图片工具１

ImageUtils

/*
 * Copyright (c) JForum Team
 * All rights reserved.

 * Redistribution and use in source and binary forms, 
 * with or without modification, are permitted provided 
 * that the following conditions are met:

 * 1) Redistributions of source code must retain the above 
 * copyright notice, this list of conditions and the 
 * following  disclaimer.
 * 2)  Redistributions in binary form must reproduce the 
 * above copyright notice, this list of conditions and 
 * the following disclaimer in the documentation and/or 
 * other materials provided with the distribution.
 * 3) Neither the name of "Rafael Steil" nor 
 * the names of its contributors may be used to endorse 
 * or promote products derived from this software without 
 * specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT 
 * HOLDERS AND CONTRIBUTORS "AS IS" AND ANY 
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, 
 * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR 
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL 
 * THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE 
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES 
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, 
 * OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER 
 * IN CONTRACT, STRICT LIABILITY, OR TORT 
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN 
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF 
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE
 * 
 * This file creation date: 21/04/2004 - 19:54:16
 * The JForum Project
 * http://www.jforum.net
 */

import java.awt.Dimension;
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.awt.image.PixelGrabber;
import java.io.File;
import java.io.IOException;
import java.util.Iterator;
import java.util.Locale;

import javax.imageio.IIOImage;
import javax.imageio.ImageIO;
import javax.imageio.ImageWriteParam;
import javax.imageio.ImageWriter;
import javax.imageio.plugins.jpeg.JPEGImageWriteParam;
import javax.imageio.stream.ImageOutputStream;


/**
 * Utilities methods for image manipulation. It does not support writting of GIF images, but it can
 * read from. GIF images will be saved as PNG.
 * 
 * @author Rafael Steil
 * @version $Id: ImageUtils.java,v 1.23 2007/09/09 01:05:22 rafaelsteil Exp $
 */
public class ImageUtils
{
  public static final int IMAGE_UNKNOWN = -1;
  public static final int IMAGE_JPEG = 0;
  public static final int IMAGE_PNG = 1;
  public static final int IMAGE_GIF = 2;

  /**
   * Resizes an image
   * 
   * @param imgName The image name to resize. Must be the complet path to the file
   * @param type int
   * @param maxWidth The image's max width
   * @param maxHeight The image's max height
   * @return A resized <code>BufferedImage</code>
   */
  public static BufferedImage resizeImage(String imgName, int type, int maxWidth, int maxHeight)
  {
    try {
      return resizeImage(ImageIO.read(new File(imgName)), type, maxWidth, maxHeight);
    }
    catch (IOException e) {
      e.printStackTrace();
    }
  }

  /**
   * Resizes an image.
   * 
   * @param image
   *            The image to resize
   * @param maxWidth
   *            The image's max width
   * @param maxHeight
   *            The image's max height
   * @return A resized <code>BufferedImage</code>
   * @param type
   *            int
   */
  public static BufferedImage resizeImage(BufferedImage image, int type, int maxWidth, int maxHeight)
  {
    Dimension largestDimension = new Dimension(maxWidth, maxHeight);

    // Original size
    int imageWidth = image.getWidth(null);
    int imageHeight = image.getHeight(null);

    float aspectRatio = (float) imageWidth / imageHeight;

    if (imageWidth > maxWidth || imageHeight > maxHeight) {
      if ((float) largestDimension.width / largestDimension.height > aspectRatio) {
        largestDimension.width = (int) Math.ceil(largestDimension.height * aspectRatio);
      }
      else {
        largestDimension.height = (int) Math.ceil(largestDimension.width / aspectRatio);
      }

      imageWidth = largestDimension.width;
      imageHeight = largestDimension.height;
    }

    return createHeadlessSmoothBufferedImage(image, type, imageWidth, imageHeight);
  }

  /**
   * Saves an image to the disk.
   * 
   * @param image  The image to save
   * @param toFileName The filename to use
   * @param type The image type. Use <code>ImageUtils.IMAGE_JPEG</code> to save as JPEG images,
   *  or <code>ImageUtils.IMAGE_PNG</code> to save as PNG.
   * @return <code>false</code> if no appropriate writer is found
   */
  public static boolean saveImage(BufferedImage image, String toFileName, int type)
  {
    try {
      return ImageIO.write(image, type == IMAGE_JPEG ? "jpg" : "png", new File(toFileName));
    }
    catch (IOException e) {
      e.printStackTrace();
    }
  }

  /**
   * Compress and save an image to the disk. Currently this method only supports JPEG images.
   * 
   * @param image The image to save
   * @param toFileName The filename to use
   * @param type The image type. Use <code>ImageUtils.IMAGE_JPEG</code> to save as JPEG images,
   * or <code>ImageUtils.IMAGE_PNG</code> to save as PNG.
   */
  public static void saveCompressedImage(BufferedImage image, String toFileName, int type)
  {
    try {
      if (type == IMAGE_PNG) {
        throw new UnsupportedOperationException("PNG compression not implemented");
      }

      Iterator iter = ImageIO.getImageWritersByFormatName("jpg");
      ImageWriter writer;
      writer = (ImageWriter) iter.next();

      ImageOutputStream ios = ImageIO.createImageOutputStream(new File(toFileName));
      writer.setOutput(ios);

      ImageWriteParam iwparam = new JPEGImageWriteParam(Locale.getDefault());

      iwparam.setCompressionMode(ImageWriteParam.MODE_EXPLICIT);
      iwparam.setCompressionQuality(0.7F);

      writer.write(null, new IIOImage(image, null, null), iwparam);

      ios.flush();
      writer.dispose();
      ios.close();
    }
    catch (IOException e) {
      e.printStackTrace();
    }
  }

  /**
   * Creates a <code>BufferedImage</code> from an <code>Image</code>. This method can
   * function on a completely headless system. This especially includes Linux and Unix systems
   * that do not have the X11 libraries installed, which are required for the AWT subsystem to
   * operate. This method uses nearest neighbor approximation, so it's quite fast. Unfortunately,
   * the result is nowhere near as nice looking as the createHeadlessSmoothBufferedImage method.
   * 
   * @param image  The image to convert
   * @param w The desired image width
   * @param h The desired image height
   * @return The converted image
   * @param type int
   */
  public static BufferedImage createHeadlessBufferedImage(BufferedImage image, int type, int width, int height)
  {
    if (type == ImageUtils.IMAGE_PNG && hasAlpha(image)) {
      type = BufferedImage.TYPE_INT_ARGB;
    }
    else {
      type = BufferedImage.TYPE_INT_RGB;
    }

    BufferedImage bi = new BufferedImage(width, height, type);

    for (int y = 0; y < height; y++) {
      for (int x = 0; x < width; x++) {
        bi.setRGB(x, y, image.getRGB(x * image.getWidth() / width, y * image.getHeight() / height));
      }
    }

    return bi;
  }

  /**
   * Creates a <code>BufferedImage</code> from an <code>Image</code>. This method can
   * function on a completely headless system. This especially includes Linux and Unix systems
   * that do not have the X11 libraries installed, which are required for the AWT subsystem to
   * operate. The resulting image will be smoothly scaled using bilinear filtering.
   * 
   * @param source The image to convert
   * @param w The desired image width
   * @param h The desired image height
   * @return The converted image
   * @param type  int
   */
  public static BufferedImage createHeadlessSmoothBufferedImage(BufferedImage source, int type, int width, int height)
  {
    if (type == ImageUtils.IMAGE_PNG && hasAlpha(source)) {
      type = BufferedImage.TYPE_INT_ARGB;
    }
    else {
      type = BufferedImage.TYPE_INT_RGB;
    }

    BufferedImage dest = new BufferedImage(width, height, type);

    int sourcex;
    int sourcey;

    double scalex = (double) width / source.getWidth();
    double scaley = (double) height / source.getHeight();

    int x1;
    int y1;

    double xdiff;
    double ydiff;

    int rgb;
    int rgb1;
    int rgb2;

    for (int y = 0; y < height; y++) {
      sourcey = y * source.getHeight() / dest.getHeight();
      ydiff = scale(y, scaley) - sourcey;

      for (int x = 0; x < width; x++) {
        sourcex = x * source.getWidth() / dest.getWidth();
        xdiff = scale(x, scalex) - sourcex;

        x1 = Math.min(source.getWidth() - 1, sourcex + 1);
        y1 = Math.min(source.getHeight() - 1, sourcey + 1);

        rgb1 = getRGBInterpolation(source.getRGB(sourcex, sourcey), source.getRGB(x1, sourcey), xdiff);
        rgb2 = getRGBInterpolation(source.getRGB(sourcex, y1), source.getRGB(x1, y1), xdiff);

        rgb = getRGBInterpolation(rgb1, rgb2, ydiff);

        dest.setRGB(x, y, rgb);
      }
    }

    return dest;
  }

  private static double scale(int point, double scale)
  {
    return point / scale;
  }

  private static int getRGBInterpolation(int value1, int value2, double distance)
  {
    int alpha1 = (value1 & 0xFF000000) >>> 24;
    int red1 = (value1 & 0x00FF0000) >> 16;
    int green1 = (value1 & 0x0000FF00) >> 8;
    int blue1 = (value1 & 0x000000FF);

    int alpha2 = (value2 & 0xFF000000) >>> 24;
    int red2 = (value2 & 0x00FF0000) >> 16;
    int green2 = (value2 & 0x0000FF00) >> 8;
    int blue2 = (value2 & 0x000000FF);

    int rgb = ((int) (alpha1 * (1.0 - distance) + alpha2 * distance) << 24)
      | ((int) (red1 * (1.0 - distance) + red2 * distance) << 16)
      | ((int) (green1 * (1.0 - distance) + green2 * distance) << 8)
      | (int) (blue1 * (1.0 - distance) + blue2 * distance);

    return rgb;
  }

  /**
   * Determines if the image has transparent pixels.
   * 
   * @param image The image to check for transparent pixel.s
   * @return <code>true</code> of <code>false</code>, according to the result
   */
  public static boolean hasAlpha(Image image)
  {
    try {
      PixelGrabber pg = new PixelGrabber(image, 0, 0, 1, 1, false);
      pg.grabPixels();

      return pg.getColorModel().hasAlpha();
    }
    catch (InterruptedException e) {
      return false;
    }
  }
}