QQmlEngine

The QQmlEngine class provides an environment for instantiating QML components. More

Inheritance diagram of PySide6.QtQml.QQmlEngine

Inherited by: QQmlApplicationEngine

Synopsis

Functions

Static functions

Detailed Description

Each QML component is instantiated in a QQmlContext . QQmlContext ‘s are essential for passing data to QML components. In QML, contexts are arranged hierarchically and this hierarchy is managed by the QQmlEngine .

Prior to creating any QML components, an application must have created a QQmlEngine to gain access to a QML context. The following example shows how to create a simple Text item.

QQmlEngine engine;
QQmlComponent component(&engine);
component.setData("import QtQuick 2.0\nText { text: \"Hello world!\" }", QUrl());
QQuickItem *item = qobject_cast<QQuickItem *>(component.create());

//add item to view, etc
...

In this case, the Text item will be created in the engine’s root context .

See also

QQmlComponent QQmlContext QML Global Object

class PySide6.QtQml.QQmlEngine([p=None])
Parameters

pPySide6.QtCore.QObject

Create a new QQmlEngine with the given parent.

PySide6.QtQml.QQmlEngine.addImageProvider(id, arg__2)
Parameters

Sets the provider to use for images requested via the image: url scheme, with host providerId. The QQmlEngine takes ownership of provider.

Image providers enable support for pixmap and threaded image requests. See the QQuickImageProvider documentation for details on implementing and using image providers.

All required image providers should be added to the engine before any QML sources files are loaded.

See also

removeImageProvider() QQuickImageProvider QQmlImageProviderBase

PySide6.QtQml.QQmlEngine.addImportPath(dir)
Parameters

dir – str

Adds path as a directory where the engine searches for installed modules in a URL-based directory structure.

The path may be a local filesystem directory, a Qt Resource path (:/imports), a Qt Resource url (qrc:/imports) or a URL.

The path will be converted into canonical form before it is added to the import path list.

The newly added path will be first in the importPathList() .

See also

setImportPathList() QML Modules

PySide6.QtQml.QQmlEngine.addNamedBundle(arg__1, arg__2)
Parameters
  • arg__1 – str

  • arg__2 – str

Return type

bool

Note

This function is deprecated.

PySide6.QtQml.QQmlEngine.addPluginPath(dir)
Parameters

dir – str

Adds path as a directory where the engine searches for native plugins for imported modules (referenced in the qmldir file).

By default, the list contains only ., i.e. the engine searches in the directory of the qmldir file itself.

The newly added path will be first in the pluginPathList() .

PySide6.QtQml.QQmlEngine.addUrlInterceptor(urlInterceptor)
Parameters

urlInterceptorPySide6.QtQml.QQmlAbstractUrlInterceptor

Adds a urlInterceptor to be used when resolving URLs in QML. This also applies to URLs used for loading script files and QML types. The URL interceptors should not be modifed while the engine is loading files, or URL selection may be inconsistent. Multiple URL interceptors, when given, will be called in the order they were added for each URL.

QQmlEngine does not take ownership of the interceptor and won’t delete it.

PySide6.QtQml.QQmlEngine.baseUrl()
Return type

PySide6.QtCore.QUrl

Return the base URL for this engine. The base URL is only used to resolve components when a relative URL is passed to the QQmlComponent constructor.

If a base URL has not been explicitly set, this method returns the application’s current working directory.

See also

setBaseUrl()

PySide6.QtQml.QQmlEngine.captureProperty(object, property)
Parameters

Capture the given property as part of a binding.

PySide6.QtQml.QQmlEngine.clearComponentCache()

Clears the engine’s internal component cache.

This function causes the property metadata of all components previously loaded by the engine to be destroyed. All previously loaded components and the property bindings for all extant objects created from those components will cease to function.

This function returns the engine to a state where it does not contain any loaded component data. This may be useful in order to reload a smaller subset of the previous component set, or to load a new version of a previously loaded component.

Once the component cache has been cleared, components must be loaded before any new objects can be created.

static PySide6.QtQml.QQmlEngine.contextForObject(arg__1)
Parameters

arg__1PySide6.QtCore.QObject

Return type

PySide6.QtQml.QQmlContext

Returns the QQmlContext for the object, or 0 if no context has been set.

When the QQmlEngine instantiates a QObject , the context is set automatically.

See also

setContextForObject() qmlContext()qmlEngine()

PySide6.QtQml.QQmlEngine.exit(retCode)
Parameters

retCode – int

PySide6.QtQml.QQmlEngine.imageProvider(id)
Parameters

id – str

Return type

PySide6.QtQml.QQmlImageProviderBase

Returns the image provider set for providerId if found; otherwise returns None.

See also

QQuickImageProvider

PySide6.QtQml.QQmlEngine.importPathList()
Return type

list of strings

Returns the list of directories where the engine searches for installed modules in a URL-based directory structure.

For example, if /opt/MyApp/lib/imports is in the path, then QML that imports com.mycompany.Feature will cause the QQmlEngine to look in /opt/MyApp/lib/imports/com/mycompany/Feature/ for the components provided by that module. A qmldir file is required for defining the type version mapping and possibly QML extensions plugins.

By default, the list contains the directory of the application executable, paths specified in the QML2_IMPORT_PATH environment variable, and the builtin Qml2ImportsPath from QLibraryInfo .

PySide6.QtQml.QQmlEngine.importPlugin(filePath, uri, errors)
Parameters
  • filePath – str

  • uri – str

  • errorsQList

Return type

bool

Imports the plugin named filePath with the uri provided. Returns true if the plugin was successfully imported; otherwise returns false.

On failure and if non-null, the errors list will have any errors which occurred prepended to it.

The plugin has to be a Qt plugin which implements the QQmlEngineExtensionPlugin interface.

PySide6.QtQml.QQmlEngine.incubationController()
Return type

PySide6.QtQml.QQmlIncubationController

PySide6.QtQml.QQmlEngine.interceptUrl(url, type)
Parameters
Return type

PySide6.QtCore.QUrl

Run the current URL interceptors on the given url of the given type and return the result.

PySide6.QtQml.QQmlEngine.networkAccessManager()
Return type

PySide6.QtNetwork.QNetworkAccessManager

Returns a common QNetworkAccessManager which can be used by any QML type instantiated by this engine.

If a QQmlNetworkAccessManagerFactory has been set and a QNetworkAccessManager has not yet been created, the QQmlNetworkAccessManagerFactory will be used to create the QNetworkAccessManager ; otherwise the returned QNetworkAccessManager will have no proxy or cache set.

PySide6.QtQml.QQmlEngine.networkAccessManagerFactory()
Return type

PySide6.QtQml.QQmlNetworkAccessManagerFactory

Returns the current QQmlNetworkAccessManagerFactory .

PySide6.QtQml.QQmlEngine.offlineStorageDatabaseFilePath(databaseName)
Parameters

databaseName – str

Return type

str

Returns the file path where a Local Storage database with the identifier databaseName is (or would be) located.

See also

LocalStorage.openDatabaseSync()

PySide6.QtQml.QQmlEngine.offlineStoragePath()
Return type

str

PySide6.QtQml.QQmlEngine.outputWarningsToStandardError()
Return type

bool

Returns true if warning messages will be output to stderr in addition to being emitted by the signal, otherwise false.

The default value is true.

PySide6.QtQml.QQmlEngine.pluginPathList()
Return type

list of strings

Returns the list of directories where the engine searches for native plugins for imported modules (referenced in the qmldir file).

By default, the list contains only ., i.e. the engine searches in the directory of the qmldir file itself.

PySide6.QtQml.QQmlEngine.quit()
PySide6.QtQml.QQmlEngine.removeImageProvider(id)
Parameters

id – str

Removes the image provider for providerId.

See also

addImageProvider() QQuickImageProvider

PySide6.QtQml.QQmlEngine.removeUrlInterceptor(urlInterceptor)
Parameters

urlInterceptorPySide6.QtQml.QQmlAbstractUrlInterceptor

Remove a urlInterceptor that was previously added using addUrlInterceptor . The URL interceptors should not be modifed while the engine is loading files, or URL selection may be inconsistent.

This does not delete the interceptor, but merely removes it from the engine. You can re-use it on the same or a different engine afterwards.

PySide6.QtQml.QQmlEngine.retranslate()

Refreshes all binding expressions that use strings marked for translation.

Call this function after you have installed a new translator with installTranslator , to ensure that your user-interface shows up-to-date translations.

Note

Due to a limitation in the implementation, this function refreshes all the engine’s bindings, not only those that use strings marked for translation. This may be optimized in a future release.

PySide6.QtQml.QQmlEngine.rootContext()
Return type

PySide6.QtQml.QQmlContext

Returns the engine’s root context.

The root context is automatically created by the QQmlEngine . Data that should be available to all QML component instances instantiated by the engine should be put in the root context.

Additional data that should only be available to a subset of component instances should be added to sub-contexts parented to the root context.

PySide6.QtQml.QQmlEngine.setBaseUrl(arg__1)
Parameters

arg__1PySide6.QtCore.QUrl

Set the base URL for this engine to url.

See also

baseUrl()

static PySide6.QtQml.QQmlEngine.setContextForObject(arg__1, arg__2)
Parameters

Sets the QQmlContext for the object to context. If the object already has a context, a warning is output, but the context is not changed.

When the QQmlEngine instantiates a QObject , the context is set automatically.

PySide6.QtQml.QQmlEngine.setImportPathList(paths)
Parameters

paths – list of strings

Sets paths as the list of directories where the engine searches for installed modules in a URL-based directory structure.

By default, the list contains the directory of the application executable, paths specified in the QML2_IMPORT_PATH environment variable, and the builtin Qml2ImportsPath from QLibraryInfo .

PySide6.QtQml.QQmlEngine.setIncubationController(arg__1)
Parameters

arg__1PySide6.QtQml.QQmlIncubationController

PySide6.QtQml.QQmlEngine.setNetworkAccessManagerFactory(arg__1)
Parameters

arg__1PySide6.QtQml.QQmlNetworkAccessManagerFactory

Sets the factory to use for creating QNetworkAccessManager (s).

QNetworkAccessManager is used for all network access by QML. By implementing a factory it is possible to create custom QNetworkAccessManager with specialized caching, proxy and cookie support.

The factory must be set before executing the engine.

Note

QQmlEngine does not take ownership of the factory.

PySide6.QtQml.QQmlEngine.setOfflineStoragePath(dir)
Parameters

dir – str

PySide6.QtQml.QQmlEngine.setOutputWarningsToStandardError(arg__1)
Parameters

arg__1 – bool

Set whether warning messages will be output to stderr to enabled.

If enabled is true, any warning messages generated by QML will be output to stderr and emitted by the signal. If enabled is false, only the signal will be emitted. This allows applications to handle warning output themselves.

The default value is true.

PySide6.QtQml.QQmlEngine.setPluginPathList(paths)
Parameters

paths – list of strings

Sets the list of directories where the engine searches for native plugins for imported modules (referenced in the qmldir file) to paths.

By default, the list contains only ., i.e. the engine searches in the directory of the qmldir file itself.

PySide6.QtQml.QQmlEngine.setUrlInterceptor(urlInterceptor)
Parameters

urlInterceptorPySide6.QtQml.QQmlAbstractUrlInterceptor

Note

This function is deprecated.

PySide6.QtQml.QQmlEngine.trimComponentCache()

Trims the engine’s internal component cache.

This function causes the property metadata of any loaded components which are not currently in use to be destroyed.

A component is considered to be in use if there are any extant instances of the component itself, any instances of other components that use the component, or any objects instantiated by any of those components.

PySide6.QtQml.QQmlEngine.urlInterceptor()
Return type

PySide6.QtQml.QQmlAbstractUrlInterceptor

Note

This function is deprecated.

This API is private for 5.1

Returns the last QQmlAbstractUrlInterceptor . It must not be modified outside the GUI thread.

PySide6.QtQml.QQmlEngine.warnings(warnings)
Parameters

warnings