When the application developer creates a custom renderer, as described
in Delegating Rendering to a Renderer, you
must register it using the appropriate render kit. Because the image map
application implements an HTML image map, the AreaRenderer and
MapRenderer classes in the Duke’s Bookstore case study should be
registered using the HTML render kit.
You register the renderer either by using the @FacesRenderer
annotation, as described in Creating the
Renderer Class, or by using the render-kit element of the application
configuration resource file. Here is a hypothetical configuration of
AreaRenderer:
<render-kit>
<renderer>
<component-family>Area</component-family>
<renderer-type>DemoArea</renderer-type>
<renderer-class>
dukesbookstore.renderers.AreaRenderer
</renderer-class>
<attribute>
<attribute-name>onmouseout</attribute-name>
<attribute-class>java.lang.String</attribute-class>
</attribute>
<attribute>
<attribute-name>onmouseover</attribute-name>
<attribute-class>java.lang.String</attribute-class>
</attribute>
<attribute>
<attribute-name>styleClass</attribute-name>
<attribute-class>java.lang.String</attribute-class>
</attribute>
</renderer>
...
Attributes specified in a renderer tag override any settings in the
@FacesRenderer annotation.
The render-kit element represents a javax.faces.render.RenderKit
implementation. If no render-kit-id is specified, the default HTML
render kit is assumed. The renderer element represents a
javax.faces.render.Renderer implementation. By nesting the renderer
element inside the render-kit element, you are registering the
renderer with the RenderKit implementation associated with the
render-kit element.
The renderer-class is the fully qualified class name of the
Renderer.
The component-family and renderer-type elements are used by a
component to find renderers that can render it. The component-family
identifier must match that returned by the component class’s getFamily
method. The component family represents a component or set of components
that a particular renderer can render. The renderer-type must match
that returned by the getRendererType method of the tag handler class.
By using the component family and renderer type to look up renderers for
components, the JavaServer Faces implementation allows a component to be
rendered by multiple renderers and allows a renderer to render multiple
components.
Each of the attribute tags specifies a render-dependent attribute and
its type. The attribute element doesn’t affect the runtime execution
of your application. Rather, it provides information to tools about the
attributes the Renderer supports.
The object responsible for rendering a component (be it the component
itself or a renderer to which the component delegates the rendering) can
use facets to aid in the rendering process. These facets allow the
custom component developer to control some aspects of rendering the
component. Consider this custom component tag example:
<d:dataScroller>
<f:facet name="header">
<h:panelGroup>
<h:outputText value="Account Id"/>
<h:outputText value="Customer Name"/>
<h:outputText value="Total Sales"/>
</h:panelGroup>
</f:facet>
<f:facet name="next">
<h:panelGroup>
<h:outputText value="Next"/>
<h:graphicImage url="/images/arrow-right.gif" />
</h:panelGroup>
</f:facet>
...
</d:dataScroller>
The dataScroller component tag includes a component that will render
the header and a component that will render the Next button. If the
renderer associated with this component renders the facets, you can
include the following facet elements in the renderer element:
<facet>
<description>This facet renders as the header of the table. It should be
a panelGroup with the same number of columns as the data.
</description>
<display-name>header</display-name>
<facet-name>header</facet-name>
</facet>
<facet>
<description>This facet renders as the content of the "next" button in
the scroller. It should be a panelGroup that includes an outputText
tag that has the text "Next" and a right arrow icon.
</description>
<display-name>Next</display-name>
<facet-name>next</facet-name>
</facet>
If a component that supports facets provides its own rendering and you
want to include facet elements in the application configuration
resource file, you need to put them in the component’s configuration
rather than the renderer’s configuration.