檢查 event 是否為 QEvent.KeyPress 即可
from PyQt5.QtCore import QEvent

def eventFilter(self, obj, event):
if (event.type() == QtCore.QEvent.KeyPress):
key = event.key()
if key != Qt.Key_Escape:
print("Escape key")

return False # will not be filtered out (ie. event will be processed)