/*

 * Copyright (c) 1997, 1999, 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

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 */

package java.awt.image;

/**

 * The <code>Kernel</code> class defines a matrix that describes how a

 * specified pixel and its surrounding pixels affect the value

 * computed for the pixel's position in the output image of a filtering

 * operation.  The X origin and Y origin indicate the kernel matrix element

 * that corresponds to the pixel position for which an output value is

 * being computed.

 *

 * @see ConvolveOp

 */

public class Kernel implements Cloneable {

    private int  width;

    private int  height;

    private int  xOrigin;

    private int  yOrigin;

    private float data[];

    private static native void initIDs();

    static {

        ColorModel.loadLibraries();

        initIDs();

    }

    /**

     * Constructs a <code>Kernel</code> object from an array of floats.

     * The first <code>width</code>*<code>height</code> elements of

     * the <code>data</code> array are copied.

     * If the length of the <code>data</code> array is less

     * than width*height, an <code>IllegalArgumentException</code> is thrown.

     * The X origin is (width-1)/2 and the Y origin is (height-1)/2.

     * @param width         width of the kernel

     * @param height        height of the kernel

     * @param data          kernel data in row major order

     * @throws IllegalArgumentException if the length of <code>data</code>

     *         is less than the product of <code>width</code> and

     *         <code>height</code>

     */

    public Kernel(int width, int height, float data[]) {

        this.width  = width;

        this.height = height;

        this.xOrigin  = (width-1)>>1;

        this.yOrigin  = (height-1)>>1;

        int len = width*height;

        if (data.length < len) {

            throw new IllegalArgumentException("Data array too small "+

                                               "(is "+data.length+

                                               " and should be "+len);

        }

        this.data = new float[len];

        System.arraycopy(data, 0, this.data, 0, len);

    }

    /**

     * Returns the X origin of this <code>Kernel</code>.

     * @return the X origin.

     */

    final public int getXOrigin(){

        return xOrigin;

    }

    /**

     * Returns the Y origin of this <code>Kernel</code>.

     * @return the Y origin.

     */

    final public int getYOrigin() {

        return yOrigin;

    }

    /**

     * Returns the width of this <code>Kernel</code>.

     * @return the width of this <code>Kernel</code>.

     */

    final public int getWidth() {

        return width;

    }

    /**

     * Returns the height of this <code>Kernel</code>.

     * @return the height of this <code>Kernel</code>.

     */

    final public int getHeight() {

        return height;

    }

    /**

     * Returns the kernel data in row major order.

     * The <code>data</code> array is returned.  If <code>data</code>

     * is <code>null</code>, a new array is allocated.

     * @param data  if non-null, contains the returned kernel data

     * @return the <code>data</code> array containing the kernel data

     *         in row major order or, if <code>data</code> is

     *         <code>null</code>, a newly allocated array containing

     *         the kernel data in row major order

     * @throws IllegalArgumentException if <code>data</code> is less

     *         than the size of this <code>Kernel</code>

     */

    final public float[] getKernelData(float[] data) {

        if (data == null) {

            data = new float[this.data.length];

        }

        else if (data.length < this.data.length) {

            throw new IllegalArgumentException("Data array too small "+

                                               "(should be "+this.data.length+

                                               " but is "+

                                               data.length+" )");

        }

        System.arraycopy(this.data, 0, data, 0, this.data.length);

        return data;

    }

    /**

     * Clones this object.

     * @return a clone of this object.

     */

    public Object clone() {

        try {

            return super.clone();

        } catch (CloneNotSupportedException e) {

            // this shouldn't happen, since we are Cloneable

        }

    }

}