scaledpixmap.py

from PyQt5.QtWidgets import QLabel
from PyQt5.Qt import Qt, QSize
from PyQt5.QtGui import QPixmap, QPainter
from PyQt5 import QtCore


class ScaledPixmap(QLabel):
    workPixmap = None
    stored_pixmap = None
    originalSize = None

    keepAspectRatio = True
    overscalingEnabled = True

    loadFinished = QtCore.pyqtSignal()

    def getPixmap(self):
        return self.workPixmap

    def pixmap(self):
        return self.stored_pixmap

    def overscaleEnabled(self):
        return self.overscalingEnabled

    def keepAspectRatioEnabled(self):
        return self.keepAspectRatio

    def fitsToScreen(self, screenSize):
        return (screenSize.width() >= self.originalSize.width()) and (screenSize.height() >= self.originalSize.height())

    def paintEvent(self, event):
        painter = QPainter(self)
        if self.workPixmap is not None:
            centerPoint = QtCore.QPoint(0, 0)
            scaledSize = self.size() if self.overscaleEnabled() else (self.originalSize if self.fitsToScreen(self.size()) else self.size())
            scaledPixmap = self.workPixmap.scaled(scaledSize,
                                                  Qt.KeepAspectRatio if self.keepAspectRatio else Qt.IgnoreAspectRatio)
            centerPoint.setX((self.size().width() - scaledPixmap.width()) / 2)
            centerPoint.setY((self.size().height() - scaledPixmap.height()) / 2)
            painter.drawPixmap(centerPoint, scaledPixmap)

        super().paintEvent(event)

    @QtCore.pyqtSlot(QPixmap, name='setScaledPixmap')
    def setScaledPixmap(self, pixmap):
        self.workPixmap = pixmap
        self.originalSize = pixmap.size()
        self.update()

    @QtCore.pyqtSlot(str, name='loadPixmapData')
    def loadPixmapData(self, source):
        pixmap = QPixmap(source)
        if pixmap is not None:
            self.setScaledPixmap(pixmap)
            self.stored_pixmap = pixmap


    @QtCore.pyqtSlot(QPixmap, name='loadPixmapData')
    def loadPixmapData(self, pixmap):
        if pixmap is not None:
            self.setScaledPixmap(pixmap)
            self.stored_pixmap = pixmap


    @QtCore.pyqtSlot(int, name='setOverscaleEnabled')
    def setOverscaleEnabled(self, enabled):
        self.overscalingEnabled = enabled
        self.update()

    @QtCore.pyqtSlot(int, name='setKeepAspectRatioEnabled')
    def setKeepAspectRatioEnabled(self, enabled):
        self.keepAspectRatio = enabled
        self.update()