The Filter interface must be implemented by all filters in the filtering system. This interface is used simply as a base on which all other interfaces are implemented. Only one method is specified by this interface and that is the setPrefs() method. This method is called by the filter's factory to initialize a filter with a set of filter-dependent parameters which can be used to configure various filter features. The intent is to allow each filter to be user-customizable and to also allow customizations to be saved. The Filter Factory section later in this chapter will discuss how this can be done. Figure 4.5 shows the Java code for the Filter interface.
