Creates a thumbnail from an image. - Java 2D Graphics

Java examples for 2D Graphics:BufferedImage Create

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Description

Creates a thumbnail from an image.

Demo Code

/*/*from w w  w  .j  av a  2s  .  c o m*/
 * Copyright (c) 2005 Sun Microsystems, Inc. All Rights Reserved.
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 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
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 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES,
 * INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A
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 */
//package com.java2s;
import java.awt.*;
import java.awt.image.*;

public class Main {
    /**
     * Creates a thumbnail from an image. A thumbnail is a scaled down version of the original picture.
     * This method will retain the width to height ratio of the original picture and return a new
     * instance of <code>BufferedImage</code>. The original picture is not modified.
     *
     * @param image The original image to sample down
     * @param thumbWidth The width of the thumbnail to be created
     *
     * @throws IllegalArgumentException If thumbWidth is greater than image.getWidth()
     *
     * @return A thumbnail with the requested width or the original picture if thumbWidth = image.getWidth()
     */
    public static BufferedImage createThumbnail(final BufferedImage image,
            final int thumbWidth) {
        // Thanks to Romain Guy for this utility
        if (thumbWidth > image.getWidth()) {
            throw new IllegalArgumentException(
                    "Thumbnail width must be greater than image width");
        }

        if (thumbWidth == image.getWidth()) {
            return image;
        }

        final float ratio = (float) image.getWidth()
                / (float) image.getHeight();
        int width = image.getWidth();
        BufferedImage thumb = image;

        do {
            width /= 2;
            if (width < thumbWidth) {
                width = thumbWidth;
            }

            final BufferedImage temp = createCompatibleImage(width,
                    (int) (width / ratio));
            final Graphics2D g2 = temp.createGraphics();
            g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION,
                    RenderingHints.VALUE_INTERPOLATION_BILINEAR);
            g2.drawImage(thumb, 0, 0, temp.getWidth(), temp.getHeight(),
                    null);
            g2.dispose();
            thumb = temp;
        } while (width != thumbWidth);

        return thumb;
    }

    /**
     * Creates a <code>BufferedImage</code> with a pixel format compatible with the graphics
     * environment. The returned image can thus benefit from hardware accelerated operations
     * in Java2D API.
     *
     * @param width The width of the image to be created
     * @param height The height of the image to be created
     *
     * @return A instance of <code>BufferedImage</code> with a type compatible with the graphics card.
     */
    public static BufferedImage createCompatibleImage(final int width,
            final int height) {
        final GraphicsConfiguration configuration = GraphicsEnvironment
                .getLocalGraphicsEnvironment().getDefaultScreenDevice()
                .getDefaultConfiguration();
        return configuration.createCompatibleImage(width, height);
    }
}

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