package cn.hlgc.util; 
  
 import java.awt.image.BufferedImage; 
  
 import org.apache.log4j.Logger; 
  
 public class ResizePicUtil { 
 	private int width; 
 	private int height; 
 	private int scaleWidth; 
 	double support = (double) 3.0; 
 	double PI = (double) 3.14159265358978; 
 	double[] contrib; 
 	double[] normContrib; 
 	double[] tmpContrib; 
 	int startContrib, stopContrib; 
 	int nDots; 
 	int nHalfDots; 
  
 	private static Logger logger = Logger.getLogger(ResizePicUtil.class); 
  
 	public BufferedImage imageZoomOut(BufferedImage srcBufferImage, int w, int h) { 
 		width = srcBufferImage.getWidth(); 
 		height = srcBufferImage.getHeight(); 
 		scaleWidth = w; 
 		logger.info("原图宽度为[" + width + "px]..."); 
 		logger.info("原图高度为[" + height + "px]..."); 
 		if (DetermineResultSize(w, h) == 1) { 
 			logger.info("不需要将图片进行缩小..."); 
 			return srcBufferImage; 
 		} 
 		logger.info("计算缩小图片的宽度和高度..."); 
 		double wh = ((double) width) / ((double) height); 
 		double hw = ((double) height) / ((double) width); 
 		if (wh > hw) { 
 			h = (int) (w * hw); 
 		} else { 
 			w = (int) (h * wh); 
 		} 
 		logger.info("图片宽度调整为[" + w + "px]..."); 
 		logger.info("图片高度调整为[" + h + "px]..."); 
 		long begin = System.currentTimeMillis(); 
 		CalContrib(); 
 		BufferedImage pbOut = HorizontalFiltering(srcBufferImage, w); 
 		BufferedImage pbFinalOut = VerticalFiltering(pbOut, h); 
 		long end = System.currentTimeMillis(); 
 		logger.info("图片高宽调整完毕,耗时[" + (end - begin) + "]毫秒..."); 
 		return pbFinalOut; 
 	} 
  
 	private int DetermineResultSize(int w, int h) { 
 		double scaleH, scaleV; 
 		scaleH = (double) w / (double) width; 
 		scaleV = (double) h / (double) height; 
 		if (scaleH >= 1.0 && scaleV >= 1.0) { 
 			return 1; 
 		} 
 		return 0; 
 	} 
  
 	private double Lanczos(int i, int inWidth, int outWidth, double Support) { 
 		double x; 
  
 		x = (double) i * (double) outWidth / (double) inWidth; 
  
 		return Math.sin(x * PI) / (x * PI) * Math.sin(x * PI / Support) 
 				/ (x * PI / Support); 
  
 	} 
  
 	private void CalContrib() { 
 		nHalfDots = (int) ((double) width * support / (double) scaleWidth); 
 		nDots = nHalfDots * 2 + 1; 
 		try { 
 			contrib = new double[nDots]; 
 			normContrib = new double[nDots]; 
 			tmpContrib = new double[nDots]; 
 		} catch (Exception e) { 
 			System.out.println("init   contrib,normContrib,tmpContrib" + e); 
 		} 
  
 		int center = nHalfDots; 
 		contrib[center] = 1.0; 
  
 		double weight = 0.0; 
 		int i = 0; 
 		for (i = 1; i  <= center; i++) { 
 			contrib[center + i] = Lanczos(i, width, scaleWidth, support); 
 			weight += contrib[center + i]; 
 		} 
  
 		for (i = center - 1; i >= 0; i--) { 
 			contrib[i] = contrib[center * 2 - i]; 
 		} 
  
 		weight = weight * 2 + 1.0; 
  
 		for (i = 0; i  <= center; i++) { 
 			normContrib[i] = contrib[i] / weight; 
 		} 
  
 		for (i = center + 1; i  < nDots; i++) { 
 			normContrib[i] = normContrib[center * 2 - i]; 
 		} 
 	} 
  
 	// 处理边缘 
 	private void CalTempContrib(int start, int stop) { 
 		double weight = 0; 
  
 		int i = 0; 
 		for (i = start; i  <= stop; i++) { 
 			weight += contrib[i]; 
 		} 
  
 		for (i = start; i  <= stop; i++) {