RFR: 8259680: Need API to query states of CAPS LOCK and NUM LOCK keys

Kevin Rushforth kcr at openjdk.java.net
Mon Jan 25 14:59:42 UTC 2021

On Sat, 23 Jan 2021 23:46:04 GMT, Nir Lisker <nlisker at openjdk.org> wrote:

>> The JavaFX API does not provide a way to get the state of CAPS LOCK or NUM LOCK on the keyboard. Being able to read the lock state would allow an application to inform the user that caps lock was enabled for passwords or other usages where the keyboard input might not be echoed. It would also allow an application to do spell checking / auto-correction that might ordinarily be skipped when typing all upper-case letters.
>> We need an equivalent JavaFX API to the existing AWT `java.awt.ToolKit::getLockingKeyState` method. A natural place to put this in JavaFX is in the `javafx.application.Platform` class, so we propose to create a new `Platform::isKeyLocked` method, which will take a `KeyCode` -- either `CAPS` or `NUM_LOCK` -- and return an `Optional<Boolean>` indicating whether or not that key is in the locked or "on" state. If we can't read the key state on a particular platform, we will return `Optional.empty()`, rather than throwing a runtime exception as AWT does.
>> I have provided both an automated Robot test and a manual test. The latter is needed primarily because we can't set the CAPS lock on Mac using Robot, but also because we want  way to test the case where the user has enabled CAPS lock before the program starts.
> modules/javafx.graphics/src/main/java/javafx/application/Platform.java line 342:
>> 340:      * specified {@code keyCode}, an empty {@code Optional} is returned.
>> 341:      * If the keyboard attached to the system doesn't have the specified key,
>> 342:      * {@code Boolean.FALSE} is returned.
> Not `Optional.of(false)`?

Yes, that would be more accurate. So the replacement could be either `{@code Optional.of(false)}` or `an @{code Optional} containing {@code false}`. At least one JDK method uses something like the latter, so I'll probably go with that.


PR: https://git.openjdk.java.net/jfx/pull/385

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