Java example source code file (ChainEnd.java)

This example Java source code file (ChainEnd.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

chainend, curvelink, internalerror, linking

The ChainEnd.java Java example source code

/*
 * Copyright (c) 1998, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package sun.awt.geom;

final class ChainEnd {
    CurveLink head;
    CurveLink tail;
    ChainEnd partner;
    int etag;

    public ChainEnd(CurveLink first, ChainEnd partner) {
        this.head = first;
        this.tail = first;
        this.partner = partner;
        this.etag = first.getEdgeTag();
    }

    public CurveLink getChain() {
        return head;
    }

    public void setOtherEnd(ChainEnd partner) {
        this.partner = partner;
    }

    public ChainEnd getPartner() {
        return partner;
    }

    /*
     * Returns head of a complete chain to be added to subcurves
     * or null if the links did not complete such a chain.
     */
    public CurveLink linkTo(ChainEnd that) {
        if (etag == AreaOp.ETAG_IGNORE ||
            that.etag == AreaOp.ETAG_IGNORE)
        {
            throw new InternalError("ChainEnd linked more than once!");
        }
        if (etag == that.etag) {
            throw new InternalError("Linking chains of the same type!");
        }
        ChainEnd enter, exit;
        // assert(partner.etag != that.partner.etag);
        if (etag == AreaOp.ETAG_ENTER) {
            enter = this;
            exit = that;
        } else {
            enter = that;
            exit = this;
        }
        // Now make sure these ChainEnds are not linked to any others...
        etag = AreaOp.ETAG_IGNORE;
        that.etag = AreaOp.ETAG_IGNORE;
        // Now link everything up...
        enter.tail.setNext(exit.head);
        enter.tail = exit.tail;
        if (partner == that) {
            // Curve has closed on itself...
            return enter.head;
        }
        // Link this chain into one end of the chain formed by the partners
        ChainEnd otherenter = exit.partner;
        ChainEnd otherexit = enter.partner;
        otherenter.partner = otherexit;
        otherexit.partner = otherenter;
        if (enter.head.getYTop() < otherenter.head.getYTop()) {
            enter.tail.setNext(otherenter.head);
            otherenter.head = enter.head;
        } else {
            otherexit.tail.setNext(enter.head);
            otherexit.tail = enter.tail;
        }
        return null;
    }

    public void addLink(CurveLink newlink) {
        if (etag == AreaOp.ETAG_ENTER) {
            tail.setNext(newlink);
            tail = newlink;
        } else {
            newlink.setNext(head);
            head = newlink;
        }
    }

    public double getX() {
        if (etag == AreaOp.ETAG_ENTER) {
            return tail.getXBot();
        } else {
            return head.getXBot();
        }
    }
}