When an image containing a constant value is selected for displaying level histograms, the x axis limits of the LevelsHistogram plot are set to a very small range, i.e. xmin and xmax are nearly the same. This cause self.range (XRangeSelection) to be drawn very far in canvas frame coordinates, which cause a failure in XRangeSelection.draw(), for
painter.drawLine(center_x, top, center_x, bottom)
as center_x may be an integer below -2147483648 or above 2147483647, which may be not the case
it can be corrected by changing this line to:
painter.drawLine(QPointF(center_x, top), QPointF(center_x, bottom))
When an image containing a constant value is selected for displaying level histograms, the x axis limits of the LevelsHistogram plot are set to a very small range, i.e. xmin and xmax are nearly the same. This cause self.range (XRangeSelection) to be drawn very far in canvas frame coordinates, which cause a failure in XRangeSelection.draw(), for
painter.drawLine(center_x, top, center_x, bottom)
as center_x may be an integer below -2147483648 or above 2147483647, which may be not the case
it can be corrected by changing this line to:
painter.drawLine(QPointF(center_x, top), QPointF(center_x, bottom))