Edje is a complex graphical design and layout library based on Evas that provides an abstraction layer between the application code and the interface, while allowing extremely flexible dynamic layouts and animations. In more popular terms, Edje makes every application that uses it "skinable" . "Edje is an attempt to find a middleground between theming and programming without turning the theme itself into just yet another program." -- Carsten Haitzler (The Rasterman) It's purpose is to be a sequel to "Ebits" which to date has serviced the needs of Enlightenment development for version 0.17. The original design parameters under which Ebits came about were a lot more restricted than the resulting use of them, thus Edje was born. Edje is a more complex layout engine compared to Ebits. It doesn't pretend to do containing and regular layout like a widget set. It still inherits the more simplistic layout ideas behind Ebits, but it now does them a lot more cleanly, allowing for easy expansion, and the ability to cover much more ground than Ebits ever could. For the purposes of Enlightenment 0.17, Edje should serve all the purposes of creating visual elements (borders of windows, scrollbars, etc.) and allow the designer the ability to animate, layout and control the look and feel of any program using Edje as its basic GUI constructor. This library allows for multiple collections of Layouts in one file, sharing the same image database and thus allowing a whole theme to be conveniently packaged into 1 file and shipped around. Edje, unlike Ebits, separates the layout and behavior logic. Edje files ship with an image database, used by all the parts in all the collections to source graphical data. It has a directory of logical part names pointing to the part collection entry ID in the file (thus allowing for multiple logical names to point to the same part collection, allowing for the sharing of data between display elements). Each part collection consists of a list of visual parts, as well as a list of programs. A program is a conditionally run program that if a particular event occurs (a button is pressed, a mouse enters or leaves a part) will trigger an action that may affect other parts. In this way a part collection can be "programmed" via its file as to hilight buttons when the mouse passes over them or show hidden parts when a button is clicked somewhere etc. The actions performed in changing from one state to another are also allowed to transition over a period of time, allowing animation. This separation and simplistic event driven style of programming can produce almost any look and feel one could want for basic visual elements. Anything more complex is likely the domain of an application or widget set that may use Edje as a convenient way of being able to configure parts of the display.

13:23 on Feb 13, 2012