Pyside6, How do I resize a QLabel without loosing the size aspect ratio?

Question

My issue goes excactly as in those related posts:

Only difference is that I'm using Pyside instead of PyQt and that I've already found the answer but I did't want to create any confusion by posting it anywhere else besides here.

Giorgos Xou · Accepted Answer · 2022-05-11T18:08:34.343

Thanks to this PyQt answer !!!

I was able to find out how to do the same thing in PySide6 pretty flawlessly by following those simple example steps:

Open pyside6-designer\Qt-designer:

1. Create a new window like this one:	2. Right-Click on label and go to "Promote to...":

3. Select `Form > View Python Code..` & save it as `ui_main.py`

^{click here if you have an issue at step 3.: "Unable to Launch Qt uic"}

Create files :

# custom_widgets.py

from PySide6 import QtCore, QtGui, QtWidgets


class ScaledLabel(QtWidgets.QLabel):
    def __init__(self, *args, **kwargs):
        QtWidgets.QLabel.__init__(self)
        self._pixmap = self.pixmap()
        self._resised= False
    
    def resizeEvent(self, event):
        self.setPixmap(self._pixmap)     

    def setPixmap(self, pixmap): #overiding setPixmap
        if not pixmap:return 
        self._pixmap = pixmap
        return QtWidgets.QLabel.setPixmap(self,self._pixmap.scaled(
                self.frameSize(),
                QtCore.Qt.KeepAspectRatio))

# main.py

from   PySide6.QtWidgets import *
from   PySide6           import QtCore
from   PySide6.QtGui     import QPixmap
from   PySide6.QtCore    import QPropertyAnimation
from   ui_main           import Ui_MainWindow
import sys, os


CWD = os.path.dirname(__file__) + os.sep
class MainWindow(QMainWindow): 
    def __init__(self):
        QMainWindow.__init__(self)
        self.ui = Ui_MainWindow()
        self.ui.setupUi(self)
        self.ui.label.setPixmap(QPixmap(CWD + 'lenna.jpg'))
        self.ui.pushButton.clicked.connect(lambda: self.resizeMainWindow(1200,500))
        self.show()

    def resizeMainWindow(self, width, height):
        self.animation = QPropertyAnimation(self, b"size")
        self.animation.setLoopCount(3)
        self.animation.setDuration(3000)
        self.animation.setKeyValueAt(0   ,QtCore.QSize(self.width()  ,self.height()  ))
        self.animation.setKeyValueAt(0.25,QtCore.QSize(self.width()/2,self.height()/2))
        self.animation.setKeyValueAt(0.5 ,QtCore.QSize(self.width()/2,self.height()  ))
        self.animation.setKeyValueAt(0.75,QtCore.QSize(self.width()  ,self.height()/2))
        self.animation.setKeyValueAt(1   ,QtCore.QSize(self.width()  ,self.height()  ))
        self.animation.setEasingCurve(QtCore.QEasingCurve.InOutSine)
        self.animation.start()


if __name__ == "__main__":
    app = QApplication(sys.argv)
    window = MainWindow()
    sys.exit(app.exec_())
    
    
    
"""
 * [QPixmap only works with absolute Path](https://stackoverflow.com/a/26323327/11465149)
 * [Relative paths in Python](https://stackoverflow.com/a/918178/11465149)
 * [resizeMainWindow()](https://github.com/Wanderson-Magalhaes/QPropertyAnimation_PySide2_PyQt5_Widgets_Animation/blob/master/main.py#L60)
"""

^{if everything went fine so far, you should also have a kind of similar ui_main.py file in your working directory like this one.}

✔️ And you should have a working example like the one demonstrated here left:

With `ScaledLabel`	With `QLabel`

Pyside6, How do I resize a QLabel without loosing the size aspect ratio?

1 Answers1

Thanks to this PyQt answer !!!