PyQt4学习笔记2：事件和信号

事件是任何 GUI 程序中很重要的部分。所有 GUI 应用都是事件驱动的。一个应用对其生命期产生的不同的事件类型做出反应。事件是主要由应用的用户产生。但是，也可以通过其他方法产生，比如，网络通信，窗口的管理者，计时器。

PyQt 4.5 引入了新的 API 用于信号和槽。

这是旧式的 API 。

QtCore.QObject.connect(self.ui.button_open,QtCore.SIGNAL("clicked()"), self.file_dialog)

新式的更接近 Python 的标准

button.clicked.connect(self.onClicked)

self.ui对应窗口，通过它我们可以访问窗口中的部件。因此，self.ui.button_open对应“打开”按钮。self.file_dialog是信号对应的函数，它是比较重要的部分。

test.py测试代码：

import sys
from PyQt4 import QtCore, QtGui
from ui_test import Ui_notepad

class MyForm(QtGui.QMainWindow):
    def __init__(self, parent=None):
        QtGui.QWidget.__init__(self, parent)
        self.ui = Ui_notepad()
        self.ui.setupUi(self)
        # here we connect signals with our slots
        QtCore.QObject.connect(self.ui.button_open,QtCore.SIGNAL("clicked()"), self.file_dialog)
    def file_dialog(self):
        #self.ui.editor_window.setText('aaaaaaaaaa')
        fd = QtGui.QFileDialog(self)
        self.filename = fd.getOpenFileName()
        from os.path import isfile
        if isfile(self.filename):
            text = open(self.filename).read()
            self.ui.editor_window.setText(text)

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

ui_test.py  UI生成代码：

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

# Form implementation generated from reading ui file 'test.ui'
#
# Created: Sat Jan 11 22:11:39 2014
#      by: PyQt4 UI code generator 4.10.3
#
# 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_notepad(object):
    def setupUi(self, notepad):
        notepad.setObjectName(_fromUtf8("notepad"))
        notepad.resize(692, 462)
        self.button_open = QtGui.QPushButton(notepad)
        self.button_open.setGeometry(QtCore.QRect(60, 10, 75, 23))
        self.button_open.setObjectName(_fromUtf8("button_open"))
        self.button_close = QtGui.QPushButton(notepad)
        self.button_close.setGeometry(QtCore.QRect(290, 10, 75, 23))
        self.button_close.setObjectName(_fromUtf8("button_close"))
        self.editor_window = QtGui.QTextEdit(notepad)
        self.editor_window.setGeometry(QtCore.QRect(20, 50, 651, 381))
        self.editor_window.setObjectName(_fromUtf8("editor_window"))
        self.button_save = QtGui.QPushButton(notepad)
        self.button_save.setGeometry(QtCore.QRect(180, 10, 75, 23))
        self.button_save.setObjectName(_fromUtf8("button_save"))

        self.retranslateUi(notepad)
        QtCore.QObject.connect(self.button_close, QtCore.SIGNAL(_fromUtf8("clicked()")), notepad.close)
        QtCore.QMetaObject.connectSlotsByName(notepad)

    def retranslateUi(self, notepad):
        notepad.setWindowTitle(_translate("notepad", "Form", None))
        self.button_open.setText(_translate("notepad", "打开", None))
        self.button_close.setText(_translate("notepad", "关闭", None))
        self.button_save.setText(_translate("notepad", "保存", None))