How to go through next and previous list items with buttons?

Question

I have a list:

files = ["image1.png", "image2.png", "image3.png", "image4.png", "image5.png", "image6.png"]

And PyQt5 buttons and a label:

How can I have the first item of the list on the label and go through the list one by one with the:

Next button (click, image2.png, click, image3.png, click, image4.png...)

Previous button (click, image3.png, click, image2.png, click, image1.png...)

And the label should update accordingly.

I've tried all day and searched for answers but couldn't get it to work. This could help maybe, my skills weren't enough to utilize the advice, though.

All the code to create the above window with buttons:

import sys
from PyQt5.QtWidgets import QApplication, QWidget, QPushButton, QLabel
from PyQt5.QtGui import QIcon
from PyQt5.QtCore import pyqtSlot

class App(QWidget):

    def __init__(self):
        super().__init__()
        self._files = deque()
        self._filesCount = len(self._files)
        self._setupUI()
        self._connectSignalsSlots()

    def __init__(self):
        super().__init__()
        self.title = 'PyQt5 button - pythonspot.com'
        self.left = 10
        self.top = 10
        self.width = 320
        self.height = 200
        self.initUI()

    def initUI(self):
        self.setWindowTitle(self.title)
        self.setGeometry(self.left, self.top, self.width, self.height)

        button = QPushButton('Print Files List', self)
        button.move(100,70)
        button.clicked.connect(self.loadFiles)

        self.setWindowTitle(self.title)
        self.setGeometry(self.left, self.top, self.width, self.height)

        button = QPushButton('Print Next Filename', self)
        button.move(160,110)
        button.clicked.connect(self.nextFilename)
        label = QLabel('image1.png (should be first of the list, \n and update with button presses)', self)
        label.move(35,140)

        button = QPushButton('Print Previous Filename', self)
        button.move(10,110)
        button.clicked.connect(self.previousFilename)

        self.show()

    @pyqtSlot()
    def loadFiles(self):
        files = ["image1.png", "image2.png", "image3.png", "image4.png", "image5.png", "image6.png"]
        if len(files) > 0:
            for file in files:
                print(file)

    def nextFilename(self):
        print('nextFilenameButton click')

    def previousFilename(self):
        print('previousFilenameButton click')

if __name__ == '__main__':
    app = QApplication(sys.argv)
    ex = App()
    sys.exit(app.exec_())

Answer 1

The solution is to handle an index (or cursor) that serves to obtain the filename. And that index must be modified through the buttons

import sys

from PyQt5.QtGui import QPixmap
from PyQt5.QtWidgets import QApplication, QGridLayout, QLabel, QPushButton, QWidget


class Widget(QWidget):
    def __init__(self, parent=None):
        super().__init__(parent)
        self._current_index = 0
        self._filenames = []

        self.previous_button = QPushButton("Previous")
        self.next_button = QPushButton("Next")
        self.print_button = QPushButton("Print")
        self.label = QLabel()

        lay = QGridLayout(self)
        lay.addWidget(self.previous_button, 0, 0)
        lay.addWidget(self.next_button, 0, 1)
        lay.addWidget(self.print_button, 0, 2)
        lay.addWidget(self.label, 1, 0, 1, 3)

        self.previous_button.clicked.connect(self.handle_previous)
        self.next_button.clicked.connect(self.handle_next)
        self.print_button.clicked.connect(self.handle_print)

        self._update_button_status(False, True)

        self.load_files()

    def load_files(self):
        self._filenames = [
            "image1.png",
            "image2.png",
            "image3.png",
            "image4.png",
            "image5.png",
            "image6.png",
        ]
        self.current_index = 0

    def handle_next(self):
        self.current_index += 1

    def handle_previous(self):
        self.current_index -= 1

    def handle_print(self):
        for filename in self._filenames:
            print(filename)

    @property
    def current_index(self):
        return self._current_index

    @current_index.setter
    def current_index(self, index):
        if index <= 0:
            self._update_button_status(False, True)
        elif index >= (len(self._filenames) - 1):
            self._update_button_status(True, False)
        else:
            self._update_button_status(True, True)

        if 0 <= index < len(self._filenames):
            self._current_index = index
            filename = self._filenames[self._current_index]
            pixmap = QPixmap(filename)
            self.label.setPixmap(pixmap)

    def _update_button_status(self, previous_enable, next_enable):
        self.previous_button.setEnabled(previous_enable)
        self.next_button.setEnabled(next_enable)


if __name__ == "__main__":
    app = QApplication(sys.argv)
    w = Widget()
    w.resize(640, 480)
    w.show()
    sys.exit(app.exec_())

Note: Having 2 methods with the same name is useless since in python only the last implementation will be used.