PyQt5实现让QScrollArea支持鼠标拖动的操作方法

#!/usr/bin/evn python3# -*- coding: utf-8 -*- import sysfrom PyQt5.QtWidgets import (QApplication, QWidget, QScrollArea, QLabel)from PyQt5.QtCore import QEvent  class TestWindow(QWidget):	def __init__(self):		super(TestWindow, self).__init__()		self.resize(800, 600)		self.move(0, 0)		# self.setMouseTracking(False)		self.last_time_move = 0		self.initUI() 	def initUI(self):		self.central_widget = QWidget(self) 		self.scroll_area = QScrollArea(self)		self.scroll_area.setGeometry(0, 0, 400, 400)		self.scroll_area.setWidgetResizable(True)		self.scroll_bar = self.scroll_area.verticalScrollBar() 		self.scroll_contents = QWidget()		self.scroll_contents.setGeometry(0, 0, 400, 800)		self.scroll_contents.setMinimumSize(380, 1000) 		self.label_1 = QLabel(self.scroll_contents)		self.label_1.move(50, 100)		self.label_1.setText("HelloRyan") 		self.label_2 = QLabel(self.scroll_contents)		self.label_2.move(50, 200)		self.label_2.setText("你好") 		self.label_3 = QLabel(self.scroll_contents)		self.label_3.move(50, 300)		self.label_3.setText("-----------") 		self.label_4 = QLabel(self.scroll_contents)		self.label_4.move(50, 400)		self.label_4.setText("542543255235432543252") 		self.label_5 = QLabel(self.scroll_contents)		self.label_5.move(50, 500)		self.label_5.setText("5432543262542") 		self.label_6 = QLabel(self.scroll_contents)		self.label_6.move(50, 600)		self.label_6.setText("4325432532") 		self.scroll_area.setWidget(self.scroll_contents)		self.scroll_area.installEventFilter(self) 	# def mouseMoveEvent(self, event):	# 	if event.pos().x() > 0 and event.pos().x() < 400 and event.pos().y() > 0 and event.pos().y() < 400:	# 		if self.last_time_move == 0:	# 			self.last_time_move = event.pos().y()	#	# 		distance = self.last_time_move - event.pos().y()	# 		self.scroll_bar.setValue(self.scroll_bar.value() + distance)	#	# 		self.last_time_move = event.pos().y()	# 		print("move%d" % event.pos().y())	#	# def mouseReleaseEvent(self, event):	# 	self.last_time_move = 0	# 	print("up") 	def eventFilter(self, source, event):		if event.type() == QEvent.MouseMove:			print(event.pos().y())						if self.last_time_move == 0:				self.last_time_move = event.pos().y()							distance = self.last_time_move - event.pos().y()			self.scroll_bar.setValue(self.scroll_bar.value() + distance)			self.last_time_move = event.pos().y()					elif event.type() == QEvent.MouseButtonRelease:			self.last_time_move = 0		return QWidget.eventFilter(self, source, event)  if __name__ == "__main__":	app = QApplication(sys.argv)	test = TestWindow()	test.show()	sys.exit(app.exec_())