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Realization
The generic approach,
as was already shown in the configuration, continues in
realization and implementation. Modularity and exchangeability
are generally achieved by consistent use of the UNO service
concept.
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Service Description
The
following services were specified:
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com.sun.star.document.MediaDescriptor
This is not really a service. Rather, it is a
structure that tries to unite all the document information. This
is where e.g. URL, MediaType, FilterName, Referrer, Version and
an InputStream are available. The point is to take
the MediaDescriptor through all the processes of type detection
(detect flat/deep, filter, load...). Resulting information should
be added or corrected so that it is available for the next step
in the process.
Some things to be aware of:
The UNO feature that
corresponds to this service is a sequence of elements of the
com.sun.star.beans.PropertyValue type. It is thus not a real
service in the sense of an object.
e.g. in C++
"::com::sun::star::uno::Sequence<
::com::sun::star::beans::PropertyValue > lProperties"
The elements may only be referenced or kept as a copy for
the time necessary for direct processing.
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com.sun.star.document.TypeDetection
interface
com.sun.star.document.XTypeDetection
Makes flat or
deep detection of the type of contents, described by the URL or
a MediaDescriptor. The result you receive is the internal name
of the detected type. This can be used to get registered loaders
or filters. The FrameLoaderFactory and FilterFactory services
help you do this.
interface
com.sun.star.container.XNameAccess
Allows read-access
to the configuration data of all types.
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com.sun.star.frame.FrameLoaderFactory
interface
com.sun.star.lang.XMultiServiceFactory
Creates a
loader service registered to one type. You enter the internal
type name you received from a TypeDetection and get a reference
to the object produced. The loader factory already initializes
the object produced with its configuration data.
See also
FrameLoader/SynchronousFrameLoader
for further information.
interface
com.sun.star.container.XNameAccess Allows read-access
to the configuration of all FrameLoaders.
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com.sun.star.frame.FrameLoader
com.sun.star.frame.SynchronousFrameLoader
interface
com.sun.star.frame.XFrameLoader |
com.sun.star.frame.XSynchronousFrameLoader
With the help of the methods load() and cancel(), you can
start processing a document or also abort it. The various
services differ only in the way results are returned. The
FrameLoader returns immediately and allows the client to listen
for the loading completion, whereas the SynchronousFrameLoader
returns when finished loading with the result of the process. If
an object implements both interfaces, the synchronous version is
preferred.
interface
com.sun.star.lang.XInitialization
interface
com.sun.star.beans.XPropertySet
[property, readonly]
sequence< string > Name
[property, readonly] sequence<
string > Types
[property, readonly] string UIName
These
interfaces must be supported by a loader implementation, thus
making configuration data available by asking the object instead
of retrieving it from the FrameLoaderFactory. The
properties are re defined as read-only because it does not make
sense to make changes at run-time. The XInitialization interface
is used by the FrameLoaderFactory to provide the Loader with its
configuration data, clients can get them via XPropertySet.
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com.sun.star.document.FilterFactory
interface
com.sun.star.lang.XMultiServiceFactory
Use this to
create a registered filter suitable for a determined type. You
transfer the internal type names and receive a reference to the
filter object. The factory then initializes the object with its
configuration data.
See also import/export
filters
interface
com.sun.star.container.XNameAccess
Allows read-access
to the configuration of all filters.
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com.sun.star.document.ImportFilter
com.sun.star.document.ExportFilter
interface
com.sun.star.document.XFilter
This interface is
supported by both services. Use it to start or interrupt the
actual filter process. The result is indicated synchronously.
The interface only supports a synchronous loading.
interface
com.sun.star.document.XImporter
interface
com.sun.star.document.XExporter
A filter is
identified as an import and/or export filter by appropriate
flags in its configuration data (see also filter configuration).
It can implement one or both interfaces. The purpose of these
interfaces is to transfer an interface to the output or target
document to the filter.
The following algorithm is used:
a) get suitable interface for
respective process (XImporter/XExporter)
b)
set the document on it (setTargetDocument()/setSourceDocument())
c) get XFilter interface for
the same object and start the process with filter()
Problems
might be caused by simultaneous implementation of both
interfaces. Then the implementation must detect the method
called for setting the document, and, based on that, infer the
type of filter process.
interface
com.sun.star.lang.XInitialization
interface
com.sun.star.beans.XPropertySet
[property, readonly] string
Name;
[property, readonly] string Type;
[property,
readonly] string UIName;
[property, readonly] string
DocumentService;
[property, readonly] string
FilterService;
[property, readonly] string Flags;
[property,
readonly] string UserData;
[property, readonly] string
FileFormatVersion;
[property, readonly] string
TemplateName;
A filter must also
make its own configuration accessible to others by implementing
these interfaces.
See also the description
FrameLoader/SynchronousFrameLoader!
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