On Thu, 4 Jul 2024 19:40:57 GMT, Michael Strauß <mstra...@openjdk.org> wrote:
>> This PR completes the CSS Transitions story (see #870) by adding
>> interpolation support for backgrounds and borders, making them targetable by
>> transitions.
>>
>> `Background` and `Border` objects are deeply immutable, but not
>> interpolatable. Consider the following `Background`, which describes the
>> background of a `Region`:
>>
>>
>> Background {
>> fills = [
>> BackgroundFill {
>> fill = Color.RED
>> }
>> ]
>> }
>>
>>
>> Since backgrounds are deeply immutable, changing the region's background to
>> another color requires the construction of a new `Background`, containing a
>> new `BackgroundFill`, containing the new `Color`.
>>
>> Animating the background color using a CSS transition therefore requires the
>> entire Background object graph to be interpolatable in order to generate
>> intermediate backgrounds.
>>
>> More specifically, the following types will now implement `Interpolatable`.
>>
>> - `Insets`
>> - `Background`
>> - `BackgroundFill`
>> - `BackgroundImage`
>> - `BackgroundPosition`
>> - `BackgroundSize`
>> - `Border`
>> - `BorderImage`
>> - `BorderStroke`
>> - `BorderWidths`
>> - `CornerRadii`
>> - `ImagePattern`
>> - `LinearGradient`
>> - `RadialGradient`
>> - `Stop`
>>
>> ## Interpolation of composite objects
>>
>> As of now, only `Color`, `Point2D`, and `Point3D` are interpolatable. Each
>> of these classes is an aggregate of `double` values, which are combined
>> using linear interpolation. However, many of the new interpolatable classes
>> comprise of not only `double` values, but a whole range of other types. This
>> requires us to more precisely define what we mean by "interpolation".
>>
>> Mirroring the CSS specification, the `Interpolatable` interface defines
>> several types of component interpolation:
>>
>> | Interpolation type | Description |
>> |---|---|
>> | default | Component types that implement `Interpolatable` are interpolated
>> by calling the `interpolate(Object, double)}` method. |
>> | linear | Two components are combined by linear interpolation such that `t
>> = 0` produces the start value, and `t = 1` produces the end value. This
>> interpolation type is usually applicable for numeric components. |
>> | discrete | If two components cannot be meaningfully combined, the
>> intermediate component value is equal to the start value for `t < 0.5` and
>> equal to the end value for `t >= 0.5`. |
>> | pairwise | Two lists are combined by pairwise interpolation. If the start
>> list has fewer elements than the target list, the missing elements are
>> copied from the target li...
>
> Michael Strauß has updated the pull request with a new target base due to a
> merge or a rebase. The incremental webrev excludes the unrelated changes
> brought in by the merge/rebase. The pull request contains 13 additional
> commits since the last revision:
>
> - fix line separators
> - add documentation to Point2D/3D
> - change documentation
> - add specification
> - add exports
> - revert change
> - revert change
> - added more tests
> - added specification and tests
> - Merge branch 'master' into feature/interpolatable
> - ... and 3 more: https://git.openjdk.org/jfx/compare/d436b7df...08ed751b
I've added a new "interpolation type" specification for all components of
interpolatable classes. This mirrors the "animation type" of the CSS
specification, which is listed as an entry in the property table. Please also
read the updated top-level post of this PR, which goes into more detail about
this new specification.
@kevinrushforth This might be a candidate for a late enhancement, because the
risk is relatively low (it's mostly the addition of the `interpolate()` method
to various types), and it seems to be important to make the CSS transitions
feature useful (backgrounds and borders will probably be one of the most
obvious things developers will want to animate).
-------------
PR Comment: https://git.openjdk.org/jfx/pull/1471#issuecomment-2209504560
