pyqt : addStretch()方法的参数的是些什么值？分别有什么表现？
import sys
from PyQt4 import QtGui

class Example(QtGui.QWidget):

def __init__(self):
super(Example, self).__init__()

self.initUI()

def initUI(self):

okButton = QtGui.QPushButton("OK")
cancelButton = QtGui.QPushButton("Cancel")

hbox = QtGui.QHBoxLayout()
hbox.addStretch(1)
hbox.addWidget(okButton)
hbox.addWidget(cancelButton)

vbox = QtGui.QVBoxLayout()
vbox.addStretch(1)
vbox.addLayout(hbox)

self.setLayout(vbox)

self.setGeometry(300, 300, 300, 150)
self.setWindowTitle('Buttons')
self.show()

def main():

app = QtGui.QApplication(sys.argv)
ex = Example()
sys.exit(app.exec_())


if __name__ == '__main__':
main()



这两行代码有什么作用？
hbox.addStretch(1)

vbox.addStretch(1)

另外，可作为这个addStretch()方法的参数的是些什么值？分别有什么表现？



[解决办法]
QBoxLayout.addStretch (self, int stretch = 0)
Adds a stretchable space (a QSpacerItem) with zero minimum size and stretch factor stretch to the end of this box layout.

See also insertStretch(), addItem(), and QSpacerItem.