Since everyone knows the basics we can get into the various stages starting with the XML handling.
XML Input --------- FOP can take the input XML in a number of ways: - SAX Events through SAX Handler - DOM which is converted into SAX Events - data source which is parsed and converted into SAX Events - XML+XSLT which is transformed using an XSLT Processor and the result is fired as SAX Events The SAX Events which are fired on the SAX Handler, class FOTreeBuilder, must represent an XSL:FO document. If not there will be an error. Any problems with the XML being well formed are handled here. Element Mappings ---------------- The element mappings is a hashmap of all the elements in a particular namespace. This makes it easy to create a different object for each element. Element mappings are static to save on memory. To add an extension a developer can put a jar in the classpath that contains the file "/META-INF/services/org.apache.fop.fo.ElementMapping". This must contain a line with the fully qualified name of a class that implements the "org.apache.fop.fo.ElementMapping" interface. This will then be loaded automatically at the start. Internal mappings are: FO, SVG and Extension (pdf bookmarks) Tree Building ------------- The SAX Events will fire all the information for the document with start element, end element, text data etc. This information is used to build up a representation of the FO document. To do this for a namespace there is a set of element mappings. When an element + namepsace mapping is found then it can create an object for that element. If the element is not found then it creates a dummy object or a generic DOM for unknown namespaces. The object is then setup and then given attributes for the element. For the FO Tree the attributes are converted into properties. The FO objects use a property list mapping to convert the attributes into a list of properties for the element. For other XML, for example SVG, a DOM of the XML is constructed. This DOM can then be passed through to the renderer. Other element mappings can be used in different ways for example to create elements that create areas during the layout process or Setup information for the renderer etc. While the tree building is mainly about creating the FO Tree there are some stages that can propagate to the renderer. At the end of a page sequence we know that all pages in the page sequence can be rendered without being effected by any further XML. The end of the XML document also tells us that we can finalise the output document. Associated Tasks ---------------- Error handling for xml not well formed. Error handling for other XML parsing errors. Developer info for adding namespace handlers. --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, email: [EMAIL PROTECTED]
