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############################################################################
##
## Copyright (C) 2021 The Qt Company Ltd.
## Contact: https://www.qt.io/licensing/
##
## This file is part of the Qt for Python examples of the Qt Toolkit.
##
## $QT_BEGIN_LICENSE:BSD$
## Commercial License Usage
## Licensees holding valid commercial Qt licenses may use this file in
## accordance with the commercial license agreement provided with the
## Software or, alternatively, in accordance with the terms contained in
## a written agreement between you and The Qt Company. For licensing terms
## and conditions see https://www.qt.io/terms-conditions. For further
## information use the contact form at https://www.qt.io/contact-us.
##
## BSD License Usage
## Alternatively, you may use this file under the terms of the BSD license
## as follows:
##
## "Redistribution and use in source and binary forms, with or without
## modification, are permitted provided that the following conditions are
## met:
## * Redistributions of source code must retain the above copyright
## notice, this list of conditions and the following disclaimer.
## * Redistributions in binary form must reproduce the above copyright
## notice, this list of conditions and the following disclaimer in
## the documentation and/or other materials provided with the
## distribution.
## * Neither the name of The Qt Company Ltd nor the names of its
## contributors may be used to endorse or promote products derived
## from this software without specific prior written permission.
##
##
## THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
## "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
## LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
## A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
## OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
## SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
## LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
## DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
## THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
## (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
## OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
##
## $QT_END_LICENSE$
##
############################################################################
import os
from pathlib import Path
from PySide6.QtWidgets import QFileDialog, QDialog
from PySide6.QtCore import QBuffer, QIODeviceBase, Slot, QSharedMemory, QDataStream, qVersion
from PySide6.QtGui import QImage, QPixmap
from ui_dialog import Ui_Dialog
class Dialog(QDialog):
def __init__(self, parent=None):
super().__init__(parent)
v = qVersion()
name = f"QSharedMemoryExample_v{v}"
self._shared_memory = QSharedMemory(name)
self.ui = Ui_Dialog()
self.ui.setupUi(self)
self.ui.loadFromFileButton.clicked.connect(self.load_from_file)
self.ui.loadFromSharedMemoryButton.clicked.connect(self.load_from_memory)
self.setWindowTitle("SharedMemory Example")
def ensure_detached(self):
if self._shared_memory.isAttached():
self.detach()
def closeEvent(self, e):
self.ensure_detached()
e.accept()
@Slot()
def load_from_file(self):
self.ensure_detached()
self.ui.label.setText("Select an image file")
dir = Path(__file__).resolve().parent
fileName, _ = QFileDialog.getOpenFileName(self, "Choose Image",
os.fspath(dir),
"Images (*.png *.jpg)")
if not fileName:
return
image = QImage()
if not image.load(fileName):
self.ui.label.setText("Selected file is not an image, please select another.")
return
self.ui.label.setPixmap(QPixmap.fromImage(image))
# load into shared memory
buffer = QBuffer()
buffer.open(QIODeviceBase.WriteOnly)
out = QDataStream(buffer)
out << image
buffer.close()
size = buffer.size()
if not self._shared_memory.create(size):
self.ui.label.setText("Unable to create shared memory segment.")
return
self._shared_memory.lock()
_to = memoryview(self._shared_memory.data())
_from = buffer.data().data()
_to[0:size] = _from[0:size]
self._shared_memory.unlock()
@Slot()
def load_from_memory(self):
if not self._shared_memory.isAttached() and not self._shared_memory.attach():
self.ui.label.setText("Unable to attach to shared memory segment.\n"
"Load an image first.")
return
self._shared_memory.lock()
mv = memoryview(self._shared_memory.constData())
buffer = QBuffer()
buffer.setData(mv.tobytes())
buffer.open(QBuffer.ReadOnly)
_in = QDataStream(buffer)
image = QImage()
_in >> image
buffer.close()
self._shared_memory.unlock()
self._shared_memory.detach()
self.ui.label.setPixmap(QPixmap.fromImage(image))
def detach(self):
if not self._shared_memory.detach():
self.ui.label.setText(tr("Unable to detach from shared memory."))
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