Q:

How to smoother animation with animate()?

I am using animate() and properties left, but if is motion slowly, then image moves pixel to pixel and not correspondence double type variable.
Is there a solution for this problem?

A:

It's usually more efficient to animate using the css transform translate, instead of setting left. See this article. Here's an article which explains why this is the case.
It looks like modern browsers support sub pixel translate values i.e '5.2px'. For browsers that don't you can also use translate scale to shrink your element down to 1/10 it's normal size, this will allow you to translate an element 1/10 of a pixel.
This question isn't specific to Dart, consider rewording it, and adding javascript and css tags as it will then be exposed to a wider audience.

