RFR: 8341514: Add reducedMotion and reducedTransparency preferences [v3]

[Kevin Rushforth]

On Mon, 7 Oct 2024 15:27:21 GMT, Michael Strauß <mstrauss at openjdk.org> wrote:

>> This PR adds the `Platform.Preferences.reducedMotion` and `Platform.Preferences.reducedTransparency` accessibility preferences:
>> 
>> interface Preferences {
>>     /**
>>      * Specifies whether applications should minimize the amount of non-essential animations,
>>      * reducing discomfort for users who experience motion sickness or vertigo.
>>      * <p>
>>      * If the platform does not report this preference, this property defaults to {@code false}.
>>      *
>>      * @return the {@code reducedMotion} property
>>      * @defaultValue {@code false}
>>      * @since 24
>>      */
>>     ReadOnlyBooleanProperty reducedMotionProperty();
>> 
>>     /**
>>      * Specifies whether applications should minimize the amount of transparent or translucent
>>      * layer effects, which can help to increase contrast and readability for some users.
>>      * <p>
>>      * If the platform does not report this preference, this property defaults to {@code false}.
>>      *
>>      * @return the {@code reducedTransparency} property
>>      * @defaultValue {@code false}
>>      * @since 24
>>      */
>>     ReadOnlyBooleanProperty reducedTransparencyProperty();
>> 
>>     ...
>> }
>> 
>> 
>> On Windows, these preferences correspond to "Transparency effects" and "Animation effects" in the system settings:
>> <img src="https://github.com/user-attachments/assets/b286850d-ebbc-444c-9c09-5380f97d0e91" width="400" >
>> 
>> On macOS, these preferences correspond to "Reduce motion" and "Reduce transparency" in the system settings:
>> <img src="https://github.com/user-attachments/assets/4c7b92f8-0cd9-4d1f-91df-40cb449f91ff" width="400" >
>> 
>> On Linux, the `reducedMotion` preference corresponds to `gtk-enable-animations`. On my Ubuntu 24.04 system, GTK3 does not pick up the "Settings / Accessibility / Reduce Animations" system setting, and therefore GTK always reports `gtk-enable-animations == true`. Changing the preference requires manually editing `etc/gtk-3.0/settings.ini`. The `reducedTransparency` preference has no corresponding GTK setting.
>
> Michael Strauß has updated the pull request incrementally with one additional commit since the last revision:
> 
>   seal Platform.Preferences

The API changes look good. I'll review the impl changes later; create the CSR whenever you are ready.

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PR Review: https://git.openjdk.org/jfx/pull/1592#pullrequestreview-2352502347