4.5 Writing Transcoder Plug-ins

A transcoder plug-in consists of an ImageTranscoderSpi, which performs the same functions as do the Spi classes for other plug-ins, and an object that implements the ImageTranscoder interface:

IIOMetadata convertStreamMetadata(IIOMetadata inData,
                                  ImageWriteParam param);

IIOMetadata convertImageMetadata(IIOMetadata inData,
                                 ImageTypeSpecifier imageType,
                                 ImageWriteParam param);

The ImageTranscoder may use the standard interfaces to unpack the incoming metadata, or it may make use of interfaces that are specific to the actual object at hand. For example, it could access the keywords and values instance variables of the MyFormatMetadata class defined above; these were made public, but not documented, precisely in order to allow a transcoder plug-in developer to access them without having to go through a DOM representation.