If you are looking for a quick and simple way to integrate image cropping functionality into your web-based application, Jcrop is just for you.
Jcrop is a powerful image cropping plugin for jQuery. Combining reliable cross-platform DHTML cropping engine and simplicity of a jQuery plugin structure, Jcrop provides clean and well-organized code that can easily integrate image cropping features into web application. This image cropping engine doesn’t hinder power or flexibility of your web-based app and is working on all major platforms (Mozilla 2+, Safari 3+, Opera 9.5+, Chrome 0.2+, IE 6+).
Jcrop attaches unobtrusively to images or block objects and provides API features to add interactivity, including animation. It allows to upload or choose an image to crop and displayes page with cropping interface. When user selects area, coordinates are recorded as form values. After form submission server performs image crop. There is capability to save, replace, update, display, etc. the resultant image. Also Jcrop supports minSize/maxSize setting, aspect ratio locking, and CSS styling (later versions use LESS). It features keyboard support for nudging selection, as well as touch support for iOS, Android, etc.
There is an add-on that provides Jcrop integration into Plone - plone.app.imagecropping. It adds image cropping functionality to Plone CMS by providing @@croppingeditor view. This package was made as minimally invasive as possible. Its main advantage is support of both archetypes and dexterity content types.
Take a closer look at JCrop plugin if you want to offer users an image cropping capabilities. Visit Jcrop page or github repository for more information.