gcu::Loader Class Reference

class used to implement serialization engines. More...

#include <gcu/loader.h>

Public Member Functions
	Loader ()
virtual	~Loader ()
virtual ContentType	Read (Document *doc, GsfInput *in, char const *mime_type, GOIOContext *io)
virtual bool	Write (Object const *obj, GsfOutput *out, char const *mime_type, GOIOContext *io, ContentType type=ContentTypeMisc)

Static Public Member Functions
static void	Init (Application *app)
static bool	GetFirstLoader (std::map< std::string, LoaderStruct >::iterator &it)
static bool	GetNextLoader (std::map< std::string, LoaderStruct >::iterator &it)
static Loader *	GetLoader (char const *mime_type)
static Loader *	GetSaver (char const *mime_type)

Protected Member Functions
void	AddMimeType (const char *mime_type)
void	RemoveMimeType (const char *mime_type)

Protected Attributes
std::list< std::string >	MimeTypes

Detailed Description

class used to implement serialization engines.

This class is used to load and save files of various types, using the gcu::Object framework. Derived classes should be implemented in plugins, using the goffice plugins API. When Loader::Init is called, the framework collects informations about the services exposed by each plugin in XML files. For the CDX file loader plugin, the corresponding plugin.xml.in file content is:

<?xml version="1.0" encoding="UTF-8"?>
<plugin id="GCULoader_cdxml">
        <information>
                <_name>Loader : cdxml</_name>
                <_description>Chemdraw XML files loader.</_description>
        </information>
        <loader type="Gnumeric_Builtin:module">
                <attribute name="module_file" value="cdxml"/>
        </loader>
        <services>
                <service type="chemical_loader" id="GCULoader_cdxml">
                        <mime_type name="chemical/x-cdxml" capabilities="r" scope="2"/>
                        <information>
                                <_description>Chemdraw XML files loader</_description>
                        </information>
                </service>
        </services>
</plugin>

In the present context, the important node is the mime type related one. Its attributes are:

• name: the mime type.
• capabilities: what is supported: r for reading, w for writing. Both "rw" and "wr" are valid.
• scope: 2 and 3 mean 2D and 3D structures, repectively, c means crystal structure, and s, spectra . Any combination might be used.

Other fields are standard in the goffice world. The plugin is loaded only when needed.

Each plugin should implement at least one derived class and a static instance of this class. The CDX loader has:

class CDXLoader: public gcu::Loader
{
public:
        CDXLoader ();
        virtual ~CDXLoader ();

        bool Read (Document *doc, GsfInput *in, char const *mime_type, IOContext *io);
        bool Write (Document *doc, GsfOutput *out, char const *mime_type, IOContext *io);

private:
        ...
};

...
static CDXLoader loader;

Definition at line 144 of file loader.h.

Constructor & Destructor Documentation

gcu::Loader::Loader

(

)

The constructor. Derived class need to call Loader::AddMimeType for each mime type they support.

virtual gcu::Loader::~Loader ( )

virtual

The destructor Derived class should call Loader::RemoveMimeType for each mime type they support.

Member Function Documentation

void gcu::Loader::AddMimeType ( const char *  mime_type )

protected

Parameters

mime_type

a mime type.

Registers a mime type and stores the instance calling it as the Loader for this mime type.

static bool gcu::Loader::GetFirstLoader ( std::map< std::string, LoaderStruct >::iterator &  it )

static

Parameters

it	a std::map iterator.

Must be called to access the first LoaderStruct instance. When successful the iterator can be used to retrieve both the mime type ((*it).first), and the corresponding LoaderStruct ((*it).second)

Returns

true if successful, false otherwise.

static Loader* gcu::Loader::GetLoader ( char const *  mime_type )

static

Parameters

mime_type

a mime type.

Returns

the Loader instance able to read the mime type if any.

static bool gcu::Loader::GetNextLoader ( std::map< std::string, LoaderStruct >::iterator &  it )

static

Parameters

it	a std::map iterator initialized by Loader::GetFirstLoader

Gets the next LoderStruct and its associated mime type.

Returns

true if successful, false otherwise.

static Loader* gcu::Loader::GetSaver ( char const *  mime_type )

static

Parameters

mime_type

a mime type.

Returns

the Loader instance able to write the mime type if any.

static void gcu::Loader::Init ( Application *  app )

static

Parameters

app	an Application instance.

Initializes the load/save engines system. This must be called before trying to use any loader (no one will be available before, anyway).

virtual ContentType gcu::Loader::Read ( Document *  doc, GsfInput *  in, char const *  mime_type, GOIOContext *  io  )

virtual

Parameters

doc	the gcu::Document being read.
in	a GsfInput (see the libgsf documentation at http://library.gnome.org/devel/gsf/stable/gsf-Input-from-unstructured-files.html#GsfInput).
mime_type	the mime type of the data.
io	a GOffice IOContext.

This function must be overloaded by a derived class able to read. Default implementation just return false.

Returns

true on success, false otherwise.

void gcu::Loader::RemoveMimeType ( const char *  mime_type )

protected

Parameters

mime_type

a mime type.

Unregisters a mime type.

virtual bool gcu::Loader::Write ( Object const *  obj, GsfOutput *  out, char const *  mime_type, GOIOContext *  io, ContentType  type = ContentTypeMisc  )

virtual

Parameters

obj	the gcu::Object being written.
out	a GsfOutput (see the libgsf documentation at http://library.gnome.org/devel/gsf/stable/gsf-Output-to-unstructured-files.html#GsfOutput).
mime_type	the mime type of the data.
io	a GOffice IOContext.
type	the type of the data to be saved (see gcu::ContentType).

This function must be overloaded by a derived class able to write. Default implementation just return false.

Returns

true on success, false otherwise.

Member Data Documentation

std::list<std::string> gcu::Loader::MimeTypes

protected

The list of supported mime types.

Definition at line 241 of file loader.h.

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The documentation for this class was generated from the following file:

• loader.h