Develop Reference

How to check if a key is down without a listener in JavaFX?

Is it possible to simply check if a key is currently pressed in JavaFX without listening for a KeyEvent? In my case I want to check if a key is down while a button is being pressed.
button.setOnAction(e -> {
// This is where I want to check if a specific key is currently down.
if(keyIsDown) {
// do something
} else {
// do something else
}
});
I can think of a couple of workarounds. I'm just wondering if there is a right way to do this.

Here you go this code works like a charm with me when I'm pressing any button on keyboard then click a button prints key down
SimpleBooleanProperty simpleBooleanProperty = new SimpleBooleanProperty();
scene.setOnKeyPressed(new EventHandler<KeyEvent>() {
#Override
public void handle(KeyEvent event) {
simpleBooleanProperty.setValue(true);
}
});
scene.setOnKeyReleased(new EventHandler<KeyEvent>() {
#Override
public void handle(KeyEvent event) {
simpleBooleanProperty.setValue(false);
}
});
done.setOnMouseClicked(new EventHandler<MouseEvent>() {
#Override
public void handle(MouseEvent event) {
if(simpleBooleanProperty.get()){
System.out.println("Key Down");
}else { //key released
System.out.println("Key Up");
}
}
});

EventHandlers overriding each other? JavaFX

I have a context menu which activated on right click of a node in my JavaFX application. Originally I just had one menu item, but I decided to add another. When I added another, the second menu item worked but the first menu item stopped working. Here was my code:
final ContextMenu contextMenu = new ContextMenu();
MenuItem delete = new MenuItem("Delete");
MenuItem hyperlink = new MenuItem("Hyperlink...");
contextMenu.getItems().addAll(delete, hyperlink);
//handles deletion
webView.setOnMousePressed(new EventHandler<MouseEvent>() {
#Override
public void handle(MouseEvent e){
if (e.isSecondaryButtonDown()){
contextMenu.show(workspace, e.getScreenX(), e.getScreenY());
delete.setOnAction(new EventHandler<ActionEvent>() {
#Override
public void handle(ActionEvent event)
{
//do stuff
}
});
}
}
});
//handles hyperlink
webView.setOnMousePressed(new EventHandler<MouseEvent>() {
#Override
public void handle(MouseEvent e){
if (e.isSecondaryButtonDown()){
contextMenu.show(workspace, e.getScreenX(), e.getScreenY());
hyperlink.setOnAction(new EventHandler<ActionEvent>() {
#Override
public void handle(ActionEvent event)
{
//do stuff
}
});
}
}
});
}
I assumed this was because the listeners were overriding each other, so I changed it to add event handlers. Here's how I changed the code:
final ContextMenu contextMenu = new ContextMenu();
MenuItem delete = new MenuItem("Delete");
MenuItem hyperlink = new MenuItem("Hyperlink...");
contextMenu.getItems().addAll(delete, hyperlink);
//handles deletion
webView.addEventHandler(MouseEvent.MOUSE_CLICKED, new EventHandler<MouseEvent>() {
#Override
public void handle(MouseEvent e){
if (e.isSecondaryButtonDown()){
contextMenu.show(workspace, e.getScreenX(), e.getScreenY());
delete.setOnAction(new EventHandler<ActionEvent>() {
#Override
public void handle(ActionEvent event)
{
//do stuff
}
});
}
}
});
//handles hyperlink
webView.addEventHandler(MouseEvent.MOUSE_CLICKED, new EventHandler<MouseEvent>() {
#Override
public void handle(MouseEvent e){
if (e.isSecondaryButtonDown()){
contextMenu.show(workspace, e.getScreenX(), e.getScreenY());
hyperlink.setOnAction(new EventHandler<ActionEvent>() {
#Override
public void handle(ActionEvent event)
{
//do stuff
}
});
}
}
});
Now, NOTHING is happening when I right-click the node. Can someone explain why, and what my solution might be?

There is a number of things:
Yes, in your first version, the handlers were overriding each other.
Direct translation to addEventHandler style would use event type MouseEvent.MOUSE_PRESSED, not MOUSE_CLICKED, since MOUSE_CLICKED occurs only after the mouse button has been released, thus the isSecondaryButtonDown() test always returns false—that's why nothing is happening.
Instead of detecting mouse presses, you can listen to CONTEXT_MENU_REQUESTED events:
webView.setOnContextMenuRequested(new EventHandler<ContextMenuEvent>() {
#Override
public void handle(ContextMenuEvent e) {
contextMenu.show(workspace, e.getScreenX(), e.getScreenY());
}
}
You should set the menu item's action right after its creation, not on each right click:
MenuItem delete = new MenuItem("Delete");
delete.setOnAction(new EventHandler<ActionEvent>() {
#Override
public void handle(ActionEvent event)
{
//do stuff
}
});
The only thing you need to do on right click is show the context menu, as shown above.

Why are you duplicating code. Just follow your first approach and do both things inside the same EventHandler.
One more note: Define your ActionEvents for the MenuItems outside of the webView handlers. What you are doing now is every time you click a menuItem you are resetting the ActionEvents. From your code, I can only see that you need to detect the MouseEvent just to show the Context Menu. Which can be done in one webView.setOnMousePressed(...).

JavaFX key listener for multiple keys pressed implementation?

I would like to create an event handler that listens for multiple key combinations such as holding Ctrl and C at the same time.
Why doesn't something like if((... == Control) && (... == C)) work?
Here is the code I trying to work with:
textField.addEventHandler(KeyEvent.KEY_PRESSED, new EventHandler<KeyEvent>() {
public void handle(KeyEvent event) {
if ((event.getCode() == KeyCode.CONTROL) && (event.getCode() == KeyCode.C)) {
System.out.println("Control pressed");
}
};
});

You can try this solution, it worked for me!
final KeyCombination keyCombinationShiftC = new KeyCodeCombination(
KeyCode.C, KeyCombination.CONTROL_DOWN);
textField.setOnKeyPressed(new EventHandler<KeyEvent>() {
#Override
public void handle(KeyEvent event) {
if (keyCombinationShiftC.match(event)) {
logger.info("CTRL + C Pressed");
}
}
});

One way to tackle this problem is to create a KeyCombination object and set some of its properties to what you see below.
Try the following:
textfield.getScene().getAccelerators().put(new KeyCodeCombination(
KeyCode.C, KeyCombination.CONTROL_ANY), new Runnable() {
#Override public void run() {
//Insert conditions here
textfield.requestFocus();
}
});

This would be of some help. KeyCombination.
final KeyCombination keyComb1=new KeyCodeCombination(KeyCode.C,KeyCombination.CONTROL_DOWN);
https://code.google.com/p/javafx-demos/source/browse/trunk/javafx-demos/src/main/java/com/ezest/javafx/demogallery/KeyCombinationDemo.java?r=27

A bit more concise (avoids new KeyCombination()):
public void handle(KeyEvent event) {
if (event.isControlDown() && (event.getCode() == KeyCode.C)) {
System.out.println("Control+C pressed");
}
};
There are methods of the type KeyEvent.isXXXDown() for the other modifier keys as well.

Disable Key press event temporarily

Is it possible, in GWT, to temporarily suspend a certain key press until it is desired to allow that key press again? Like a global suspension. I have an issue where when I open the date picker on a RelativeDateItem in SmartGWT, that it causes the entire page to scroll out of view until the user hits the UP arrow again.

This is working for me for a JEditorPane:
#Override
public void keyTyped(KeyEvent evt) {
if (inTag() > -1) {
evt.consume();
}
The javadoc shows:
void java.awt.event.InputEvent.consume()
consume
public void consume()
Consumes this event so that it will not be processed in the default manner by the source which originated it.
The JEditorPane is in a JFrame which implements KeyListener and the JEditorPane does:
jEditorPaneSource.addKeyListener(this);

datepicker.addKeyPressHandler(new com.smartgwt.client.widgets.events.KeyPressHandler() {
public void onKeyPress(
com.smartgwt.client.widgets.events.KeyPressEvent event) {
event.preventDefault();
}
});

I believe you can block it with this.
Event.addNativePreviewHandler(new NativePreviewHandler(){
#Override
public void onPreviewNativeEvent(NativePreviewEvent event) {
EventTarget eventTarget = event.getNativeEvent().getEventTarget();
Element el = Element.as(eventTarget);
switch (event.getTypeInt()){
case Event.ONKEYPRESS:
case Event.ONKEYUP:
case Event.ONKEYDOWN:
if (el.getNodeName().equalsIgnoreCase("NODE FROM DATEPICKER")) {
if (event.getNativeEvent().getKeyCode() == "yourKeyCodeToBlock"
event.cancel();
}
}
break;
}
}
});

In GWT is there a way to create a KeyPressEvent for the entire view instead of a single input element?

Right now I have the following code working:
#UiHandler("usernameTextBox")
void onUsernameTextBoxKeyPress(KeyPressEvent event) {
keyPress(event);
}
#UiHandler("passwordTextBox")
void onPasswordTextBoxKeyPress(KeyPressEvent event) {
keyPress(event);
}
void keyPress(KeyPressEvent event) {
if (event.getNativeEvent().getKeyCode() == KeyCodes.KEY_ENTER) {
submit();
}
}
I would like the ability to have just one listener for all elements on the view without duplicating an event for each textbox.
The end goal is that if they press enter, regardless of where they are on the page, it should submit the form.
Thanks!

What works, but still requires you to specify it for each widget, but doesn't require duplicate code:
#UiHandler({"usernameTextBox", "passwordTextBox"})
void onPasswordTextBoxKeyPress(KeyPressEvent event) {
keyPress(event);
}

Yes jackcrews is correct. Also you can try the following. It may be VerticalPanel, DockLayoutPanel etc....
UiBinder.ui.xml
<gwt:VerticalPanel ui:field="mainPanel">
<gwt:Label>Name</gwt:TextBox>
<gwt:TextBox ui:field="textBox">
</gwt:VerticalPanel>
Main.java
#UiField
VerticalPanel mainPanel;
public Main() {
focushandler();
}
void focusHandler() {
mainPanel.addDomHandler(new Handler(), KeyPressEvent.getType());
}
final class Handler implements KeyPressHandler {
#Override
public void onKeyPress(KeyPressEvent event) {
//Code what you expect
}
}
Actually this has more number of lines. But it is good practice.
Regards,
Gnik

I found out that the g:FocusPanel allows me to capture events for everything inside the panel.
#UiHandler("focusPanel")
void onFocusPanelKeyPress(KeyPressEvent event) {
if (event.getNativeEvent().getKeyCode() == KeyCodes.KEY_ENTER) {
submit();
}
}