[FIXED] Qt: how to dynamic change the position of other widget?

Issue

Let's say I have a GUI:

When I click the left button, I expect the object would locate at left just like:

layout.addWidget(object)
layout.addStretch()

How can I dynamically change the position?

from PyQt5.QtCore import *
from PyQt5.QtGui import *
from PyQt5.QtWidgets import *
import sys
class Widget(QWidget):

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

        layout = QVBoxLayout()
        self.setLayout(layout)

        self.btnPos = QPushButton('left')
        self.btnPos.clicked.connect(self.btnClick)

        self.btnLayout = QHBoxLayout()

        self.btn = QPushButton('object')
        self.btnLayout.addStretch()
        self.btnLayout.addWidget(self.btn)
        self.btnLayout.addStretch()
        layout.addWidget(self.btnPos)
        layout.addLayout(self.btnLayout)

    def btnClick(self, check=False):
        print('click')
        pass

if __name__ == '__main__':

    app = QApplication(sys.argv)
    win = Widget()
    win.show()
    app.exec_()

Solution

In your btnClick function, you can set the Stretch parameter for each item in self.btnLayout. In this case you want to set the Stretch for the spacer on the left to 0 and the right spacer to 1:

def btnClick(self, check=False):
    print('click')
    # align button left
    self.btnLayout.setStretch(0,0)
    self.btnLayout.setStretch(1,1)
    self.btnLayout.setStretch(2,1)
    pass

For centering the button, set left and right spacers stretch to 1:

# button is centered
self.btnLayout.setStretch(0,1)
self.btnLayout.setStretch(1,1)
self.btnLayout.setStretch(2,1)

And to align button on right, set left spacer to 1, right spacer to zero:

# align button right
self.btnLayout.setStretch(0,1)
self.btnLayout.setStretch(1,1)
self.btnLayout.setStretch(2,0)

Answered By - bfris