code: public BufferedImage scale(double scaleW, double scaleH) {
          width = (int) (width * scaleW);
          height = (int) (height * scaleH);
  
          BufferedImage newImage = new BufferedImage(width, height,
                  image.getType());
          Graphics g = newImage.getGraphics();
          g.drawImage(image, 0, 0, width, height, null);
          g.dispose();
          image = newImage;
          return image;
      }
docs: 缩放图片
  
  @param scaleW 水平缩放比例
  @param scaleH 垂直缩放比例
  @return bufferedImage