How to wait for an animation to finish?

How-to
#1

Description

Hello, I want to execute a function after an animation has finished. I am using the Tileview Widget and want to change the color of a tile once I swipe it away. The problem is that once I release the current tile, the animation to show the next tile starts but the color of the “swiped” tile already changes. Is there any event I can receive regarding animations?

Best regards

What MCU/Processor/Board and compiler are you using?

VS-Simulator on Windows

What LVGL version are you using?

v7.9.1

What do you want to achieve?

Execute a function when an animation has finished.

What have you tried so far?

Sleep(TheAnimationTime), while(lv_anim_count_running) {;}

#2

There is a lv_anim_ready_cb() thats called when an animation finishes that might be what you are after

#3

You could do it like so

lv_anim_set_ready_cb(&YourAnim, anim_ready_cb);

void anim_ready_cb(lv_anim_t * a) {
//Do whatever you want to do. Like change color
}
#4

Thanks for hint, that might be it!

But how can I access the animation created by the tileview?

I also thought about creating a task which checks if there are any active animations but it’s the same problem accessing the tileviews animation.

#5

I would’ve to implement something into lv_tileview.c, maybe also create a new event that triggers when the animation finishes.

#6

Yeah, I can see that. Don’t know if there is an easy fix but I’ll be on the lookout. Else you would probably be better off asking @embeddedt, since I´m not well acquainted with all of LVGL, or someone else with more knowledge :smiley:

#7

Thank you :slight_smile: I’m currently working on a task which checks the animation. I’ll post updates here

#8

Maybe something like this could be applicable?
Mind you i haven’t tested this:

lv_obj_t* tileview = lv_tileview_create(screen, NULL); //This is of course just a test object.
lv_anim_t* a  = lv_anim_get(lv_page_get_scrollable(tileview), NULL);
if (a != NULL) {
lv_anim_set_ready_cb(&a, anim_ready_cb);
}

If you take a look at lv_tileview_set_tile_act in lv_tileview.c here: tileview.c the animation is applied to the object returned from lv_page_get_scrollable(tileview). So my thought was that we get that object (called lv_obj_t* scrl) like in lv_tileview.c and somehow figure out when its created, and call the aboce code which apllies a ready_cb. It´s a bit of a gamble, and there might be better solutions, but I wanted to share the thought :smiley:

#9

Oh man that’s a little high level for me as a beginner. I found that the following works for now:

lv_task_t* task = lv_task_create(waitForAnim, 20, LV_TASK_PRIO_HIGH, NULL);

void waitForAnim(lv_task_t* task)
{ 
    if (pageChanged)
    {
        if (lv_anim_count_running() == 0)
        {
            pageChanged = false;

            changeColor();
        }
    }
}

I know this might be a little inefficient but for now it works!

#10

I’ll try to figure out a way to use your approach, because the relevant mechanics are already there and just need to be connected…

#11

Yours look quite good as well, but my only concern regarding it could be that you would end up reacting on a whole other animation that might be running simultaneously, but that might be a bit unlikely i don’t know. Just a thought

#12

Yes thats why I added the bool pageChanged so the task only reacts when exactly this animation executes. And for now I don’t think there willl be any other animations in my project.