exec_cb and custom_exec_cb are unexpectedly executed in the animation timeline.

[amk3y]

LVGL version

v9.2.2

Platform

Board: ESP32-C3 Super Mini (esp32-c3-devkitm-1)
Framework: esp-idf v5.3.1

IDE: Clion 2024.3 + PlatformIO
Build Machine: macOS 15.1.1 arm64

What happened?

I created a timeline with two animations that perform a fade-in and fade-out of an image.
However, I found that the first animation (the fade-in) is skipped.

So, I added a line to exec_cb to print the value of the animations.

void anim_cb_set_opa(lv_anim_t* anim, int32_t value){
    ESP_LOGI("anim", "value: %lu", value);
    lv_obj_set_style_image_opa(anim->var, value, 0);
}

Then I noticed that the exec_cb and custom_exec_cb of every animation in a timeline are executed even if the animation has not started or has already ended.
(the fade-out animation overrides the fade-in animation in this case)

I tried to comment out these lines in anim_timeline_set_act_time

        if(act_time < start_time && a->early_apply) {
            //...
            //if(a->exec_cb) a->exec_cb(a->var, value);
            //if(a->custom_exec_cb) a->custom_exec_cb(a, value);
            //...
        }
        else if(act_time >= start_time && act_time <= (start_time + a->duration)) {
            //...
            if(a->exec_cb) a->exec_cb(a->var, value);
            if(a->custom_exec_cb) a->custom_exec_cb(a, value);
            //...
        } 
        else if(act_time > start_time + a->duration) {
            //...
            //if(a->exec_cb) a->exec_cb(a->var, value);
            //if(a->custom_exec_cb) a->custom_exec_cb(a, value);
            //...
        }

Then this modification got my animations to work.

But I am not sure if it broke anything. Could you take a look at it?

How to reproduce?

Full Code: https://github.com/amk3y/lvgl_gif_lab/blob/main/src/main.c

void anim_cb_set_opa(lv_anim_t* anim, int32_t value){
    lv_obj_set_style_image_opa(anim->var, value, 0);
}

void enter_lvgl_scene(void){
    LV_IMAGE_DECLARE(image_logo);

    lv_obj_t* lv_image_logo = lv_image_create(lv_screen_active());
    lv_obj_set_style_image_opa(lv_image_logo, LV_OPA_TRANSP, 0);
    lv_image_set_src(lv_image_logo, &image_logo);
    lv_obj_align(lv_image_logo, LV_ALIGN_CENTER, 0, 0);

    lv_anim_t intro_fade_in_anim;
    lv_anim_init(&intro_fade_in_anim);
    lv_anim_set_duration(&intro_fade_in_anim, 1000);
    lv_anim_set_var(&intro_fade_in_anim, lv_image_logo);
    lv_anim_set_values(&intro_fade_in_anim,0, 255);
    lv_anim_set_path_cb(&intro_fade_in_anim, lv_anim_path_ease_in_out);
    lv_anim_set_custom_exec_cb(&intro_fade_in_anim, anim_cb_set_opa);

    lv_anim_t intro_fade_out_anim;
    lv_anim_init(&intro_fade_out_anim);
    lv_anim_set_duration(&intro_fade_out_anim, 1000);
    lv_anim_set_var(&intro_fade_out_anim, lv_image_logo);
    lv_anim_set_values(&intro_fade_out_anim,255, 0);
    lv_anim_set_path_cb(&intro_fade_out_anim, lv_anim_path_ease_in_out);
    lv_anim_set_custom_exec_cb(&intro_fade_out_anim, anim_cb_set_opa);

    lv_anim_timeline_t* timeline = lv_anim_timeline_create();
    lv_anim_timeline_add(timeline, 10, &intro_fade_in_anim);
    lv_anim_timeline_add(timeline, 2000, &intro_fade_out_anim);

    lv_anim_timeline_start(timeline);
}

void app_main() {
  // ...
  enter_lvgl_scene();
  // ...
}

[kisvegabor]

Sorry for the late reply. The problem is that you need to add
lv_anim_set_early_apply(&intro_fade_out_anim, false);

By default the animations have early_apply=true to apply the start value when they start even if there is a delay. In your case both animations had early_apply=true so the first set opa=0, then it was overwritten by opa=255.

We definitely need to document it in a clean way. cc @vwheeler63

[vwheeler63]

We definitely need to document it in a clean way.

Agreed! Added to list.