Resizes image down to specified width and height - Java 2D Graphics

Java examples for 2D Graphics:BufferedImage Resize

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Description

Resizes image down to specified width and height

Demo Code

/*//from   w w  w .  j a  v  a  2 s.  co m
 * @(#)ImageChangeUtil.java
 * 
 * Copyright 2013 MBARI
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
import java.awt.Graphics2D;
import java.awt.geom.AffineTransform;
import java.awt.image.AffineTransformOp;
import java.awt.image.BufferedImage;

public class Main{
    /**
     * Resizes image down to specified width and height
     *
     * @param toWidth width to scale to
     * @param toHeight height to scale to
     *
     * @return ResizedImage Returns null if the image did not need to be resized.
     */
    public static BufferedImage resizeImageDown(BufferedImage image,
            double toWidth, double toHeight) throws Exception {
        if (toWidth < 10) {
            return null;
        }

        if (toHeight < 10) {
            return null;
        }

        float t = ImageChangeUtil.calcThetaDown(image.getWidth(),
                image.getHeight(), toWidth, toHeight);

        if (t > 0.f) {

            // System.out.println("Resizing Needed!");
            return scale(image, t);
        }

        return null;
    }
    /**
     * Calculates how to size the picture up or down to fit in the area given.
     *
     * @param fromWidth original image width to scale from
     * @param fromHeight original image height to scale from
     *
     * @param toWidth width to scale down to
     * @param toHeight height to scale down to
     *
     * @return the floating theta value to scale both width and height dimensions
     * to fit into the given <code>toWidth</code> and <code>toHeight</code>
     */
    public static float calcThetaDown(int fromWidth, int fromHeight,
            double toWidth, double toHeight) {

        // System.out.println("Converting From: w: " + fromWidth + " h: " + fromHeight);
        // System.out.println("Converting To: w: " + toWidth + " h: " + toHeight);
        float wideBy = 0;

        if (fromWidth > toWidth) {
            wideBy = (float) toWidth / fromWidth;
        }

        float highBy = 0;

        if (fromHeight > toHeight) {
            highBy = (float) toHeight / fromHeight;
        }

        // Take the smaller fraction to result in the highest size reduction.
        float theta = 0;

        // If both the same, take one of them.
        if (wideBy == highBy) {
            theta = highBy;
        } // Otherwise take the smallest number greater than zero.
        else {
            if ((wideBy > 0) && (highBy > 0)) {
                if (wideBy < highBy) {
                    theta = wideBy;
                } else {
                    theta = highBy;
                }
            } else if (wideBy > 0) {
                theta = wideBy;
            } else if (highBy > 0) {
                theta = highBy;
            }

            // System.out.println("DOWN wide by: " + wideBy + "  high by: " + highBy);
            // System.out.println("DOWN Theta: " + theta);
        }

        return theta;
    }
    /**
     * Scales a <code>BufferedImage</code> using a theta that
     * defines the scaling in both width and height.
     *
     *
     * @param image BufferedImage
     * @param theta scaling factor. Must be between 0-1.0
     *
     * @return a scaled version of the original {@code BufferedImage}.
     * Throws exception if {@link java.awt.image.AffineTransformOp AffineTransformOp} fails to scale.
     */
    public static BufferedImage scale(BufferedImage image, float theta)
            throws Exception {

        // //System.out.println("theta: " + t);
        try {
            BufferedImage newimage = image;
            AffineTransform at = AffineTransform.getScaleInstance(
                    (double) theta, (double) theta);
            AffineTransformOp op = new AffineTransformOp(at, null);

            return op.filter(newimage, null);
        } catch (Exception ex) {
            System.err.println(ex.toString());
            ex.printStackTrace();

            // Fail safe because this randomly blew up once in Linux.
            // Might not be a real problem, but what the heck!
            return image;
        }
    }
}

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