如何在鼠标指针下获取（ListView的）Cell？

Question

我编写了一个线程，该线程不断检查鼠标是否在ListView上，因为我想显示一个弹出窗口，其中包含有关用鼠标指向的单元格的信息。

因此，检查鼠标是否在ListView上没有问题。

但是如何检查鼠标是否在某个单元格上，因为我无法使用ListCell.localToScreen(ListCell.getBoundsInLocal()); 在屏幕上获取单元格坐标？

我不想使用ListCell事件，例如onMouseEntered。

Answer 1

在每个ListCell上为mouseEntered和mouseExited事件注册处理程序，或者观察ListCell的hoverProperty 。 这是使用第二种方法的示例：

import java.util.stream.IntStream;

import javafx.animation.FadeTransition;
import javafx.application.Application;
import javafx.geometry.Bounds;
import javafx.scene.Node;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.control.ListCell;
import javafx.scene.control.ListView;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.VBox;
import javafx.stage.Popup;
import javafx.stage.Stage;
import javafx.util.Duration;


public class PopupOnListCellHover extends Application {

    private Popup popup ;
    private Node popupContent ;
    private Label titleLabel ;
    private Label detailsLabel ;
    private FadeTransition fadeOut ;

    @Override
    public void start(Stage primaryStage) {
        ListView<Item> listView = new ListView<>();

        popup = new Popup();
        titleLabel = new Label();
        titleLabel.setStyle("-fx-font-size: 1.5em ; -fx-font-weight: bold;");
        detailsLabel = new Label();
        popupContent = new VBox(10, titleLabel, detailsLabel);
        popupContent.setStyle("-fx-background-color: -fx-background; "+
            "-fx-background: lightskyblue; -fx-padding:12px;");
        popup.getContent().add(popupContent);

        fadeOut = new FadeTransition(Duration.millis(500), popupContent);
        fadeOut.setFromValue(1.0);
        fadeOut.setToValue(0.0);
        fadeOut.setOnFinished(e -> popup.hide());

        listView.setCellFactory(lv -> {
            ListCell<Item> cell = new ListCell<Item>() {
                @Override
                public void updateItem(Item item, boolean empty) {
                    super.updateItem(item, empty);
                    if (empty) {
                        setText(null);
                    } else {
                        setText(item.getName());
                    }
                }
            };
            cell.hoverProperty().addListener((obs, wasHovered, isNowHovered) -> {
                if (isNowHovered && ! cell.isEmpty()) {
                    showPopup(cell);
                } else {
                    hidePopup();
                }
            });

            return cell ;
        });

        IntStream.rangeClosed(1, 100).mapToObj(i -> new Item("Item "+i, i))
            .forEach(listView.getItems()::add);

        BorderPane root = new BorderPane(listView);
        Scene scene = new Scene(root, 250, 400);
        primaryStage.setScene(scene);
        primaryStage.show();
    }

    private void showPopup(ListCell<Item> cell) {
        fadeOut.stop();
        popupContent.setOpacity(1.0);
        Bounds bounds = cell.localToScreen(cell.getBoundsInLocal());
        popup.show(cell, bounds.getMaxX(), bounds.getMinY());
        Item item = cell.getItem() ;
        titleLabel.setText(item.getName());
        detailsLabel.setText(String.format("This is %s.%nIt has value %d.", 
            item.getName(), item.getValue()));
    }

    private void hidePopup() {
        fadeOut.playFromStart();
    }

    public static class Item {
        private final int value ;
        private final String name ;

        public Item(String name, int value) {
            this.name = name ;
            this.value = value ;
        }

        public int getValue() {
            return value ;
        }

        public String getName() {
            return name ;
        }
    }

    public static void main(String[] args) {
        launch(args);
    }
}

要对mouseEntered和mouseExited使用处理程序，请替换

    cell.hoverProperty().addListener((obs, wasHovered, isNowHovered) -> {
        if (isNowHovered && ! cell.isEmpty()) {
            showPopup(cell);
        } else {
            hidePopup();
        }
    });

与

    cell.setOnMouseEntered(e -> showPopup(cell));
    cell.setOnMouseExited(e -> hidePopup());