import OpenGL.GL as GL
from pyqtgraph.Qt import QtCore, QtGui, QtWidgets
import pyqtgraph as pg

class GLWidget(QtWidgets.QOpenGLWidget):
    
    def _updateScreen(self, screen):
        self._updatePixelRatio()
        if screen is not None:
            screen.physicalDotsPerInchChanged.connect(self._updatePixelRatio)
            screen.logicalDotsPerInchChanged.connect(self._updatePixelRatio)
    
    def _updatePixelRatio(self):
        event = QtGui.QResizeEvent(self.size(), self.size())
        self.resizeEvent(event)
    
    # def showEvent(self, event):
    #     window = self.window().windowHandle()
    #     window.screenChanged.connect(self._updateScreen)
    #     self._updateScreen(window.screen())
        
    def paintGL(self):
        GL.glClearColor(0, 0, 0, 1)
        GL.glClear(GL.GL_COLOR_BUFFER_BIT | GL.GL_DEPTH_BUFFER_BIT)
        GL.glLineWidth(2)

        GL.glColor4f(1, 0, 0, 1)
        GL.glBegin(GL.GL_LINES)
        GL.glVertex2f(-1, -1)
        GL.glVertex2f(1, 1)
        GL.glEnd()

        GL.glColor4f(0, 1, 0, 1)
        GL.glBegin(GL.GL_LINES)
        GL.glVertex2f(-1, 1)
        GL.glVertex2f(1, -1)
        GL.glEnd()

    def resizeGL(self, *args):
        print('resizeGL', args)

if __name__ == '__main__':
    pg.mkQApp()

    main = GLWidget()
    main.show()

    pg.exec()