PyQt 的交互操作

environment

• Windows
• python 2.7
• PyQt 4.11.4

useful guide / startup

• Introduction to GUI development using Qt, 简单明了的介绍了qt gui的基本特性
• PyQt Tutorial, learn PyQt step by step.
• PyQt: Threading Basics Tutorial, 防止UI阻塞, 使用线程

Generate basic UI file

• use Qt Designer to create basic UI
  • New->Widget->drag PushButton to Form Window
  • Save it, for example demo.ui
• make sure pyuic4.bat is in the System PATH
  • input pyuic4.bat -h in shell, check the response.
• change .ui to .py file
  • run pyuic4.bat -x -o demo.py demo.ui in the working folder.
  • -o means output, set the output filename.
  • -x will generate if __name__ == '__main__': then can run directly
  • pyuic4.bat demo.ui > demo.py is also OK.
• the sample of demo.py, generated automatically by pyuic4.bat

# -*- coding: utf-8 -*-

# Form implementation generated from reading ui file 'demo.ui'
#
# Created by: PyQt4 UI code generator 4.11.4
#
# WARNING! All changes made in this file will be lost!

from PyQt4 import QtCore, QtGui

try:
    _fromUtf8 = QtCore.QString.fromUtf8
except AttributeError:
    def _fromUtf8(s):
        return s

try:
    _encoding = QtGui.QApplication.UnicodeUTF8
    def _translate(context, text, disambig):
        return QtGui.QApplication.translate(context, text, disambig, _encoding)
except AttributeError:
    def _translate(context, text, disambig):
        return QtGui.QApplication.translate(context, text, disambig)

class Ui_Form(object):
    def setupUi(self, Form):
        Form.setObjectName(_fromUtf8("Form"))
        self.pushButton = QtGui.QPushButton(Form)
        self.pushButton.setGeometry(QtCore.QRect(40, 40, 75, 23))
        self.pushButton.setObjectName(_fromUtf8("pushButton"))

        self.retranslateUi(Form)
        QtCore.QMetaObject.connectSlotsByName(Form)

    def retranslateUi(self, Form):
        Form.setWindowTitle(_translate("Form", "Form", None))
        self.pushButton.setText(_translate("Form", "PushButton", None))

# using -x will generate the following code
if __name__ == "__main__":
    import sys
    app = QtGui.QApplication(sys.argv)
    Form = QtGui.QWidget()
    ui = Ui_Form()
    ui.setupUi(Form)
    Form.show()
    sys.exit(app.exec_())

• run & check the　UI
  • run python demo.py in the working folder.
  • OR run directly in editor like atom.

click then do sth

• create a new py file, for example show.py. input code like:

import sys
import demo  # generated from xxx.ui
from PyQt4 import QtGui


class MyForm(QtGui.QWidget, demo.Ui_Form):

    def __init__(self):
        super(self.__class__, self).__init__()  # QtGui.QWidget.__init__()
        self.setupUi(self)
        self.pushButton.clicked.connect(
            self.handleButton)  # here is important line

    def handleButton(self):
        print ("hello, https://draapho.github.io/")
        # size = self.geometry()
        # self.resize(size.width() + 2, size.height() + 2)


if __name__ == "__main__":
    app = QtGui.QApplication(sys.argv)
    form = MyForm()
    form.show()
    sys.exit(app.exec_())

• look at self.ui.pushButton.clicked.connect(self.handleButton)
  it links clicked event with handleButton function.
• if you want to resize the window after clicked the button. change handleButton to

def handleButton(self):
    # print ("hello, https://draapho.github.io/")
    size = self.geometry()
    self.resize(size.width() + 2, size.height() + 2)

click then do heavy work

• bad code, UI totally dead

  from PyQt4 import QtGui
  import sys
  import demo
  import time
  
  
  class MyForm(QtGui.QWidget, demo.Ui_Form):
  
      def __init__(self):
          super(self.__class__, self).__init__()
          self.setupUi(self)
          self.pushButton.clicked.connect(self.startCount)
  
      def startCount(self):
          self.pushButton.clicked.disconnect()
          self.pushButton.clicked.connect(self.stopCount)
          i = 0
          while i < 15:
              i += 1
              self.pushButton.setText(str(i))
              print i
              time.sleep(1)
  
      def stopCount(self):
          self.pushButton.clicked.disconnect()
          self.pushButton.clicked.connect(self.startCount)
          self.pushButton.setText("PushButton")
  
  if __name__ == '__main__':
      app = QtGui.QApplication(sys.argv)
      form = MyForm()
      form.show()
      app.exec_()

• use thread, can do everything in UI

  from PyQt4 import QtGui
  from PyQt4.QtCore import QThread, SIGNAL
  import sys
  import demo
  
  
  class getCountThread(QThread):
  
      def __init__(self):
          QThread.__init__(self)
          self.count = 0
  
      def __del__(self):
          self.wait()
  
      def run(self):
          while self.count < 15:
              self.count += 1
              self.emit(SIGNAL('showCount(int)'), self.count)
              print self.count
              self.sleep(1)
  
  
  class MyForm(QtGui.QWidget, demo.Ui_Form):
  
      def __init__(self):
          super(self.__class__, self).__init__()
          self.setupUi(self)
          self.pushButton.clicked.connect(self.startCount)
  
      def startCount(self):
          self.pushButton.clicked.disconnect()
          self.get_thread = getCountThread()
          self.connect(self.get_thread, SIGNAL("showCount(int)"), self.showCount)
          self.connect(self.get_thread, SIGNAL("finished()"), self.done)
          self.get_thread.start()
          # must be under the self.get_thread.start()
          self.pushButton.clicked.connect(self.get_thread.terminate)
  
      def showCount(self, count):
          self.pushButton.setText(str(count))
  
      def done(self):
          self.pushButton.clicked.disconnect()
          self.pushButton.setText("PushButton")
          self.pushButton.clicked.connect(self.startCount)
  
  
  if __name__ == '__main__':
      app = QtGui.QApplication(sys.argv)
      form = MyForm()
      form.show()
      app.exec_()

• explanation
  • getCountThread 子线程类, 执行繁重任务
  • MyForm->startCount 点击按键后执行, 设置好信号, 启动子线程
  • self.connect(self.get_thread, SIGNAL("showCount(int)"), self.showCount)
    准备接收来自线程的信号, 并在 showCount 更新UI
  • self.connect(self.get_thread, SIGNAL("finished()"), self.done)
    准备接收来自线程的结束信号, 然后在 done 下更新标记和UI
  • self.get_thread.start()
    启动子线程
  • self.pushButton.clicked.connect(self.get_thread.terminate)
    将按键的功能设置为终止子线程, 必须放在 self.get_thread.start() 下面

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原创于 DRA&PHO