title: About QPixmap change opacity
body: <p>I have a QPixmap on QLabel and QLabel has yellow color, Question is
  i am just trying to change opactiy of QPixmap Color, is there any way to solve this.</p>
  
  <pre><code>from PyQt5.QtWidgets import QApplication, QLabel
  from PyQt5.QtGui import QPixmap
  from PyQt5.QtCore import Qt
  import sys
  
  class Pixmap(QPixmap):
      def __init__(self):
          super().__init__(700, 400)
          self.fill(Qt.yellow)
  
  class Drawing(QLabel):
      def __init__(self):
          super().__init__()
          pix = Pixmap()
          self.setPixmap(pix)
  
  if __name__ == "__main__":
      app = QApplication(sys.argv)
      draw = Drawing()
      draw.show()
      sys.exit(app.exec_())
  </code></pre>