Animations

You can automatically change the value of a variable between a start and an end value using animations. Animation will happen by periodically calling an "animator" function with the corresponding value parameter.

The animator functions have the following prototype:

void func(void * var, lv_anim_var_t value);

This prototype is compatible with the majority of the property set functions in LVGL. For example lv_obj_set_x(obj, value) or lv_obj_set_width(obj, value)

Create an animation

To create an animation an lv_anim_t variable has to be initialized and configured with lv_anim_set_...() functions.


/* INITIALIZE AN ANIMATION
 *-----------------------*/

lv_anim_t a;
lv_anim_init(&a);

/* MANDATORY SETTINGS
 *------------------*/

/*Set the "animator" function*/
lv_anim_set_exec_cb(&a, (lv_anim_exec_xcb_t) lv_obj_set_x); 

/*Set target of the animation*/
lv_anim_set_var(&a, obj); 

/*Length of the animation [ms]*/
lv_anim_set_time(&a, duration);

/*Set start and end values. E.g. 0, 150*/
lv_anim_set_values(&a, start, end);

/* OPTIONAL SETTINGS
 *------------------*/

/*Time to wait before starting the animation [ms]*/
lv_anim_set_delay(&a, delay);

/*Set path (curve). Default is linear*/
lv_anim_set_path(&a, lv_anim_path_ease_in);

/*Set a callback to indicate when the animation is ready (idle).*/
lv_anim_set_ready_cb(&a, ready_cb);

/*Set a callback to indicate when the animation is started (after delay).*/
lv_anim_set_start_cb(&a, start_cb);

/*When ready, play the animation backward with this duration. Default is 0 (disabled) [ms]*/
lv_anim_set_playback_time(&a, time);

/*Delay before playback. Default is 0 (disabled) [ms]*/
lv_anim_set_playback_delay(&a, delay);

/*Number of repetitions. Default is 1. LV_ANIM_REPEAT_INFINITE for infinite repetition*/
lv_anim_set_repeat_count(&a, cnt);

/*Delay before repeat. Default is 0 (disabled) [ms]*/
lv_anim_set_repeat_delay(&a, delay);

/*true (default): apply the start value immediately, false: apply start value after delay when the anim. really starts. */
lv_anim_set_early_apply(&a, true/false);

/* START THE ANIMATION
 *------------------*/
lv_anim_start(&a);                             /*Start the animation*/

You can apply multiple different animations on the same variable at the same time. For example, animate the x and y coordinates with lv_obj_set_x and lv_obj_set_y. However, only one animation can exist with a given variable and function pair and lv_anim_start() will remove any existing animations for such a pair.

Animation path

You can control the path of an animation. The most simple case is linear, meaning the current value between start and end is changed with fixed steps. A path is a function which calculates the next value to set based on the current state of the animation. Currently, there are the following built-in path functions:

  • lv_anim_path_linear linear animation

  • lv_anim_path_step change in one step at the end

  • lv_anim_path_ease_in slow at the beginning

  • lv_anim_path_ease_out slow at the end

  • lv_anim_path_ease_in_out slow at the beginning and end

  • lv_anim_path_overshoot overshoot the end value

  • lv_anim_path_bounce bounce back a little from the end value (like hitting a wall)

Speed vs time

By default, you set the animation time directly. But in some cases, setting the animation speed is more practical.

The lv_anim_speed_to_time(speed, start, end) function calculates the required time in milliseconds to reach the end value from a start value with the given speed. The speed is interpreted in unit/sec dimension. For example, lv_anim_speed_to_time(20,0,100) will yield 5000 milliseconds. For example, in the case of lv_obj_set_x unit is pixels so 20 means 20 px/sec speed.

Delete animations

You can delete an animation with lv_anim_del(var, func) if you provide the animated variable and its animator function.

Timeline

A timeline is a collection of multiple animations which makes it easy to create complex composite animations.

Firstly, create an animation element but don’t call lv_anim_start().

Secondly, create an animation timeline object by calling lv_anim_timeline_create().

Thirdly, add animation elements to the animation timeline by calling lv_anim_timeline_add(at, start_time, &a). start_time is the start time of the animation on the timeline. Note that start_time will override the value of delay.

Finally, call lv_anim_timeline_start(at) to start the animation timeline.

It supports forward and backward playback of the entire animation group, using lv_anim_timeline_set_reverse(at, reverse).

Call lv_anim_timeline_stop(at) to stop the animation timeline.

Call lv_anim_timeline_set_progress(at, progress) function to set the state of the object corresponding to the progress of the timeline.

Call lv_anim_timeline_get_playtime(at) function to get the total duration of the entire animation timeline.

Call lv_anim_timeline_get_reverse(at) function to get whether to reverse the animation timeline.

Call lv_anim_timeline_del(at) function to delete the animation timeline.

../_images/anim-timeline.png

Examples

Start animation on an event

C code  

 GitHub
#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_SWITCH

static void anim_x_cb(void * var, int32_t v)
{
    lv_obj_set_x(var, v);
}

static void sw_event_cb(lv_event_t * e)
{
    lv_obj_t * sw = lv_event_get_target(e);
    lv_obj_t * label = lv_event_get_user_data(e);

    if(lv_obj_has_state(sw, LV_STATE_CHECKED)) {
        lv_anim_t a;
        lv_anim_init(&a);
        lv_anim_set_var(&a, label);
        lv_anim_set_values(&a, lv_obj_get_x(label), 100);
        lv_anim_set_time(&a, 500);
        lv_anim_set_exec_cb(&a, anim_x_cb);
        lv_anim_set_path_cb(&a, lv_anim_path_overshoot);
        lv_anim_start(&a);
    } else {
        lv_anim_t a;
        lv_anim_init(&a);
        lv_anim_set_var(&a, label);
        lv_anim_set_values(&a, lv_obj_get_x(label), -lv_obj_get_width(label));
        lv_anim_set_time(&a, 500);
        lv_anim_set_exec_cb(&a, anim_x_cb);
        lv_anim_set_path_cb(&a, lv_anim_path_ease_in);
        lv_anim_start(&a);
    }

}

/**
 * Start animation on an event
 */
void lv_example_anim_1(void)
{
    lv_obj_t * label = lv_label_create(lv_scr_act());
    lv_label_set_text(label, "Hello animations!");
    lv_obj_set_pos(label, 100, 10);


    lv_obj_t * sw = lv_switch_create(lv_scr_act());
    lv_obj_center(sw);
    lv_obj_add_state(sw, LV_STATE_CHECKED);
    lv_obj_add_event_cb(sw, sw_event_cb, LV_EVENT_VALUE_CHANGED, label);
}

#endif

MicroPython code  

 GitHub Simulator
def anim_x_cb(label, v):
    label.set_x(v)

def sw_event_cb(e,label):
    sw = e.get_target()

    if sw.has_state(lv.STATE.CHECKED): 
        a = lv.anim_t()
        a.init()
        a.set_var(label)
        a.set_values(label.get_x(), 100)
        a.set_time(500)
        a.set_path_cb(lv.anim_t.path_overshoot)
        a.set_custom_exec_cb(lambda a,val: anim_x_cb(label,val))
        lv.anim_t.start(a)
    else:
        a = lv.anim_t()
        a.init()
        a.set_var(label)
        a.set_values(label.get_x(), -label.get_width())
        a.set_time(500)
        a.set_path_cb(lv.anim_t.path_ease_in)
        a.set_custom_exec_cb(lambda a,val: anim_x_cb(label,val))
        lv.anim_t.start(a)

#
# Start animation on an event
#

label = lv.label(lv.scr_act())
label.set_text("Hello animations!")
label.set_pos(100, 10)


sw = lv.switch(lv.scr_act())
sw.center()
sw.add_state(lv.STATE.CHECKED)
sw.add_event_cb(lambda e: sw_event_cb(e,label), lv.EVENT.VALUE_CHANGED, None)




Playback animation

C code  

 GitHub
#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_SWITCH


static void anim_x_cb(void * var, int32_t v)
{
    lv_obj_set_x(var, v);
}

static void anim_size_cb(void * var, int32_t v)
{
    lv_obj_set_size(var, v, v);
}

/**
 * Create a playback animation
 */
void lv_example_anim_2(void)
{

    lv_obj_t * obj = lv_obj_create(lv_scr_act());
    lv_obj_set_style_bg_color(obj, lv_palette_main(LV_PALETTE_RED), 0);
    lv_obj_set_style_radius(obj, LV_RADIUS_CIRCLE, 0);

    lv_obj_align(obj, LV_ALIGN_LEFT_MID, 10, 0);

    lv_anim_t a;
    lv_anim_init(&a);
    lv_anim_set_var(&a, obj);
    lv_anim_set_values(&a, 10, 50);
    lv_anim_set_time(&a, 1000);
    lv_anim_set_playback_delay(&a, 100);
    lv_anim_set_playback_time(&a, 300);
    lv_anim_set_repeat_delay(&a, 500);
    lv_anim_set_repeat_count(&a, LV_ANIM_REPEAT_INFINITE);
    lv_anim_set_path_cb(&a, lv_anim_path_ease_in_out);

    lv_anim_set_exec_cb(&a, anim_size_cb);
    lv_anim_start(&a);
    lv_anim_set_exec_cb(&a, anim_x_cb);
    lv_anim_set_values(&a, 10, 240);
    lv_anim_start(&a);
}

#endif

MicroPython code  

 GitHub Simulator
def anim_x_cb(obj, v):
    obj.set_x(v)

def anim_size_cb(obj, v):
    obj.set_size(v, v)


#
# Create a playback animation
#
obj = lv.obj(lv.scr_act())
obj.set_style_bg_color(lv.palette_main(lv.PALETTE.RED), 0)
obj.set_style_radius(lv.RADIUS.CIRCLE, 0)

obj.align(lv.ALIGN.LEFT_MID, 10, 0)

a1 = lv.anim_t()
a1.init()
a1.set_var(obj)
a1.set_values(10, 50)
a1.set_time(1000)
a1.set_playback_delay(100)
a1.set_playback_time(300)
a1.set_repeat_delay(500)
a1.set_repeat_count(lv.ANIM_REPEAT.INFINITE)
a1.set_path_cb(lv.anim_t.path_ease_in_out)
a1.set_custom_exec_cb(lambda a1,val: anim_size_cb(obj,val))
lv.anim_t.start(a1)

a2 = lv.anim_t()
a2.init()
a2.set_var(obj)
a2.set_values(10, 240)
a2.set_time(1000)
a2.set_playback_delay(100)
a2.set_playback_time(300)
a2.set_repeat_delay(500)
a2.set_repeat_count(lv.ANIM_REPEAT.INFINITE)
a2.set_path_cb(lv.anim_t.path_ease_in_out)
a2.set_custom_exec_cb(lambda a1,val: anim_x_cb(obj,val))
lv.anim_t.start(a2)

Animation timeline

C code  

 GitHub
#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES

static lv_anim_timeline_t * anim_timeline = NULL; 

static lv_obj_t * obj1 = NULL;
static lv_obj_t * obj2 = NULL;
static lv_obj_t * obj3 = NULL;

static const lv_coord_t obj_width = 90;
static const lv_coord_t obj_height = 70;

static void set_width(void * var, int32_t v)
{
    lv_obj_set_width((lv_obj_t *)var, v);
}

static void set_height(void * var, int32_t v)
{
    lv_obj_set_height((lv_obj_t *)var, v);
}

static void anim_timeline_create(void)
{
    /* obj1 */
    lv_anim_t a1;
    lv_anim_init(&a1);
    lv_anim_set_var(&a1, obj1);
    lv_anim_set_values(&a1, 0, obj_width);
    lv_anim_set_early_apply(&a1, false);
    lv_anim_set_exec_cb(&a1, (lv_anim_exec_xcb_t)set_width);
    lv_anim_set_path_cb(&a1, lv_anim_path_overshoot);
    lv_anim_set_time(&a1, 300);

    lv_anim_t a2;
    lv_anim_init(&a2);
    lv_anim_set_var(&a2, obj1);
    lv_anim_set_values(&a2, 0, obj_height);
    lv_anim_set_early_apply(&a2, false);
    lv_anim_set_exec_cb(&a2, (lv_anim_exec_xcb_t)set_height);
    lv_anim_set_path_cb(&a2, lv_anim_path_ease_out);
    lv_anim_set_time(&a2, 300);

    /* obj2 */
    lv_anim_t a3;
    lv_anim_init(&a3);
    lv_anim_set_var(&a3, obj2);
    lv_anim_set_values(&a3, 0, obj_width);
    lv_anim_set_early_apply(&a3, false);
    lv_anim_set_exec_cb(&a3, (lv_anim_exec_xcb_t)set_width);
    lv_anim_set_path_cb(&a3, lv_anim_path_overshoot);
    lv_anim_set_time(&a3, 300);

    lv_anim_t a4;
    lv_anim_init(&a4);
    lv_anim_set_var(&a4, obj2);
    lv_anim_set_values(&a4, 0, obj_height);
    lv_anim_set_early_apply(&a4, false);
    lv_anim_set_exec_cb(&a4, (lv_anim_exec_xcb_t)set_height);
    lv_anim_set_path_cb(&a4, lv_anim_path_ease_out);
    lv_anim_set_time(&a4, 300);

    /* obj3 */
    lv_anim_t a5;
    lv_anim_init(&a5);
    lv_anim_set_var(&a5, obj3);
    lv_anim_set_values(&a5, 0, obj_width);
    lv_anim_set_early_apply(&a5, false);
    lv_anim_set_exec_cb(&a5, (lv_anim_exec_xcb_t)set_width);
    lv_anim_set_path_cb(&a5, lv_anim_path_overshoot);
    lv_anim_set_time(&a5, 300);

    lv_anim_t a6;
    lv_anim_init(&a6);
    lv_anim_set_var(&a6, obj3);
    lv_anim_set_values(&a6, 0, obj_height);
    lv_anim_set_early_apply(&a6, false);
    lv_anim_set_exec_cb(&a6, (lv_anim_exec_xcb_t)set_height);
    lv_anim_set_path_cb(&a6, lv_anim_path_ease_out);
    lv_anim_set_time(&a6, 300);

    /* Create anim timeline */
    anim_timeline = lv_anim_timeline_create();
    lv_anim_timeline_add(anim_timeline, 0, &a1);
    lv_anim_timeline_add(anim_timeline, 0, &a2);
    lv_anim_timeline_add(anim_timeline, 200, &a3);
    lv_anim_timeline_add(anim_timeline, 200, &a4);
    lv_anim_timeline_add(anim_timeline, 400, &a5);
    lv_anim_timeline_add(anim_timeline, 400, &a6);
}

static void btn_start_event_handler(lv_event_t * e)
{
    lv_obj_t * btn = lv_event_get_target(e);

    if (!anim_timeline) {
        anim_timeline_create();
    }

    bool reverse = lv_obj_has_state(btn, LV_STATE_CHECKED);
    lv_anim_timeline_set_reverse(anim_timeline, reverse);
    lv_anim_timeline_start(anim_timeline);
}

static void btn_del_event_handler(lv_event_t * e)
{
    LV_UNUSED(e);
    if (anim_timeline) {
        lv_anim_timeline_del(anim_timeline);
        anim_timeline = NULL;
    }
}

static void btn_stop_event_handler(lv_event_t * e)
{
    LV_UNUSED(e);
    if (anim_timeline) {
        lv_anim_timeline_stop(anim_timeline);
    }
}

static void slider_prg_event_handler(lv_event_t * e)
{
    lv_obj_t * slider = lv_event_get_target(e);

    if (!anim_timeline) {
        anim_timeline_create();
    }

    int32_t progress = lv_slider_get_value(slider);
    lv_anim_timeline_set_progress(anim_timeline, progress);
}

/**
 * Create an animation timeline
 */
void lv_example_anim_timeline_1(void)
{
    lv_obj_t * par = lv_scr_act();
    lv_obj_set_flex_flow(par, LV_FLEX_FLOW_ROW);
    lv_obj_set_flex_align(par, LV_FLEX_ALIGN_SPACE_AROUND, LV_FLEX_ALIGN_CENTER, LV_FLEX_ALIGN_CENTER);

    /* create btn_start */
    lv_obj_t * btn_start = lv_btn_create(par);
    lv_obj_add_event_cb(btn_start, btn_start_event_handler, LV_EVENT_VALUE_CHANGED, NULL);
    lv_obj_add_flag(btn_start, LV_OBJ_FLAG_IGNORE_LAYOUT);
    lv_obj_add_flag(btn_start, LV_OBJ_FLAG_CHECKABLE);
    lv_obj_align(btn_start, LV_ALIGN_TOP_MID, -100, 20);

    lv_obj_t * label_start = lv_label_create(btn_start);
    lv_label_set_text(label_start, "Start");
    lv_obj_center(label_start);

    /* create btn_del */
    lv_obj_t * btn_del = lv_btn_create(par);
    lv_obj_add_event_cb(btn_del, btn_del_event_handler, LV_EVENT_CLICKED, NULL);
    lv_obj_add_flag(btn_del, LV_OBJ_FLAG_IGNORE_LAYOUT);
    lv_obj_align(btn_del, LV_ALIGN_TOP_MID, 0, 20);

    lv_obj_t * label_del = lv_label_create(btn_del);
    lv_label_set_text(label_del, "Delete");
    lv_obj_center(label_del);

    /* create btn_stop */
    lv_obj_t * btn_stop = lv_btn_create(par);
    lv_obj_add_event_cb(btn_stop, btn_stop_event_handler, LV_EVENT_CLICKED, NULL);
    lv_obj_add_flag(btn_stop, LV_OBJ_FLAG_IGNORE_LAYOUT);
    lv_obj_align(btn_stop, LV_ALIGN_TOP_MID, 100, 20);

    lv_obj_t * label_stop = lv_label_create(btn_stop);
    lv_label_set_text(label_stop, "Stop");
    lv_obj_center(label_stop);

    /* create slider_prg */
    lv_obj_t * slider_prg = lv_slider_create(par);
    lv_obj_add_event_cb(slider_prg, slider_prg_event_handler, LV_EVENT_VALUE_CHANGED, NULL);
    lv_obj_add_flag(slider_prg, LV_OBJ_FLAG_IGNORE_LAYOUT);
    lv_obj_align(slider_prg, LV_ALIGN_BOTTOM_MID, 0, -20);
    lv_slider_set_range(slider_prg, 0, 65535);

    /* create 3 objects */
    obj1 = lv_obj_create(par);
    lv_obj_set_size(obj1, obj_width, obj_height);

    obj2 = lv_obj_create(par);
    lv_obj_set_size(obj2, obj_width, obj_height);

    obj3 = lv_obj_create(par);
    lv_obj_set_size(obj3, obj_width, obj_height);
}

#endif

MicroPython code  

 GitHub Simulator
class LV_ExampleAnimTimeline_1(object):

    def __init__(self):
        self.obj_width = 120
        self.obj_height = 150
        #
        # Create an animation timeline
        #

        self.par = lv.scr_act()
        self.par.set_flex_flow(lv.FLEX_FLOW.ROW)
        self.par.set_flex_align(lv.FLEX_ALIGN.SPACE_AROUND, lv.FLEX_ALIGN.CENTER, lv.FLEX_ALIGN.CENTER)
        
        self.btn_run = lv.btn(self.par)
        self.btn_run.add_event_cb(self.btn_run_event_handler, lv.EVENT.VALUE_CHANGED, None)
        self.btn_run.add_flag(lv.obj.FLAG.IGNORE_LAYOUT)
        self.btn_run.add_flag(lv.obj.FLAG.CHECKABLE)
        self.btn_run.align(lv.ALIGN.TOP_MID, -50, 20)
        
        self.label_run = lv.label(self.btn_run)
        self.label_run.set_text("Run")
        self.label_run.center()
        
        self.btn_del = lv.btn(self.par)
        self.btn_del.add_event_cb(self.btn_del_event_handler, lv.EVENT.CLICKED, None)
        self.btn_del.add_flag(lv.obj.FLAG.IGNORE_LAYOUT)
        self.btn_del.align(lv.ALIGN.TOP_MID, 50, 20)
        
        self.label_del = lv.label(self.btn_del)
        self.label_del.set_text("Stop")
        self.label_del.center()
        
        self.slider = lv.slider(self.par)
        self.slider.add_event_cb(self.slider_prg_event_handler, lv.EVENT.VALUE_CHANGED, None)
        self.slider.add_flag(lv.obj.FLAG.IGNORE_LAYOUT)
        self.slider.align(lv.ALIGN.BOTTOM_RIGHT, -20, -20)
        self.slider.set_range(0, 65535)
        
        self.obj1 = lv.obj(self.par)
        self.obj1.set_size(self.obj_width, self.obj_height)
        
        self.obj2 = lv.obj(self.par)
        self.obj2.set_size(self.obj_width, self.obj_height)
        
        self.obj3 = lv.obj(self.par)
        self.obj3.set_size(self.obj_width, self.obj_height)
        
        self.anim_timeline = None

    def set_width(self,obj, v):
        obj.set_width(v)

    def set_height(self,obj, v):
        obj.set_height(v)

    def anim_timeline_create(self):
        # obj1 
        self.a1 = lv.anim_t()
        self.a1.init()
        self.a1.set_values(0, self.obj_width)
        self.a1.set_early_apply(False)
        self.a1.set_custom_exec_cb(lambda a,v: self.set_width(self.obj1,v))
        self.a1.set_path_cb(lv.anim_t.path_overshoot)
        self.a1.set_time(300)
        
        self.a2 = lv.anim_t()
        self.a2.init()
        self.a2.set_values(0, self.obj_height)
        self.a2.set_early_apply(False)
        self.a2.set_custom_exec_cb(lambda a,v: self.set_height(self.obj1,v))
        self.a2.set_path_cb(lv.anim_t.path_ease_out)
        self.a2.set_time(300)
        
        # obj2 
        self.a3=lv.anim_t()
        self.a3.init()
        self.a3.set_values(0, self.obj_width)
        self.a3.set_early_apply(False)
        self.a3.set_custom_exec_cb(lambda a,v: self.set_width(self.obj2,v))
        self.a3.set_path_cb(lv.anim_t.path_overshoot)
        self.a3.set_time(300)
        
        self.a4 = lv.anim_t()
        self.a4.init()
        self.a4.set_values(0, self.obj_height)
        self.a4.set_early_apply(False)
        self.a4.set_custom_exec_cb(lambda a,v: self.set_height(self.obj2,v))
        self.a4.set_path_cb(lv.anim_t.path_ease_out)
        self.a4.set_time(300)
        
        # obj3 
        self.a5 = lv.anim_t()
        self.a5.init()
        self.a5.set_values(0, self.obj_width)
        self.a5.set_early_apply(False)
        self.a5.set_custom_exec_cb(lambda a,v: self.set_width(self.obj3,v))
        self.a5.set_path_cb(lv.anim_t.path_overshoot)
        self.a5.set_time(300)
        
        self.a6 = lv.anim_t()
        self.a6.init()
        self.a6.set_values(0, self.obj_height)
        self.a6.set_early_apply(False)
        self.a6.set_custom_exec_cb(lambda a,v: self.set_height(self.obj3,v))
        self.a6.set_path_cb(lv.anim_t.path_ease_out)
        self.a6.set_time(300)
    
        # Create anim timeline
        print("Create new anim_timeline")
        self.anim_timeline = lv.anim_timeline_create()
        lv.anim_timeline_add(self.anim_timeline, 0, self.a1)
        lv.anim_timeline_add(self.anim_timeline, 0, self.a2)
        lv.anim_timeline_add(self.anim_timeline, 200, self.a3)
        lv.anim_timeline_add(self.anim_timeline, 200, self.a4)
        lv.anim_timeline_add(self.anim_timeline, 400, self.a5)
        lv.anim_timeline_add(self.anim_timeline, 400, self.a6)
        
    def slider_prg_event_handler(self,e):
        slider = e.get_target()

        if  not self.anim_timeline:
            self.anim_timeline_create()

        progress = slider.get_value()
        lv.anim_timeline_set_progress(self.anim_timeline, progress)


    def btn_run_event_handler(self,e):
        btn = e.get_target()
        if not self.anim_timeline:
            self.anim_timeline_create()
        
        reverse = btn.has_state(lv.STATE.CHECKED)
        lv.anim_timeline_set_reverse(self.anim_timeline,reverse)
        lv.anim_timeline_start(self.anim_timeline)

    def btn_del_event_handler(self,e):
        if self.anim_timeline:
            lv.anim_timeline_del(self.anim_timeline)
        self.anim_timeline = None;


lv_example_anim_timeline_1 = LV_ExampleAnimTimeline_1()

API

Typedefs

typedef int32_t (*lv_anim_path_cb_t)(const struct _lv_anim_t*)

Get the current value during an animation

typedef void (*lv_anim_exec_xcb_t)(void*, int32_t)

Generic prototype of "animator" functions. First parameter is the variable to animate. Second parameter is the value to set. Compatible with lv_xxx_set_yyy(obj, value) functions The x in _xcb_t means it's not a fully generic prototype because it doesn't receive lv_anim_t * as its first argument

typedef void (*lv_anim_custom_exec_cb_t)(struct _lv_anim_t*, int32_t)

Same as lv_anim_exec_xcb_t but receives lv_anim_t * as the first parameter. It's more consistent but less convenient. Might be used by binding generator functions.

typedef void (*lv_anim_ready_cb_t)(struct _lv_anim_t*)

Callback to call when the animation is ready

typedef void (*lv_anim_start_cb_t)(struct _lv_anim_t*)

Callback to call when the animation really stars (considering delay)

typedef int32_t (*lv_anim_get_value_cb_t)(struct _lv_anim_t*)

Callback used when the animation values are relative to get the current value

typedef struct _lv_anim_t lv_anim_t

Describes an animation

Enums

enum lv_anim_enable_t

Can be used to indicate if animations are enabled or disabled in a case

Values:

enumerator LV_ANIM_OFF
enumerator LV_ANIM_ON

Functions

LV_EXPORT_CONST_INT(LV_ANIM_REPEAT_INFINITE)
void _lv_anim_core_init(void)

Init. the animation module

void lv_anim_init(lv_anim_t *a)

Initialize an animation variable. E.g.: lv_anim_t a; lv_anim_init(&a); lv_anim_set_...(&a); lv_anim_start(&a);

Parameters

a -- pointer to an lv_anim_t variable to initialize

static inline void lv_anim_set_var(lv_anim_t *a, void *var)

Set a variable to animate

Parameters
  • a -- pointer to an initialized lv_anim_t variable

  • var -- pointer to a variable to animate

static inline void lv_anim_set_exec_cb(lv_anim_t *a, lv_anim_exec_xcb_t exec_cb)

Set a function to animate var

Parameters
  • a -- pointer to an initialized lv_anim_t variable

  • exec_cb -- a function to execute during animation LVGL's built-in functions can be used. E.g. lv_obj_set_x

static inline void lv_anim_set_time(lv_anim_t *a, uint32_t duration)

Set the duration of an animation

Parameters
  • a -- pointer to an initialized lv_anim_t variable

  • duration -- duration of the animation in milliseconds

static inline void lv_anim_set_delay(lv_anim_t *a, uint32_t delay)

Set a delay before starting the animation

Parameters
  • a -- pointer to an initialized lv_anim_t variable

  • delay -- delay before the animation in milliseconds

static inline void lv_anim_set_values(lv_anim_t *a, int32_t start, int32_t end)

Set the start and end values of an animation

Parameters
  • a -- pointer to an initialized lv_anim_t variable

  • start -- the start value

  • end -- the end value

static inline void lv_anim_set_custom_exec_cb(lv_anim_t *a, lv_anim_custom_exec_cb_t exec_cb)

Similar to lv_anim_set_exec_cb but lv_anim_custom_exec_cb_t receives lv_anim_t * as its first parameter instead of void *. This function might be used when LVGL is bound to other languages because it's more consistent to have lv_anim_t * as first parameter. The variable to animate can be stored in the animation's user_sata

Parameters
  • a -- pointer to an initialized lv_anim_t variable

  • exec_cb -- a function to execute.

static inline void lv_anim_set_path_cb(lv_anim_t *a, lv_anim_path_cb_t path_cb)

Set the path (curve) of the animation.

Parameters
  • a -- pointer to an initialized lv_anim_t variable

  • path_cb -- a function to set the current value of the animation.

static inline void lv_anim_set_start_cb(lv_anim_t *a, lv_anim_ready_cb_t start_cb)

Set a function call when the animation really starts (considering delay)

Parameters
  • a -- pointer to an initialized lv_anim_t variable

  • start_cb -- a function call when the animation starts

static inline void lv_anim_set_get_value_cb(lv_anim_t *a, lv_anim_get_value_cb_t get_value_cb)

Set a function to use the current value of the variable and make start and end value relative the the returned current value.

Parameters
  • a -- pointer to an initialized lv_anim_t variable

  • get_value_cb -- a function call when the animation starts

static inline void lv_anim_set_ready_cb(lv_anim_t *a, lv_anim_ready_cb_t ready_cb)

Set a function call when the animation is ready

Parameters
  • a -- pointer to an initialized lv_anim_t variable

  • ready_cb -- a function call when the animation is ready

static inline void lv_anim_set_playback_time(lv_anim_t *a, uint32_t time)

Make the animation to play back to when the forward direction is ready

Parameters
  • a -- pointer to an initialized lv_anim_t variable

  • time -- the duration of the playback animation in in milliseconds. 0: disable playback

static inline void lv_anim_set_playback_delay(lv_anim_t *a, uint32_t delay)

Make the animation to play back to when the forward direction is ready

Parameters
  • a -- pointer to an initialized lv_anim_t variable

  • delay -- delay in milliseconds before starting the playback animation.

static inline void lv_anim_set_repeat_count(lv_anim_t *a, uint16_t cnt)

Make the animation repeat itself.

Parameters
  • a -- pointer to an initialized lv_anim_t variable

  • cnt -- repeat count or LV_ANIM_REPEAT_INFINITE for infinite repetition. 0: to disable repetition.

static inline void lv_anim_set_repeat_delay(lv_anim_t *a, uint32_t delay)

Set a delay before repeating the animation.

Parameters
  • a -- pointer to an initialized lv_anim_t variable

  • delay -- delay in milliseconds before repeating the animation.

static inline void lv_anim_set_early_apply(lv_anim_t *a, bool en)

Set a whether the animation's should be applied immediately or only when the delay expired.

Parameters
  • a -- pointer to an initialized lv_anim_t variable

  • en -- true: apply the start value immediately in lv_anim_start; false: apply the start value only when delay ms is elapsed and the animations really starts

static inline void lv_anim_set_user_data(lv_anim_t *a, void *user_data)

Set the custom user data field of the animation.

Parameters
  • a -- pointer to an initialized lv_anim_t variable

  • user_data -- pointer to the new user_data.

lv_anim_t *lv_anim_start(const lv_anim_t *a)

Create an animation

Parameters

a -- an initialized 'anim_t' variable. Not required after call.

Returns

pointer to the created animation (different from the a parameter)

static inline uint32_t lv_anim_get_delay(lv_anim_t *a)

Get a delay before starting the animation

Parameters

a -- pointer to an initialized lv_anim_t variable

Returns

delay before the animation in milliseconds

static inline void *lv_anim_get_user_data(lv_anim_t *a)

Get the user_data field of the animation

Parameters

a -- pointer to an initialized lv_anim_t variable

Returns

the pointer to the custom user_data of the animation

bool lv_anim_del(void *var, lv_anim_exec_xcb_t exec_cb)

Delete an animation of a variable with a given animator function

Parameters
  • var -- pointer to variable

  • exec_cb -- a function pointer which is animating 'var', or NULL to ignore it and delete all the animations of 'var

Returns

true: at least 1 animation is deleted, false: no animation is deleted

void lv_anim_del_all(void)

Delete all the animations

lv_anim_t *lv_anim_get(void *var, lv_anim_exec_xcb_t exec_cb)

Get the animation of a variable and its exec_cb.

Parameters
  • var -- pointer to variable

  • exec_cb -- a function pointer which is animating 'var', or NULL to return first matching 'var'

Returns

pointer to the animation.

static inline bool lv_anim_custom_del(lv_anim_t *a, lv_anim_custom_exec_cb_t exec_cb)

Delete an animation by getting the animated variable from a. Only animations with exec_cb will be deleted. This function exists because it's logical that all anim. functions receives an lv_anim_t as their first parameter. It's not practical in C but might make the API more consequent and makes easier to generate bindings.

Parameters
  • a -- pointer to an animation.

  • exec_cb -- a function pointer which is animating 'var', or NULL to ignore it and delete all the animations of 'var

Returns

true: at least 1 animation is deleted, false: no animation is deleted

uint16_t lv_anim_count_running(void)

Get the number of currently running animations

Returns

the number of running animations

uint32_t lv_anim_speed_to_time(uint32_t speed, int32_t start, int32_t end)

Calculate the time of an animation with a given speed and the start and end values

Parameters
  • speed -- speed of animation in unit/sec

  • start -- start value of the animation

  • end -- end value of the animation

Returns

the required time [ms] for the animation with the given parameters

void lv_anim_refr_now(void)

Manually refresh the state of the animations. Useful to make the animations running in a blocking process where lv_timer_handler can't run for a while. Shouldn't be used directly because it is called in lv_refr_now().

int32_t lv_anim_path_linear(const lv_anim_t *a)

Calculate the current value of an animation applying linear characteristic

Parameters

a -- pointer to an animation

Returns

the current value to set

int32_t lv_anim_path_ease_in(const lv_anim_t *a)

Calculate the current value of an animation slowing down the start phase

Parameters

a -- pointer to an animation

Returns

the current value to set

int32_t lv_anim_path_ease_out(const lv_anim_t *a)

Calculate the current value of an animation slowing down the end phase

Parameters

a -- pointer to an animation

Returns

the current value to set

int32_t lv_anim_path_ease_in_out(const lv_anim_t *a)

Calculate the current value of an animation applying an "S" characteristic (cosine)

Parameters

a -- pointer to an animation

Returns

the current value to set

int32_t lv_anim_path_overshoot(const lv_anim_t *a)

Calculate the current value of an animation with overshoot at the end

Parameters

a -- pointer to an animation

Returns

the current value to set

int32_t lv_anim_path_bounce(const lv_anim_t *a)

Calculate the current value of an animation with 3 bounces

Parameters

a -- pointer to an animation

Returns

the current value to set

int32_t lv_anim_path_step(const lv_anim_t *a)

Calculate the current value of an animation applying step characteristic. (Set end value on the end of the animation)

Parameters

a -- pointer to an animation

Returns

the current value to set

struct _lv_anim_t
#include <lv_anim.h>

Describes an animation

Public Members

void *var

Variable to animate

lv_anim_exec_xcb_t exec_cb

Function to execute to animate

lv_anim_start_cb_t start_cb

Call it when the animation is starts (considering delay)

lv_anim_ready_cb_t ready_cb

Call it when the animation is ready

lv_anim_get_value_cb_t get_value_cb

Get the current value in relative mode

void *user_data

Custom user data

lv_anim_path_cb_t path_cb

Describe the path (curve) of animations

int32_t start_value

Start value

int32_t current_value

Current value

int32_t end_value

End value

int32_t time

Animation time in ms

int32_t act_time

Current time in animation. Set to negative to make delay.

uint32_t playback_delay

Wait before play back

uint32_t playback_time

Duration of playback animation

uint32_t repeat_delay

Wait before repeat

uint16_t repeat_cnt

Repeat count for the animation

uint8_t early_apply

1: Apply start value immediately even is there is delay

uint8_t playback_now

Play back is in progress

uint8_t run_round

Indicates the animation has run in this round

uint8_t start_cb_called

Indicates that the start_cb was already called

uint32_t time_orig