[External] : Re: Pivot properties [was: Enhancements for JavaFX 18]

[Michael Strauß]

I think normalized coordinates are a very natural fit for the
definition of a pivot point, which is why the current default value is
an implicitly-specified normalized coordinate. Adding general-purpose
coordinate transformations here feels like bringing a sledgehammer to
crack a nut.

Having a property with an automagically updated "initial" value is
quite non-standard behavior for properties. It would appear as if the
property was bound, yet there's no binding. That's markedly different
from a Transition's 'from' and 'to' properties, which are standard
properties with normal behavior. A running transition doesn't bind to
those properties, it uses a snapshot of their values when the
transition starts.


On Sun, Aug 22, 2021 at 9:55 PM Nir Lisker <nlisker at gmail.com> wrote:
>
> Now I understand what you meant. However, the concept of normalized coordinates does not appear anywhere in JavaFX (at least not in these contexts). I still think that coordinate transformations should be handled via dedicated means, like coordinate system transformations are. Maybe when we work on mapped bindings (I forgot that I need to review that) this pain point will be alleviated.
>
> Kevin, what if we only set the initial value of the pivot (doesn't matter what the implementation detail is) to the center of the node for backwards compatibility, but if the developer changes it to a custom value then it's on them to compute the value again if they want to go back? The default behavior remains.
> Another relevant point is that Transitions do something similar with their from_,  to_ and by_ methods. They start with Double.NaN to signal that the value should be ignored. While the developer can reset the value to NaN, it is not something that is likely to happen during, say, an interpolation or as a result of a binding.
>