Annotation for global key handlers

[Clashsoft]

Is your feature request related to a problem? Please describe. Some apps require keyboard shortcuts that cannot be reasonably attached to a node. Usually that is because the node in question is not focusable. An annotation to create global key listeners (as implemented below) would be helpful.

Describe the solution you'd like

class MyController {
  private final BooleanProperty paused = new SimpleBooleanProperty(false);

  @OnKey(code = KeyCode.ESCAPE)
  void onEscape() {
    paused.set(true);
  }
}

Describe alternatives you've considered

class MyController {
    private final BooleanProperty paused = new SimpleBooleanProperty(false);
    private final EventHandler<KeyEvent> onKeyReleased = event -> {
        if (event.getCode() == KeyCode.ESCAPE) {
            paused.set(true);
        }
    };

    @onRender
    void addKeyReleased() {
        app.stage().addEventFilter(KeyEvent.KEY_RELEASED, onKeyReleased);
    }

    @onDestroy
    void removeKeyReleased() {
        app.stage().removeEventFilter(KeyEvent.KEY_RELEASED, onKeyReleased);
    }
}

Detailed description The @OnKey annotation could be defined like this:

@interface OnKey {
  KeyCode code() = KeyCode.UNDEFINED;
  EventType type() = KeyEvent.KEY_PRESSED; // see https://docs.oracle.com/javase/8/javafx/api/javafx/scene/input/KeyEvent.html
  String character() = "";
  String text() = "";
  boolean shiftDown, boolean controlDown, boolean altDown, boolean metaDown
}

The method should optionally allow a KeyEvent parameter (just like methods called from FXML). It could be used to inspect the event in case the KeyCode is dynamic/configurable.

@OnKey
void onKey(KeyEvent event) {
  if (event.getCode() == keyMappings.getCode(KeyMapping.WALK_FORWARD) {
    // ...
  }
}

[LeStegii]

I like the idea, this would certainly remove a lot of boilerplate code. However, I got a few questions:

• In your description, you switch from @onKey to @onEvent and back. What exactly should be the name and therefore the functionality?
• What exactly is text and character for if there already is code? (edit: Found it in the key event class)
• KeyEvent.KEY_PRESSED cannot be used inside of annotations as it is not a constant. This could be solved by creating an own enum instead which then internally references the event or by using the event name

[Clashsoft]

I changed it to @OnKey everywhere. The different key event types would need to be an enum. But there are only a few cases so it should be ok. Example:

@interface OnKey {
  enum Type { ANY, PRESSED, RELEASED, TYPED };
  Type type() = PRESSED;
}