创建图片的缩略图 createThumbnail

  1. private void createThumbnail(String filename, int thumbWidth, int thumbHeight, int quality, String outFilename)
  2.         throws InterruptedException, FileNotFoundException, IOException
  3.     {
  4.         // load image from filename  
  5.         Image image = Toolkit.getDefaultToolkit().getImage(filename);
  6.         MediaTracker mediaTracker = new MediaTracker(new Container());
  7.         mediaTracker.addImage(image, 0);
  8.         mediaTracker.waitForID(0);
  9.         // use this to test for errors at this point: System.out.println(mediaTracker.isErrorAny());  
  11.         // determine thumbnail size from WIDTH and HEIGHT  
  12.         double thumbRatio = (double)thumbWidth / (double)thumbHeight;
  13.         int imageWidth = image.getWidth(null);
  14.         int imageHeight = image.getHeight(null);
  15.         double imageRatio = (double)imageWidth / (double)imageHeight;
  16.         if (thumbRatio < imageRatio) {
  17.             thumbHeight = (int)(thumbWidth / imageRatio);
  18.         } else {
  19.             thumbWidth = (int)(thumbHeight * imageRatio);
  20.         }
  22.         // draw original image to thumbnail image object and  
  23.         // scale it to the new size on-the-fly  
  24.         BufferedImage thumbImage = new BufferedImage(thumbWidth, thumbHeight, BufferedImage.TYPE_INT_RGB);
  25.         Graphics2D graphics2D = thumbImage.createGraphics();
  26.         graphics2D.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
  27.         graphics2D.drawImage(image, 0, 0, thumbWidth, thumbHeight, null);
  29.         // save thumbnail image to outFilename  
  30.         BufferedOutputStream out = new BufferedOutputStream(new FileOutputStream(outFilename));
  31.         JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
  32.         JPEGEncodeParam param = encoder.getDefaultJPEGEncodeParam(thumbImage);
  33.         quality = Math.max(0, Math.min(quality, 100));
  34.         param.setQuality((float)quality / 100.0f, false);
  35.         encoder.setJPEGEncodeParam(param);
  36.         encoder.encode(thumbImage);
  37.         out.close();
  38.     }

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