Decorators in AngularJS, $provide.decorator

$provide.decorator if defined in config section of the application code and modifies original object which is passed as $delegate argument into decorator.

Here is set of examples giving better view on a powerful feature of decorators, available in AngularJS:

• adding a custom method to 3rd party service,  by tamakisquare - http://plnkr.co/edit/lj9srM2KXZmwmTxLb1p7?p=preview
• logging time while the async call is performed, using Promise.always - by K. Scott Allen http://odetocode.com/blogs/scott/archive/2013/06/06/decorating-angularjs-services.aspx  
• creating more detailed response description, https://egghead.io/lessons/angularjs-provide-decorator
• adding custom method reload method to $state provider - stackoverflow.com/a/23198743/405623

angularJS photoshop demo

This demo uses canvas drawing directive and bootstrap-css for UI.
It has basic palette of colours and brush sizes and also layers that can be added/removed, activated or hidden.
Check it here: http://embed.plnkr.co/sn5eZV/