RFR: 8311895: CSS Transitions [v17]

[Michael Strauß]

On Sat, 25 May 2024 19:28:56 GMT, Nir Lisker <nlisker at openjdk.org> wrote:

>> Michael Strauß has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 57 commits:
>> 
>>  - Merge branch 'refs/heads/master' into feature/css-transitions
>>  - extract magic string to named constant
>>  - use existing property in test
>>  - fixed documentation
>>  - Merge branch 'master' into feature/css-transitions
>>  - update 'since' tags
>>  - Fix javadoc error
>>  - Change javadoc comment
>>  - Merge branch 'master' into feature/css-transitions
>>  - Discard redundant transitions in StyleableProperty impls
>>  - ... and 47 more: https://git.openjdk.org/jfx/compare/94aa2b68...a43dee30
>
> modules/javafx.graphics/src/main/docs/javafx/scene/doc-files/cssref.html line 688:
> 
>> 686:     <h3><a id="introtransitions">Transitions</a></h3>
>> 687:     <p>JavaFX supports <em>implicit transitions</em> for properties that are styled by CSS. When a property value is
>> 688:         changed, it smoothly transitions to the new value over a period of time. Implicit transitions are supported
> 
> Maybe not so smoothly when using a step interpolator?

I've changed the wording a bit.

> modules/javafx.graphics/src/main/java/com/sun/javafx/css/TransitionDefinition.java line 40:
> 
>> 38:  * @param duration duration of the transition
>> 39:  * @param delay delay after which the transition is started; if negative, the transition starts
>> 40:  *              immediately, but will appear to have begun at an earlier point in time
> 
> Why accept a negative delay? An [`Animation`](https://openjfx.io/javadoc/22/javafx.graphics/javafx/animation/Animation.html#getDelay()) doesn't accept it.

The W3C specification for the [transition-delay](https://www.w3.org/TR/css-transitions-1/#transition-delay-property) property mandates it, and this PR is a complete implementation of the specification. You're right that `Animation` doesn't support negative delays, but at least for implicit transitions, negative delays have some utility.

Maye we can revisit the choice to disallow negative delays for `Animation` later.

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PR Review Comment: https://git.openjdk.org/jfx/pull/870#discussion_r1614870557
PR Review Comment: https://git.openjdk.org/jfx/pull/870#discussion_r1614870213