30 Jan 2012
There have been many times you have come across the need to take an image and cut an irregular shape out of it. Normally, when a developer comes across this requirement, the only thing to do is to open the image up with your favorite graphics editor, use the select tool to cut out the shape you want, and then save the result as a PNG, since it is the only image format used by all web browsers that support alpha channels.
The problem is that PNG images, while compressed, are not as small as JPEGs if the source image is a photograph, and the download time of a page can balloon to unacceptable levels if there are many of these types of image on a page.
polyClip.js is a jQuery plugin that uses HTML5 canvas to clip a JPEG (or any other image for that matter). The library also supports older versions of IE (7-8) using the Excanvas JavaScript library which polyfills canvas using VML.
