如何为猕猴桃布局子类设置动画？

Question

I am subclassing kivy.uix.layout . The goal is to animate the child widgets by recalculating their position on each frame.

What's the correct way of doing this?

I can schedule a re-layout by doing this:

self.layout_clock = Clock.schedule_interval(self._trigger_layout, -1)

But I get lots of errors:

[CRITICAL] [Clock       ] Warning, too much iteration done before the next frame. Check your code, or increase the Clock.max_iteration attribute

I guess by changing the childrens' positions inside of do_layout , I trigger do_layout again by some event binding and thus create an infinite loop, right?

So how do I do this?

Answer 1

I think, I have found the solution myself. Kinda.

Referring to the chapter Schedule before frame in the docs, I thought a timeout of -1 was what I needed as I wanted to first calculate all positions and then have the app draw all widgets there.

However, this does the above mentioned mess-up. I don't quite understand why this is causing the described callback loop. If anybody likes to explain :-)

Anyway, what does work is a timeout of either 0 or 1/60 (for a framerate of 60).

self.layout_clock = Clock.schedule_interval(self._trigger_layout, 0)

Now all my widgets move buttery smooth and there's no more warnings.