create Thumbnail - Java 2D Graphics

Java examples for 2D Graphics:BufferedImage Scale

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Description

create Thumbnail

Demo Code


//package com.java2s;
import java.awt.Graphics2D;

import java.awt.Image;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import javax.imageio.ImageIO;

public class Main {
    public static byte[] createThumbnail(byte[] source_bytes,
            int maximum_width, int maximum_height) throws IOException {

        byte[] out_bytes = new byte[0];

        Image image = ImageIO.read(new ByteArrayInputStream(source_bytes));
        if (image == null)
            return out_bytes;

        int width = image.getWidth(null);
        int height = image.getHeight(null);

        /* nothing to do, the image is smaller */
        if (width < maximum_width && height < maximum_height) {
            System.out.println("Invalid dimensions");
            return out_bytes;
        }/* www .  j a v  a2 s. c  o m*/

        double scale = (double) maximum_height / (double) height;

        if (width > height) {
            scale = (double) maximum_width / (double) width;
        }

        int scale_width = (int) (scale * width);
        int scale_height = (int) (scale * height);

        BufferedImage image_out = new BufferedImage(scale_width,
                scale_height, BufferedImage.TYPE_INT_RGB);

        AffineTransform at = new AffineTransform();

        if (scale < 1.0d) {
            at.scale(scale, scale);
        }
        Graphics2D g2d = image_out.createGraphics();

        image_out.flush();
        g2d.drawImage(image, at, null);
        g2d.dispose();
        ByteArrayOutputStream baos = new ByteArrayOutputStream();

        ImageIO.write(image_out, "jpg", baos);

        return baos.toByteArray();
    }
}

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