previewimage.java

java写的blog

/*
 * Created on 2004-11-14
 * Author: Xuefeng, Copyright (C) 2004, Xuefeng.
 */
package org.crystalblog.logic;

import java.awt.geom.AffineTransform;
import java.awt.image.AffineTransformOp;
import java.awt.image.BufferedImage;
import java.io.File;

import javax.imageio.ImageIO;

import org.crystalblog.domain.Image;

/**
 * Create preview image.
 * 
 * @author Xuefeng
 */
public class PreviewImage {

    private static final int IMAGE_SIZE = 120;
    private static AffineTransform transform = new AffineTransform();

    public static void createPreviewImage(String srcFile, String destFile, String type) {
        String imageType = null;
        if(type.equals(Image.TYPE_JPG))
            imageType = "jpeg";
        else if(type.equals(Image.TYPE_GIF))
            imageType = "gif";
        else if(type.equals(Image.TYPE_PNG))
            imageType = "png";
        else
            throw new RuntimeException("Unsupported image type: " + type);
        try {
            File fi = new File(srcFile); // src
            File fo = new File(destFile); // dest

            BufferedImage bis = ImageIO.read(fi);

            int w = bis.getWidth();
            int h = bis.getHeight();
            double scale = (double)w/h;

            int nw = IMAGE_SIZE;
            int nh = (nw * h) / w;
            if( nh>IMAGE_SIZE ) {
                nh = IMAGE_SIZE;
                nw = (nh * w) / h;
                if(nw==0) nw = 1;
            }

            double sx = (double)nw / w;
            double sy = (double)nh / h;

            transform.setToScale(sx,sy);

            AffineTransformOp ato = new AffineTransformOp(transform, null);
            BufferedImage bid = new BufferedImage(nw, nh, BufferedImage.TYPE_3BYTE_BGR);
            ato.filter(bis,bid);
            ImageIO.write(bid, imageType, fo);
        } catch(Exception e) {
            e.printStackTrace();
            throw new RuntimeException("Failed in create preview image. Error: " + e.getMessage());
        }
    }
}