The following article discusses how can we get foreground role of the image view object in PyQTGraph. There are basically two types of roles in image view one is foreground and the other one is background. The foreground role defines the color from the image view’s palette that is used to draw the foreground.
PyQtGraph is a graphics and user interface Python library for functionalities commonly required in designing and science applications. Its provides fast, interactive graphics for displaying data (plots, video, etc.). 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 will be displayed. Displays histogram of image data with movable region defining the dark/light levels and editable gradient provides a color lookup table for reference.
For creating an image view ImageView() is used
Syntax:
imv = pg.ImageView()
To fetch foreground role we use foregroundRole() method with the image view object. It takes no arguments and returns a QPalette object.
Syntax :
imv.foregroundRole()
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)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 # 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) # getting foreground role of the image view value = imv.foregroundRole() # setting text to the label label.setText("Foreground Role : " + str(value))# create pyqt5 appApp = QApplication(sys.argv)# create the instance of our Windowwindow = Window()# start the appsys.exit(App.exec()) |
Output :
