I am implmenting a cusom component where the user can type into a TextField and a TableView is pops up then the user can look for items in that table.
I have a problem with the standard KeyEvents of the TextFieldlike Ctrl+A or Home. After the pane with the TableView pops up, those key events are not working anymore.
I have checked if the TextField lost the focus but it doesn't, and if I set an EventFilter to see what is happening, it shows that those events are triggered but I see no effect on UI. Even the popup's setHideOnEscape is not working.
Here is a simple code to verify it:
The fxml:
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.TextField?>
<?import javafx.scene.layout.AnchorPane?>
<AnchorPane xmlns="http://javafx.com/javafx"
xmlns:fx="http://javafx.com/fxml"
fx:controller="textField.Controller">
<TextField fx:id="textField" prefWidth="400"/>
</AnchorPane>
The controller:
public class Controller implements Initializable {
@FXML
private TextField textField;
@Override
public void initialize(URL location, ResourceBundle resources) {
Popup popUp = new Popup();
TableView<Object> table = new TableView<>();
table.prefWidthProperty().bind(textField.widthProperty());
popUp.getContent().add(table);
popUp.setHideOnEscape(true);
popUp.setAutoHide(true);
// To see if the KeyEvent is triggered
textField.addEventFilter(KeyEvent.ANY, System.out::println);
textField.setOnKeyTyped(event -> {
if(!popUp.isShowing()){
popUp.show(
textField.getScene().getWindow(),
textField.getScene().getWindow().getX()
+ textField.localToScene(0, 0).getX()
+ textField.getScene().getX(),
textField.getScene().getWindow().getY()
+ textField.localToScene(0, 0).getY()
+ textField.getScene().getY()
+ textField.getHeight() - 1);
}
});
}
}
And the main:
public class Main extends Application {
public void start(Stage primaryStage) throws Exception {
FXMLLoader loader = new FXMLLoader(getClass().getResource("View.fxml"));
AnchorPane pane = loader.load();
primaryStage.setScene(new Scene(pane, 800, 600));
primaryStage.show();
}
public static void main(String[] args) {
launch(args);
}
}
Here is the console output
KeyEvent [source = TextField[id=textField, styleClass=text-input text-field], target = TextField[id=textField, styleClass=text-input text-field], eventType = KEY_PRESSED, consumed = false, character = , text = a, code = A]
KeyEvent [source = TextField[id=textField, styleClass=text-input text-field], target = TextField[id=textField, styleClass=text-input text-field], eventType = KEY_TYPED, consumed = false, character = a, text = , code = UNDEFINED]
KeyEvent [source = TextField[id=textField, styleClass=text-input text-field], target = TextField[id=textField, styleClass=text-input text-field], eventType = KEY_RELEASED, consumed = false, character = , text = a, code = A]
KeyEvent [source = TextField[id=textField, styleClass=text-input text-field], target = TextField[id=textField, styleClass=text-input text-field], eventType = KEY_PRESSED, consumed = false, character = , text = , code = CONTROL, controlDown, shortcutDown]
KeyEvent [source = TextField[id=textField, styleClass=text-input text-field], target = TextField[id=textField, styleClass=text-input text-field], eventType = KEY_TYPED, consumed = false, character = , text = , code = UNDEFINED, controlDown, shortcutDown]
KeyEvent [source = TextField[id=textField, styleClass=text-input text-field], target = TextField[id=textField, styleClass=text-input text-field], eventType = KEY_RELEASED, consumed = false, character = , text = a, code = A, controlDown, shortcutDown]
KeyEvent [source = TextField[id=textField, styleClass=text-input text-field], target = TextField[id=textField, styleClass=text-input text-field], eventType = KEY_RELEASED, consumed = false, character = , text = , code = CONTROL]
Any idea why are those events consumed even if it says they aren't?
The reason that the textField doesn't react to some/all "standard function keys" is that their KEY_PRESSED type never reaches it - they are redirected to the table in the popup and most/all of them consumed by the table.
A naive first approximation would be to set the table's focusTraversable property to false: this effectively prevents all keys from being delivered to it. Real-world requirements might be a bit less simplistic, in that some of those should reach the table while others should bubble up to the textField.
This can be achieved by a custom EventDispatcher (on the table) which examines all keyEvents and decides which to deliver/not to the table's original dispatcher. A code snippet where interceptor is a predicate used for the decision (at the end there's complete working example for convenience):
private BasicEventDispatcher original;
private Predicate<Event> interceptor;
@Override
public Event dispatchEvent(Event event, EventDispatchChain tail) {
if (!interceptor.test(event)) {
event = original.dispatchCapturingEvent(event);
if (event.isConsumed()) {
return null;
}
}
event = tail.dispatchEvent(event);
if (event != null && !interceptor.test(event)) {
event = original.dispatchBubblingEvent(event);
if (event.isConsumed()) {
return null;
}
}
return event;
}
It's usage: if f.i. we want LEFT and RIGT be bubbled up to that textField, while all others should be handled normally by the table
List<KeyCode> toIntercept = List.of(KeyCode.LEFT, KeyCode.RIGHT);
Predicate<Event> interceptor = e -> {
if (e instanceof KeyEvent) {
return toIntercept.contains(((KeyEvent) e).getCode());
}
return false;
};
table.setEventDispatcher(new InterceptingEventDispatcher(
(BasicEventDispatcher) table.getEventDispatcher(), interceptor));
A complete example to play with:
public class ViewPopupApplication extends Application {
public static class InterceptingEventDispatcher implements EventDispatcher {
private BasicEventDispatcher original;
private Predicate<Event> interceptor;
public InterceptingEventDispatcher(BasicEventDispatcher original, Predicate<Event> interceptor) {
this.original = original;
this.interceptor = interceptor;
}
@Override
public Event dispatchEvent(Event event, EventDispatchChain tail) {
if (!interceptor.test(event)) {
event = original.dispatchCapturingEvent(event);
if (event.isConsumed()) {
return null;
}
}
event = tail.dispatchEvent(event);
if (event != null && !interceptor.test(event)) {
event = original.dispatchBubblingEvent(event);
if (event.isConsumed()) {
return null;
}
}
return event;
}
}
private Parent createContent() {
TableView<Locale> table = new TableView<>(FXCollections.observableArrayList(Locale.getAvailableLocales()));
// just to see that right/left are intercepted while up/down are handled
table.getSelectionModel().setCellSelectionEnabled(true);
TableColumn<Locale, String> country = new TableColumn<>("Country");
country.setCellValueFactory(new PropertyValueFactory<>("displayCountry"));
TableColumn<Locale, String> language = new TableColumn<>("Language");
language.setCellValueFactory(new PropertyValueFactory<>("displayLanguage"));
table.getColumns().addAll(country, language);
// disables default focus traversal
// table.setFocusTraversable(false);
// decide which keys to intercept
List<KeyCode> toIntercept = List.of(KeyCode.LEFT, KeyCode.RIGHT);
Predicate<Event> interceptor = e -> {
if (e instanceof KeyEvent) {
return toIntercept.contains(((KeyEvent) e).getCode());
}
return false;
};
table.setEventDispatcher(new InterceptingEventDispatcher(
(BasicEventDispatcher) table.getEventDispatcher(), interceptor));
TextField textField = new TextField("something to show");
textField.setPrefColumnCount(20);
textField.setText("something to see");
table.prefWidthProperty().bind(textField.widthProperty());
Popup popUp = new Popup();
popUp.getContent().add(table);
textField.setOnKeyTyped(event -> {
if(!popUp.isShowing()){
popUp.show(
textField.getScene().getWindow(),
textField.getScene().getWindow().getX()
+ textField.localToScene(0, 0).getX()
+ textField.getScene().getX(),
textField.getScene().getWindow().getY()
+ textField.localToScene(0, 0).getY()
+ textField.getScene().getY()
+ textField.getHeight() - 1);
}
});
BorderPane content = new BorderPane(textField);
return content;
}
@Override
public void start(Stage stage) throws Exception {
stage.setScene(new Scene(createContent()));
stage.show();
}
public static void main(String[] args) {
launch(args);
}
}