title: Image inside canvas crop with custom rectangle JQuery
body: <p>I have a Canvas element with inside an image ( the canvas has the same dimension of the image), i want to crop this image using a selection rectangle! For my project i use the javascript's framework JQuery and i'm searching a plugin that implementing a custom selection rectangle on canvas!
  Anyone know one plugin that do this (I founded a lot of plugin that implements this functionality but only on  elements)?
  If no, what is the way to implement a custom rectangle on Canvas elements?</p>
  
  <p>I hope in yours answers!</p>