Qt 5.13 | Qt Quick Demo - Photo Surface

Qt 5.13.2 Reference Documentation

# Qt Quick Demo - Photo Surface

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      #ifdef QT_WIDGETS_LIB
      #include <QtWidgets/QApplication>
      #else
      #include <QtGui/QGuiApplication>
      #endif
      #include <QtQml/QQmlApplicationEngine>
      #include <QtQml/QQmlContext>
      #include <QtQuick/QQuickWindow>
      #include <QtGui/QImageReader>
      #include <QtCore/QCommandLineParser>
      #include <QtCore/QCommandLineOption>
      #include <QtCore/QDebug>
      #include <QtCore/QDir>
      #include <QtCore/QMimeDatabase>
      #include <QtCore/QStandardPaths>
      #include <QtCore/QUrl>

      static QStringList imageNameFilters()
      {
          QStringList result;
          QMimeDatabase mimeDatabase;
          const auto supportedMimeTypes = QImageReader::supportedMimeTypes();
          for (const QByteArray &m : supportedMimeTypes) {
              const auto suffixes = mimeDatabase.mimeTypeForName(m).suffixes();
              for (const QString &suffix : suffixes)
                  result.append(QLatin1String("*.") + suffix);
          }
          return result;
      }

      int main(int argc, char* argv[])
      {
          // The reason to use QApplication is that QWidget-based dialogs
          // are the native dialogs on Qt-based platforms like KDE,
          // but they cannot be instantiated if this is a QGuiApplication.
      #ifdef QT_WIDGETS_LIB
          QApplication app(argc, argv);
      #else
          QGuiApplication app(argc, argv);
      #endif
          QQuickWindow::setDefaultAlphaBuffer(true);

          QCoreApplication::setApplicationName(QStringLiteral("Photosurface"));
          QCoreApplication::setOrganizationName(QStringLiteral("QtProject"));
          QCoreApplication::setApplicationVersion(QLatin1String(QT_VERSION_STR));
          QCommandLineParser parser;
          parser.setApplicationDescription(QStringLiteral("Qt Quick Demo - Photo Surface"));
          parser.addHelpOption();
          parser.addVersionOption();
          parser.addPositionalArgument(QStringLiteral("directory"),
                                       QStringLiteral("The image directory or URL to show."));
          parser.process(app);

          QUrl initialUrl;
          if (!parser.positionalArguments().isEmpty()) {
              initialUrl = QUrl::fromUserInput(parser.positionalArguments().first(),
                                               QDir::currentPath(), QUrl::AssumeLocalFile);
              if (!initialUrl.isValid()) {
                  qWarning().nospace() << "Invalid argument: \""
                      << parser.positionalArguments().first() << "\": " << initialUrl.errorString();
                  return 1;
              }
          }

          const QStringList nameFilters = imageNameFilters();

          QQmlApplicationEngine engine;
          QQmlContext *context = engine.rootContext();

          QUrl picturesLocationUrl = QUrl::fromLocalFile(QDir::homePath());
          const QStringList picturesLocations = QStandardPaths::standardLocations(QStandardPaths::PicturesLocation);
          if (!picturesLocations.isEmpty()) {
              picturesLocationUrl = QUrl::fromLocalFile(picturesLocations.first());
              if (initialUrl.isEmpty()
                  && !QDir(picturesLocations.first()).entryInfoList(nameFilters, QDir::Files).isEmpty()) {
                  initialUrl = picturesLocationUrl;
              }
          }

          context->setContextProperty(QStringLiteral("contextPicturesLocation"), picturesLocationUrl);
          context->setContextProperty(QStringLiteral("contextInitialUrl"), initialUrl);
          context->setContextProperty(QStringLiteral("contextImageNameFilters"), nameFilters);

          engine.load(QUrl("qrc:///photosurface.qml"));
          if (engine.rootObjects().isEmpty())
              return -1;

          return app.exec();
      }