## wxFilterClassFactory

Allows the creation of filter streams to handle compression formats such as gzip and bzip2.

For example, given a filename you can search for a factory that will handle it and create a stream to decompress it:

        factory = wxFilterClassFactory::Find(filename, wxSTREAM_FILEEXT);
        if (factory)
            stream = factory->NewStream(new wxFFileInputStream(filename));

Find() can also search for a factory by MIME type, HTTP encoding or by wxFileSystem protocol. The available factories can be enumerated using GetFirst() and GetNext().

Derived from

wxObject

Include files

<wx/stream.h>

Data structures

    enum wxStreamProtocolType
    {
        wxSTREAM_PROTOCOL,  // wxFileSystem protocol (should be only one)
        wxSTREAM_MIMETYPE,  // MIME types the stream handles
        wxSTREAM_ENCODING,  // The HTTP Content-Encodings the stream handles
        wxSTREAM_FILEEXT    // File extensions the stream handles
    };

See also

wxFilterInputStream
wxFilterOutputStream
wxArchiveClassFactory
Archive formats such as zip

Members

wxFilterClassFactory::CanHandle
wxFilterClassFactory::Find
wxFilterClassFactory::GetFirst/GetNext
wxFilterClassFactory::GetProtocol
wxFilterClassFactory::GetProtocols
wxFilterClassFactory::NewStream
wxFilterClassFactory::PopExtension
wxFilterClassFactory::PushFront
wxFilterClassFactory::Remove

### wxFilterClassFactory::CanHandle

bool CanHandle(const wxChar* protocol, wxStreamProtocolType type = wxSTREAM_PROTOCOL) const

Returns true if this factory can handle the given protocol, MIME type, HTTP encoding or file extension.

When using wxSTREAM_FILEEXT for the second parameter, the first parameter can be a complete filename rather than just an extension.

### wxFilterClassFactory::Find

static const wxFilterClassFactory* Find(const wxChar* protocol, wxStreamProtocolType type = wxSTREAM_PROTOCOL)

A static member that finds a factory that can handle a given protocol, MIME type, HTTP encoding or file extension. Returns a pointer to the class factory if found, or NULL otherwise. It does not give away ownership of the factory.

When using wxSTREAM_FILEEXT for the second parameter, the first parameter can be a complete filename rather than just an extension.

### wxFilterClassFactory::GetFirst/GetNext

static const wxFilterClassFactory* GetFirst()

const wxFilterClassFactory* GetNext() const

GetFirst and GetNext can be used to enumerate the available factories.

For example, to list them:

        wxString list;
        const wxFilterClassFactory *factory = wxFilterClassFactory::GetFirst();

        while (factory) {
            list << factory->GetProtocol() << _T("\n");
            factory = factory->GetNext();
        }

GetFirst()/GetNext() return a pointer to a factory or NULL if no more are available. They do not give away ownership of the factory.

### wxFilterClassFactory::GetProtocol

wxString GetProtocol() const

Returns the wxFileSystem protocol supported by this factory. Equivalent to wxString(*GetProtcols()).

### wxFilterClassFactory::GetProtocols

const wxChar * const* GetProtocols(wxStreamProtocolType type = wxSTREAM_PROTOCOL) const

Returns the protocols, MIME types, HTTP encodings or file extensions supported by this factory, as an array of null terminated strings. It does not give away ownership of the array or strings.

For example, to list the file extensions a factory supports:

        wxString list;
        const wxChar *const *p;

        for (p = factory->GetProtocols(wxSTREAM_FILEEXT); *p; p++)
            list << *p << _T("\n");

### wxFilterClassFactory::NewStream

wxFilterInputStream* NewStream(wxInputStream& stream) const

wxFilterOutputStream* NewStream(wxOutputStream& stream) const

wxFilterInputStream* NewStream(wxInputStream* stream) const

wxFilterOutputStream* NewStream(wxOutputStream* stream) const

Create a new input or output stream to decompress or compress a given stream.

If the parent stream is passed as a pointer then the new filter stream takes ownership of it. If it is passed by reference then it does not.

### wxFilterClassFactory::PopExtension

wxString PopExtension(const wxString& location) const

Remove the file extension of location if it is one of the file extensions handled by this factory.

### wxFilterClassFactory::PushFront

void PushFront()

Adds this class factory to the list returned by GetFirst()/GetNext().

It is not necessary to do this to use the filter streams. It is usually used when implementing streams, typically the implementation will add a static instance of its factory class.

It can also be used to change the order of a factory already in the list, bringing it to the front. This isn't a thread safe operation so can't be done when other threads are running that will be using the list.

The list does not take ownership of the factory.

### wxFilterClassFactory::Remove

void Remove()

Removes this class factory from the list returned by GetFirst()/GetNext().

Removing from the list isn't a thread safe operation so can't be done when other threads are running that will be using the list.

The list does not own the factories, so removing a factory does not delete it.