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

/**

@mainpage Edje Library Documentation
@image html  e.png
@version 1.0.999.57208
@author Carsten Haitzler <raster@@rasterman.com>
@author Tilman Sauerbeck (tilman at code-monkey de)
@author ZigsMcKenzie <zigsmckenzie@@gmail.com>
@author Cedric BAIL <cedric.bail@@free.fr>
@author Brian Mattern <rephorm@@rephorm.com>
@author Mathieu Taillefumier <mathieu.taillefumier@@free.fr>
@author Tristan <blunderer@@gmail.com>
@author Gustavo Lima Chaves <glima@@profusion.mobi>
@author Bruno Dilly <bdilly@@profusion.mobi>
@author Fabiano Fidêncio <fidencio@@profusion.mobi>
@author Jihoon Kim <jihoon48.kim@@samsung.com>
@author Tiago Falcão <tiago@@profusion.mobi>
@author Davide Andreoli <dave@@gurumeditation.it>
@author Sebastian Dransfeld <sd@@tango.flipp.net>
@author Tom Hacohen <tom@@stosb.com>
@author Aharon Hillel <a.hillel@@partner.samsung.com>
@author Shilpa Singh <shilpa.singh@samsung.com> <shilpasingh.o@gmail.com>
@author Mike Blumenkrantz <mike@zentific.com
@date 2003-2011










@section intro What is Edje?

Edje is a complex graphical design & layout library.

It doesn't pretend to do containing and regular layout like a widget
set, but it is the base for such components. Based on the requirements
of Enlightenment 0.17, Edje should serve all the purposes of creating
visual elements (borders of windows, buttons, 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 and font database and thus allowing a whole
theme to be conveniently packaged into 1 file and shipped around.

Edje separates the layout and behavior logic. Edje files ship with an
image and font 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. Programs and animations can be run in
"parallel".

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.

For details of Edje's history, see the \ref history section.








@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)
  - Embryo (library)
  - Eina (library)

Evas needs to be build with the JPEG, 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.

Eina, Eet and Embryo have no interesting options so just build and
install them.

It is suggested right now that you get the latest SVN 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 Eina from the trunk svn branch.

  svn co http://svn.enlightenment.org/svn/e/trunk/eina/
  cd eina
  ./autogen.sh
  ./configure
  make
  sudo make install
  cd

2. You need Eet from the trunk svn branch.

  svn co http://svn.enlightenment.org/svn/e/trunk/eet/
  cd eet
  ./autogen.sh
  ./configure
  make
  sudo make install
  cd

3. You need Evas from the trunk svn branch built with eet, png and jpeg loader support.

  svn co http://svn.enlightenment.org/svn/e/trunk/evas/
  cd evas
  ./autogen.sh
  ./configure --enable-image-loader-eet --enable-font-loader-eet --enable-image-loader-jpeg --enable-image-loader-png --enable-buffer
  make
  sudo make install
  cd

4. You need Ecore from the trunk svn branch built with ecore-x and ecore-evas.

  svn co http://svn.enlightenment.org/svn/e/trunk/ecore/
  cd ecore
  ./autogen.sh
  ./configure --enable-ecore-x --enable-ecore-evas --enable-ecore-evas-software-buffer --enable-ecore-evas-software-x11 --enable-ecore-evas-software-buffer
  make
  sudo make install
  cd

5. You need embryo from the trunk svn branch

  svn co http://svn.enlightenment.org/svn/e/trunk/embryo/
  cd 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 need input
data. There are lots of examples in SVN, the best one is
Enlightenment's own theme file.

You may use different tools to edit and view the generated ".edj"
files, for instance:

  - editje (http://trac.enlightenment.org/e/wiki/Editje)
  - edje_viewer (http://trac.enlightenment.org/e/wiki/Edje_Viewer)










@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 .edj 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 .edj file that contains this information, images and any other
data needed.

The application using Edje will then create an object in its Evas
canvas and set the bundle file to use, specifying the @b group name to
use. Edje will load such information and create all the required
children objects with the specified properties as defined in each @b
part of the given group. See the following annotated example:

@code
/*
 * edje_example.c:
 *
 *    Creates a window using Ecore_Evas and inside it an object with
 *    the edje group "my_group" from file "edje_example.edj".
 *
 *     Requires edje_example.edj in the current folder.
 *
 * Compile:
 *    gcc -o edje_example edje_example.c `pkg-config --cflags --libs eina evas ecore ecore-evas edje`
 */

#include <Eina.h>
#include <Evas.h>
#include <Ecore.h>
#include <Ecore_Evas.h>
#include <Edje.h>

#define WIDTH 320
#define HEIGHT 240

static Evas_Object *create_my_group(Evas *canvas, const char *text)
{
   Evas_Object *edje;

   /* create the edje object where we'll load our file */
   edje = edje_object_add(canvas);
   if (!edje)
     {
	EINA_LOG_CRIT("could not create edje object!");
	return NULL;
     }

   /* load our desired file */
   if (!edje_object_file_set(edje, "edje_example.edj", "my_group"))
     {
	int err = edje_object_load_error_get(edje);
	const char *errmsg = edje_load_error_str(err);
	EINA_LOG_ERR("could not load 'my_group' from edje_example.edj: %s",
		     errmsg);

	evas_object_del(edje);
	return NULL;
     }

   if (text)
     {
	/* this is will replace the string used by "text" part in "my_group" */
	if (!edje_object_part_text_set(edje, "text", text))
	  {
	     EINA_LOG_WARN("could not set the text. "
			   "Maybe part 'text' does not exist?");
	  }
     }

   /* operate on edje as any other object */
   evas_object_move(edje, 0, 0);
   evas_object_resize(edje, WIDTH, HEIGHT);
   evas_object_show(edje);
   return edje;
}

int main(int argc, char *argv[])
{
   Ecore_Evas *window;
   Evas *canvas;
   Evas_Object *edje;
   const char *text;

   eina_init();
   evas_init();
   ecore_init();
   ecore_evas_init();
   edje_init();

   window = ecore_evas_new(NULL, 0, 0, WIDTH, HEIGHT, NULL);
   if (!window)
     {
	EINA_LOG_CRIT("could not create window.");
	return -1;
     }
   canvas = ecore_evas_get(window);

   text = (argc > 1) ? argv[1] : NULL;

   edje = create_my_group(canvas, text);
   if (!edje)
     return -2;

   ecore_evas_show(window);
   ecore_main_loop_begin();

   evas_object_del(edje);
   ecore_evas_free(window);

   return 0;
}
@endcode

It requires the following source Edje file:
@code
// compile: edje_cc edje_example.edc
collections {
   group {
      name: "my_group"; // must be the same as in edje_example.c

      parts {
         part {
            name: "background";
            type: RECT; // plain boring rectangle
            mouse_events: 0; // we don't need any mouse event on the background

            // just one state "default"
            description {
               state: "default" 0.0; // must always exist
               color: 255 255 255 255; // white

               // define part coordinates:

               rel1 { // top-left point at (0, 0) [WIDTH * 0 + 0, HEIGHT * 0 + 0]
                  relative: 0.0 0.0;
                  offset: 0 0;
               }
               rel2 { // bottom-right point at (WIDTH * 1.0 - 1, HEIGHT * 1.0 - 1)
                  relative: 1.0 1.0;
                  offset: -1 -1;
               }
            }
         }

         part {
            name: "text";
            type: TEXT;
            mouse_events: 1; // we want to change the color on mouse-over

            // 2 states, one "default" and another "over" to be used
            // on mouse over effect

            description {
               state: "default" 0.0;
               color: 255 0 0 255; // red

               // define part coordinates:

               rel1 { // top-left at (WIDTH * 0.1 + 5, HEIGHT * 0.2 + 10)
                  relative: 0.1 0.2;
                  offset: 5 10;
               }
               rel2 { // bottom-right at (WIDTH * 0.9 - 6, HEIGHT * 0.8 - 11)
                  relative: 0.9 0.8;
                  offset: -6 -11;
               }

               // define text specific state details
               text {
                  font: "Sans"; /* using fontconfig name! */
                  size: 10;
                  text: "hello world";
               }
            }

            description {
               state: "over" 0.0;
               inherit: "default" 0.0; // copy everything from "default" at this point

               color: 0 255 0 255; // override color, now it is green
            }
         }

         // do programs to change color on text mouse in/out (over)
         programs {
            program {
               // what triggers this program:
               signal: "mouse,in";
               source: "text";

               // what this program does:
               action: STATE_SET "over" 0.0;
               target: "text";

               // do the state-set in a nice interpolation animation
               // using linear time in 0.1 second
               transition: LINEAR 0.1;
            }

            program {
               // what triggers this program:
               signal: "mouse,out";
               source: "text";

               // what this program does:
               action: STATE_SET "default" 0.0;
               target: "text";

               // do the state-set in a nice interpolation animation
               // using linear time in 0.1 second
               transition: LINEAR 0.1;
            }
         }
      }
   }
}
@endcode


One should save these files as edje_example.c and edje_example.edc then:
@verbatim
gcc -o edje_example edje_example.c `pkg-config --cflags --libs eina evas ecore ecore-evas edje`
edje_cc edje_example.edc

./edje_example "some text"
@endverbatim

Although simple, this example illustrates that animations and state
changes can be done from the Edje file itself without any requirement
in the C application.

Before digging into changing or creating your own Edje source (edc)
files, read the \ref edcref.



@section history Edje History

It's a sequel to "Ebits" which has serviced the needs of Enlightenment
development for early 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 was conceived to serve all the
purposes of creating visual elements (borders of windows, buttons,
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.

Unlike Ebits, Edje separates the layout and behavior logic.









@todo Complete documentation of API
@todo Bytecode language for extending programs... but what/how?

*/


/**

@example embryo_custom_state.edc
This example show how to create a custom state from embryo. Clicking on the
3 labels will rotate the object in the given direction.

@example embryo_pong.edc
Super-simple Pong implementation in pure embryo.

@example embryo_run_program.edc
This example show how to run an edje program from embryo code.

@example embryo_set_state.edc
This example show how to change the state of a part from embryo code.

@example embryo_set_text.edc
This example show how to set the text in TEXT part from embryo code.

@example embryo_timer.edc
This example show the usage of timers in embryo.

@example external_elm_anchorblock.edc
This example use an elementary anchorblock and a button to animate the text.

@example external_elm_button.edc
This example create some elementary buttons and do some actions on user click.

@example external_elm_check.edc
This example show EXTERNAL checkbox in action.

@example external_elm_panes.edc
This example show EXTERNAL elementary panes in action.

@example external_emotion_elm.edc
Super-concise video player example using Edje/Emotion/Elementary.

@example lua_script.edc
This example show the usage of lua scripting to create and animate some
objects in the canvas.

@example toggle_using_filter.edc
This example show how to toggle the state of a part using the 'filter'
param in edje programs

*/