* @defgroup Elm_Layout Layout
* @ingroup Elementary
* @image html layout_inheritance_tree.png
* @image latex layout_inheritance_tree.eps
* @image html img/widget/layout/preview-00.png
* @image latex img/widget/layout/preview-00.eps width=\textwidth
* @image html img/layout-predefined.png
* @image latex img/layout-predefined.eps width=\textwidth
* A Layout is a direct realization of @ref elm-layout-class.
* This is a container widget that takes a standard Edje design file
* and wraps it very thinly in a widget.
* An Edje design (theme) file has a very wide range of possibilities
* to describe the behavior of elements forming a layout. Check out
* the Edje documentation and the EDC reference to get more
* information about what can be done with Edje.
* Just like @ref Elm_List, @ref Elm_Box, and other container widgets, any
* object added to the Layout will become its child, meaning that it
* will be deleted if the Layout is deleted, moved if the Layout is
* moved, and so on.
* The layout widget may contain as many parts/children as described
* in its theme file. Some of these children can have special types,
* such as content holder ones (swallow spots), boxes or tables. These
* are parts meant to contain others. For instance, objects can be
* added to different table parts by specifying the respective table
* part names. The same is valid for swallows and boxes.
* The objects added as children of a layout will behave as described
* in the part description where they were added. There are 3 possible
* types of parts where a child can be added:
* @section secContent Content (@c SWALLOW part)
* Only one object can be added to the @c SWALLOW part at a time (but
* you still can have many @c SWALLOW parts and one object on each of
* them). Use the @c elm_layout_content_set()/get/unset functions to
* set, retrieve and unset objects as content of the @c SWALLOW. After
* being set to this part, the object's size, position, visibility,
* clipping and other description properties will be totally
* controlled by the description of the given part (inside the Edje
* theme file).
* One can use @c evas_object_size_hint_* functions on the child to
* have some kind of control over its behavior, but the resulting
* behavior will still depend heavily on the @c SWALLOW part's
* The Edje theme also can change the part description, based on
* signals or scripts running inside the theme. This change can also
* be animated. All of this will affect the child object set as
* content accordingly. The object's size will be changed if the part
* size is changed, it will animate moving accordingly if the part is
* moving, and so on.
* The following picture demonstrates a layout widget with a child
* object added to its @c SWALLOW:
* @image html layout_swallow.png
* @image latex layout_swallow.eps width=\textwidth
* @section secBox Box (@c BOX part)
* An Edje @c BOX part is very similar to the Elementary @ref Elm_Box
* widget. It allows one to add objects to the box and have them
* distributed along its area, accordingly to the specified @c layout
* property (now by @c layout we mean the chosen layouting design of
* the Box, not the layout widget itself).
* A similar effect for having a box with its position, size and other
* things controlled by the layout theme would be to create an
* Elementary @ref Elm_Box widget and add it as content in a @c SWALLOW part.
* The main difference to that, by using the layout box instead, is
* that its behavior, like layouting format, padding, align, etc.,
* will <b>all be controlled by the theme</b>. This means, for
* example, that a signal could be sent to the layout's theme (with
* elm_layout_signal_emit()) and the signal be handled by changing the
* box's padding, or alignment, or both. Using the Elementary @ref Elm_Box
* widget is not necessarily harder or easier, it just depends on the
* circumstances and requirements.
* The layout box can be used through the @c elm_layout_box_* set of
* The following picture demonstrates a Layout widget with many child
* objects added to its @c BOX part:
* @image html layout_box.png
* @image latex layout_box.eps width=\textwidth
* @section secTable Table (@c TABLE part)
* Just like the @ref secBox, the layout table is very similar to the
* Elementary @ref Elm_Table widget. It allows one to add objects to the
* table by specifying the row and column where the object should be
* added, and any column or row span, if necessary.
* Again, we could have this design by adding a @ref Elm_Table widget to a
* @c SWALLOW part, using elm_layout_content_set(). The same
* difference happens here when choosing to use the layout table (a
* @c TABLE part) instead of the @ref Elm_Table in a @c SWALLOW part. It's
* just a matter of convenience.
* The layout table can be used through the @c elm_layout_table_* set of
* The following picture demonstrates a layout widget with many child
* objects added to its @c TABLE part:
* @image html layout_table.png
* @image latex layout_table.eps width=\textwidth
* @section secPredef Predefined Layouts
* Another interesting thing about the layout widget is that it offers
* some predefined themes that come with the default Elementary
* theme. These themes can be set by the call elm_layout_theme_set(),
* and provide some basic functionality depending on the theme used.
* Most of them already send some signals, some already provide a
* toolbar or back and next buttons.
* These are the available predefined theme layouts. All of them have
* class = @c layout, group = @c application, and style = one of the
* following options:
* @li @c toolbar-content - for applications with a toolbar and main
* content area
* @li @c toolbar-content-back - for applications with a toolbar and
* main content (with a back button)
* and title areas
* @li @c toolbar-content-back-next - for applications with a toolbar
* and main content (with back and
* next buttons) and title areas
* @li @c content-back - for application with main content (with a
* back button) and title areas
* @li @c content-back-next - for applications with main content (with
* back and next buttons) and title areas
* @li @c toolbar-vbox - for applications with a toolbar and main
* content area as a vertical box
* @li @c toolbar-table - for applications with a toolbar and main
* content area as a table
* @section layout-signals Emitted signals
* This widget emits the following signals:
* @li "theme,changed" - The theme was changed.
* @li "language,changed" - the program's language changed
* @section secExamples Examples
* Some examples of the Layout widget can be found here:
* @li @ref layout_example_01
* @li @ref layout_example_02
* @li @ref layout_example_03
* @li @ref layout_example_edc