class_docstr: example application main window 
code: def __init__(self):
      super().__init__()
      self.resize(420, 400)
      self.show()
  
      plot = self.addPlot()
      # Example: Transformed display of ImageItem
  
      tr = QtGui.QTransform()  # prepare ImageItem transformation:
      tr.scale(6.0, 3.0)  # scale horizontal and vertical axes
      tr.translate(
          -1.5, -1.5
      )  # move 3x3 image to locate center at axis origin
  
      img = pg.ImageItem(
          image=np.eye(3), levels=(0, 1)
      )  # create example image
      img.setTransform(tr)  # assign transform
  
      plot.addItem(img)  # add ImageItem to PlotItem
      plot.showAxes(True)  # frame it with a full set of axes
      plot.invertY(True)  # vertical axis counts top to bottom
  
      self.timer = pg.QtCore.QTimer(singleShot=True)
      self.timer.timeout.connect(self.export)
      self.timer.start(100)
  
file_path: pyqtgraph/doc/source/images/gen_example_imageitem_transform.py
imports: import numpy
  import pyqtgraph
  import pyqtgraph.exporters
  from pyqtgraph.Qt import QtGui, mkQApp
label_desc: Use image node_id 1 to create a new MainWindow object from inherited base classes: pg with example: obj = MainWindow()