1 files changed, 151 insertions, 0 deletions
diff --git a/examples/network/loopback/dialog.py b/examples/network/loopback/dialog.py
new file mode 100644
index 000000000..673afce28
--- /dev/null
+++ b/examples/network/loopback/dialog.py
@@ -0,0 +1,151 @@
+# Copyright (C) 2022 The Qt Company Ltd.
+# SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
+from PySide6.QtCore import QByteArray, Qt
+from PySide6.QtGui import QGuiApplication
+from PySide6.QtNetwork import (QAbstractSocket, QHostAddress, QTcpServer,
+                               QTcpSocket)
+from PySide6.QtWidgets import (QDialog, QDialogButtonBox, QLabel, QMessageBox,
+                               QProgressBar, QPushButton, QVBoxLayout)
+
+
+class Dialog(QDialog):
+    def __init__(self, parent=None):
+        super().__init__(parent)
+
+        self.total_bytes = 50 * 1024 * 1024  # 50 MB
+        self.payload_size = 64 * 1024  # 64 KB
+
+        self.bytes_to_write = 0
+        self.bytes_written = 0
+        self.bytes_received = 0
+
+        self.client_progress_bar = QProgressBar()
+        self.client_status_label = QLabel("Client ready")
+        self.server_progress_bar = QProgressBar()
+        self.server_status_label = QLabel("Server ready")
+
+        self.start_button = QPushButton("&Start")
+        self.quit_button = QPushButton("&Quit")
+
+        self.button_box = QDialogButtonBox()
+        self.button_box.addButton(self.start_button, QDialogButtonBox.ActionRole)
+        self.button_box.addButton(self.quit_button, QDialogButtonBox.RejectRole)
+
+        self.start_button.clicked.connect(self.start)
+        self.quit_button.clicked.connect(self.close)
+
+        self.tcp_server = QTcpServer()
+        self.tcp_client = QTcpSocket()
+        self.tcp_server.newConnection.connect(self.accept_connection)
+        self.tcp_client.connected.connect(self.start_transfer)
+        self.tcp_client.bytesWritten.connect(self.update_client_progress)
+        self.tcp_client.errorOccurred.connect(self.display_error)
+
+        main_layout = QVBoxLayout()
+        main_layout.addWidget(self.client_progress_bar)
+        main_layout.addWidget(self.client_status_label)
+        main_layout.addWidget(self.server_progress_bar)
+        main_layout.addWidget(self.server_status_label)
+        main_layout.addStretch(1)
+        main_layout.addSpacing(10)
+        main_layout.addWidget(self.button_box)
+        self.setLayout(main_layout)
+
+        self.setWindowTitle("Loopback")
+
+    def start(self):
+
+        self.start_button.setEnabled(False)
+
+        QGuiApplication.setOverrideCursor(Qt.WaitCursor)
+
+        self.bytes_written = 0
+        self.bytes_received = 0
+
+        while not self.tcp_server.isListening() and not self.tcp_server.listen():
+            ret: QMessageBox.StandardButton = QMessageBox.critical(
+                self,
+                "Loopback",
+                f"Unable to start the test {self.tcp_server.errorString()}",
+                QMessageBox.Retry | QMessageBox.Cancel,
+            )
+            if ret == QMessageBox.Cancel:
+                return
+
+        self.server_status_label.setText("Listening")
+        self.client_status_label.setText("Connecting")
+        self.tcp_client.connectToHost(QHostAddress.LocalHost, self.tcp_server.serverPort())
+
+    def accept_connection(self):
+
+        self.tcp_server_connection = self.tcp_server.nextPendingConnection()
+        if not self.tcp_server_connection:
+            self.server_status_label.setText("Error: got invalid pending connection")
+            return
+
+        self.tcp_server_connection.readyRead.connect(self.update_server_progress)
+        self.tcp_server_connection.errorOccurred.connect(self.display_error)
+        self.tcp_server_connection.disconnected.connect(self.tcp_server_connection.deleteLater)
+
+        self.server_status_label.setText("Accepted connection")
+        self.tcp_server.close()
+
+    def start_transfer(self):
+
+        # Called when the TCP client has connected to the loopback server
+        self.bytes_to_write = self.total_bytes - self.tcp_client.write(
+            QByteArray(self.payload_size, "@")
+        )
+        self.client_status_label.setText("Connected")
+
+    def update_server_progress(self):
+
+        self.bytes_received += self.tcp_server_connection.bytesAvailable()
+        self.tcp_server_connection.readAll()
+
+        self.server_progress_bar.setMaximum(self.total_bytes)
+        self.server_progress_bar.setValue(self.bytes_received)
+        self.server_status_label.setText(f"Received {self.bytes_received / (1024 ** 2)} MB")
+
+        if self.bytes_received == self.total_bytes:
+
+            self.tcp_server_connection.close()
+            self.start_button.setEnabled(True)
+
+            QGuiApplication.restoreOverrideCursor()
+
+    def update_client_progress(self, num_bytes: int):
+
+        # called when the TCP client has written some bytes
+        self.bytes_written += num_bytes
+
+        # only write more if not finished and when the Qt write buffer is below a certain size
+        if self.bytes_to_write > 0 and self.tcp_client.bytesToWrite() <= 4 * self.payload_size:
+            self.bytes_to_write -= self.tcp_client.write(
+                QByteArray(min(self.bytes_to_write, self.payload_size), "@")
+            )
+
+        self.client_progress_bar.setMaximum(self.total_bytes)
+        self.client_progress_bar.setValue(self.bytes_written)
+        self.client_status_label.setText(f"Sent {self.bytes_written / (1024 ** 2)} MB")
+
+    def display_error(self, socket_error: QAbstractSocket.SocketError):
+        if socket_error == QAbstractSocket.RemoteHostClosedError:
+            return
+
+        QMessageBox.information(
+            self,
+            "Network error",
+            f"The following error occurred: {self.tcp_client.errorString()}",
+        )
+
+        self.tcp_client.close()
+        self.tcp_server.close()
+        self.client_progress_bar.reset()
+        self.server_progress_bar.reset()
+        self.client_status_label.setText("Client ready")
+        self.server_status_label.setText("Server ready")
+        self.start_button.setEnabled(True)
+
+        QGuiApplication.restoreOverrideCursor()