java图片生成等比例图片

最近在倒弄个一个网站，www.thinkdee.com 还在做，有一个上传图片LOGO需求，当然用户上传的图片不可能是原样输出的，这里要用等比例处理一下，不多说，附上代码：
  1 package com.thinkdee.util;
  2 
  3 
  4 import java.awt.image.BufferedImage;
  5 import java.io.File;
  6 
  7 import javax.imageio.ImageIO;
  8 
  9 public class ScaleImage {
 10 
 11     public ScaleImage() {
 12         support = 3D;
 13         PI = 3.1415926535897798D;
 14     }
 15 
 16 
 17     /**
 18      * 
 19      * <b>Summary: </b>
 20      *     saveImageAsJpg(生成等比例图片)
 21      * @param fromFileStr
 22      * @param saveToFileStr
 23      * @param formatWideth
 24      * @param formatHeight
 25      * @throws Exception
 26      */
 27     public void saveImageAsJpg(String fromFileStr, String saveToFileStr,
 28             int formatWideth, int formatHeight) throws Exception {
 29         File saveFile = new File(saveToFileStr);
 30         File fromFile = new File(fromFileStr);
 31         BufferedImage srcImage = ImageIO.read(fromFile);
 32         int imageWideth = srcImage.getWidth(null);
 33         int imageHeight = srcImage.getHeight(null);
 34         int changeToWideth = 0;
 35         int changeToHeight = 0;
 36         if (imageWideth > 0 && imageHeight > 0)
 37             if (imageWideth / imageHeight >= formatWideth / formatHeight) {
 38                 if (imageWideth > formatWideth) {
 39                     changeToWideth = formatWideth;
 40                     changeToHeight = (imageHeight * formatWideth) / imageWideth;
 41                 } else {
 42                     changeToWideth = imageWideth;
 43                     changeToHeight = imageHeight;
 44                 }
 45             } else if (imageHeight > formatHeight) {
 46                 changeToHeight = formatHeight;
 47                 changeToWideth = (imageWideth * formatHeight) / imageHeight;
 48             } else {
 49                 changeToWideth = imageWideth;
 50                 changeToHeight = imageHeight;
 51             }
 52         srcImage = imageZoomOut(srcImage, changeToWideth, changeToHeight);
 53         ImageIO.write(srcImage, "JPEG", saveFile);
 54     }
 55 
 56     public BufferedImage imageZoomOut(BufferedImage srcBufferImage, int w, int h) {
 57         width = srcBufferImage.getWidth();
 58         height = srcBufferImage.getHeight();
 59         scaleWidth = w;
 60         if (DetermineResultSize(w, h) == 1) {
 61             return srcBufferImage;
 62         } else {
 63             CalContrib();
 64             BufferedImage pbOut = HorizontalFiltering(srcBufferImage, w);
 65             BufferedImage pbFinalOut = VerticalFiltering(pbOut, h);
 66             return pbFinalOut;
 67         }
 68     }
 69 
 70     private int DetermineResultSize(int w, int h) {
 71         double scaleH = (double) w / (double) width;
 72         double scaleV = (double) h / (double) height;
 73         return scaleH < 1.0D || scaleV < 1.0D ? 0 : 1;
 74     }
 75 
 76     private double Lanczos(int i, int inWidth, int outWidth, double Support) {
 77         double x = ((double) i * (double) outWidth) / (double) inWidth;
 78         return ((Math.sin(x * PI) / (x * PI)) * Math.sin((x * PI) / Support))
 79                 / ((x * PI) / Support);
 80     }
 81 
 82     private void CalContrib() {
 83         nHalfDots = (int) (((double) width * support) / (double) scaleWidth);
 84         nDots = nHalfDots * 2 + 1;
 85         try {
 86             contrib = new double[nDots];
 87             normContrib = new double[nDots];
 88             tmpContrib = new double[nDots];
 89         } catch (Exception e) {
 90             System.out.println("init   contrib,normContrib,tmpContrib" + e);
 91         }
 92         int center = nHalfDots;
 93         contrib[center] = 1.0D;
 94         double weight = 0.0D;
 95         int i = 0;
 96         for (i = 1; i <= center; i++) {
 97             contrib[center + i] = Lanczos(i, width, scaleWidth, support);
 98             weight += contrib[center + i];
 99         }
100 
101         for (i = center - 1; i >= 0; i--)
102             contrib[i] = contrib[center * 2 - i];
103 
104         weight = weight * 2D + 1.0D;
105         for (i = 0; i <= center; i++)
106             normContrib[i] = contrib[i] / weight;
107 
108         for (i = center + 1; i < nDots; i++)
109             normContrib[i] = normContrib[center * 2 - i];
110 
111     }
112 
113     private void CalTempContrib(int start, int stop) {
114         double weight = 0.0D;
115         int i = 0;
116         for (i = start; i <= stop; i++)
117             weight += contrib[i];
118 
119         for (i = start; i <= stop; i++)
120             tmpContrib[i] = contrib[i] / weight;
121 
122     }
123 
124     private int GetRedValue(int rgbValue) {
125         int temp = rgbValue & 0xff0000;
126         return temp >> 16;
127     }
128 
129     private int GetGreenValue(int rgbValue) {
130         int temp = rgbValue & 0xff00;
131         return temp >> 8;
132     }
133 
134     private int GetBlueValue(int rgbValue) {
135         return rgbValue & 0xff;
136     }
137 
138     private int ComRGB(int redValue, int greenValue, int blueValue) {
139         return (redValue << 16) + (greenValue << 8) + blueValue;
140     }
141 
142     private int HorizontalFilter(BufferedImage bufImg, int startX, int stopX,
143             int start, int stop, int y, double pContrib[]) {
144         double valueRed = 0.0D;
145         double valueGreen = 0.0D;
146         double valueBlue = 0.0D;
147         int valueRGB = 0;
148         int i = startX;
149         for (int j = start; i <= stopX; j++) {
150             valueRGB = bufImg.getRGB(i, y);
151             valueRed += (double) GetRedValue(valueRGB) * pContrib[j];
152             valueGreen += (double) GetGreenValue(valueRGB) * pContrib[j];
153             valueBlue += (double) GetBlueValue(valueRGB) * pContrib[j];
154             i++;
155         }
156 
157         valueRGB = ComRGB(Clip((int) valueRed), Clip((int) valueGreen),
158                 Clip((int) valueBlue));
159         return valueRGB;
160     }
161 
162     private BufferedImage HorizontalFiltering(BufferedImage bufImage, int iOutW) {
163         int dwInW = bufImage.getWidth();
164         int dwInH = bufImage.getHeight();
165         int value = 0;
166         BufferedImage pbOut = new BufferedImage(iOutW, dwInH, 1);
167         for (int x = 0; x < iOutW; x++) {
168             int X = (int) (((double) x * (double) dwInW) / (double) iOutW + 0.5D);
169             int y = 0;
170             int startX = X - nHalfDots;
171             int start;
172             if (startX < 0) {
173                 startX = 0;
174                 start = nHalfDots - X;
175             } else {
176                 start = 0;
177             }
178             int stopX = X + nHalfDots;
179             int stop;
180             if (stopX > dwInW - 1) {
181                 stopX = dwInW - 1;
182                 stop = nHalfDots + (dwInW - 1 - X);
183             } else {
184                 stop = nHalfDots * 2;
185             }
186             if (start > 0 || stop < nDots - 1) {
187                 CalTempContrib(start, stop);
188                 for (y = 0; y < dwInH; y++) {
189                     value = HorizontalFilter(bufImage, startX, stopX, start,
190                             stop, y, tmpContrib);
191                     pbOut.setRGB(x, y, value);
192                 }
193 
194             } else {
195                 for (y = 0; y < dwInH; y++) {
196                     value = HorizontalFilter(bufImage, startX, stopX, start,
197                             stop, y, normContrib);
198                     pbOut.setRGB(x, y, value);
199                 }
200 
201             }
202         }
203 
204         return pbOut;
205     }
206 
207     private int VerticalFilter(BufferedImage pbInImage, int startY, int stopY,
208             int start, int stop, int x, double pContrib[]) {
209         double valueRed = 0.0D;
210         double valueGreen = 0.0D;
211         double valueBlue = 0.0D;
212         int valueRGB = 0;
213         int i = startY;
214         for (int j = start; i <= stopY; j++) {
215             valueRGB = pbInImage.getRGB(x, i);
216             valueRed += (double) GetRedValue(valueRGB) * pContrib[j];
217             valueGreen += (double) GetGreenValue(valueRGB) * pContrib[j];
218             valueBlue += (double) GetBlueValue(valueRGB) * pContrib[j];
219             i++;
220         }
221 
222         valueRGB = ComRGB(Clip((int) valueRed), Clip((int) valueGreen),
223                 Clip((int) valueBlue));
224         return valueRGB;
225     }
226 
227     private BufferedImage VerticalFiltering(BufferedImage pbImage, int iOutH) {
228         int iW = pbImage.getWidth();
229         int iH = pbImage.getHeight();
230         int value = 0;
231         BufferedImage pbOut = new BufferedImage(iW, iOutH, 1);
232         for (int y = 0; y < iOutH; y++) {
233             int Y = (int) (((double) y * (double) iH) / (double) iOutH + 0.5D);
234             int startY = Y - nHalfDots;
235             int start;
236             if (startY < 0) {
237                 startY = 0;
238                 start = nHalfDots - Y;
239             } else {
240                 start = 0;
241             }
242             int stopY = Y + nHalfDots;
243             int stop;
244             if (stopY > iH - 1) {
245                 stopY = iH - 1;
246                 stop = nHalfDots + (iH - 1 - Y);
247             } else {
248                 stop = nHalfDots * 2;
249             }
250             if (start > 0 || stop < nDots - 1) {
251                 CalTempContrib(start, stop);
252                 for (int x = 0; x < iW; x++) {
253                     value = VerticalFilter(pbImage, startY, stopY, start, stop,
254                             x, tmpContrib);
255                     pbOut.setRGB(x, y, value);
256                 }
257 
258             } else {
259                 for (int x = 0; x < iW; x++) {
260                     value = VerticalFilter(pbImage, startY, stopY, start, stop,
261                             x, normContrib);
262                     pbOut.setRGB(x, y, value);
263                 }
264 
265             }
266         }
267 
268         return pbOut;
269     }
270 
271     int Clip(int x) {
272         if (x < 0)
273             return 0;
274         if (x > 255)
275             return 255;
276         else
277             return x;
278     }
279 
280     private int width;
281     private int height;
282     private int scaleWidth;
283     double support;
284     double PI;
285     double contrib[];
286     double normContrib[];
287     double tmpContrib[];
288     int startContrib;
289     int stopContrib;
290     int nDots;
291     int nHalfDots;
292 }
posted on 2013-05-22 11:09 游鱼阅读(1554) 评论(0) 编辑收藏举报