QScrollArea in QGridLayout

Question

In PySide6 (the same as PySide2 and PyQt5)

I wanted to divide the QMainWindow into four parts, each with a QScrollArea for displaying an image.Here is the minimal reproducible example.

from PySide6.QtCore import *
from PySide6.QtGui import *
from PySide6.QtWidgets import *
import sys
import numpy as np

class MainWindow(QMainWindow):
    def __init__(self):
        super(MainWindow, self).__init__()
        self.setupUi()

    def setupUi(self, *args,**kwargs):
        self.mainWindow = MainWindow
        self.resize(800,600)
        self.load()

    def load(self):

        internalWidget = QWidget()
        gridLayout = QGridLayout(internalWidget)
        internalWidget.setLayout(gridLayout)
        self.setCentralWidget(internalWidget)
        # row, column, rowSpan, columnSpan
        config = [
            [0, 0, 1, 1], 
            [0, 1, 1, 1], 
            [1, 0, 1, 1], 
            [1, 1, 1, 1],
        ]
        for row, column, rowSpan, columnSpan in config:

            # create scrollArea
            scrollArea = QScrollArea()
            scrollArea.setSizePolicy(QSizePolicy.Expanding,QSizePolicy.Expanding)
            scrollArea.setViewportMargins(0,0,0,0)
            scrollArea.setWidgetResizable(True)
            gridLayout.setContentsMargins(0,0,0,0)
            #########################random pixmap#####################################
            arr = np.random.randint(0,255,(200+row*200,200+column*100))# random a image
            if [row, column, rowSpan, columnSpan] == [0, 1, 1, 1]:
                arr = np.random.randint(0,255,(1000,1000))
            image = QImage(arr[:], arr.shape[1], arr.shape[0], arr.shape[1] * 3, QImage.Format_RGB888)
            pixmap = QPixmap.fromImage(image)
            ###########################################################################
            label = QLabel()
            label.setPixmap(pixmap)
            scrollArea.setWidget(label)
            scrollArea.setAlignment(Qt.AlignCenter)
            label.show()

            gridLayout.addWidget(scrollArea, row, column, rowSpan, columnSpan, alignment=Qt.AlignCenter)
            scrollArea.show()

if __name__ == "__main__":

    app = QApplication(sys.argv)
    window = MainWindow()
    window.show()
    sys.exit(app.exec_())

But when I ran it, the QScrollArea could fill a grid of QGridLayout only if the image was large enough. If the image is smaller than a grid, the QScrollArea becomes the same size as the image (smaller than a grid).

snapshot:

How can I make each QScrollArea always fill a grid without resizing the image? (Not that each QScrollArea is different in size)

Answer 1

If you want each QScrollArea to occupy the same space then set the same stretch factor in each row and column:

import random
import sys


from PySide6.QtCore import QSize, Qt
from PySide6.QtGui import QColor, QPixmap
from PySide6.QtWidgets import (
    QApplication,
    QGridLayout,
    QLabel,
    QMainWindow,
    QScrollArea,
    QWidget,
)


class MainWindow(QMainWindow):
    def __init__(self):
        super(MainWindow, self).__init__()
        self.setupUi()

    def setupUi(self):
        self.resize(800, 600)
        self.load()

    def load(self):

        internalWidget = QWidget()
        gridLayout = QGridLayout(internalWidget)
        gridLayout.setContentsMargins(0, 0, 0, 0)
        self.setCentralWidget(internalWidget)
        config = [
            [0, 0],
            [0, 1],
            [1, 0],
            [1, 1],
        ]
        for row, column in config:
            scrollArea = QScrollArea(widgetResizable=True)
            scrollArea.setViewportMargins(0, 0, 0, 0)

            pixmap = QPixmap(QSize(*random.sample(range(0, 500), 2)))
            pixmap.fill(QColor(*random.sample(range(0, 255), 3)))

            label = QLabel(alignment=Qt.AlignCenter)
            label.setPixmap(pixmap)
            scrollArea.setWidget(label)

            gridLayout.addWidget(scrollArea, row, column)

        gridLayout.setColumnStretch(0, 1)
        gridLayout.setColumnStretch(1, 1)
        gridLayout.setRowStretch(0, 1)
        gridLayout.setRowStretch(1, 1)


if __name__ == "__main__":

    app = QApplication(sys.argv)
    window = MainWindow()
    window.show()
    sys.exit(app.exec_())