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2. Qt 6.10.1
3. Qt QML
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5. QQmlApplicationEngine

#include <QGuiApplication>
#include <QQmlApplicationEngine>
int main(int argc, char *argv[])
{
    QGuiApplication app(argc, argv);
    QQmlApplicationEngine engine("main.qml");
    return app.exec();
}
					

qt_add_translations(App
    RESOURCE_PREFIX /qt/qml/Translated/i18n
    TS_FILE_BASE qml
    TS_FILE_DIR i18n
)
					

成員函數文檔編製

QQmlApplicationEngine:: QQmlApplicationEngine ( QObject * parent = nullptr)

Create a new QQmlApplicationEngine with the given parent . You will have to call load () later in order to load a QML file.

QQmlApplicationEngine:: QQmlApplicationEngine (const QString & filePath , QObject * parent = nullptr)

Create a new QQmlApplicationEngine and loads the QML file at the given filePath , which must be a local file or qrc path. If a relative path is given then it will be interpreted as relative to the working directory of the application.

This is provided as a convenience, and is the same as using the empty constructor and calling load afterwards.

QQmlApplicationEngine:: QQmlApplicationEngine (const QUrl & url , QObject * parent = nullptr)

Create a new QQmlApplicationEngine and loads the QML file at the given url . This is provided as a convenience, and is the same as using the empty constructor and calling load afterwards.

[explicit, since 6.5] QQmlApplicationEngine:: QQmlApplicationEngine ( QAnyStringView uri , QAnyStringView typeName , QObject * parent = nullptr)

Create a new QQmlApplicationEngine and loads the QML type specified by uri and typeName This is provided as a convenience, and is the same as using the empty constructor and calling loadFromModule afterwards.

該函數在 Qt 6.5 引入。

[override virtual noexcept] QQmlApplicationEngine:: ~QQmlApplicationEngine ()

銷毀 QQmlApplicationEngine and all QML objects it loaded.

[slot] void QQmlApplicationEngine:: load (const QString & filePath )

Loads the root QML file located at filePath . filePath must be a path to a local file or a path to a file in the resource file system. If filePath is a relative path, it is taken as relative to the application's working directory. The object tree defined by the file is instantiated immediately.

若齣現錯誤，打印錯誤消息采用 qWarning .

注意： 此槽被重載。要連接到此槽：

// Connect using qOverload:
connect(qmlApplicationEngine, qOverload(&QQmlApplicationEngine::load),
        receiver, &ReceiverClass::slot);
// Or using a lambda:
connect(qmlApplicationEngine, qOverload(&QQmlApplicationEngine::load),
        this, [](const QString &filePath) { /* handle load */ });
			

更多範例和方式，見 連接到重載槽 .

[slot] void QQmlApplicationEngine:: load (const QUrl & url )

Loads the root QML file located at url . The object tree defined by the file is created immediately for local file urls. Remote urls are loaded asynchronously, listen to the objectCreated signal to determine when the object tree is ready.

If an error occurs, the objectCreated signal is emitted with a null pointer as parameter and error messages are printed with qWarning .

注意： 此槽被重載。要連接到此槽：

// Connect using qOverload:
connect(qmlApplicationEngine, qOverload(&QQmlApplicationEngine::load),
        receiver, &ReceiverClass::slot);
// Or using a lambda:
connect(qmlApplicationEngine, qOverload(&QQmlApplicationEngine::load),
        this, [](const QUrl &url) { /* handle load */ });
			

更多範例和方式，見 連接到重載槽 .

[slot] void QQmlApplicationEngine:: loadData (const QByteArray & data , const QUrl & url = QUrl())

Loads the QML given in data . The object tree defined by data is instantiated immediately.

若 url is specified it is used as the base url of the component. This affects relative paths within the data and error messages.

若齣現錯誤，打印錯誤消息采用 qWarning .

[slot, since 6.5] void QQmlApplicationEngine:: loadFromModule ( QAnyStringView uri , QAnyStringView typeName )

Loads the QML type typeName from the module specified by uri . If the type originates from a QML file located at a remote url, the type will be loaded asynchronously. Listen to the objectCreated signal to determine when the object tree is ready.

If an error occurs, the objectCreated signal is emitted with a null pointer as parameter and error messages are printed with qWarning .

QQmlApplicationEngine engine;
engine.loadFromModule("QtQuick", "Rectangle");
			

注意： The module identified by uri is searched in the import 路徑 , in the same way as if you were doing import uri inside a QML file. If the module cannot be located there, this function will fail.

該函數在 Qt 6.5 引入。

另請參閱 QQmlComponent::loadFromModule .

[signal] void QQmlApplicationEngine:: objectCreated ( QObject * object , const QUrl & url )

This signal is emitted when an object finishes loading. If loading was successful, object contains a pointer to the loaded object, otherwise the pointer is NULL.

The url to the component the object came from is also provided.

注意： If the path to the component was provided as a QString containing a relative path, the url will contain a fully resolved path to the file.

[signal, since 6.4] void QQmlApplicationEngine:: objectCreationFailed (const QUrl & url )

This signal is emitted when loading finishes because an error occurred.

The url to the component that failed to load is provided as an argument.

QGuiApplication app(argc, argv);
QQmlApplicationEngine engine;
// exit on error
QObject::connect(&engine, &QQmlApplicationEngine::objectCreationFailed,
    &app, []() { QCoreApplication::exit(-1); }, Qt::QueuedConnection);
engine.load(QUrl());
return app.exec();
			

注意： If the path to the component was provided as a QString containing a relative path, the url will contain a fully resolved path to the file.

另請參閱 QQmlApplicationEngine::objectCreated , which will be emitted in addition to this signal (even though creation failed).

該函數在 Qt 6.4 引入。

QList < QObject *> QQmlApplicationEngine:: rootObjects () const

Returns a list of all the root objects instantiated by the QQmlApplicationEngine . This will only contain objects loaded via load () or a convenience constructor.

注意： In Qt versions prior to 5.9, this function is marked as non- const .

[slot, since 6.0] void QQmlApplicationEngine:: setExtraFileSelectors (const QStringList & extraFileSelectors )

設置 extraFileSelectors to be passed to the internal QQmlFileSelector used for resolving URLs to local files. The extraFileSelectors are applied when the first QML file is loaded. Setting them afterwards has no effect.

該函數在 Qt 6.0 引入。

另請參閱 QQmlFileSelector and QFileSelector::setExtraSelectors .

[slot] void QQmlApplicationEngine:: setInitialProperties (const QVariantMap & initialProperties )

設置 initialProperties with which the QML component gets initialized after it gets loaded.

QQmlApplicationEngine engine;
EventDatabase eventDatabase;
EventMonitor eventMonitor;
engine.setInitialProperties({
    { "eventDatabase", QVariant::fromValue(&eventDatabase) },
    { "eventMonitor", QVariant::fromValue(&eventMonitor) }
});
			

另請參閱 QQmlComponent::setInitialProperties , QQmlApplicationEngine::load ，和 QQmlApplicationEngine::loadData .