[pkgs/u/ui-gadget.git] / include / SLP_UI_Gadget_PG.h

/*
 * Copyright (c) 2000 - 2012 Samsung Electronics Co., Ltd All Rights Reserved
 *
 * This file is part of the UI Gadget
 * Written by Jayoun Lee <airjany@samsung.com>, Jinwoo Nam <jwoo.nam@samsung.com>
 *
 * PROPRIETARY/CONFIDENTIAL
 *
 * This software is the confidential and proprietary information of
 * SAMSUNG ELECTRONICS (Confidential Information).
 * You shall not disclose such Confidential Information and shall
 * use it only in accordance with the terms of the license agreement
 * you entered into with SAMSUNG ELECTRONICS.  SAMSUNG make no
 * representations or warranties about the suitability
 * of the software, either express or implied, including but not
 * limited to the implied warranties of merchantability, fitness for a particular purpose, or non-
 * infringement. SAMSUNG shall not be liable for any damages suffered by licensee as
 * a result of using, modifying or distributing this software or its derivatives.
 *
 */

/**
 *
 * @ingroup SLP_PG
 * @defgroup SLP_PG_UI_GADGET UI gadget library
 * @{

<h1 class="pg">Introduction</h1>
<h2 class="pg">Purpose of this document</h2>
The purpose of this document is to describe how to develop/use UI gadget. This document gives programming guidelines to UI gadget devlopers and users.
<h2 class="pg">Scope</h2>
The scope of this document is limited to UI gadget component interface and API usage.

<h1 class="pg">UI gadget architecture</h1>
<h2 class="pg">UI gadget</h2>
An UI gadget is a visual component providing views (or features) of other applications, e.g., phonebook, myfile. Because UI gadgets are supposed to deliver most commonly used features that the platform can natively support, developers can avoid unnecessary massive code writing using UI gadgets. Hence an UI gadget eventually includes logics to handle simple request. UI gadget is able to be managed by UI gadget library.
\image html SLP_UI_Gadget_PG_image00.png "Picture 1. UI gadget architecture diagram"

<h2 class="pg">UI gadget features</h2>
UI Gadget Library has the following features:
- It provides component interfaces for UI Gadget
- It manages UI gadget instances in an application according to their lifecycle

<h2 class="pg">Lifecycle</h2>
Essentially, an UI gadget has following five states (See Picture 2)
- The initial state is \b Ready
- If an UI gadget has been created, it is \b Created
- If an UI gadget has been started, it is \b Running
- If the application that is using an UI gadget is put into background, it is \b Stopped
- If an UI gadget has been destroyed, it is \b Destroyed

An UI gadget has five callback methods that you can implement to perform operations when the UI gadget moves between states
- When an UI gadget is created, \b create() is invoked
- When an UI gadget is started, \b start() is invoked
- When the application that is using an UI gadget is put into background, \b pause() is invoked
- When the application that is using an UI gadget is brought to the foreground, \b resume() is invoked.
- When an UI gadget is destroyed, \b destroy() is invoked

In addition, an UI gadget has callback methods for system events and message:
- When an system event is generated, event() is invoked
- When an UI gadget receives message from the caller, message() is invoked

\image html SLP_UI_Gadget_PG_image01.png "Picture 2. UI gadget state diagram"

<h2 class="pg">Management</h2>
UI gadgets in an application are managed as a TREE structure (See Picture 3.) The features for the tree are:
- Root of the tree is the UI gadget manager
- UI gadget caller is parent of callees
- Parents arrange the layout of their children

Every application which is using UI gadgets has one UI gadget manager as a root of the tree. And the UI gadget manager propagates system events and task management events by post-order traversal. Available system events are <i>low memory, low battery, language changed, and window rotate event</i>. And task management events are <i>pause and resume</i>.

\image html SLP_UI_Gadget_PG_image02.png "Picture 3. UI gadget management policy"

<h1 class="pg">Getting started</h1>
<h2 class="pg">How to make UI gadget</h2>
In this section, we are going to write your first UI gadget called "helloUG-efl". Before we get started, make sure you have read the overview, especially, lifecycle section. We will mainly deal with the operations of lifecycle.

\note <b>Sample codes</b> are included in the UI gadget source package. The samples for UI gadget developers are located in "/test/ug/", and the samples for UI gadget users are in "/test/app/." For instance, "helloUG-efl" codes are in "/test/ug/helloUG-efl/."
\note <b>Naming rule:</b> The name of UI gadget must be "{NAME}-{UI LIB NAME}", e.g., "helloUG-efl"

<br>
<h3 class="pg">UI gadget template</h3>
To create an UI gadget, start by generating boilerplate code using UI gadget template as follow:
@verbatim
# ug-gen.sh helloUG-efl helloUG-efl EFL
@endverbatim

\note <b>How to install UI gadget template:</b>
@verbatim
# apt-get install ui-gadget-template
@endverbatim

\note <b>How to use UI gadget template:</b>
@verbatim
# ug-gen.sh [destination] [name] [UI library]
@endverbatim
- destination: destination directory
- name: UI gadget name
- UI library: UI library to use. Only EFL is available for now

After you generate code, you get following files:
- <i>helloUG-efl.c</i>  (Source)
- <i>helloUG-efl.h</i>  (Private header)
- <i>CMakeList.txt</i>  (Build script)
- <i>po/*</i>           (I18N files)

<i>helloUG-efl.c</i> contains base code, and the most important parts are <i>UG_MODULE_INIT</i> and <i>UG_MODULE_EXIT</i> which are symbols to export for dynamic linking. <i>UG_MODULE_INIT</i> is invoked when the UI gadget is loading, and it sets operations, private data, and the option. <i>UG_MODULE_EXIT</i> is invoked when the UI gadget is unloading, and it clears private data.<br><br>
Even if you don't understand generated code right now, don't worry about it. What you have to do is just implementation of operations according to their role (see next section.)
@code
// in helloUG-efl.c
UG_MODULE_API int UG_MODULE_INIT(struct ug_module_ops *ops)
{
        struct ug_data *ugd;            // User defined private data

        if (!ops)
                return -1;

        ugd = calloc(1, sizeof(struct ug_data));
        if (!ugd)
                return -1;

        // create operation
        ops->create = on_create;
        // start operation
        ops->start = on_start;
        // pause operation
        ops->pause = on_pause;
        // resume operation
        ops->resume = on_resume;
        // destroy operation
        ops->destroy = on_destroy;
        // message operation
        ops-> message = on_message;
        // event operation
        ops->event = on_event;
        // private data
        ops->priv = ugd;
        // option
        ops->opt = UG_OPT_INDICATOR_ENABLE;

        return 0;
}

UG_MODULE_API void UG_MODULE_EXIT(struct ug_module_ops *ops)
{
        struct ug_data *ugd;

        if (!ops)
                return;

        ugd = ops->priv;
        if (ugd)
                free(ugd);              // clear private data
}

@endcode

\note <b>struct ug_module_ops</b> is a data structure describing operations, private data, and the option of UI gadget:
@code
struct ug_module_ops {
        void *(*create)(struct ui_gadget *ug, enum ug_mode mode, bundle *data, void *priv);
        void (*start)(struct ui_gadget *ug, bundle *data, void *priv);
        void (*pause)(struct ui_gadget *ug, bundle *data, void *priv);
        void (*resume)(struct ui_gadget *ug, bundle *data, void *priv);
        void (*destroy)(struct ui_gadget *ug, bundle *data, void *priv);
        void (*message)(struct ui_gadget *ug, bundle *msg, bundle *data, void *priv);
        void (*event)(struct ui_gadget *ug, enum ug_event event, bundle *data, void *priv);
        void *reserved[5];
        void *priv;
        enum ug_option opt;
};
@endcode

\note <b>enum ug_option</b> is UI gadget options, available options are:
@code
// Enable indicator
UG_OPT_INDICATOR_ENABLE
// Enable indicator with portrait window
UG_OPT_INDICATOR_PORTRAIT_ONLY
// Enable indicator with landscape window
UG_OPT_INDICATOR_LANDSCAPE_ONLY
// Disable indicator
UG_OPT_INDICATOR_DISABLE
@endcode

\note <b>struct ug_data</b> is a user defined private data structure describing base layout, own UI gadget handler, and whatever you need:
@code
struct ug_data {
        Evas_Object *base;
        struct ui_gadget *ug;

        // PUT WHATEVER YOU NEED
}
@endcode

<br>
<h3 class="pg">Operations</h3>
There are five state operations, a message operation, and an event operation: <i>create, start, pause, resume, destroy, message, and event.</i>
<br><br>
When "helloUG-efl" is created, the create operation is invoked. The implementation of create operation is <b>on_create()</b>. Basically, in the operation, we have to make a base layout and return it. Hence, we made base layout using <i>"window layout winset."</i> In case of fullview, we let indicator area be shown, otherwise, we don't (see <i>create_fullview()</i> and <i>create_frameview()</i>.) In addition, in the base layout, we put a box including a label and two buttons (see <i>create_content()</i>.) The label is labeled "Hello UI Gadget." And the first button, labeled "Send result", is for sending result to the "helloUG-efl" caller. The other button, labeled "Back", is for sending destroy request to the caller. For more information about two buttons, please see <i>Send results and request to destroy section</i>.

\note <b>Arguments:</b> All operations receive bundle type data which is named <i>data</i> (see \ref bundle_PG "bundle programming guide") And the argument <i>data</i> is automatically released by UI gadget manager after the UI gadget is destroyed.

@code
// in helloUG-efl.c
static void *on_create(struct ui_gadget *ug, enum ug_mode mode, bundle *data, void *priv)
{
        Evas_Object *parent;
        Evas_Object *content;
        struct ug_data *ugd;

        if (!ug || !priv)
                return NULL;

        ugd = priv;
        ugd->ug = ug;

        parent = ug_get_parent_layout(ug);
        if (!parent)
                return NULL;

        if (mode == UG_MODE_FULLVIEW)
                ugd->base = create_fullview(parent, ugd);
        else
                ugd->base = create_frameview(parent, ugd);

        if (ugd->base) {
                content = create_content(parent, ugd);
                elm_layout_content_set(ugd->base, "elm.swallow.content", content);
        }
        return ugd->base;
}

static Evas_Object *create_fullview(Evas_Object *parent, struct ug_data *ugd)
{
        Evas_Object *base;

        base = elm_layout_add(parent);
        if (!base)
                return NULL;

        elm_layout_theme_set(base, "standard", "window", "integration");
        // In case of fullview, show indicator area
        edje_object_signal_emit(_EDJ(base), "elm,state,show,indicator", "elm");
        edje_object_signal_emit(_EDJ(base), "elm,state,show,content", "elm");

        return base;
}

static Evas_Object *create_frameview(Evas_Object *parent, struct ug_data *ugd)
{
        Evas_Object *base;

        base = elm_layout_add(parent);
        if (!base)
                return NULL;

        // In case of frameview, do not show indicator area

        elm_layout_theme_set(base, "standard", "window", "integration");
        edje_object_signal_emit(_EDJ(base), "elm,state,show,content", "elm");

        return base;
}

static Evas_Object *create_content(Evas_Object *parent, struct ug_data *ugd)
{
        Evas_Object *bx, *eo;

        // add box
        bx = elm_box_add(parent);

        // add label and pack it in the box
        eo = elm_label_add(parent);
        elm_label_label_set(eo, _("Hello UI Gadget"));
        evas_object_size_hint_align_set(eo, 0.5, EVAS_HINT_FILL);
        evas_object_size_hint_weight_set(eo, EVAS_HINT_EXPAND, EVAS_HINT_EXPAND);
        evas_object_show(eo);
        elm_box_pack_end(bx, eo);

        // add buttons and pack it in the box
        eo = elm_button_add(parent);
        elm_button_label_set(eo, _("Send result"));
        evas_object_size_hint_align_set(eo, EVAS_HINT_FILL, EVAS_HINT_FILL);
        evas_object_smart_callback_add(eo, "clicked", result_cb, ugd);
        elm_object_style_set(eo, "bottom_btn");

        evas_object_show(eo);
        elm_box_pack_end(bx, eo);

        eo = elm_button_add(parent);
        elm_button_label_set(eo, _("Back"));
        evas_object_size_hint_align_set(eo, EVAS_HINT_FILL, EVAS_HINT_FILL);
        evas_object_smart_callback_add(eo, "clicked", back_cb, ugd);
        elm_object_style_set(eo, "bottom_btn");

        evas_object_show(eo);
        elm_box_pack_end(bx, eo);
        return bx;
}

@endcode

When "helloUG-efl" starts, the start operation is invoked. The implementation of start operation is <b>on_start()</b>. In this operation, we do nothing:

@code
// in helloUG-efl.c
static void on_start(struct ui_gadget *ug, bundle *data, void *priv)
{

}
@endcode

When "helloUG-efl" is destroyed, the destroy operation is invoked. The implementation of destroy operation is <b>on_destroy()</b>. In the method, we delete base layout:

@code
// in helloUG-efl.c
static void on_destroy(struct ui_gadget *ug, bundle *data, void *priv)
{
        struct ug_data *ugd;

        if (!ug || !priv)
                return;

        ugd = priv;

        evas_object_del(ugd->base);
        ugd->base = NULL;
}
@endcode

When the application using "helloUG-efl" is put into background, the pause operation is invoked. When the application is brought to the foreground, the resume operation is invoked. Besides, when an UI gadget receives message from its caller, the message operation is invoked. And when a system event is generated, the event operation is invoked. The implementation of pause, resume, message, and event operations are <b>on_pause(), on_resume(), on_message(), and on_event()</b>. In these operations, we do nothing:

@code
// in helloUG-efl.c
static void on_pause(struct ui_gadget *ug, bundle *data, void *priv)
{
}
static void on_resume(struct ui_gadget *ug, bundle *data, void *priv)
{
}

static void on_message(struct ui_gadget *ug, bundle *msg, bundle *data, void *priv)
{
}

static void on_event(struct ui_gadget *ug, enum ug_event event, bundle *data, void *priv)
{
        switch (event) {
                case UG_EVENT_LOW_MEMORY:
                        break;
                case UG_EVENT_LOW_BATTERY:
                        break;
                case UG_EVENT_LANG_CHANGE:
                        break;
                case UG_EVENT_ROTATE_PORTRAIT:
                        break;
                case UG_EVENT_ROTATE_PORTRAIT_UPSIDEDOWN:
                        break;
                case UG_EVENT_ROTATE_LANDSCAPE:
                        break;
                case UG_EVENT_ROTATE_LANDSCAPE_UPSIDEDOWN:
                        break;
                default:
                        break;
        }
}
@endcode

\warning Message data of message operation is bundle type data, named <i>msg.</i> <b>Because the message data is released after message operation is finished,</b> if you want to keep using it, please use <b>bundle_dup()</b> which duplicates given bundle data (see \ref bundle_PG "bundle programming guide")

<br>
<h3 class="pg">Send results and request to destroy</h3>
Usually, an UI gadget needs to send results or destroy request to the UI gadget caller. To send result, use <b>ug_send_result()</b>, and to send the destroy request, use <b>ug_destroy_me().</b>
<br>
We use bundle library for composing result data. The bundle provides us a few APIs to make a list of dictionary data that consists of key and value. (ex. {"name"  "John Doe"}) To get more information of bundle, please see \ref bundle_PG "bundle programming guide".

\warning After send your result data, you have to release it using <b>bundle_free()</b> API.

In our "helloUG-efl", we made two buttons for sending results and destroy request as below:
@code
// in helloUG-efl.c

//Include to use bundle APIs
#include <bundle.h>

static void result_cb(void *data, Evas_Object *obj, void *event_info)
{
        bundle *b;
        struct ug_data *ugd;

        if (!data)
                return;

        ugd = data;
        b = bundle_create();
        if (!b)
                return;

        bundle_add(b, "name", "helloUG-efl");
        bundle_add(b, "description", "sample UI gadget");
        //Send result
        ug_send_result(ugd->ug, b);

        //release bundle
        bundle_free(b);
}

static void back_cb(void *data, Evas_Object *obj, void *event_info)
{
        struct ug_data *ugd;

        if (!data)
                return;
        ugd = data;

        //Send destroy request
        ug_destroy_me(ugd->ug);
}
@endcode

\note <b>To use bundle</b>
- Install libbundle-dev package
- Modify CMakeFile.txt to use bundle package as follow:
@code
        …
                pkg_check_modules(pkgs REQUIRED elementary ui-gadget-efl bundle)
        …
@endcode

<br>
<h3 class="pg">Internationalization</h3>
Basically, we use <b><i>dgettext</i></b> for translating a text string into the user's native language because each UI gadget uses different textdomain. Fortunately, if you generate your code using UI gadget template, you don't need to worry about <i>dgettext</i> and textdomain because a few macros are kindly provided by template. In helloUG-efl.h, which is a generated private header of "helloUG-efl", there are a few macros for convenience:
@code
// in helloUG-efl.h
#define PKGNAME                 "ug-helloUG-efl"
#define _(s)                    dgettext(PKGNAME, s)
#define dgettext_noop(s)        (s)
#define N_(s)                   dgettext_noop(s)
@endcode

The PKGNAME is textdomain of "helloUG-efl", and _() is a dgettext wrapper, and N_() is dummy macro. In addition, _() and N_() are additional keywords for marking translatable string for xgettext. Especially, N_() is a dummy keyword for special case as follow:
@code
static const char *message[] = {
        N_("translatable string"),
};
@endcode

For more information, please see <a href="http://www.gnu.org/software/gettext/manual/gettext.html">GNU gettext utilities</a>.

\note <b>xgettext</b> extracts gettext strings from given input files. The canonical keyword for marking translatable strings is 'gettext'. For convenience, many packages use '_' as a keyword instead of 'gettext', and write '_("translatable string")' instead of 'gettext("translatable string")'.

<br>
<h3 class="pg">Rotation and indicator</h3>
When the UI gadget is created as fullview, we have to consider whether the indicator is shown or not. For instance, "Image viewer" shows the indicator on the portrait mode but not on the landscape mode. Hence, we provided option field named <i>opt</i> of <i>struct ug_module_ops</i> in UG_MODULE_INIT.
Available options are as following:
- UG_OPT_INDICATOR_ENABLE (default)
- UG_OPT_INDICATOR_POTRAIT_ONLY
- UG_OPT_LANDSCAPE_ONLY
- UG_OPT_INDICATOR_DISABLE

And we used UG_OPT_INDICATOR_ENABLE in "helloUG-efl"

<br>
<h3 class="pg">Build and test</h3>
Before you build, you have to make sure whether translatable strings exist or not. IF translatable strings EXIST, please follow these steps before you build:
@verbatim
# cd po
# ./update-po.sh
# cd ..
@endverbatim
IF NOT, please remove the following line in your CMakeList.txt
@verbatim
ADD_SUBDIRECTORY(po)
@endverbatim

To build "helloUG-efl", follow these steps:
@verbatim
# mkdir build
# cd build
# cmake -DCMAKE_INSTALL_PREFIX=/usr ..
# make
# make install
@endverbatim

\note <b>Naming rule:</b> The output library name is <b>"libug-helloUG-efl.so"</b>, and we use <b>"helloUG-efl"</b> as UI gadget name except prefix <b>"libug-"</b> and postfix ".so" In other word, when you make an UI gadget, the name of library MUST be <b>"libug-XXXXXX.so"</b>
\note <b>Installation directory:</b> UI gadgets MUST be installed in "${PREFIX}/lib/ug/"

Finally, we made our first UI gadget, "helloUG-efl." Let's test it using <i>ug-launcher</i> which is simple UI gadget launcher. Because we are using beat style buttons in our UI gadget, we specify "beat" as ELM_THEME.
Fullview test
@verbatim
# ELM_THEME=beat ug-launcher -n helloUG-efl
@endverbatim
Frameview test
@verbatim
# ELM_THEME=beat ug-launcher -n helloUG-efl -f
@endverbatim

\note <b>How to install UG launcher</b>
@verbatim
# apt-get install ui-gadget-tools
@endverbatim
\note <b>How to use UG launcher</b>
@verbatim
# ug-launcher [-F] [-f] -n <UG_NAME> [-d <Argument>]
@endverbatim
- -d: argument, key, value pair.
- -F: Fullview mode (default)
- -f: frameview mode
\note <b> Example: </b>
@verbatim
# ug-launcher -F -n helloUG-efl -d "name,John doe" -d "age,30"
@endverbatim

\image html SLP_UI_Gadget_PG_image03.png "Picture 3. helloUG-efl test: Fullview (left) and Frameview (right)

<br>
<h2 class="pg">How to use UI gadget</h2>
Now, we are going to use "helloUG-efl" of previous section.

<br>
<h3 class="pg">Initialize</h3>

If you are UI gadget developer who is trying to use UI gadgets, please skip this section. This section is for application developers who use UI gadgets.
You have to initialize UI gadget manager before you use UI gadgets. To initialize, use <b>ug_init()</b> with arguments: <i>disp, xid, win and opt</i>. <i>disp</i> is default display, and <i>xid</i> is X window id of win. <i>win</i> is window evas object for UI gadgets, and it is usually main window. <i>opti</i> is rotation and indicator option for your application (see <i>Rotation and indicator section</i>.)

The <i>disp</i> and <i>xid</i> are used for indicator management. If you don't know how to get display and X window ID, just use following macro: <b>UG_INIT_EFL(win, opt);</b>

\note <b>Prototype of ug_init():</b>
@code
int ug_init (Display *disp, Window xid, void *win, enum ug_option opt);
@endcode
\note <b>Macros for convenience (see 3 API reference quide):</b>
@code
UG_INIT_EFL(win, opt);
@endcode

<br>
<h3 class="pg">Create UI gadget instance</h3>

To create UI gadget instance, you have to invoke <b>ug_create()</b> which has five arguments: <i>parent, name, mode, data, and cbs.</i>

First, the <i>parent</i> is provided for specifying parent UI gadget, and it helps UI gadget manager to manage UI gadget tree (see <i>Management section.</i>) For instance, if the UI gadget 'A' uses other UI gadgets,  the parent has to be the 'A.' Otherwise, if an application uses UI gadgets, the <i>parent</i> has to be NULL.

Second, the <i>name</i> is the UI gadget's name (ex. "helloUG-efl")

Third, the <i>mode</i> could be UG_MODE_FULLVIEW to show the UI gadget as fullview, or UG_MODE_FRAMEVIEW to show it as frameview.

Fourth, the <i>data</i> is arguments for the UI gadget which is bundle type (see \ref bundle_PG "bundle programming guide")

\warning After create UI gadget, you have to release the argument using <b>bundle_free()</b> API.

Fifth, the <i>cbs</i> is data describing layout callback, result callback, destroy callback, and private data. In detail, layout callback is used for layout arrangement, and it invoked after the UI gadget is created, and result callback is invoked to receive result from the UI gadget. And destroy callback is invoked to deal with destroy request from the UI gadget.

\warning Result data of the result callback is bundle type data, named <i>result</i>. <b>Because the result data is released after result callback is finished</b>, if you want to keep using it, please use <b>bundle_dup()</b> which duplicates given bundle data (see \ref bundle_PG "bundle programming guide")

\note <b>Prototype of ug_create():</b>
@code
struct ui_gadget *ug_create (struct ui_gadget *parent,
                        const char *name,
                        enum ug_mode mode,
                        bundle *data,
                        struct ug_cbs *cbs);

\note <b>struct ug_cbs</b> is describing some callbacks and private data:
@code
struct ug_cbs {
        void (*layout_cb)(struct ui_gadget *ug, enum ug_mode mode, void *priv);
        void (*result_cb)(struct ui_gadget *ug, bundle *result, void *priv);
        void (*destroy_cb)(struct ui_gadget *ug, void *priv);
        void *priv;
};
@endcode

Here are some examples:

@code
// FULLVIEW example
struct my_data {
        struct ui_gadget *ug;
};

static void layout_cb(struct ui_gadget *ug, enum ug_mode mode, void *priv)
{
        Evas_Object *base, *win;

        if (!ug || !priv)
                return;

        base = ug_get_layout(ug);
        if (!base)
                return;

        win = ug_get_window();

        switch (mode) {
                case UG_MODE_FULLVIEW:
                        evas_object_size_hint_weight_set(base, EVAS_HINT_EXPAND, EVAS_HINT_EXPAND);
                        elm_win_resize_object_add(win, base);
                        evas_object_show(base);
                        break;
                default:
                        break;
        }
}

static void result_cb(struct ui_gadget *ug, bundle *result, void *priv)
{
        struct my_data *mydata;
        const char *val;

        if (!ug || !priv)
                return;

        mydata = priv;
        if (result) {
                val = bundle_get_val(result, "name");
                if (val)
                        fprintf(stderr, "The name of UI gadget that sends result is %s\n", val);
        }
        ug_destroy(ug);
        mydata->ug = NULL;

}

static void destroy_cb(struct ui_gadget *ug, void *priv)
{
        struct my_data *mydata;

        if (!ug || !priv)
                return;

        mydata = priv;

        ug_destroy(ug);
        mydata->ug = NULL;
}

struct ui_gadget *create_ug(struct my_data *data)
{
        struct ui_gadget *ug;
        struct ug_cbs cbs = {0, };

        cbs.layout_cb = layout_cb;
        cbs.result_cb = result_cb;
        cbs.destroy_cb = destroy_cb;
        cbs.priv = (void *)data;

        ug = ug_create(NULL, "helloUG-efl", UG_MODE_FULLVIEW, NULL, &cbs);

        return ug;
}
@endcode

@code
// FRAMEVIEW example
struct my_data {
        struct ui_gadget *ug;
        Evas_Object *main_layout;
};

static void layout_cb(struct ui_gadget *ug, enum ug_mode mode, void *priv)
{
        Evas_Object *base, *win;
        struct my_data *mydata;

        if (!ug || !priv)
                return;

        mydata = priv;

        base = ug_get_layout(ug);
        if (!base)
                return;

        win = ug_get_window();

        switch (mode) {
                case UG_MODE_FRAMEVIEW:
                        elm_layout_content_set(mydata->main_layout, "content", base);
                        break;
                default:
                        break;
        }
}

static void result_cb(struct ui_gadget *ug, bundle *result, void *priv)
{
        struct my_data *mydata;
        const char *val;

        if (!ug || !priv)
                return;

        mydata = priv;

        if (result) {
                val = bundle_get_val(result, "name");
                if (val)
                        fprintf(stderr, "The name of UI gadget that sends result is %s\n", val);
        }

        ug_destroy(ug);
        mydata->ug = NULL;

}

static void destroy_cb(struct ui_gadget *ug, void *priv)
{
        struct my_data *mydata;

        if (!ug || !priv)
                return;

        mydata = priv;

        ug_destroy(ug);
        mydata->ug = NULL;
}

struct ui_gadget *create_ug(struct my_data *data)
{
        struct ui_gadget *ug;
        struct ug_cbs cbs = {0, };

        cbs.layout_cb = layout_cb;
        cbs.result_cb = result_cb;
        cbs.destroy_cb = destroy_cb;
        cbs.priv = (void *)data;

        ug = ug_create(NULL, "helloUG-efl", UG_MODE_FRAMEVIEW, NULL, &cbs);

        return ug;
}
@endcode

<br>
<h2 class="pg">Send message</h2>

We provide API for sending message: <b>ug_send_message()</b>. When you send a message, you have to use bundle type data (see \ref bundle_PG "bundle programming guide").

\note <b>Prototype of ug_send_message():</b>
@code
int ug_send_message (struct ui_gadget *ug, bundle *msg);
@endcode

\warning After send your message, you have to release it using <b>bundle_free()</b> API.
@code
//example
bundle *b;

b = bundle_create();
if (!b)
        return;

        bundle_add(b, "name", "helloUG-efl");
        bundle_add(b, "type", "test message");

        //Send message
        ug_send_message(ug b);

        //release bundle
        bundle_free(b);

@endcode

<br>
<h2 class="pg">Propagate event</h2>

If you are UI gadget developer who is trying to use UI gadgets, please skip this section. This section is for application developers who use UI gadgets.

We provide some APIs for event propagation: <b>ug_pause(), ug_resume(), and ug_send_event()</b>. <b>ug_pause()</b> and <b>ug_resume()</b> are used for task-managing. If the application is put into background, invoke <b>ug_pause()</b>, otherwise, if the application is brought to the foreground, invoke <b>ug_resume()</b>. <b>ug_send_event()</b> is used for system event: <i>low memory, low battery, language change, rotate portrait, rotate portrait upside-down, rotate landscape, and rotate landscape upside-down.</i>

\note <b>Prototype of ug_pause(), ug_resume(), and ug_send_event():</b>
@code
int ug_pause (void);
int ug_resume (void);
int ug_send_event (enum ug_event event);
@endcode

<br>
<h2 class="pg">Destroy all UI gadgets</h2>

If you are UI gadget developer who is trying to use UI gadgets, please skip this section. This section is for application developers who use UI gadgets.

When you terminate your application, destroy all UI gadgets using <b>ug_destroy_all()</b>.

\note <b>Prototype of ug_destroy_all: </b>
@code
int ug_destroy_all (void);
@endcode

 * @}
 */