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/AbstractOffDocumentItem.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: AbstractOffDocumentItem.java 679326 2008-07-24 09:35:34Z vhennebert $ */

package org.apache.fop.area;

/**
 * Abstract base class for objects that are processed by the renderer outside
 * of the actual document.
 * This object can be handled by the renderer according to these
 * possibilities: IMMEDIATELY, AFTER_PAGE, START_OF_DOC or END_OF_DOC.
 */
public abstract class AbstractOffDocumentItem implements OffDocumentItem {

    /**
     * Process this extension immediately when
     * being handled by the area tree.
     */
    public static final int IMMEDIATELY = 0;

    /**
     * Process this extension after the next page is rendered
     * or prepared when being handled by the area tree.
     */
    public static final int AFTER_PAGE = 1;

    /**
     * Process this extension at the end of the document once
     * all pages have been fully rendered.
     */
    public static final int END_OF_DOC = 2;

    /**
     * Process this extension at the start of the document right
     * before the first page-sequence is processed.
     */
    public static final int START_OF_DOC = 2;


    /** Indicates in what phase the item should be processed. */
    protected int whenToProcess = IMMEDIATELY;

    /**
     * Get an indicator of when this item should be processed
     * @return int constant (IMMEDIATELY, AFTER_PAGE, START_OF_DOC, END_OF_DOC)
     */
    public int getWhenToProcess() {
        return whenToProcess;
    }

    /**
     * Return a human-readable name for this ODI (for error messages, etc.)
     * @return String name of ODI
     */
    public abstract String getName();
}

⏎ org/apache/fop/area/AbstractOffDocumentItem.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)