Animators are a specific type of timer, specially designed for on-screen animation purposes:

  • The time interval is usually known when they are created.
  • They are called at each screen refresh and their interval can vary. The interval can depend on the system load, the target power consumption, and other factors. The exact interval is not relevant.

To implement animators, Ecore provides the Ecore animator subsystem.

Table of Contents

Forever-running Animator

To create an animation that runs for an indefinite time:

Eina_Bool my_anim_cb(void *data)
   static int count = 0;
   if (count < 5)
ecore_animator_add(my_anim_cb, my_data);

This example looks the same as the one using an Ecore timer. The ecore_animator_add() function takes the callback function and data to pass to it, and returns an Ecore_Animator object. The function is called at a system-defined interval until it returns ECORE_CALLBACK_CANCEL instead of ECORE_CALLBACK_RENEW.

Specific-duration Animator

An animator callback for an animator running a specific time has a different prototype than the forever running animator.

This callback function receives both data and a position which represents the current time among the full timeline, 0 meaning the beginning of the animation, and 1 meaning the end of the animation, returning ECORE_CALLBACK_CANCEL to abort, or ECORE_CALLBACK_RENEW to continue.

To create and destroy the animator

To create the animator

Use the ecore_animator_timeline_add() function. The first parameter specifies the animator duration, the second parameter is the callback function, and the third parameter is the data to pass to the callback. The data parameter is optional.

Eina_Bool my_anim_cb(void *data, double position)
   if (position < .5)
ecore_animator_timeline_add(5., my_anim_cb, my_data);

In this example, the animator is specified to run for five seconds. The function returns ECORE_CALLBACK_CANCEL as soon as the position among the timeline passes half of the duration, 2.5 seconds.

Ecore can generate a virtual position from the original one using ecore_animator_pos_map(position, map, v1, v2). Several maps are available:

  • ECORE_POS_MAP_LINEAR: linear from 0.0 to 1.0.
  • ECORE_POS_MAP_ACCELERATE: start slow, then speed up.
  • ECORE_POS_MAP_DECELERATE: start fast, then slow down.
  • ECORE_POS_MAP_SINUSOIDAL: start slow, speed up, then slow down at the end.
  • ECORE_POS_MAP_ACCELERATE_FACTOR: start slow, then speed up, v1 being a power factor: 0.0 is linear, 1.0 is standard acceleration, 2.0 is a much more pronounced acceleration (squared), and 3.0 is cubed.
  • ECORE_POS_MAP_DECELERATE_FACTOR: start fast, then slow down, v1 being a power factor: 0.0 is linear, 1.0 is standard deceleration, 2.0 is a much more pronounced deceleration (squared), and 3.0 is cubed.
  • ECORE_POS_MAP_SINUSOIDAL_FACTOR: start slow, speed up, then slow down at the end, v1 being a power factor: 0.0 is linear, 1.0 is a standard sinusoidal, 2.0 is a much more pronounced sinusoidal (squared), and 3.0 is cubed.
  • ECORE_POS_MAP_DIVISOR_INTERP: start at gradient * v1, interpolated with the power of v2 curve.
  • ECORE_POS_MAP_BOUNCE: start at 0.0, then drop like a ball bouncing to the ground at 1.0, and bounce v2 times, with a decay factor of v1.
  • ECORE_POS_MAP_SPRING: start at 0.0, then wobble like a spring to the rest position 1.0, and wobble v2 times, with a decay factor of v1.

To destroy the animator

Use the ecore_animator_del() function. The animator to destroy must be running, that is, it has not returned a false value. If the animator is not running, the function cannot be called.

To manage the animator

To pause the currently running animator

Use the ecore_animator_freeze() function. Note that time continues ticking even if the animator is frozen, and that resuming the animation using the ecore_animator_thaw() function does not actually resume, if the full runtime has been passed in the meanwhile.

To query Ecore for the interval between 2 animator calls

Use the ecore_animator_frametime_get() function.

To change the interval

Use the ecore_animator_frametime_set(interval) function. Note that too small a value causes performance and power consumption issues, and too high a value makes the animation jerky.