Hi all-
I am trying to implement a way to interactively invert greyscale image
colours. I would like to do this by changing the way the colours are
displayed rather than changing the original data (the original data can be
somewhat complicated) - the best way of doing this that I could find is to
extract the current ColorMap, apply its .reverse() method and re-apply that
altered ColorMap. This feature seems to have been introduced in PyQtGraph
0.12.2 and has been working fine in my code in a small test script based on
the PyQtGraph example code in ImageView.py. Essentially this:
inv_cmap = imw.ui.histogram.gradient.colorMap()
inv_cmap.reverse()
imw.setColorMap(inv_cmap)
Which does this nicely.
[image: image.png]
I am subclassing pg.ImageView in my main code - the code I have been
using works just fine in 0.12.1, but raises an odd exception in 0.12.2 and
0.12.3 (traceback included below.) So I want the ColorMap.reverse() method
but I am unable to use 0.12.2 or .3... :(
Can anyone help me here? I would like to fix the subclassing if possible,
and then use the .reverse() ColorMap method. I am probably doing this
wrong somewhere.
If this is important, I am variably using PySide6, PySide2 and maybe PyQt 5
on old Macs where I have trouble installing PySide. These tracebacks were
generated on PySide6, on Python 3.9.
Here is minimum code which reproduces the issues:
from PySide6.QtWidgets import QApplication, QMainWindow, QPushButton
from PySide6.QtWidgets import QWidget, QVBoxLayout
import pyqtgraph as pg
import numpy as np
import sys
class MainWindow(QMainWindow):
def __init__(self):
super().__init__()
self.cw = QWidget(self)
self.cw.setAutoFillBackground(True)
self.setCentralWidget(self.cw)
self.layout = QVBoxLayout()
self.cw.setLayout(self.layout)
self.ImgWidget = MyImageWidget(parent=self)
self.layout.addWidget(self.ImgWidget)
self.inv_btn = QPushButton('Invert Image')
self.inv_btn.clicked.connect(self.ImgWidget.invert_image)
self.layout.addWidget(self.inv_btn)
self.resize(800, 800)
self.show()
class MyImageWidget(pg.ImageView):
def __init__(self, parent):
super().__init__(parent, view=pg.PlotItem())
# Clean up the interface
self.ui.histogram.hide()
self.ui.roiBtn.hide()
self.ui.menuBtn.hide()
self.plot = self.getView()
self.plot.hideAxis('left')
self.plot.hideAxis('bottom')
self.plot.setMenuEnabled(False)
self.inverted = False
# 300x200 img random noise
img = np.random.normal(size=(300, 200))
self.setImage(img)
self.def_cmap = self.ui.histogram.gradient.colorMap()
self.inv_cmap = self.ui.histogram.gradient.colorMap()
self.inv_cmap.reverse()
def invert_image(self):
self.inverted = not(self.inverted)
if self.inverted:
self.setColorMap(self.inv_cmap)
else:
self.setColorMap(self.def_cmap)
def main():
app = QApplication(sys.argv)
main = MainWindow()
main.show()
sys.exit(app.exec_())
if __name__ == '__main__':
main()
in 0.12.2 and 0.12.3 the code fails on creation of the subclassed
pg.ImageView - specifically the super statement.
Traceback (most recent call last):
File "c:/Users/oli_n/pycode/examview/test-reverse.py", line 71, in
<module>
main()
File "c:/Users/oli_n/pycode/examview/test-reverse.py", line 65, in main
main = MainWindow()
File "c:/Users/oli_n/pycode/examview/test-reverse.py", line 20, in
__init__
self.ImgWidget = MyImageWidget(parent=self)
*File "c:/Users/oli_n/pycode/examview/test-reverse.py", line 33, in
__init__*
* super().__init__(parent, view=pg.PlotItem())*
...edit...
File
"c:\Users\oli_n\pycode\examview\.examview.env\lib\site-packages\pyqtgraph\graphicsItems\GradientEditorItem.py",
line 642, in getGradient
g.setStops([(x, QtGui.QColor(t.color)) for t,x in ticks])
*AttributeError: 'PySide6.QtGui.QLinearGradient' object has no attribute
'setStops'*
QPaintDevice: Cannot destroy paint device that is being painted
In 0.12.1 the subclassing seems to work OK, however an exception is thrown
when trying the .reverse() ColorMap method - of course this method is not
implemented in 0.12.1, only 0.12.2 and later.
Thanks!
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