更改比例后，pyqtgraph中的ScaleBar不会更新

Question

当我更改图像轴的比例时，我的ScaleBar显示不正确的比例。更改轴时如何更新比例尺？

from PyQt5 import QtWidgets
import pyqtgraph as pg
import numpy as np

if __name__ == '__main__':
    import sys

    app = QtWidgets.QApplication(sys.argv)

    imvOCTTopLeft = pg.ImageView(view=pg.PlotItem())
    imvOCTTopLeft.setImage(np.random.normal(size=(100,100)))

    imvOCTTopLeft.view.getAxis('left').setScale(0.6)
    imvOCTTopLeft.view.getAxis('bottom').setScale(0.4)

    scale = pg.ScaleBar(size=10,suffix = "px")
    viewbox = imvOCTTopLeft.view
    if not isinstance(viewbox, pg.ViewBox): viewbox = viewbox.getViewBox()
    scale.setParentItem(viewbox)
    scale.anchor((1, 1), (1, 1), offset=(-20, -20))
    imvOCTTopLeft.show()

    sys.exit(app.exec_())

此图像显示比例尺显示大约4个像素，但指出它显示10个像素。

我认为这是因为我更改了轴刻度。

Answer 1

这似乎是一个错误：link。发出sigRangeChanged后，视图框会重新缩放。

“ Hacky”解决方案是延迟ScaleBar更新： （您可能需要尝试time，100和10为我工作。如果不起作用，请增加它。）

from PyQt5 import QtWidgets, QtCore
import pyqtgraph as pg
import numpy as np


def updateDelay(scale, time):
    QtCore.QTimer.singleShot(time, scale.updateBar)


if __name__ == '__main__':
    import sys

    app = QtWidgets.QApplication(sys.argv)

    plotItem = pg.PlotItem()
    imvOCTTopLeft = pg.ImageView(view=plotItem)
    imvOCTTopLeft.setImage(np.random.normal(size=(100, 100)))

    imvOCTTopLeft.view.getAxis('left').setScale(0.6)
    scale = 0.4 #edit
    imvOCTTopLeft.view.getAxis('bottom').setScale(scale) #edit

    scale = pg.ScaleBar(size=10*(1/scale), suffix="px") #edit
    scale.text.setText('10 px') #edit
    plotItem.sigRangeChanged.connect(lambda: updateDelay(scale, 10))  # here: time=10ms
    viewbox = imvOCTTopLeft.view
    if not isinstance(viewbox, pg.ViewBox): viewbox = viewbox.getViewBox()
    scale.setParentItem(viewbox)
    scale.anchor((1, 1), (1, 1), offset=(-20, -20))
    imvOCTTopLeft.show()
    updateDelay(scale, 100)  # here time=100ms

    sys.exit(app.exec_())

结果：