efl/legacy/edje/doc/edje.dox.in

/** 
@file
@brief Edje Graphical Design Library
 
These routines are used for Edje.
*/

/**

@mainpage Edje Library Documentation
@image html  edje.png
@version 0.5.0
@author Carsten Haitzler <raster\@rasterman.com>
@date 2003-2004










@section intro What is Edje?

Edje is a complex graphical design & layout library.

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.










@section requirements What does Edje require?

Edje requires fairly little on your system. to use the Edje runtime library
you need:

  - Evas (library)
  - Ecore (library)
  - Eet (library)

Evas needs to be build with the PNG and EET image loaders enabled at a
minimum. Edje uses X for the test program, so you will need the SOFTWARE_X11
engine built into Evas as well. A suggested configure list is below in the
"cheat sheet" for Evas.

Ecore needs the ECORE, ECORE_EVAS and ECORE_X modules built at a minimum.
It's suggested to build all the Ecore modules, but the ECORE_FB modules is
definitely optional.

Eet has no options so just build and install it.

It is suggested right now that you get the latest CVS versions of the
required libraries. You also need to build them in the right order and make
sure the right options are enabled in the required libraries. Here is a
quick "cheat sheet" on how to get started.

@verbatim
1. You need Eet from the HEAD cvs branch (must be up-to-date)

  cvs co e17/libs/eet
  cd e17/libs/eet
  ./autogen.sh
  ./configure
  make
  sudo make install
  cd

2. You need Evas from the HEAD branch built with eet loader support.

  cvs co e17/libs/evas
  cd e17/libs/evas
  ./autogen.sh
  ./configure
  make
  sudo make install
  cd
  
3. You need Ecore from the HEAD cvs branch

  cvs co e17/libs/ecore
  cd e17/libs/ecore
  ./autogen.sh
  ./configure
  make
  sudo make install
  cd

4. You need embryo from the HEAD cvs branch

  cvs co e17/libs/embryo
  cd e17/libs/embryo
  ./autogen.sh
  ./configure
  make
  sudo make install
  cd

@endverbatim









@section compiling How to compile and test Edje

Now you need to compile and install Edje.

@verbatim
  ./configure
  make
  sudo make install
@endverbatim

You now have it installed and ready to go, but you are missing data files. In
data/ there are data sets for you to look at as examples. To try one out do:

@verbatim
   cd data
   ./e_logo.sh
   
   edje ./e_logo.eet
@endverbatim

The Edje test program/viewer is able to view multiple Edje data sets. The
following will view 3 of them at once in the one window (which you can resize
to give you more space to move and resize the Edje data sets around):

@verbatim
  edje ./e_logo.eet ./e_logo.eet ./e_logo.eet
@endverbatim











@section details So how does this all work?

Edje internally holds a geometry state machine and state graph of what is
visible, not, where, at what size, with what colors etc. This is described
to Edje from an Edje .eet file containing this information. These files can
be produced by using edje_cc to take a text file (a .edc file) and "compile"
an output .eet file that contains this information, images and any other
data needed.










@todo See src/lib/edje_private.h for a list of FIXME's
@todo Complete documentation of API
@todo Bytecode language for extending programs... but what/how?

*/