PyQtGraph – Setting Custom Cursor for Image View

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In this article, we will see how we can set a custom cursor to the 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 a movable region defining the dark/light levels, editable gradient provides a color lookup table. In computer user interfaces, a cursor is an indicator used to show the current position for user interaction on a computer monitor or other display device that will respond to input from a text input or pointing device. The mouse cursor is also called a pointer, owing to its resemblance in usage to a pointing stick.
We can create an image view with the help of the command given below

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

In order to do this we use setCursor method with the image view object
Syntax : imv.setCursor(cursor)
Argument : It takes QCursor object as argument
Return : It returns None

Below is the implementation

Python3

# importing Qt widgets
from PyQt5.QtWidgets import *
 
# importing system
import sys
 
# importing numpy as np
import numpy as np
 
# importing pyqtgraph as pg
import pyqtgraph as pg
from PyQt5.QtGui import *
from PyQt5.QtCore import *
 
 
# Image View class
class ImageView(pg.ImageView):
 
    # constructor which inherit original
    # ImageView
    def __init__(self, *args, **kwargs):
        pg.ImageView.__init__(self, *args, **kwargs)
 
 
class Window(QMainWindow):
 
    def __init__(self):
        super().__init__()
 
        # setting title
        self.setWindowTitle("PyQtGraph")
 
        # setting geometry
        self.setGeometry(100, 100, 600, 500)
 
        # icon
        icon = QIcon("skin.png")
 
        # setting icon to the window
        self.setWindowIcon(icon)
 
        # calling method
        self.UiComponents()
 
        # showing all the widgets
        self.show()
 
        # setting fixed size of window
        #self.setFixedSize(QSize(600, 500))
 
    # method for components
    def UiComponents(self):
 
        # creating a widget object
        widget = QWidget()
 
        # creating a label
        label = QLabel("Geeksforzambiatek Image View")
 
        # setting minimum width
        label.setMinimumWidth(130)
 
        # making label do word wrap
        label.setWordWrap(True)
 
        # setting configuration options
        pg.setConfigOptions(antialias=True)
 
        # creating image view  object
        imv = ImageView()
 
        # Create random 3D data set with noisy signals
        img = pg.gaussianFilter(np.random.normal(
            size=(200, 200)), (5, 5)) * 20 + 100
 
        # setting new axis to image
        img = img[np.newaxis, :, :]
 
        # decay data
        decay = np.exp(-np.linspace(0, 0.3, 100))[:, np.newaxis, np.newaxis]
 
        # random data
        data = np.random.normal(size=(100, 200, 200))
        data += img * decay
        data += 2
 
        # adding time-varying signal
        sig = np.zeros(data.shape[0])
        sig[30:] += np.exp(-np.linspace(1, 10, 70))
        sig[40:] += np.exp(-np.linspace(1, 10, 60))
        sig[70:] += np.exp(-np.linspace(1, 10, 30))
 
        sig = sig[:, np.newaxis, np.newaxis] * 3
        data[:, 50:60, 30:40] += sig
 
        # setting image to image view
        # Displaying the data and assign each frame a time value from 1.0 to 3.0
        imv.setImage(data, xvals=np.linspace(1., 3., data.shape[0]))
 
        # Set a custom color map
        colors = [
            (0, 0, 0),
            (4, 5, 61),
            (84, 42, 55),
            (15, 87, 60),
            (208, 17, 141),
            (255, 255, 255)
        ]
 
        # color map
        cmap = pg.ColorMap(pos=np.linspace(0.0, 1.0, 6), color=colors)
 
        # setting color map to the image view
        imv.setColorMap(cmap)
 
        # Creating a grid layout
        layout = QGridLayout()
 
        # minimum width value of the label
        label.setFixedWidth(130)
 
        # setting this layout to the widget
        widget.setLayout(layout)
 
        # adding label in the layout
        layout.addWidget(label, 1, 0)
 
        # plot window goes on right side, spanning 3 rows
        layout.addWidget(imv, 0, 1, 3, 1)
 
        # setting this widget as central widget of the main window
        self.setCentralWidget(widget)
 
        # creating a cursor
        cursor = Qt.ClosedHandCursor
 
        # setting cursor to the image view
        imv.setCursor(cursor)
 
 
# create pyqt5 app
App = QApplication(sys.argv)
 
# create the instance of our Window
window = Window()
 
# start the app
sys.exit(App.exec())