添加成比例的收缩量，如果收缩量为0时，所有的控件都分布在界面的左边

当收缩量不为0时

Stretch.py 

"""
设置控件的伸缩量
"""

import sys, math
from PyQt5.QtWidgets import *
from PyQt5.QtCore import Qt

class Stretch(QWidget):
    def __init__(self):
        super(Stretch, self).__init__()
        self.setWindowTitle("设置控件的伸缩量")

        btn1 = QPushButton(self)
        btn2 = QPushButton(self)
        btn3 = QPushButton(self)
        btn1.setText("按钮1")
        btn2.setText("按钮2")
        btn3.setText("按钮3")

        layout = QHBoxLayout()
        layout.addStretch(1)
        layout.addWidget(btn1)

        layout.addStretch(2)
        layout.addWidget(btn2)

        layout.addStretch(1)
        layout.addWidget(btn3)

        self.setLayout(layout)


if __name__ == "__main__":
    app = QApplication(sys.argv)

    main = Stretch()
    main.show()

    sys.exit(app.exec_())

 

收缩量为0的时候

"""
设置控件的伸缩量
"""

import sys, math
from PyQt5.QtWidgets import *
from PyQt5.QtCore import Qt

class Stretch(QWidget):
    def __init__(self):
        super(Stretch, self).__init__()
        self.setWindowTitle("设置控件的伸缩量")
        self.resize(800, 100)
        btn1 = QPushButton(self)
        btn2 = QPushButton(self)
        btn3 = QPushButton(self)
        btn4 = QPushButton(self)
        btn5 = QPushButton(self)
        btn1.setText("按钮1")
        btn2.setText("按钮2")
        btn3.setText("按钮3")
        btn4.setText("按钮4")
        btn5.setText("按钮5")

        layout = QHBoxLayout()

        layout.addStretch(0)
        layout.addWidget(btn1)
        layout.addWidget(btn2)
        layout.addWidget(btn3)
        layout.addWidget(btn4)
        layout.addWidget(btn5)

        btnOk = QPushButton(self)
        btnOk.setText("确定")
        btnCancel = QPushButton(self)
        btnCancel.setText("取消")
        layout.addStretch(1)
        layout.addWidget(btnOk)
        layout.addWidget(btnCancel)
        self.setLayout(layout)


if __name__ == "__main__":
    app = QApplication(sys.argv)

    main = Stretch()
    main.show()

    sys.exit(app.exec_())