From: "Hanspeter Portner" <ventosus@airpost.net>

From: "Hanspeter Portner" <ventosus@airpost.net>

This concerns Ticket #109: Add Lua support for Edje

It adds Lua as scripting facility to Edje, letting Embryo untouched.
It should be easier to use and be more flexible than Embryo, imho ;-)

---
The patch
---

Lua 5.1 is used in sandboxed mode. Lua byte code is not
platform/architecture independent, Lua code is saved as text in the Edje
container and parsed at load time, therefore.

The patch goes in two directions

1) Analogous to Embryo for scripting logic, messaging and custom states.
The same things are implemented as in Embryo:

    - messaging from and to C
        - manual creation of timers, animators, pollers for custom events /
            animations
                - manual manipulation of Edje parts by means of the public
                    edje_object_part_* and internal functions and custom states

                        -> those routines are actually implemented as Lua
bindings to
    functions in Edje.h and Ecore.h
        -> the implementation is done in an object oriented way, so that the
            interface gives the feel of an object description language, pretty
                similar to EDC itself
                    -> combining custom states and custom animators allows
for fancy
    animations and transitions, e.g circular/spline translations or
        complex/conditional transitions, etc.
            -> this is just the same as Embryo does, but implemented in Lua, so
                nothing new here, actually

                2) Dynamic object creation and manipulation

                    - this interface stems from the 'script_only' objects in
Edje. Those
    objects are a kind of scriptable Edje counterparts to Evas_Smart
        objects. The infrastructure for Embryo is already there, but has
            never been used
                - I added this in Lua and added some first bindings to
experiment
    with
        - I thought it would be useful to allow for a limited dynamic
            creation of ui parts
                - We can create instances of groups from within the same Edje
                    container and use them just like the main Edje object as
stated in
    1)
        - And there are some stand-alone bindings to dynamically create
            Evas_Image, Evas_Table, Evas_Line, Evas_Polygon as examples

                -> this may be useful to decouple the program from the ui
even more,
    to be able to do things that have to be done in the program itself
        atm, but actually belong to the user interface, but need dynamic
            creation of objects or complex interactions
                -> those objects are manipulated manually with Lua bindings
to the
    corresponding edje_object_* and evas_object_* functions

    ---
    Discussion points
    ---

    Both stuff in 1) & 2) is functioning, but needs testing, feedback,
    improvements, ...

    Stuff in 1) can already fully replace Embryo scripting with Lua
    scripting. There still is space for improvements/additions, though.

    Of the stuff in 2), I think it may only make sense to add the dynamic
    creation of groups defined in the same Edje container.  Dynamic creation
    of other Evas_Objects makes not much sense, as most of them can already
    be used as Edje parts and be manipulated with custom states (apart from
    polygons and lines) and it would make the whole theming potentially more
    programing-like and much more susceptible for errors, etc.

    Would this be useful, or drop it all?

    The scripting should be there just for logic, conditionals, custom
    states and animations, not for a whole dynamic canvas, imho.

    There is a patch around with EXTERNAL Edje parts. Seems to be a better,
    faster, more secure way to extend Edje with custom objects.

    There would be the possibility of precompiling Lua code at compile time
    (edje_cc) for faster loading, but we would have to patch and run our own
    Lua version.
    The Lua parser is pretty fast, though, and using
    byte-converted/endianness-swapped byte-code does only pay off for Lua
    chunks of some kilo lines.
    Byte code also occupies much more space than text in the final Edje
    container, as it includes debug symbols.

    ---

    Cedric and Vincent told me, that the plan was to replace Embryo totally
    by Lua before the official release of Edje at the end of the year? So it
    would make sense to bring Lua to svn soon and look how it fits in, test,
    debug, adapt it further to the themers needs, decide on its final shape,
    GATHER SOME PEOPLE TO HELP ;-)

    ---

    The Lua enhanced Edje is in sync with svn and can be get directly here
       git clone git://repo.or.cz/edje_lua.git
          cd edje_lua
             git checkout -b lua_patch origin/lua_patch

             or apply the attached patch

             There are also some examples to show the usage of the things
mentioned
above
    - showcase.edj: shows usage of custom animators, custom states,
        messaging and the script_only object
            - test.edj: test cases of script usage and bindings (custom states,
                custom transitions, tween_states, animators, timers,
object_parts),
    but most of it are experimental script_only objects

    http://didgmo.sourceforge.net/showcase.edj
    http://didgmo.sourceforge.net/test.edj

    The source of showcase.edc is attached, too, to just have a glimpse at
    Lua inside of EDC

    ---

    So, what do you guys think?

    Thanks and sry for the looong mail, hehe ;-)

git-svn-id: svn+ssh://svn.enlightenment.org/var/svn/e/trunk/edje@41802 7cbeb6ba-43b4-40fd-8cce-4c39aea84d33