This topic describes how you can create lightweight Java components and
add them to HTML topics using the HTML
<OBJECT> tag.  The last section in this
topic contains references to supplemental information about
lightweight components and the HTML <OBJECT>
tag.
  References to 
  supplemental information are included at the end of this topic.
 References to 
  supplemental information are included at the end of this topic. 
Components intended for HTML topic pages are very similar to generic lightweight components. Components that do not require information about the View, or have parameters that can be set, can be used without modification.
 Lightweight components that require information about the View 
  must implement javax/javahelp/impl/ViewAwareComponent. These components 
  implement the method setViewData(). The component can determine 
  information from the View about the environment in which it is 
  executing. For example, in the code snippet below the Document 
  object is derived from the View: 
    private View myView;
    static private URL base;
    public void setViewData(View v) {
        myView = v;
        Document d = myView.getDocument();
        // System.err.println("myDocument is: "+d);
        base = ((HTMLDocument) d).getBase();
        // System.err.println(" base is: "+base);
    }
For more information about the Document interface see the following 
Swing API: 
http://java.sun.com/j2se/1.4.1/docs/api/javax/swing/text/Document.htmlText formatting information can be derived from the
View by querying 
its attribute set. Use the method getAttributes as shown below: 
AttributeSet as = v.getAttributes();Format attributes can be used by the component when the
AttributeSet 
is passed as a parameter to a StyleConstants method. There are methods 
that can be used to determine a number of attributes, including the font family, 
font size, font weight, font style, underlining, background color, and foreground 
color. For example, to determine the default background color of an object, you 
can do the following: 
Color color=StyleContants.getBackground(as)For a full list of formatting attributes and corresponding methods see:
http://java.sun.com/j2se/1.4.1/docs/api/javax/swing/text/StyleConstants.html
If your component takes parameters, you should follow these two additional steps:
BeanInfo class that corresponds to the lightweight 
    component class. 
 The component 
must accept parameter elements in any order.
 The component 
must accept parameter elements in any order. 
 Add accessor methods that enable the component to access the parameters through 
  the Java reflection mechanism. In the following example, the AButton 
  class has implemented accessor methods for the parameter "data" in the methods 
  getData and setData: 
    private String data = "";
    public void setData(String s) {
	data = s;
    }
    public String getData() {
	return data;
    }
|   | Even if the internal representation is not a String, 
      both the returned value for the getter method and the parameter in the setter 
      method must be aString. | 
 Create a BeanInfo class that provides explicit information about 
  the lightweight component. The only method used by the ContentViewer 
  from the BeanInfo classes is getPropertyDescriptors. 
  In the complete example below, JHSecondaryViewerBeanInfo defines 
  the property data accessible through the getData() and setData() 
  methods in JHSecondaryViewer: 
public class JHSecondaryViewerBeanInfo extends SimpleBeanInfo {
   public JHSecondaryViewerBeanInfo() {
   }
    
   public PropertyDescriptor[] getPropertyDescriptors() {
      PropertyDescriptor back[] = new PropertyDescriptor[15];
      try {
         back[0] = new PropertyDescriptor("content", JHSecondaryViewer.class);
         back[1] = new PropertyDescriptor("id", JHSecondaryViewer.class);
         back[2] = new PropertyDescriptor("viewerName", JHSecondaryViewer.class);
         back[3] = new PropertyDescriptor("viewerActivator", JHSecondaryViewer.class);
         back[4] = new PropertyDescriptor("viewerStyle", JHSecondaryViewer.class);
         back[5] = new PropertyDescriptor("viewerLocation", JHSecondaryViewer.class);
         back[6] = new PropertyDescriptor("viewerSize", JHSecondaryViewer.class);
         back[7] = new PropertyDescriptor("iconByName", JHSecondaryViewer.class);
         back[8] = new PropertyDescriptor("iconByID", JHSecondaryViewer.class);
         back[9] = new PropertyDescriptor("text", JHSecondaryViewer.class);
         back[10] = new PropertyDescriptor("textFontFamily", JHSecondaryViewer.class);
         back[11] = new PropertyDescriptor("textFontSize", JHSecondaryViewer.class);
         back[12] = new PropertyDescriptor("textFontWeight", JHSecondaryViewer.class);
         back[13] = new PropertyDescriptor("textFontStyle", JHSecondaryViewer.class);
         back[14] = new PropertyDescriptor("textColor", JHSecondaryViewer.class);
         return back;
      } catch (Exception ex) {
	 return null;
      }
   }
   }
 When naming parameters, be sure to avoid names reserved in the HTML 4.0 specification 
  for use as <OBJECT> tag attributes. For a complete list of 
  <OBJECT> attributes see the HTML 4.0 specification: 
http://w3c.org/TR/REC-html40/
<OBJECT> Tag You add lightweight components to JavaHelp topics by means of the <OBJECT> 
  tag and its classid attribute. The help viewer only recognizes 
  classid values prefixed with the "java:" tag. All 
  other classid tags are ignored. The following example creates an 
  ALabel within the HTML topic: 
<OBJECT CLASSID="java:sunw.demo.object.ALabel"</OBJECT>You can use standard
<OBJECT> tag attributes (see the HTML 
4.0 specification for more details), but to be recognized the lightweight component 
must have getter and setter methods for those attributes. A getter or setter 
method must operate on a String. For example, in the following example 
width and height for the ALabel are set if there are getWidth/setWidth 
and getHeight/setHeight methods in ALabel: 
    <OBJECT 
        CLASSID="java:sunw.demo.object.ALabel" 
        width="400" height="500">
    </OBJECT>
 Parameters are passed to lightweight components by using the <param> 
  tag. A parameter is only recognized if the component has getter and setter 
  methods for that parameter. A getter or setter method must operate on a 
  String. In the example below, the help viewer passes a number of 
  parameters and their values to a the JHSecondaryViewer component: 
  
    <OBJECT classid="java:com.sun.java.help.impl.JHSecondaryViewer">
        <param name="content" value="../topicB/glossary_def.html">
        <param name="viewerActivator" value="javax.help.LinkLabel">
        <param name="viewerStyle" value="javax.help.Popup">
        <param name="viewerSize" value="300,400">
        <param name="text" value="Click here">
        <param name="textFontFamily" value="SansSerif">
        <param name="textFontSize" value="x-large">
        <param name="textFontWeight" value="plain">
        <param name="textFontStyle" value="italic">
        <param name="textColor" value="red">
    </OBJECT>
The following information supplements the information in this topic.
For general information about lightweight Java components see:
http://java.sun.com/j2se/1.4.1/docs/guide/awt/demos/lightweight/index.htmlJavaHelp Components
As a reference, the sources to the lightweight components
that implement JavaHelp system popups and secondary windows
(JHSecondaryViewer.java and
JHSecondaryViewerBeanInfo.java) can be found in
src.jar at:
com\sun\java\javahelp\implFor a description of how the
<OBJECT> tag is used to implement 
popups and secondary windows, see Using Popup and Secondary 
Windows. 
HTML 4.0 Specification
You can find a detailed description of the
<OBJECT> tag as part of the HTML 4.0
specification:
http://w3c.org/TR/REC-html40/