CopperSpice API  1.7.2
QAbstractFileEngineHandler Class Referenceabstract

The QAbstractFileEngineHandler class provides a mechanism to register custom file engines with your application. More...

Public Methods

 QAbstractFileEngineHandler ()
virtual ~QAbstractFileEngineHandler ()
virtual QAbstractFileEnginecreate (const QString &fileName) const = 0

Detailed Description

The QAbstractFileEngineHandler class provides a mechanism to register custom file engines with your application. QAbstractFileEngineHandler is a factory for creating QAbstractFileEngine objects (file engines), which are used internally by QFile, QFileInfo, and QDir when working with files and directories.

When you open a file CopperSpice chooses a suitable file engine by passing the file name from QFile or QDir through an internal list of registered file engine handlers. The first handler to recognize the file name is used to create the engine. CopperSpice provides internal file engines for working with regular files and resources, you can also register your own QAbstractFileEngine subclasses.

To install an application-specific file engine subclass QAbstractFileEngineHandler and reimplement create(). When you instantiate the handler (e.g. by creating an instance on the stack or on the heap), it will automatically register with CopperSpice. The latest registered handler takes precedence over existing handlers.

For example:

class ZipEngineHandler : public QAbstractFileEngineHandler
QAbstractFileEngine *create(const QString &fileName) const;
QAbstractFileEngine *ZipEngineHandler::create(const QString&fileName) const {
return fileName.toLower().endsWith(".zip") ? new ZipEngine(fileName) : nullptr;
int main(int argc, char **argv)
QApplication app(argc, argv);
ZipEngineHandler engine;
MainWindow window;;
return app.exec();

When the handler is destroyed, it is automatically removed from CopperSpice.

The most common approach to registering a handler is to create an instance as part of the start-up phase of your application. It is also possible to limit the scope of the file engine handler to a particular area of interest (e.g. a special file dialog that needs a custom file engine). By creating the handler inside a local scope, you can precisely control the area in which your engine will be applied without disturbing file operations in other parts of your application.

See also
QAbstractFileEngine, QAbstractFileEngine::create()

Constructor & Destructor Documentation

QAbstractFileEngineHandler::QAbstractFileEngineHandler ( )

Constructs a file handler and registers it with CopperSpice. Once created this handler's create() function will be called (along with all the other handlers) for any paths used. The most recently created handler that recognizes the given path (i.e. that returns a QAbstractFileEngine) is used for the new path.

See also
QAbstractFileEngineHandler::~QAbstractFileEngineHandler ( )

Destroys the file handler. This will automatically unregister the handler from CopperSpice.

Method Documentation

QAbstractFileEngine * QAbstractFileEngineHandler::create ( const QString fileName) const
pure virtual

Creates a file engine for fileName. Returns a nullptr if this file handler can not be created.

QAbstractSocketEngine *ZipEngineHandler::create(const QString &fileName) const {
return fileName.toLower().endsWith(".zip") ? new ZipEngine(fileName) : nullptr;
See also