- Qt 5.5
- Qt Widgets
- Image Gestures Example
- main.cpp Example File
- Qt 5.5.1 Reference Documentation

# main.cpp Example File

gestures/imagegestures/main.cpp

    /****************************************************************************
    **
    ** Copyright (C) 2015 The Qt Company Ltd.
    ** Contact: http://www.qt.io/licensing/
    **
    ** This file is part of the examples of the Qt Toolkit.
    **
    ** $QT_BEGIN_LICENSE:BSD$
    ** 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
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    **   * Redistributions of source code must retain the above copyright
    **     notice, this list of conditions and the following disclaimer.
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    **     notice, this list of conditions and the following disclaimer in
    **     the documentation and/or other materials provided with the
    **     distribution.
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    **     contributors may be used to endorse or promote products derived
    **     from this software without specific prior written permission.
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    ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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    #include <QtWidgets>

    #include "mainwidget.h"

    static void showHelp(QCommandLineParser &parser, const QString errorMessage = QString())
    {
        QString text;
        QTextStream str(&text);
        str << "<html><head/><body>";
        if (!errorMessage.isEmpty())
            str << "<p>" << errorMessage << "</p>";
        str << "<pre>" << parser.helpText() << "</pre></body></html>";
        QMessageBox box(errorMessage.isEmpty() ? QMessageBox::Information : QMessageBox::Warning,
                        QGuiApplication::applicationDisplayName(), text,
                        QMessageBox::Ok);
        box.setTextInteractionFlags(Qt::TextBrowserInteraction);
        box.exec();
    }

    int main(int argc, char *argv[])
    {
        QApplication app(argc, argv);
        QCoreApplication::setApplicationVersion(QT_VERSION_STR);
        QCoreApplication::setApplicationName(QStringLiteral("imagegestures"));
        QGuiApplication::setApplicationDisplayName(QStringLiteral("Image Gestures Example"));

        QCommandLineParser commandLineParser;
        const QCommandLineOption disablePanOption("no-pan", "Disable pan gesture");
        commandLineParser.addOption(disablePanOption);
        const QCommandLineOption disablePinchOption("no-pinch", "Disable pinch gesture");
        commandLineParser.addOption(disablePinchOption);
        const QCommandLineOption disableSwipeOption("no-swipe", "Disable swipe gesture");
        commandLineParser.addOption(disableSwipeOption);
        const QCommandLineOption helpOption = commandLineParser.addHelpOption();
        commandLineParser.addPositionalArgument(QStringLiteral("Directory"),
                                                QStringLiteral("Directory to display"));

        const QString description = QGuiApplication::applicationDisplayName()
            + QLatin1String("\n\nEnable \"debug\" on the logging category \"qt.examples.imagegestures\" in order to\n"
                            "in order to obtain verbose information about Qt's gesture event processing,\n"
                            "for example by setting the environment variables QT_LOGGING_RULES to\n"
                            "qt.examples.imagegestures.debug=true\n");
        commandLineParser.setApplicationDescription(description);

        commandLineParser.process(QCoreApplication::arguments());

        QStringList arguments = commandLineParser.positionalArguments();
        if (!arguments.isEmpty() && !QFileInfo(arguments.front()).isDir()) {
            showHelp(commandLineParser,
                     QLatin1Char('"') + QDir::toNativeSeparators(arguments.front())
                     + QStringLiteral("\" is not a directory."));
            return -1;
        }

        QList<Qt::GestureType> gestures;
        if (!commandLineParser.isSet(disablePanOption))
            gestures << Qt::PanGesture;
        if (!commandLineParser.isSet(disablePinchOption))
            gestures << Qt::PinchGesture;
        if (!commandLineParser.isSet(disableSwipeOption))
            gestures << Qt::SwipeGesture;

        MainWidget w;
        w.grabGestures(gestures);
        w.show();

        if (arguments.isEmpty()) {
            const QStringList picturesLocations = QStandardPaths::standardLocations(QStandardPaths::PicturesLocation);
            const QString directory =
                QFileDialog::getExistingDirectory(&w, "Select image folder",
                                                  picturesLocations.isEmpty() ? QString() : picturesLocations.front());
            if (directory.isEmpty())
                return 0;
            arguments.append(directory);
        }

        w.openDirectory(arguments.front());

        return app.exec();
    }