Extending component classes

ZIETrans provides a number of host component classes. You can extend any of the host component classes that are found in the ComponentWidget.xml file by replacing the statement public class MyCustomComponent extends Component in the created .java file for the new component with the class name of an existing component. For example:

public class MyCustomComponent 
             extends com.ibm.hats.transform.components.CommandLineComponent

Each ZIETrans component performs recognition of elements of the host screen in the recognize() method. To extend a host component and accomplish the specific recognition task you need, you can use either of these approaches:

• Extend one of the component classes that is provided by ZIETrans and override the recognize() method of the component. Somewhere in your recognize() method you should add a call like super.recognize(region, settings); to invoke the recognize() method of the class you extended. You can modify the process by changing the settings before calling the superclass, or by manipulating the output returned by the superclass.
• Extend one of the component classes that is provided by ZIETrans and override the recognize() method of the component. Instead of using the recognize() method of the superclass, invoke the recognize() method of one of the other component classes. This approach will be useful if you want to recognize a complex host component that combines aspects of more than one of the ZIETrans components.

The Create Component wizard generates a recognize() method that returns null, which indicates that the host screen region is not recognized by the new component. To change the custom component to act as the ZIETrans component it is extended from, whose elements contain all of the correct ComponentElements, remove the "return null" from the .java file and change the code in the component code. For example:

public ComponentElement[] recognize(LinearScreenRegion region, Properties settings) { 
ComponentElement [] elements = super.recognize(region, settings); 
return elements;
}