jpg图像文件缩放类 * * 本类实现一个对 JPG/JPEG 图像文件进行缩放处理的方法 即给定一个 JPG 文件，可以生成一个该 JPG 文件的缩影图像文件 (JPG 格式 ) * 提供三种生成缩影图像的方法： 1 、设置缩影文件的宽度，根据设置的宽度和源图像文件的大小来确定新缩影文件的长度来生成缩影图像 2 * 、设置缩影文件的长度，根据设置的长度和源图像文件的大小来确定新缩影文件的宽度来生成缩影图像 3 * 、设置缩影文件相对于源图像文件的比例大小，根据源图像文件的大小及设置的比例来确定新缩影文件的大小来生成缩影图像 * 新生成的缩影图像可以比原图像大，这时即是放大源图像。(Jpg image file type zoom * * achieve this kind of a JPG/JPEG image file to zoom method is given a JPG file, you can generate a miniature image file of the JPG file (JPG format) * provides three methods of generating image epitome: 1, set the width of the miniature file, according to the set the width and the source image file to determine the size of the length of the file to generate a new miniature miniature image 2 *, set the epitome of the length of the file, according to the length and the source image file to determine the size of the new miniature file width to generate images, set 3 * miniature miniature file relative to the source image file size according to the proportion. The size and set the source image file to determine the proportion of the size of the file to generate a new miniature miniature miniature image * new generated image can be compared to the original image, then that is The source image is placed.)