PyQtGraph – ROI Clicked Signal of Image View

In this article we will see how we can trigger the roi clicked signal of image view object in PyQTGraph. PyQtGraph is a graphics and user interface library for Python that provides functionality commonly required in designing and science applications. Its primary goals are to provide fast, interactive graphics for displaying data (plots, video, etc.). Widget used for display and analysis of image data. Implements many features like displaying 2D and 3D image data. For 3D data, a z-axis slider is displayed allowing the user to select which frame is displayed. Displays histogram of image data with movable region defining the dark/light levels, editable gradient provides a color lookup table, frame slider may also be moved using left/right arrow keys as well as pgup, pgdn, home, and end. This signal is emitted when the roi button on image view get clicked.
 

We can create a image view with the help of command given below.

# creating a pyqtgraph image view object
imv = pg.ImageView()

In order to trigger this signal we have to alter the image view class, below is the syntax of the class.

Syntax:

# Image View class

class ImageView(pg.ImageView):

   # constructor which inherit original

   # ImageView

   def __init__(self, *args, **kwargs):

       pg.ImageView.__init__(self, *args, **kwargs)

   # roi clicked method

   def roiClicked(self):

       # printing message

       print("ROI Changed")

Below is the implementation 

Output : 

ROI Clicked
ROI Clicked
ROI Clicked