pyside

from PySide2.QtWidgets import QApplication, QMainWindow, QHBoxLayout, \
    QVBoxLayout, QPushButton, QListWidget, QLabel, QWidget, QFileDialog
from PySide2.QtCore import Signal

import sys, os


class ImageViewer(QMainWindow):
    def __init__(self):
        super(ImageViewer, self).__init__()
        self.setWindowTitle("Simple Photo Viewer")
        # self.showMaximized()

        # must create a central widget!
        centralWidget = QWidget()
        self.setCentralWidget(centralWidget)

        mainLayout = QHBoxLayout(centralWidget)

        sideLayout = QVBoxLayout()
        mainLayout.addLayout(sideLayout)

        # create left side widgets
        self.fileBrowser = FolderList()
        photoData = PhotoData()
        browseButton = QPushButton("Browse...")

        sideLayout.addWidget(self.fileBrowser)
        sideLayout.addWidget(photoData)
        sideLayout.addWidget(browseButton)

        # add imageViewer
        imageViewer = PhotoViewer()
        mainLayout.addWidget(imageViewer)

        # connect signals
        browseButton.clicked.connect(self.browseAction)
        self.fileBrowser.imageSelected.connect(imageViewer.setImage)

    def browseAction(self):
        folder = QFileDialog.getExistingDirectory(self, "Select Folder")

        if len(folder):
            self.fileBrowser.setCurrentFolder(folder + "/")


class FolderList(QListWidget):
    imageSelected = Signal(str)

    def __init__(self):
        super(FolderList, self).__init__()
        self.currentFolder = None

        self.itemClicked.connect(self.imageSelectedAction)

    def refresh(self):
        self.clear()

        if not self.currentFolder: return

        fileList = [i for i in os.listdir(self.currentFolder) if i.lower().endswith(".jpg")]

        for f in fileList:
            self.addItem(f)

    def imageSelectedAction(self, currentItem):
        self.imageSelected.emit(self.currentFolder + currentItem.text())

    def setCurrentFolder(self, folderPath):
        if os.path.exists(folderPath):
            self.currentFolder = folderPath
            self.refresh()

class PhotoViewer(QLabel):
    def __init__(self):
        super(PhotoViewer, self).__init__()
        self.setText("IMAGE")
        self.setMinimumSize(500,500)

    def setImage(self, path):
        self.setPixmap(path)

class PhotoData(QWidget):
    def __init__(self):
        super(PhotoData, self).__init__()
        self.setMinimumSize(100, 100)

        mainLayout = QVBoxLayout(self)

        dateLabel = QLabel("Date:")
        cameraLabel = QLabel("Camera:")
        isoLabel = QLabel("ISO:")

        mainLayout.addWidget(dateLabel)
        mainLayout.addWidget(cameraLabel)
        mainLayout.addWidget(isoLabel)

# init window
app = QApplication(sys.argv)
win = ImageViewer()
win.show()
app.exec_()