textChanged(*)重点

# -*- coding: cp936 -*-

import sys

from PyQt4 import QtCore, QtGui

class MyDialog(QtGui.QDialog):

def __init__(self, parent=None):

QtGui.QDialog.__init__(self, parent)

self.quit = QtGui.QPushButton("Quit")

self.change = QtGui.QPushButton("Change")

self.change.setEnabled(False)

# funny widget

self.lcd = QtGui.QLCDNumber(2)

self.slider = QtGui.QSlider(QtCore.Qt.Horizontal)

self.slider.setRange(0, 99)

self.slider.setValue(0)

self.lineEdit = QtGui.QLineEdit()

self.connect(self.quit, QtCore.SIGNAL("clicked()"),

QtGui.qApp, QtCore.SLOT("quit()"))

self.connect(self.lineEdit, QtCore.SIGNAL("textChanged(const QString&)"),

self.enableChangeButton)

self.connect(self.slider, QtCore.SIGNAL("valueChanged(int)"),

self.SliderChange)

self.connect(self.change, QtCore.SIGNAL("clicked()"),

self.Change)

self.rightLayout = QtGui.QVBoxLayout()

self.rightLayout.addWidget(self.lineEdit)

self.rightLayout.addWidget(self.change)

self.leftLayout = QtGui.QVBoxLayout()

self.leftLayout.addWidget(self.lcd)

self.leftLayout.addWidget(self.slider)

self.layout = QtGui.QHBoxLayout()

self.layout.addWidget(self.quit)

self.layout.addLayout(self.leftLayout)

self.layout.addLayout(self.rightLayout)

self.setLayout(self.layout);

def enableChangeButton(self, text):

self.change.setEnabled(text.isEmpty() == False)#重点

def Change(self):

value = int(self.lineEdit.text())

self.lcd.display(value)

self.slider.setValue(value)

def SliderChange(self):

value = self.slider.value()

self.lcd.display(value)

self.lineEdit.setText(str(value))

app = QtGui.QApplication(sys.argv)

dialog = MyDialog()

dialog.show()

sys.exit(app.exec_())