Properties

Tree Concept	Thing (Noun)	Descriptive Item (Adjective)
XML	Element	Attribute
FO Tree	Object	Property
Area Tree	Area	Trait

- Properties -

The XML attributes on each element are passed to the object. The objects -that represent FO objects then convert the attributes into properties.

Since properties can be inherited the PropertyList class handles resolving -properties for a particular element. -All properties are specified in an XML file. Classes are created -automatically during the build process.

In some cases the element may be moved to have a different parent, for -example markers, or the inheritance could be different, for example -initial property set.

Properties (recall that FO's have properties, areas have traits, and XML -nodes have attributes) are also a concern of FOTreeBuilder. It -accomplishes this by using a PropertyListBuilder. There is a -separate PropertyListBuilder for each namespace encountered -while building the FO tree. Each Builder object contains a hash of -property names and their respective makers. It may also +

+ Overview of Processing +

The general flow of property processing is as follows:

As part of FOTreeBuilder.startElement(), FObj.handleAttrs is passed a list of attributes to be processed for the new FObj.
FObj.handleAttrs gets a PropertyListBuilder and asks it to create a Property List from them. There is currently only one static PropertyListBuilder, which handles the fo: namespace.
FObj.handleAttrs then cross-references the PropertyList with the FObj.

+ PropertyListBuilder +

Each plb object contains a hash of +property names and their respective Makers. It may also contain element-specific property maker hashes; these are based on the local name of the flow object, ie. table-row, not fo:table-row. If an element-specific property mapping exists, it is preferred to the generic mapping.

The base class for all -properties is Property, and all the property makers extend -Property.Maker. A more complete discussion of the property -architecture may be found in Properties.

The PLB handles loops through each attribute in the list, finds an appropriate "Maker" for it, then calls the Maker to convert the attribute value into a Property object of the correct type, and stores that Property in the PropertyList.

- - -

The Refinement step is part of reading and using the properties which may happen immediately or during the layout process.

- -

During XML Parsing, the FO tree is constructed. For each FO object (some -subclass of FObj), the tree builder then passes the list of all -attributes specified on the FO element to the handleAttrs method. This -method converts the attribute specifications into a PropertyList.

The actual work is done by a PropertyListBuilder (PLB for short). The -basic idea of the PLB is to handle each attribute in the list in turn, -find an appropriate "Maker" for it, call the Maker to convert the -attribute value into a Property object of the correct type, and store -that Property in the PropertyList.

Property datatypes

The property datatypes are defined in the @@ -356,9 +378,16 @@ the result is a Property object, and the actual value may be accessed

Refinement +

The Refinement step is part of reading and using the properties which may happen immediately or during the layout process.

Refined FO Tree

+ Implementation Notes +

All properties are specified in src/codegen/foproperties.xml. +The related classes are created automatically during the build process.

The base class for all properties is fo.Property, and the base class for all the property makers is the inner class Property.Maker.