PyQt基本布局常用方法之addStretch

from PyQt4.QtGui import *
from PyQt4.QtCore import *
import sys
class LayoutDialog(QDialog):
def __init__(self,parent=None):
super(LayoutDialog,self).__init__(parent)
self.resize(200,600)
btn1 = QPushButton("btn1")
btn2 = QPushButton("btn2")
btn3 = QPushButton("btn3")

vlayout = QVBoxLayout(self)
vlayout.addStretch(1)
vlayout.addWidget(btn1)
vlayout.addStretch(1)
vlayout.addWidget(btn2)
vlayout.addStretch(2)
vlayout.addWidget(btn3)
app = QApplication(sys.argv)
dialog = LayoutDialog()
dialog.show()
app.exec_()


我们先看一下addStretch的原型：

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 boxlayout.

See also insertStretch(), addItem(), andQSpacerItem.

然后通过上面的代码来学习一下addStretch的用法。

达到的效果图如下：



所以该函数的作用就是平分布局，它所带的参数就是所占的比例。