Qt 5.8 | Qt QML | C++ Classes | QQmlAbstractUrlInterceptor

Qt 5.8.0 Reference Documentation

# QQmlAbstractUrlInterceptor Class

allows you to control QML file loading. More...

Header: | #include <QQmlAbstractUrlInterceptor>
qmake: | QT += qml

- List of all members, including inherited members

## Public Types

enum | DataType { QmldirFile, JavaScriptFile, QmlFile, UrlString }

## Public Functions

| QQmlAbstractUrlInterceptor()
virtual | ~QQmlAbstractUrlInterceptor()
virtual QUrl | intercept(const QUrl &url, DataType type) = 0

## Detailed Description

allows you to control QML file loading.

QQmlAbstractUrlInterceptor is an interface which can be used to alter URLs before they are used by the QML engine. This is primarily useful for altering file urls into other file urls, such as selecting different graphical assets for the current platform.

Relative URLs are intercepted after being resolved against the file path of the current QML context. URL interception also occurs after setting the base path for a loaded QML file. This means that the content loaded for that QML file uses the intercepted URL, but inside the file the pre-intercepted URL is used for resolving relative paths. This allows for interception of .qml file loading without needing all paths (or local types) inside intercepted content to insert a different relative path.

Compared to setNetworkAccessManagerFactory, QQmlAbstractUrlInterceptor affects all URLs and paths, including local files and embedded resource files. QQmlAbstractUrlInterceptor is synchronous, and for asynchronous files must return a url with an asynchronous scheme (such as http or a custom scheme handled by your own custom QNetworkAccessManager). You can use a QQmlAbstractUrlInterceptor to change file URLs into networked URLs which are handled by your own custom QNetworkAccessManager.

To implement support for a custom networked scheme, see setNetworkAccessManagerFactory.

## Member Type Documentation

### enum QQmlAbstractUrlInterceptor::DataType

Specifies where URL interception is taking place.

Because QML loads qmldir files for locating types, there are two URLs involved in loading a QML type. The URL of the (possibly implicit) qmldir used for locating the type and the URL of the file which defines the type. Intercepting both leads to either complex URL replacement or double URL replacements for the same file.

Constant | Value | Description
--- | --- | ---
`QQmlAbstractUrlInterceptor::QmldirFile` | `2` | The URL being intercepted is for a Qmldir file. Intercepting this, but not the QmlFile, allows for swapping out entire sub trees.
`QQmlAbstractUrlInterceptor::JavaScriptFile` | `1` | The URL being intercepted is an import for a Javascript file.
`QQmlAbstractUrlInterceptor::QmlFile` | `0` | The URL being intercepted is for a Qml file. Intercepting this, but not the Qmldir file, leaves the base dir of a QML file untouched and acts like replacing the file with another file.
`QQmlAbstractUrlInterceptor::UrlString` | `0x1000` | The URL being intercepted is a url property in a QML file, and not being used to load a file through the engine.

## Member Function Documentation

### QQmlAbstractUrlInterceptor::QQmlAbstractUrlInterceptor()

Constructor for QQmlAbstractUrlInterceptor.

### `[virtual]` QQmlAbstractUrlInterceptor::~QQmlAbstractUrlInterceptor()

Destructor for QQmlAbstractUrlInterceptor.

### `[pure virtual]` QUrl QQmlAbstractUrlInterceptor::intercept(const QUrl &url, DataType type)

A pure virtual function where you can intercept the url. The returned value is taken as the new value for the url. The type of url being intercepted is given by the type variable.

Your implementation of this function must be thread-safe, as it can be called from multiple threads at the same time.