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
Python3
# importing Qt widgetsfrom PyQt5.QtWidgets import *# importing systemimport sys# importing numpy as npimport numpy as np# importing pyqtgraph as pgimport pyqtgraph as pgfrom PyQt5.QtGui import *from PyQt5.QtCore import *# Image View classclass 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 Clicked")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("Geeksforneveropen 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 # 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)# create pyqt5 appApp = QApplication(sys.argv)# create the instance of our Windowwindow = Window()# start the appsys.exit(App.exec()) |
Output :
ROI Clicked ROI Clicked ROI Clicked
