The StyleSheet renderer applies a
style sheet to a data model. The style sheet contains
style rules in
CSS2 format that describe how the objects in the
data model are displayed in the diagram.
A style rule consists of two parts:
The condition part called the selector
applies to the data model, and is used for pattern-matching.
The action part called the declarations
applies to the corresponding graphic objects, and is used for rendering.
When designing a notation, you create many style rules,
each of them matching a particular case in the data model. You define
rules that apply to objects represented as nodes, and rules that apply
to objects represented as links.
The style rules are usually defined from the most generic
to the most specific. The generic rules usually create the base symbol
for each type of object. The more specific rules add new shapes, or
change graphics properties for the symbol defined in the generic rule.
The style rules are also used to specify the options
of a diagram. Such rules have no selector and the declarations customize
the way the options operate.
The Designer for
JViews Diagrammer is perfectly suited for creating
style sheets that define the look-and-feel of diagrams. Within the
Designer, styling takes place, but the
CSS syntax is largely hidden: selectors are defined
in a natural-language editor and declarations are defined by setting
graphic properties through panels called Styling Customizers. The
style sheet generated by the Designer can be loaded into your application
at run time.
Composite graphics are used to create the symbols for
your application.
The Composite Graphics capability consists of a set of
classes that help you to combine simple graphic objects to build more
complex graphic objects according to one of several possible composite
layouts.
The composite layout declares the way additional elements
are attached to the base shape of the composite graphics.
Composite graphics are designed to be used with style
rules that define which elements are displayed and how according to
data model conditions. For example, you can dynamically add an alarm
icon to a symbol when the status property
of a node is equal to alarm.
Composite graphics can be nested to reuse simpler symbols
within more complex ones.
When the SDM engine parses the data model, it applies
the style rules, and depending on which rules apply, it creates the
composite graphics appropriately to display the nodes.
Ultimately, the composite graphics facility creates and
deletes graphics objects in the grapher.
Here again, the Designer for JViews Diagrammer helps you to create composite graphics
for your application.