一个JAVA图形缩放处理工具类
调用的例子
import java.io.FileOutputStream; import java.io.IOException; import javax.imageio.ImageIO; public class T { public static void main(String[] args) throws Exception, IOException { ImageIO.write(ImageUtils.resizeImage("d:/www.java2000.net.gif", ImageUtils.IMAGE_GIF, 30, 20), "JPEG", new FileOutputStream("d:/test.jpg")); } }?
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; 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(); return null; } } /** * 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(); return false; } } /** * 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; } } }?