RFR: 8332895: Support interpolation for backgrounds and borders [v19]
Andy Goryachev
angorya at openjdk.org
Wed Aug 7 22:19:44 UTC 2024
On Wed, 7 Aug 2024 20:03:17 GMT, Michael Strauß <mstrauss at 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`
>> - `Stop`
>> - `Paint` and all of its subclasses
>> - `Margins` (internal type)
>> - `BorderImageSlices` (internal type)
>>
>> ## 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...
>
> Michael Strauß has updated the pull request incrementally with one additional commit since the last revision:
>
> interpolate integers in real number space
Just wanted to mention that so far my testing using the Monkey Tester look good - the behavior is as expected (except for interpolating colors which does not use the _right_ algorithm, but that's a different issue).
-------------
PR Comment: https://git.openjdk.org/jfx/pull/1522#issuecomment-2274441851
More information about the openjfx-dev
mailing list