import QtQuick 1.0

Item {
    width: 200
    height: 200
}

QDeclarativeEngine *engine = new QDeclarativeEngine;
QDeclarativeComponent component(engine, QUrl::fromLocalFile("main.qml"));

QObject *myObject = component.create();
QDeclarativeItem *item = qobject_cast<QDeclarativeItem*>(myObject);
int width = item->width();  // width = 200

MyApplication::MyApplication()
{
    // ...
    component = new QDeclarativeComponent(engine, QUrl("http://www.example.com/main.qml"));
    if (component->isLoading())
        QObject::connect(component, SIGNAL(statusChanged(QDeclarativeComponent::Status)),
                         this, SLOT(continueLoading()));
    else
        continueLoading();
}

void MyApplication::continueLoading()
{
    if (component->isError()) {
        qWarning() << component->errors();
    } else {
        QObject *myObject = component->create();
    }
}

Member Function Documentation

QDeclarativeComponent::QDeclarativeComponent(QDeclarativeEngine * engine, QObject * parent = 0)

Create a QDeclarativeComponent with no data and give it the specified engine and parent. Set the data with setData().

QDeclarativeComponent::QDeclarativeComponent(QDeclarativeEngine * engine, const QString & fileName, QObject * parent = 0)

Create a QDeclarativeComponent from the given fileName and give it the specified parent and engine.

See also loadUrl().

QDeclarativeComponent::QDeclarativeComponent(QDeclarativeEngine * engine, const QUrl & url, QObject * parent = 0)

Create a QDeclarativeComponent from the given url and give it the specified parent and engine.

Ensure that the URL provided is full and correct, in particular, use QUrl::fromLocalFile() when loading a file from the local filesystem.

See also loadUrl().

[virtual] QDeclarativeComponent::~QDeclarativeComponent()

Destruct the QDeclarativeComponent.

[virtual] QObject * QDeclarativeComponent::beginCreate(QDeclarativeContext * context)

This method provides more advanced control over component instance creation. In general, programmers should use QDeclarativeComponent::create() to create a component.

Create an object instance from this component. Returns 0 if creation failed. context specifies the context within which to create the object instance.

When QDeclarativeComponent constructs an instance, it occurs in three steps:

1. The object hierarchy is created, and constant values are assigned.
2. Property bindings are evaluated for the the first time.
3. If applicable, QDeclarativeParserStatus::componentComplete() is called on objects.

QDeclarativeComponent::beginCreate() differs from QDeclarativeComponent::create() in that it only performs step 1. QDeclarativeComponent::completeCreate() must be called to complete steps 2 and 3.

This breaking point is sometimes useful when using attached properties to communicate information to an instantiated component, as it allows their initial values to be configured before property bindings take effect.

[virtual] void QDeclarativeComponent::completeCreate()

This method provides more advanced control over component instance creation. In general, programmers should use QDeclarativeComponent::create() to create a component.

Complete a component creation begin with QDeclarativeComponent::beginCreate().

[virtual] QObject * QDeclarativeComponent::create(QDeclarativeContext * context = 0)

Create an object instance from this component. Returns 0 if creation failed. context specifies the context within which to create the object instance.

If context is 0 (the default), it will create the instance in the engine' s root context.

QDeclarativeContext * QDeclarativeComponent::creationContext() const

Returns the QDeclarativeContext the component was created in. This is only valid for components created directly from QML.

QList<QDeclarativeError> QDeclarativeComponent::errors() const

Return the list of errors that occurred during the last compile or create operation. An empty list is returned if isError() is not set.

bool QDeclarativeComponent::isError() const

Returns true if status() == QDeclarativeComponent::Error.

bool QDeclarativeComponent::isLoading() const

Returns true if status() == QDeclarativeComponent::Loading.

bool QDeclarativeComponent::isNull() const

Returns true if status() == QDeclarativeComponent::Null.

bool QDeclarativeComponent::isReady() const

Returns true if status() == QDeclarativeComponent::Ready.

void QDeclarativeComponent::loadUrl(const QUrl & url)

Load the QDeclarativeComponent from the provided url.

Ensure that the URL provided is full and correct, in particular, use QUrl::fromLocalFile() when loading a file from the local filesystem.

void QDeclarativeComponent::setData(const QByteArray & data, const QUrl & url)

Sets the QDeclarativeComponent to use the given QML data. If url is provided, it is used to set the component name and to provide a base path for items resolved by this component.