Image Cropping Implemented with jQuery + HttpHandler ( Suitable for Forums, SNS )

Preface:

Last time, I shared a few jQuery plugins and some insights, and many friends (or maybe users from my own site) sent emails hoping I could provide more source code. Coincidentally, a classmate this time wanted to add an image cropping feature on their forum to generate avatars, so I helped write this plugin. Perhaps many of you might find it useful, so I'm sharing it here as well.