/* ===========================================================
 * JFreeChart : a free chart library for the Java(tm) platform
 * ===========================================================
 *
 * (C) Copyright 2000-present, by David Gilbert and Contributors.
 *
 * Project Info:  http://www.jfree.org/jfreechart/index.html
 *
 * This library is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2.1 of the License, or
 * (at your option) any later version.
 *
 * This library 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 Lesser General Public
 * License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
 * USA.
 *
 * [Oracle and Java are registered trademarks of Oracle and/or its affiliates. 
 * Other names may be trademarks of their respective owners.]
 *
 */

package org.jfree.chart.ui;

import java.awt.GradientPaint;
import java.awt.Shape;
import java.awt.geom.Rectangle2D;
import java.io.Serializable;
import org.jfree.chart.util.PublicCloneable;

/**
 * Transforms a {@code GradientPaint} to range over the width of a target 
 * shape.  Instances of this class are immutable.
 */
public class StandardGradientPaintTransformer 
    implements GradientPaintTransformer, Cloneable, PublicCloneable, 
               Serializable {
    
    /** For serialization. */
    private static final long serialVersionUID = -8155025776964678320L;

    /** The transform type. */
    private GradientPaintTransformType type;
    
    /**
     * Creates a new transformer with the type 
     * {@link GradientPaintTransformType#VERTICAL}.
     */
    public StandardGradientPaintTransformer() {
        this(GradientPaintTransformType.VERTICAL);
    }
    
    /**
     * Creates a new transformer with the specified type.
     * 
     * @param type  the transform type ({@code null} not permitted).
     */
    public StandardGradientPaintTransformer(
            final GradientPaintTransformType type) {
        if (type == null) {
            throw new IllegalArgumentException("Null 'type' argument.");
        }
        this.type = type;
    }
    
    /**
     * Returns the type of transform.
     * 
     * @return The type of transform (never {@code null}).
     */
    public GradientPaintTransformType getType() {
        return this.type;
    }
    
    /**
     * Transforms a {@code GradientPaint} instance to fit the specified
     * {@code target} shape.
     * 
     * @param paint  the original paint ({@code null} not permitted).
     * @param target  the target shape ({@code null} not permitted).
     * 
     * @return The transformed paint.
     */
    @Override
    public GradientPaint transform(GradientPaint paint, Shape target) {
        
        GradientPaint result = paint;
        Rectangle2D bounds = target.getBounds2D();
        
        if (this.type.equals(GradientPaintTransformType.VERTICAL)) {
            result = new GradientPaint((float) bounds.getCenterX(), 
                    (float) bounds.getMinY(), paint.getColor1(), 
                    (float) bounds.getCenterX(), (float) bounds.getMaxY(), 
                    paint.getColor2());
        }
        else if (this.type.equals(GradientPaintTransformType.HORIZONTAL)) {
            result = new GradientPaint((float) bounds.getMinX(), 
                    (float) bounds.getCenterY(), paint.getColor1(), 
                    (float) bounds.getMaxX(), (float) bounds.getCenterY(), 
                    paint.getColor2());            
        }
        else if (this.type.equals(
                GradientPaintTransformType.CENTER_HORIZONTAL)) {
            result = new GradientPaint((float) bounds.getCenterX(), 
                    (float) bounds.getCenterY(), paint.getColor2(), 
                    (float) bounds.getMaxX(), (float) bounds.getCenterY(), 
                    paint.getColor1(), true);            
        }
        else if (this.type.equals(GradientPaintTransformType.CENTER_VERTICAL)) {
            result = new GradientPaint((float) bounds.getCenterX(), 
                    (float) bounds.getMinY(), paint.getColor1(), 
                    (float) bounds.getCenterX(), (float) bounds.getCenterY(), 
                    paint.getColor2(), true);            
        }
        
        return result;
    }
    
    /**
     * Tests this instance for equality with an arbitrary object.
     * 
     * @param obj  the object ({@code null} permitted).
     * 
     * @return A boolean.
     */
    @Override
    public boolean equals(Object obj) {
        if (obj == this) {
            return true;   
        }
        if (!(obj instanceof StandardGradientPaintTransformer)) {
            return false;
        }
        StandardGradientPaintTransformer that 
                = (StandardGradientPaintTransformer) obj;
        if (this.type != that.type) {
            return false;
        }
        return true;
    }
    
    /**
     * Returns a clone of the transformer.  Note that instances of this class
     * are immutable, so cloning an instance isn't really necessary.
     * 
     * @return A clone.
     * 
     * @throws CloneNotSupportedException not thrown by this class, but 
     *         subclasses (if any) might.
     */
    @Override
    public Object clone() throws CloneNotSupportedException {
        return super.clone();
    }

    /**
     * Returns a hash code for this object.
     * 
     * @return A hash code.
     */
    @Override
    public int hashCode() {
        return (this.type != null ? this.type.hashCode() : 0);
    }
    
}