Basic text button

As seen in Get started with EFL tutorial, a text-only button is created as follows:

    //basic text button
    Evas_Object *button_text;
    button_text = elm_button_add(win);
 
    elm_object_text_set(button_text,"Clik me");
 
    //how a container object should resize a given child within its area
    evas_object_size_hint_weight_set(button_text, EVAS_HINT_EXPAND, EVAS_HINT_EXPAND);
    //how to align an object
    evas_object_size_hint_align_set(button_text, EVAS_HINT_FILL, 0.5);
 
    //100x30 px button
    evas_object_resize(button_text, 100, 30);
    evas_object_show(button_text);

Basic icon button

Instead of a button having only some text, you can also opt to having an icon-only button.

    //Basic icon button
    Evas_Object *button_icon, *icon;
    button_icon = elm_button_add(win);
    icon = elm_icon_add(win);
 
    //set the image file and the button as an icon
    elm_image_file_set(icon, "icon.png", NULL);
    elm_object_part_content_set(button_icon, "icon", icon);
 
    evas_object_size_hint_weight_set(button_icon, EVAS_HINT_EXPAND, EVAS_HINT_EXPAND);
    evas_object_size_hint_align_set(button_icon, EVAS_HINT_FILL, 0.5);
 
    //100x30 px button
    evas_object_resize(button_icon, 100, 30);
    evas_object_move(button_icon, 110, 0);
    evas_object_show(button_icon);

The function elm_object_part_content_set(button_icon, “icon”,icon) sets the content on part on a given container widget. All widgets deriving from the Elementary Container Class may match. This sets new content to a given part. If any object was already set as a content object, it will be deleted.

Icon and text button

You can also have buttons holding both an icon and a label.

    //Icon and text button
    Evas_Object *button_icon_text, *icon2;
    button_icon_text = elm_button_add(win);
    icon2 = elm_icon_add(win);
 
    elm_image_file_set(icon2, "icon.png", NULL);
    elm_object_part_content_set(button_icon_text, "icon", icon2);
    elm_object_text_set(button_icon_text, "Press me");
    evas_object_size_hint_weight_set(button_icon_text, EVAS_HINT_EXPAND, EVAS_HINT_EXPAND);
    evas_object_size_hint_align_set(button_icon_text, EVAS_HINT_FILL, 0.5);
 
    evas_object_resize(button_icon_text, 100, 30);
    evas_object_move(button_icon_text, 220, 0);
    evas_object_show(button_icon_text);

Disabled button

If you want to disable your button but still visible:

elm_object_disabled_set(button, EINA_TRUE);

Elementary buttons respond to user interactions thanks to several events.

Click event

The “click” event is the most basic and well-known one. The following code snippet will change the text of a button upon a click event: a press followed by an unpress.

//Click Callback: print Clicked
static void
_button_click_cb(void *data, Evas_Object *button, void *event_info){
    elm_object_text_set(button, "Clicked!");
}
 
evas_object_smart_callback_add(button_text, "clicked", button_click_cb, NULL);

Press/unpress events

The button can also respond to the press and unpress events instead of the whole click.

//Press callback: print Pressed
static void
_button_press_cb(void * data, Evas_Object *button, void *event_info){
    elm_object_text_set(button, "Pressed!");
}
 
//Unpress callback: print Unpressed
static void
_button_unpress_cb(void *data, Evas_Object *button, void *event_info){
    elm_object_text_set(button, "Unpressed!");
}
 
evas_object_smart_callback_add(button_icon, "pressed", _button_press_cb, NULL);
evas_object_smart_callback_add(button_icon, "unpressed", _button_unpress_cb, NULL);

Repeated events

The button can also receive several events in case it is being held by the user. Timings such as the initial timeout and the repeat interval can be set. In this example, the initial timeout is set to one second, and the repeat interval to half a second.

static void
_button_repeat_cb(void *data, Evas_Object *button, void *event_info){
    static int count = 0;
    char buffer[16];
 
    snprintf(buffer, sizeof(buffer), "Repeat %d", count++);
 
    //print the number of time callback was called
    elm_object_text_set(button, buffer);
}
 
    //Get whether the autorepeat feature is enabled.
    elm_button_autorepeat_set(button_icon_text, EINA_TRUE);
    //Set the initial timeout before the autorepeat event is generated.
    elm_button_autorepeat_initial_timeout_set(button_icon_text, 1.0);
    //gap between two callbacks
    elm_button_autorepeat_gap_timeout_set(button_icon_text, 0.5);
    //"repeated": the user pressed the button without releasing it.
    evas_object_smart_callback_add(button_icon_text, "repeated", _button_repeat_cb, NULL);

Focused/unfocused events

The event Focused is equivalent to click indeed callback is called when you are “focused” on the button. So, you are unfocused when you are not focused on the first button. For having two buttons, a box container will be needed.

The button can also receive event from another button in case it is being focused when you click on it and unfocused when you press and unpress another one.

static void
_button_focused_cb(void * data, Evas_Object *button, void *event_info){
    elm_object_text_set(button, "Focused");
}
 
static void
_button_unfocused_cb(void * data, Evas_Object *button, void *event_info){
    elm_object_text_set(button, "Unfocused");
}
    //Focused/unfocused event
    Evas_Object *button;
 
    button = elm_button_add(win);
    elm_object_text_set(button, "button");
    evas_object_resize(button, 100, 30);
    evas_object_move(button, 0, 40);
    evas_object_show(button);
 
    evas_object_smart_callback_add(button, "focused", _button_focused_cb, NULL);
    evas_object_smart_callback_add(button, "unfocused", _button_unfocused_cb, NULL);

The whole code: button.c

Simple Text