How does the graphic inside a Javafx ListCell catch MouseEvents? - javafx

Question

I have a custom ListCell with a ImageView as the graphic. I want this ImageView to catch MouseEvents (like mouse_over, or mouse_click). But it does not catch any events.
The custom ListCell however catches events.
Is this unusual behaviour or do I need to pass the Events from the ListCell to its graphic (somehow)?
If I add a Button, it gets Mouseevents, strangely.
If you have just a link of a working example, I would happily crawl my way through it ;)
Thanks for your effort.
Class CustomCell:
package test;
import javafx.event.EventHandler;
import javafx.scene.control.Button;
import javafx.scene.control.ContentDisplay;
import javafx.scene.control.ListCell;
import javafx.scene.image.ImageView;
import javafx.scene.input.MouseEvent;
import javafx.scene.paint.Color;
import javafx.scene.text.Font;
import javafx.scene.text.FontWeight;
public class CustomCell extends ListCell<String>{
ImageView removeTrack;
public CustomCell(){
removeTrack = new ImageView("https://lh3.googleusercontent.com/-lbN1Ca63JPs/AAAAAAAAAAI/AAAAAAAAAAQ/smvshnyosS4/s46-c-k/photo.jpg");
removeTrack.setOnMouseClicked(e -> {
System.out.println("test");
});
}
#Override
protected void updateItem(String t, boolean bln) {
super.updateItem(t, bln);
if (t != null) {
setText(t);
setGraphic(removeTrack);
setContentDisplay(ContentDisplay.RIGHT);
addEventFilter(MouseEvent.MOUSE_MOVED, new EventHandler<MouseEvent>() {
#Override
public void handle(MouseEvent arg0) {
removeTrack.setVisible(true);
}
});
addEventFilter(MouseEvent.MOUSE_EXITED, new EventHandler<MouseEvent>() {
#Override
public void handle(MouseEvent arg0) {
removeTrack.setVisible(false);
}
});
}
}
}
Main-Class:
package test;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Scanner;
import javafx.application.Application;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.scene.Scene;
import javafx.scene.control.ListCell;
import javafx.scene.control.ListView;
import javafx.stage.Stage;
import javafx.util.Callback;
public class JAVAtest extends Application{
public static void main(String[] args) {
launch(args);
}
#Override
public void start(Stage stage) throws Exception {
ObservableList<String> names = FXCollections.observableArrayList(
"Julia", "Ian", "Sue", "Matthew", "Hannah", "Stephan", "Denise");
ListView lv = new ListView(names);
lv.setCellFactory(new Callback<ListView<String>, ListCell<String>>(){
#Override
public ListCell<String> call(ListView<String> p) {
return new CustomCell();
}
});
Scene scene = new Scene(lv);
stage.setScene(scene);
stage.show();
}
}

Answer 1

Well.. I can't see why your code isn't working. Seems like a bug.
It works fine if you wrap the image view in a container of some kind. For example:
import javafx.event.EventHandler;
import javafx.scene.control.ContentDisplay;
import javafx.scene.control.ListCell;
import javafx.scene.image.ImageView;
import javafx.scene.input.MouseEvent;
import javafx.scene.layout.StackPane;
public class CustomCell extends ListCell<String> {
ImageView removeTrack;
StackPane imageContainer ;
public CustomCell() {
removeTrack = new ImageView(
"https://lh3.googleusercontent.com/-lbN1Ca63JPs/AAAAAAAAAAI/AAAAAAAAAAQ/smvshnyosS4/s46-c-k/photo.jpg");
removeTrack.setOnMouseClicked(e -> {
System.out.println("test");
});
imageContainer = new StackPane(removeTrack);
}
#Override
protected void updateItem(String t, boolean bln) {
super.updateItem(t, bln);
if (t != null) {
setText(t);
setGraphic(imageContainer);
setContentDisplay(ContentDisplay.RIGHT);
addEventFilter(MouseEvent.MOUSE_MOVED, new EventHandler<MouseEvent>() {
#Override
public void handle(MouseEvent arg0) {
imageContainer.setVisible(true);
}
});
addEventFilter(MouseEvent.MOUSE_EXITED, new EventHandler<MouseEvent>() {
#Override
public void handle(MouseEvent arg0) {
imageContainer.setVisible(false);
}
});
} else {
setText(null);
setGraphic(null);
}
}
}
(As an aside: always handle all possible cases in the updateItem(...) method. Your code will have bugs if you start removing items or possibly while scrolling, because you don't handle the empty cell / null item case.)