java - 在 JavaFX 中拖动的圆圈落后于光标

Question

我有一个程序，其中在 Pane 中拖动了 2 个圆圈。还有一条线连接它们，上面显示距离。我的问题在于，当我用鼠标缓慢拖动圆圈时，它们移动得很好，但当我更快地移动圆圈时，圆圈停止了。

这里是计算圆阻力的地方

pane.setOnMouseDragged(e -> {
        if (circle1.contains(e.getX(), e.getY())) {
            pane.getChildren().clear();
            circle1.setCenterX(e.getX());
            circle1.setCenterY(e.getY());
            pane.getChildren().addAll(getLine(circle1, circle2), circle1,
                circle2, getText(circle1, circle2));
        }
        else if (circle2.contains(e.getX(), e.getY())) {
            pane.getChildren().clear();
            circle2.setCenterX(e.getX());
            circle2.setCenterY(e.getY());
            pane.getChildren().addAll(getLine(circle1, circle2), circle1,
                circle2, getText(circle1, circle2));
        }
    });

Answer 1

我认为发生的事情是，当鼠标快速移动时，处理两个连续事件之间移动的距离超出了圆圈的范围，因此 if 条件变为假。您可能需要在圆圈本身而不是 Pane 上注册鼠标处理程序。 (顺便说一句，为什么要清除并重建 Pane ，而不是只更新行？)

下面是一个使用这些技术的例子:

import javafx.application.Application;
import javafx.beans.property.ObjectProperty;
import javafx.beans.property.SimpleObjectProperty;
import javafx.geometry.Point2D;
import javafx.scene.Scene;
import javafx.scene.layout.Pane;
import javafx.scene.paint.Color;
import javafx.scene.shape.Circle;
import javafx.scene.shape.Line;
import javafx.stage.Stage;

public class DraggingCircles extends Application {

    @Override
    public void start(Stage primaryStage) {
        Pane pane = new Pane();
        Circle circle1 = createDraggingCircle(50, 50, 25, Color.BLUE);
        Circle circle2 = createDraggingCircle(350, 350, 25, Color.RED);
        Line line = new Line();
        line.startXProperty().bind(circle1.centerXProperty());
        line.startYProperty().bind(circle1.centerYProperty());
        line.endXProperty().bind(circle2.centerXProperty());
        line.endYProperty().bind(circle2.centerYProperty());
        pane.getChildren().addAll(circle1, circle2, line);

        Scene scene = new Scene(pane, 400, 400);
        primaryStage.setScene(scene);
        primaryStage.show();
    }

    private Circle createDraggingCircle(double x, double y, double radius, Color fill) {
        Circle circle = new Circle(x, y, radius, fill);
        ObjectProperty<Point2D> mouseLocation = new SimpleObjectProperty<>();

        circle.setOnMousePressed(e -> {
            mouseLocation.set(new Point2D(e.getX(), e.getY()));
        });

        circle.setOnMouseDragged(e -> {
            double deltaX = e.getX() - mouseLocation.get().getX();
            double deltaY = e.getY() - mouseLocation.get().getY();
            circle.setCenterX(circle.getCenterX() + deltaX);
            circle.setCenterY(circle.getCenterY() + deltaY);
            mouseLocation.set(new Point2D(e.getX(), e.getY()));
        });

        return circle ;
    }

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