RFR: 8332895: Support interpolation for backgrounds and borders [v16]

[Andy Goryachev]

On Sun, 4 Aug 2024 19:08:14 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:
> 
>   use HashMap.newHashMap()

The code does not build in Eclipse.  Could you please replace modules/graphics/.classpath with this:


<?xml version="1.0" encoding="UTF-8"?>
<classpath>
	<classpathentry kind="src" path="src/main/java"/>
	<classpathentry kind="src" path="build/gensrc/jsl-prism"/>
	<classpathentry kind="src" path="build/gensrc/jsl-decora"/>
	<classpathentry kind="src" path="build/hlsl/Decora"/>
	<classpathentry kind="src" path="build/hlsl/Prism"/>
	<classpathentry kind="src" output="testbin" path="src/shims/java">
		<attributes>
			<attribute name="test" value="true"/>
		</attributes>
	</classpathentry>
	<classpathentry kind="src" output="testbin" path="src/test/java">
		<attributes>
			<attribute name="test" value="true"/>
			<attribute name="optional" value="true"/>
		</attributes>
	</classpathentry>
	<classpathentry kind="src" path="src/main/resources">
		<attributes>
			<attribute name="optional" value="true"/>
		</attributes>
	</classpathentry>
	<classpathentry kind="src" output="testbin" path="src/test/resources">
		<attributes>
			<attribute name="test" value="true"/>
			<attribute name="optional" value="true"/>
		</attributes>
	</classpathentry>
	<classpathentry combineaccessrules="false" kind="src" path="/base">
		<attributes>
			<attribute name="module" value="true"/>
			<attribute name="add-exports" value="javafx.base/com.sun.javafx.property=javafx.graphics:javafx.base/test.javafx.collections=javafx.graphics:javafx.base/test.util.memory=javafx.graphics:javafx.base/test.util=javafx.graphics"/>
		</attributes>
	</classpathentry>
	<classpathentry kind="con" path="org.eclipse.jdt.junit.JUNIT_CONTAINER/5">
		<attributes>
			<attribute name="test" value="true"/>
		</attributes>
	</classpathentry>
	<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER">
		<attributes>
			<attribute name="module" value="true"/>
			<attribute name="add-exports" value="java.base/sun.security.util=javafx.graphics"/>
		</attributes>
	</classpathentry>
	<classpathentry kind="output" path="bin"/>
</classpath>


(that simply adds a missing dependency `:javafx.base/test.util=javafx.graphics` )

And also merge the latest master in please?

-------------

PR Comment: https://git.openjdk.org/jfx/pull/1522#issuecomment-2271972593