Does anyone know how to globally listen to all keyboard events in a javafx application?
No matter which Node is focused or shown.
In Swing it was achieved by this:
KeyboardFocusManager.getCurrentKeyboardFocusManager().addKeyEventPostProcessor(new KeyEventPostProcessor() {
public boolean postProcessKeyEvent(KeyEvent e) {
//System.out.println("postProcessKeyEvent "+ e.getComponent().getName());
// If the key should not be dispatched to the
// focused component, set discardEvent to true
return false;
}
});
Thanks,
Hugo
Related
JavaFX does not execute events like the ActionEvent for Button or CheckBox, if a modifier key like CTRL or SHIFT is pressed. As far as I understand this behavior is implemented in ButtonBehavior (e.g. note the expression ! keyDown in the following method from that class):
#Override public void mouseReleased(MouseEvent e) {
// if armed by a mouse press instead of key press, then fire!
final ButtonBase button = getControl();
if (! keyDown && button.isArmed()) {
button.fire();
button.disarm();
}
}
First of all, I do not really understand the reason for this. What is the purpose of not firing a button if a key is pressed?
This is my use-case: I want to implement a checkbox that can be checked/unchecked as normal. It will toggle some state in a model. But it should have an additional feature: if the user presses some key like CTRL while checking/unchecking with the mouse, an additional flag called "locked" or "protected" should be set in the model, which will prevent that the state can be overwritten by some other logic of the application.
This should give an idea about the use-case, but if not it doesn't really matter for my actual question: How can I make it possible that a CheckBox can still be toggled (or a Button be pressed) even though the user presses a modifier key?
Thanks for your help!
That is odd you can implement it yourself like so
public class Main extends Application {
#Override
public void start(Stage primaryStage) throws Exception{
VBox vBox = new VBox();
vBox.setAlignment(Pos.CENTER);
CheckBox checkBox = new CheckBox();
checkBox.setOnMouseClicked(event -> {
if(event.isControlDown()) {
System.out.print("Control down click ");
checkBox.setSelected(!checkBox.isSelected());
}
else
System.out.print("Normal click ");
System.out.println("Checked Status:"+checkBox.isSelected());
});
Button button = new Button("Button");
button.setOnMouseClicked(event -> {
if(event.isControlDown())
System.out.println("Control down click");
else
System.out.println("Normal click");
});
vBox.getChildren().addAll(new Label("Click the box"),checkBox,button);
primaryStage.setScene(new Scene(vBox));
primaryStage.show();
}
public static void main(String[] args) { launch(args); }
}
The output for CheckBox:
Normal click Checked Status:true
Normal click Checked Status:false
Control down click Checked Status:true
Control down click Checked Status:false
The output for Button:
Normal click
Control down click
Just as the title says, how do I stop shortcut keys (accelerators) being picked up as key events in TextArea? I have tried the method suggested here with different modifications: TextArea ignore KeyEvent in JavaFX with no luck.
If you want to stop specific accelerators from working when the TextArea has focus simply add an event filter for KEY_PRESSED events.
public class AcceleratorFilter implements EventHandler<KeyEvent> {
// blacklist of KeyCombinations
private final Set<KeyCombination> combinations;
public AcceleratorFilter(KeyCombination... combinations) {
this.combinations = Set.of(combinations);
}
#Override
public void handle(Event event) {
if (combinations.stream().anyMatch(combo -> combo.match(event)) {
event.consume();
}
}
}
TextArea area = new TextArea();
area.addEventFilter(KeyEvent.KEY_PRESSED, new AcceleratorFilter(
KeyCombination.valueOf("shortcut+o"),
KeyCombination.valueOf("shortcut+s") // etc...
));
If you want to indiscriminately block all accelerators registered with the Scene then you can query the Scenes accelerators and consume the KeyEvent if appropriate.
TextArea area = new TextArea();
area.addEventFilter(KeyEvent.KEY_PRESSED, event -> {
var scene = ((Node) event.getSource()).getScene();
// #getAccelerators() = ObservableMap<KeyCombination, Runnable>
var combos = scene.getAccelerators().keySet();
if (combos.stream().anyMatch(combo -> combo.match(event)) {
event.consume();
}
});
This latter option may cause issues if you're not careful. For instance, if you have a default Button in the Scene then the above event filter may interfere with the ENTER key. Also, this option won't necessarily stop things like shortcut+c, shortcut+v, etc. because those shortcuts are registered with the TextInputControl, not the Scene.
I have about 50 buttons in my application. For all buttons I created handler this way:
#FXML
protected void handleFooButtonActionEvent(ActionEvent actionEvent) {
...
}
This way user can press buttons using mouse left button or Space key. However, it is normal practice (as I know) to allow user press button using Enter key. Is it possible to make all buttons having ActionEvent handler (see above) handle also Enter key in JavaFX, for example if we have reference to Stage stage, Scene scene or Parent root?
You can configure the Scene to do it:
scene.getAccelerators().put(
KeyCombination.valueOf("Enter"), () -> {
Node focusOwner = scene.getFocusOwner();
if (focusOwner instanceof Button) {
((Button) focusOwner).fire();
}
});
You can also do it with an event handler:
scene.addEventHandler(KeyEvent.KEY_PRESSED, e -> {
if (e.getCode() == KeyCode.ENTER) {
Node focusOwner = scene.getFocusOwner();
if (focusOwner instanceof Button) {
((Button) focusOwner).fire();
}
}
});
Normally I’d agree with James_D that changing the standard behavior of buttons is not a good idea, but I’m finding that all GTK applications allow Enter to trigger a button press, as does Firefox as you’ve mentioned.
A JavaFX MenuItem can respond to most KeyPress events by setting an ActionEvent EventHandler. However, while the event handler does catch a KeyPress of KeyCode.ENTER, it does not catch a KeyCode.TAB KeyPress event. Apparently, some key events like TAB are handled at a deeper level. For example, the arrow keys enable traversal of the menu.
My ContextMenu is a list of completions of an email address string the user has started typing in a TextField. The users want to press the arrow keys to select the desired item, and the TAB key to execute the completion.
I can attach an event handler to the ContextMenu itself and catch the TAB keypress. But the event's Source is then the ContextMenu, and I can find no variables in the ContextMenu indicating which MenuItem was highlighted when the TAB key was pressed. MenuItem allows css style to control appearance of the menu item in focus, but it does not have any properties telling whether it is in focus or not.
I have tried futzing with the EventDispatchChain via MenuItem buildEventDispatchChain() to no avail. There seems to be no way to intercept the TAB KeyPress or otherwise determine which menu item was in focus when the TAB key was pressed.
Any suggestions?
If I get this right, you want to override the default keypressed listener to add your own response, so for that we have to find where it's applied.
To get this working, we've got to get our hands dirty with private API...
ContextMenu skin (ContextMenuSkin) uses a ContextMenuContent object, as a container with all the items. Each of these items are also in a ContextMenuContent.MenuItemContainer container.
We can override the keypressed listener on the parent container, while we can add a focusedProperty listener to the items on the items container.
Using this private API
import com.sun.javafx.scene.control.skin.ContextMenuContent;
this is working for me:
private ContextMenuContent.MenuItemContainer itemSelected=null;
#Override
public void start(Stage primaryStage) {
MenuItem cmItem1 = new MenuItem("Item 1");
cmItem1.setOnAction(e->System.out.println("Item 1"));
MenuItem cmItem2 = new MenuItem("Item 2");
cmItem2.setOnAction(e->System.out.println("Item 2"));
final ContextMenu cm = new ContextMenu(cmItem1,cmItem2);
Scene scene = new Scene(new StackPane(), 300, 250);
scene.setOnMouseClicked(t -> {
if(t.getButton()==MouseButton.SECONDARY || t.isControlDown()){
cm.show(scene.getWindow(),t.getScreenX(),t.getScreenY());
ContextMenuContent cmc= (ContextMenuContent)cm.getSkin().getNode();
cmc.setOnKeyPressed(ke->{
switch (ke.getCode()) {
case UP: break;
case DOWN: break;
case TAB: ke.consume();
if(itemSelected!=null){
itemSelected.getItem().fire();
}
cm.hide();
break;
default: break;
}
});
VBox itemsContainer = cmc.getItemsContainer();
itemsContainer.getChildren().forEach(n->{
ContextMenuContent.MenuItemContainer item=(ContextMenuContent.MenuItemContainer)n;
item.focusedProperty().addListener((obs,b,b1)->{
if(b1){
itemSelected=item;
}
});
});
}
});
primaryStage.setScene(scene);
primaryStage.show();
}
Excellent! Thank you #jose! I ended up writing somewhat different code but
the key is using com.sun.javafx.scene.control.skin.ContextMenuContent, which provides
access to the ContextMenuContent.MenuItemContainer objects that hold the MenuItems.
In order to not break the existing UP/DOWN key behavior, I added a new handler
to the ContextMenuContent object; this handler only consumes the TAB KeyPress and
everthing else passes through to their normal handlers.
Looking at the ContextMenuContent class, I borrowed their existing method for
finding the focused item, so didn't have to add focusedProperty listeners.
Also, I'm on Java 1.7 and don't have lambdas and I use a very basic programming style.
public class MenuItemHandler_CMC <T extends Event> implements EventHandler {
public ContextMenuContent m_cmc;
public AddressCompletionMenuItemHandler_CMC(ContextMenuContent cmc){
m_cmc = cmc;
}
#Override
public void handle(Event event){
KeyEvent ke = (KeyEvent)event;
switch(ke.getCode()){
case TAB:
ke.consume();
MenuItem focused_menu_item = findFocusedMenuItem();
if(focused_menu_item != null){
focused_menu_item.fire();
}
break;
default: break;
}
}
public MenuItem findFocusedMenuItem() {
VBox items_container = m_cmc.getItemsContainer();
for (int i = 0; i < items_container.getChildren().size(); i++) {
Node n = items_container.getChildren().get(i);
if (n.isFocused()) {
ContextMenuContent.MenuItemContainer menu_item_container = (ContextMenuContent.MenuItemContainer)n;
MenuItem menu_item = menu_item_container.getItem();
return menu_item;
}
}
return null;
}
}
...Attach the additional handler
if(m_context_menu.getSkin() != null){
ContextMenuContent cmc = (ContextMenuContent)m_context_menu.getSkin().getNode();
MenuItemHandler_CMC menu_item_handler_cmc = new MenuItemHandler_CMC(cmc);
cmc.addEventHandler(KeyEvent.KEY_PRESSED, menu_item_handler_cmc);
}
Focus events don't work because they're not sent if you activate your window by clicking on its non-client frame. Also, if you click the internal components of the window THEY will get the focus event, not your window, but the window will still be activated, even if it wasn't active or focused before.
The event you want is QEvent::WindowActivate. Override event() to process it:
bool YourWidget::event(QEvent *e)
{
if (e->type() == QEvent::WindowActivate) {
// window was activated
}
return QWidget::event(e);
}
Qt provides several virtual event handling functions you can use. Since the activation of a window changes its state, you want to handle some change events:
void MyWidget::changeEvent(QEvent * e) {
if(e->type() == QEvent::ActivationChange && this->isActiveWindow()) {
// .. this is now the active window
}
}
References
changeEvent
isActiveWindow