首先js是不能操作客户端文件的(除非特殊情况)，所以图片的切割必须在后台处理，对于客户端的图片可以先上传再切割或者把图片和切割参数一起传递到服务器再处理（上传文件不在本次讨论范围，请自行修改）；还有是通过客户端传递的参数来处理图片，确实能得到展示图或预览图的效果。-First js is inoperable client files (unless special circumstances), so the picture cut must be processed in the background, the client images can be uploaded and then cut or the pictures and cutting parameters passed to the server with reprocessing (uploaded files are not present discussion range, please modify their own)　and by parameters passed by the client to process the image, can really get a diagram showing or preview the effect.