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Diffstat (limited to 'src/imports/sharedimage/plugin.cpp')
-rw-r--r-- | src/imports/sharedimage/plugin.cpp | 134 |
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diff --git a/src/imports/sharedimage/plugin.cpp b/src/imports/sharedimage/plugin.cpp new file mode 100644 index 0000000000..f20edc641c --- /dev/null +++ b/src/imports/sharedimage/plugin.cpp @@ -0,0 +1,134 @@ +/**************************************************************************** +** +** Copyright (C) 2017 The Qt Company Ltd. +** Contact: https://www.qt.io/licensing/ +** +** This file is part of the plugins of the Qt Toolkit. +** +** $QT_BEGIN_LICENSE:LGPL$ +** 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. +** +** GNU Lesser General Public License Usage +** Alternatively, this file may be used under the terms of the GNU Lesser +** General Public License version 3 as published by the Free Software +** Foundation and appearing in the file LICENSE.LGPL3 included in the +** packaging of this file. Please review the following information to +** ensure the GNU Lesser General Public License version 3 requirements +** will be met: https://www.gnu.org/licenses/lgpl-3.0.html. +** +** GNU General Public License Usage +** Alternatively, this file may be used under the terms of the GNU +** General Public License version 2.0 or (at your option) the GNU General +** Public license version 3 or any later version approved by the KDE Free +** Qt Foundation. The licenses are as published by the Free Software +** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3 +** included in the packaging of this file. Please review the following +** information to ensure the GNU General Public License requirements will +** be met: https://www.gnu.org/licenses/gpl-2.0.html and +** https://www.gnu.org/licenses/gpl-3.0.html. +** +** $QT_END_LICENSE$ +** +****************************************************************************/ + +#include <qqmlextensionplugin.h> +#include <qqmlengine.h> +#include <sharedimageprovider.h> + + +/*! + \qmlmodule QtQuick.SharedImage 1 + \title Qt Quick Shared Image Provider + \ingroup qmlmodules + \brief Adds an image provider which utilizes shared CPU memory + + \section2 Summary + + This module provides functionality to save memory in use cases where + several Qt Quick applications use the same local image files. It does this + by placing the decoded QImage data in shared system memory, making it + accessible to all the processes (see QSharedMemory). + + This module only shares CPU memory. It does not provide sharing of GPU + memory or textures. + + \section2 Usage + + To use this module, import it like this: + \code + import QtQuick.SharedImage 1.0 + \endcode + + The sharing functionality is provided through a QQuickImageProvider. Use + the "image:" scheme for the URL source of the image, followed by the + identifier \e shared, followed by the image file path. For example: + + \code + Image { source: "image://shared/usr/share/wallpapers/mybackground.jpg" } + \endcode + + This will look for the file \e /usr/share/wallpapers/mybackground.jpg. + The first process that does this will read the image file + using normal Qt image loading. The decoded image data will then be placed + in shared memory, using the full file path as key. Later processes + requesting the same image will discover that the data is already available + in shared memory. They will then use that instead of loading the image file + again. + + The shared image data will be kept available until the last process has deleted + its last reference to the shared image, at which point it is automatically released. + + If system memory sharing is not available, the shared image provider falls + back to normal, unshared image loading. + + The file path must be absolute. To use a relative path, make it absolute + using \e Qt.resolvedUrl() and replace the URL scheme. For example: + + \code + ... + property string imagePrefix: Qt.resolvedUrl("../myimages/").replace("file://", "image://shared/") + Image { source: imagePrefix + "myimage.png" } + \endcode + + The shared image module does not provide any directly usable QML types. +*/ + +static void initResources() +{ +#ifdef QT_STATIC + Q_INIT_RESOURCE(qmake_QtQuick_SharedImage); +#endif +} + +QT_BEGIN_NAMESPACE + +class QtQuickSharedImagePlugin : public QQmlExtensionPlugin +{ + Q_OBJECT + Q_PLUGIN_METADATA(IID QQmlExtensionInterface_iid) +public: + QtQuickSharedImagePlugin(QObject *parent = 0) : QQmlExtensionPlugin(parent) { initResources(); } + + void registerTypes(const char *uri) Q_DECL_OVERRIDE + { + Q_ASSERT(uri == QStringLiteral("QtQuick.SharedImage")); + // Need to register *something* to let our version number be known: + qmlRegisterTypeNotAvailable(uri, 1, 0, "nosuchtype", QStringLiteral("Just a dummy type, do not use")); + } + + void initializeEngine(QQmlEngine *engine, const char *uri) override + { + Q_UNUSED(uri); + engine->addImageProvider("shared", new SharedImageProvider); + } +}; + +QT_END_NAMESPACE + +#include "plugin.moc" |