What Is fop.jar? I got it from the fop-2.7-bin.zip.

fop.jar in fop-2.7-bin.zip is the JAR file for FOP 2.7, which is a print formatter driven by XSL formatting objects (XSL-FO). You can obtain fop.jar from the build folder of the fop-2.7-bin.zip file.

Below is the information about the fop.jar (2.2) file:

JAR File Size and Download Location:

JAR name: fop.jar, fop-2.7.jar
Target JDK version: 1.7
File name: fop.jar
File size: 4442817 bytes
Release date: 20-Jan-2022
Download: Apache FOP Website

Java source code files for fop.jar:

⏎ org/apache/fop/area/AreaEventProducer.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/* $Id: AreaEventProducer.java 1608161 2014-07-06 04:32:11Z gadams $ */

package org.apache.fop.area;

import org.apache.fop.events.EventBroadcaster;
import org.apache.fop.events.EventProducer;

/**
 * Event producer interface for events related to the area tree.
 */
public interface AreaEventProducer extends EventProducer {

    /**
     * Provider class for the event producer.
     */
    static final class Provider {

        private Provider() {
        }

        /**
         * Returns an event producer.
         * @param broadcaster the event broadcaster to use
         * @return the event producer
         */
        public static AreaEventProducer get(EventBroadcaster broadcaster) {
            return broadcaster.getEventProducerFor(AreaEventProducer.class);
        }
    }

    /**
     * An unresolved ID reference was encountered.
     * @param source the event source
     * @param type the type of reference
     * @param id the unresolved ID
     * @event.severity WARN
     */
    void unresolvedIDReference(Object source, String type, String id);

    /**
     * An unresolved ID reference was encountered on a page.
     * @param source the event source
     * @param page the page the ID reference was found on
     * @param id the unresolved ID
     * @event.severity WARN
     */
    void unresolvedIDReferenceOnPage(Object source, String page, String id);

    /**
     * A page could not be loaded/deserialized from a file.
     * @param source the event source
     * @param page the page to be loaded
     * @param e the original exception
     * @event.severity ERROR
     */
    void pageLoadError(Object source, String page, Exception e);

    /**
     * A page could not be saved/serialized to a file.
     * @param source the event source
     * @param page the page to be serialized
     * @param e the original exception
     * @event.severity ERROR
     */
    void pageSaveError(Object source, String page, Exception e);

    /**
     * A page could not be rendered.
     * @param source the event source
     * @param page the page to be serialized
     * @param e the original exception
     * @event.severity ERROR
     */
    void pageRenderingError(Object source, String page, Exception e);

}

⏎ org/apache/fop/area/AreaEventProducer.java

Or download all of them as a single archive file:

File name: fop-2.7-src.zip
File size: 3401312 bytes
Release date: 2022-01-20
Download 

⇒ "fop" Command in fop-2.7-bin.zip

⇐ What Is fop-2.7-bin.zip

⇑ Download and Installing of FOP 2.x

⇑⇑ FAQ for FOP (Formatting Object Processor)