.setLabel('bottom',color='black',size=30)
self.plotWidget.addItem(self.vLine, ignoreBounds=True)
self.plotWidget.addItem(self.hLine, ignoreBounds=True)
if __name__ == "__main__":
app = QtGui.QApplication(sys.argv)
window = UI()
window.show()
sys.exit(app.exec_())
上面的代码将使“十字准线”（hline 和 vline）跟随您的鼠标并显示该位置的坐标，如下所示：
如果您希望“十字准线”根据光标的 x 轴位置跟踪曲线中的点，您可以将 mouseMoved() 函数更改为：
def mouseMoved(self, evt):
pos = evt
if self.plotWidget.sceneBoundingRect().contains(pos):
mousePoint = self.plotWidget.plotItem.vb.mapSceneToView(pos)
mx = np.array([abs(i-mousePoint.x()) for i in self.plotx])
index = mx.argmin()
if index >= 0 and index < len(self.plotx):
self.cursorlabel.setHtml(
"<span style='font-size: 12pt'>x=:0.1f, \
<span style='color: red'>y=:0.1f</span>".format(
self.plotx[index], self.ploty[index])
)
self.vLine.setPos(self.plotx[index])
self.hLine.setPos(self.ploty[index])
这将是结果：
【讨论】：
【参考方案2】：mouseMoved 中 mx 计算的性能可以大大提高，以获得更快的光标响应：
def mouseMoved(self, evt):
pos = evt
if self.plotWidget.sceneBoundingRect().contains(pos):
mousePoint = self.plotWidget.plotItem.vb.mapSceneToView(pos)
mx = abs(np.ones(len(self.plotx))*mousePoint.x() - self.plotx)
index = mx.argmin()
if index >= 0 and index < len(self.plotx):
self.cursorlabel.setHtml(
"<span style='font-size: 12pt'>x=:0.1f, \
<span style='color: red'>y=:0.1f</span>".format(
self.plotx[index], self.ploty[index])
)
self.vLine.setPos(self.plotx[index])
self.hLine.setPos(self.ploty[index])
【讨论】：
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