Filler fix

[kurkle]

Fixes: #6985

The target boundary is built using the line points after update.
Those values are the view values, not the model values. This causes the bug when element is moved in the indexScale direction.

This PR adds reference to the points from where the boundary property is gotten from and updates those values before filling.

Fiddle

[benmccann]

I want to understand the issue a little better. What do you mean by "when element is moved in the indexScale direction."?

[kurkle]

I want to understand the issue a little better. What do you mean by "when element is moved in the indexScale direction."?

Let's take a usual financial chart, index scale is the x-scale. So in that case I mean x-coordinate change .
In the default animation, x-coordinate is not changed, but is initialized (reset) to the final value. When index scale range changes for any reason, then the coordinates change and that change is animated. This is where the filler falls behind (before this fix) to the x-coordinate at update time.

Now to the why: the reference line, when we are filling against origin or chart area edge, is build to match the segments of the actual line. That is done to make the path around the fill area straight forward.

And now I realized, the if (target.segments) matches to datasets too (when filling between datasets), and in that case the loop is just excess processing (doing nothing, there is no _prop or _ref in those points). Will push an update.