~~Title: Elementary Animations - Creating a Rotation Effect~~
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=== Elementary Animations ===
==== Creating a Rotation Effect ====

This effect rotates the animation target button with an angle of 360°. A
pointer to this angle is stored in the application data as ''anim->rt_angle''.

{{ :elementary_animations_rotate.gif }}

Create the button and add it to the center column.

<code c>
// The rotation button
Evas_Object *btn_rotate = elm_button_add(win);
elm_object_text_set(btn_rotate, "Rotate");
evas_object_size_hint_weight_set(btn_rotate, EVAS_HINT_FILL, EVAS_HINT_FILL);
evas_object_show(btn_rotate);
evas_object_smart_callback_add(btn_rotate, "clicked", _btn_rotate_cb, &anim);
elm_box_pack_end(center_vbox, btn_rotate);
</code>

In the rotate button callback, call the effect function with the target button
as first parameter and the rotation angle as the second one.

<code c>
static void
_btn_rotate_cb(void *data, Evas_Object *btn, void *ev)
{
   Animations *anim = (Animations *)data;

   // Setting the button text
   elm_object_text_set(anim->button, "Rotate");
   _rotation_effect(anim->button, *(anim->rt_angle));
}
</code>

The animation function rotates the animation target by adding a rotation
effect with ''elm_transit_effect_rotation_add''. This function takes three
parameters:

    * ''Elm_Transit''
    * the rotation position at which the effect begins
    * the rotation position at which the effect ends

Rotation starts at 0° to finish at 360°. The animation lasts two seconds.

<code c>
static void
_rotation_effect(Evas_Object *obj, float angle)
{
   Elm_Transit *trans = elm_transit_add();
   elm_transit_object_add(trans, obj);

   // rotates the object from its original angle to given degrees to the right
   elm_transit_effect_rotation_add(trans, 0.0, angle);
   elm_transit_duration_set(trans, 2.0);
   elm_transit_go(trans);
}
</code>
\\
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