Question

我试图在pyqtgraph / PyQt5中的ImageView中设置比例尺，但是当我为比例尺设置setParentItem时，它将不接受ImageView，ImageItem或ViewBox。没有错误消息，但是整个程序崩溃了。

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

app = QtGui.QApplication([])

imvOCTTopLeft = pg.ImageView(view=pg.PlotItem())
imvOCTTopLeft.setImage(np.random.normal(size=(100,100)))
scale = pg.ScaleBar(size=0.1)
im=imvOCTTopLeft.getImageItem()
scale.setParentItem(im)

imvOCTTopLeft.show()

app.exec_()

Answer 1

我建议您在CMD或终端中执行代码，以便获得有关该错误的更多信息，如果这样做，您将收到以下消息：

Traceback (most recent call last):
  File "/usr/lib/python3.7/site-packages/pyqtgraph/graphicsItems/GraphicsObject.py", line 23, in itemChange
    self.parentChanged()
  File "/usr/lib/python3.7/site-packages/pyqtgraph/graphicsItems/ScaleBar.py", line 44, in parentChanged
    view.sigRangeChanged.connect(self.updateBar)
AttributeError: 'ImageItem' object has no attribute 'sigRangeChanged'
Aborted (core dumped)

该错误是由于setParentItem()方法需要一个ViewBox所致，因为它具有sigRangeChanged信号，如果存在某种类型的缩放，则该信号允许更新ScaleBar。然后，您可以通过view属性获取ViewBox，但是，如果像完成操作那样使用视图在构造函数中传递参数（pg.ImageView(view = pg.PlotItem())，则必须使用getViewBox()获取该对象的viewbox。

您的代码中的另一个错误是QApplication属于PyQt5的QtWidgets子模块。

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)))
    scale = pg.ScaleBar(size=10)
    viewbox = imvOCTTopLeft.view
    if not isinstance(viewbox, pg.ViewBox): viewbox = viewbox.getViewBox()
    scale.setParentItem(viewbox)
    scale.anchor((1, 1), (1, 1), offset=(-200, -20))
    imvOCTTopLeft.show()

    sys.exit(app.exec_())

pyqtgraph中的ScaleBar不会setParentItem

1 个答案: