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from PySide2.QtCore import *
from PySide2.QtGui import *
import sys

class MyScrollArea (QAbstractScrollArea):
    widget = None

    def __init__(widget):
        self.setWidget(widget);

    def setWidget(w):
        self.widget = w;
        self.widget.setParent(viewport());
        if not self.widget.testAttribute(Qt.WA_Resized):
            self.widget.resize(widget.sizeHint())

        self.verticalScrollBar().setValue(0)
        self.verticalScrollBar().setValue(0)

        self.updateArea()


    def updateWidgetPosition():
//! [0]
        hvalue = self.horizontalScrollBar().value()
        vvalue = self.verticalScrollBar().value()
        topLeft = self.viewport().rect().topLeft()

        self.widget.move(topLeft.x() - hvalue, topLeft.y() - vvalue)
//! [0]


    def scrollContentsBy(dx, dy):
        self.updateWidgetPosition()

    def updateArea():
//! [1]
        areaSize = viewport().size()
        widgetSize = widget.size()

        self.verticalScrollBar().setPageStep(widgetSize.height())
        self.horizontalScrollBar().setPageStep(widgetSize.width())
        self.verticalScrollBar().setRange(0, widgetSize.height() - areaSize.height())
        self.horizontalScrollBar().setRange(0, widgetSize.width() - areaSize.width())
        self.updateWidgetPosition()
//! [1]

    def resizeEvent(QResizeEvent):
        self.updateArea()

app = QApplication(sys.argv)
pixmap = QPixmap("mypixmap.png")
label = QLabel()
label.setPixmap(pixmap)
area = MyScrollArea(label)
area.resize(300, 300)
area.show()

area.setWidget(label)

app.exec_();

