RegionIterator.java

/*
 * Copyright (c) 1998, 2018, 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.java2d.pipe;


/**
 * This class defines the API for iterating through the bands
 * of a region object.
 */
public class RegionIterator {
    Region region;
    int curIndex;
    int numXbands;

    RegionIterator(Region r) {
        region = r;
    }

    /**
     * Returns a new RegionIterator object representing the same
     * iteration state as this object to allow multiple iteration
     * branches from the current position.
     */
    public RegionIterator createCopy() {
        RegionIterator r = new RegionIterator(region);
        r.curIndex = this.curIndex;
        r.numXbands = this.numXbands;
        return r;
    }

    /**
     * Copies the iteration state from this RegionIterator object
     * into another RegionIterator object to allow multiple iteration
     * branches from the current position.
     */
    public void copyStateFrom(RegionIterator ri) {
        if (this.region != ri.region) {
            throw new InternalError("region mismatch");
        }
        this.curIndex = ri.curIndex;
        this.numXbands = ri.numXbands;
    }

    /**
     * Moves the iteration state to the beginning of the next
     * Y range in the region returning true if one is found
     * and recording the low and high Y coordinates of the
     * range in the array at locations 1 and 3 respectively.
     */
    public boolean nextYRange(int[] range) {
        curIndex += numXbands * 2;
        numXbands = 0;
        if (curIndex >= region.endIndex) {
            return false;
        }
        range[1] = region.bands[curIndex++];
        range[3] = region.bands[curIndex++];
        numXbands = region.bands[curIndex++];
        return true;
    }

    /**
     * Moves the iteration state to the beginning of the next
     * X band in the current Y range returning true if one is
     * found and recording the low and high X coordinates of
     * the range in the array at locations 0 and 2 respectively.
     */
    public boolean nextXBand(int[] range) {
        if (numXbands <= 0) {
            return false;
        }
        numXbands--;
        range[0] = region.bands[curIndex++];
        range[2] = region.bands[curIndex++];
        return true;
    }
}