On Mon, 3 Mar 2025 21:10:39 GMT, Andy Goryachev <ango...@openjdk.org> wrote:
>> modules/javafx.controls/src/main/java/javafx/scene/chart/AreaChart.java line
>> 546:
>>
>>> 544: symbol.setAccessibleRole(AccessibleRole.TEXT);
>>> 545: symbol.setAccessibleRoleDescription("Point");
>>> 546: symbol.setFocusTraversable(isAccessibilityActive());
>>
>> So, if I understand correctly, we can't directly do this `bind`:
>>
>>
>> symbol.focusTraversableProperty().bind(Platform.accessibilityActiveProperty())
>>
>> Because on a background thread there may not yet be an initialized
>> `Platform`? Or perhaps, `Platform` would need to initialize and we don't
>> want to do that yet on a background thread?
>
> The reason we `should not` be binding in this PR is because in part it's
> **bad design(tm)**: we are creating a zillion of listeners (one per plot data
> point); a better solution would be to create one listener and use (already
> existing series) to toggle the data points.
>
> The other reason is https://bugs.openjdk.org/browse/JDK-8351067 - the
> `Platform::accessibilityActive` property getter is not thread safe, but even
> if was, registering a listener with it may cause the change to come in
> **before** the node becomes a part of the scene graph, leading to
> unsynchronized multi-threaded access.
Was this solution considered:
ObservableValue<Boolean> partOfSceneGraph = this.sceneProperty()
.flatMap(Scene::windowProperty)
.flatMap(Window::showingProperty)
.orElse(false);
symbol.focusTraversableProperty()
.bind(Platform.accessibilityActiveProperty().when(partOfSceneGraph));
What the above code does is create a binding on the `when` statement (a
listener is added on the `when` result). However, the `when` property will not
add a listener on `Platform.accessibilityActiveProperty()` until
`partOfSceneGraph` is `true`. As soon as it does though, a listener is
installed on `Platform.accessibilityActiveProperty()` and its latest value is
set to `focusTraversableProperty` via the bind.
-------------
PR Review Comment: https://git.openjdk.org/jfx/pull/1697#discussion_r1978264839
