QQmlApplicationEngine 類

QQmlApplicationEngine 提供從單個 QML 文件加載應用程序的便捷方式。更多...

頭：	#include <QQmlApplicationEngine>
qmake:	QT += qml
Since:	Qt 5.1
繼承：	QQmlEngine

該類在 Qt 5.1 引入。

所有成員列錶，包括繼承成員

公共函數

	QQmlApplicationEngine (const QString & filePath , QObject * parent = nullptr)
	QQmlApplicationEngine (const QUrl & url , QObject * parent = nullptr)
	QQmlApplicationEngine (QObject * parent = nullptr)
virtual	~QQmlApplicationEngine () override
QList<QObject *>	rootObjects () const

公共槽

void	load (const QString & filePath )
void	load (const QUrl & url )
void	loadData (const QByteArray & data , const QUrl & url = QUrl())
void	setInitialProperties (const QVariantMap & initialProperties )

信號

void	objectCreated (QObject * object , const QUrl & url )

詳細描述

此類組閤 QQmlEngine and QQmlComponent 提供加載單個 QML 文件的便捷方式。它還嚮 QML 暴露某些中心應用程序功能，C++/QML 混閤應用程序通常從 C++ 進行控製。

它可以像這樣使用：

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

不像 QQuickView ，QQmlApplicationEngine 不會自動創建根窗口。若正使用來自 Qt Quick 的視覺項，需要將它們放入 Window .

還可以使用 QCoreApplication 采用 QQmlApplicationEngine，若未使用任何 QML 模塊要求 QGuiApplication (譬如 QtQuick ).

配置列錶的改變從默認 QQmlEngine :

連接 Qt. quit () 到 QCoreApplication::quit ()
自動從主 QML 文件相鄰 i18n 目錄下加載翻譯文件。
- Translation files must have " qml_ " prefix e.g. qml_ja_JP.qm.
翻譯被重新加載當 QJSEngine::uiLanguage / Qt.uiLanguage 特性改變。
自動設置孵化控製器，若場景包含 QQuickWindow .
自動設置 QQmlFileSelector 作為 URL 攔截器，將文件選擇器應用於所有 QML 文件和資産。

可以進一步微調引擎行為，通過使用繼承的方法從 QQmlEngine .

成員函數文檔編製

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 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.

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.

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

Loads the root QML file located at filePath . filePath must be a path to a local file. 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 .

`[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 .

`[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 .

`[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.

`[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) }
});

該函數在 Qt 5.14 引入。

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

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

銷毀 QQmlApplicationEngine and all QML objects it loaded.

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 .