Using JavaFX, write a program that lets the user click on a pane to dynamically

Question

Using JavaFX, write a program that lets the user click on a pane to dynamically create and remove. When the user left-clicks the mouse (primary button), a point (circle) is created and displayed at the mouse point. The user can remove a point by pointing to it and right- clicking the mouse (secondary button).

Explanation / Answer

import javafx.application.Application; import javafx.collections.ObservableList; import javafx.scene.Node; import javafx.scene.Scene; import javafx.scene.input.MouseButton; import javafx.scene.layout.Pane; import javafx.scene.paint.Color; import javafx.scene.shape.Circle; import javafx.stage.Stage; /** * Chapter 15 Exercise 15: * * (Geometry: add and remove points) * Write a program that lets the user click on a pane to * dynamically create and remove points (see Figure 15.28a). * When the user left-clicks the mouse (primary button), a point is * created and displayed at the mouse point. The user can remove a point * by pointing to it and right- clicking the mouse (secondary button). * * Created by Luiz Arantes Sa on 9/16/14. */ public class Exercise_15 extends Application { Pane pane = new Pane(); @Override public void start(Stage primaryStage) { double width = 400; double height = 400; pane.setOnMouseClicked(e-> { double x = e.getX(); double y = e.getY(); if (e.getButton() == MouseButton.PRIMARY) { Circle c = drawPoint(x,y); pane.getChildren().add(c); } else if (e.getButton() == MouseButton.SECONDARY) { removePoint(x, y); } }); Scene scene = new Scene(pane, width, height); primaryStage.setScene(scene); primaryStage.setTitle("click to draw circle"); primaryStage.show(); } private Circle drawPoint(double x, double y) { Circle c = new Circle(x, y, 10, Color.TRANSPARENT); c.setStroke(Color.BLACK); return c; } private void removePoint(double x, double y) { ObservableList list = pane.getChildren(); for (int i = list.size() - 1; i >= 0; i--) { Node c = list.get(i); if (c instanceof Circle && c.contains(x, y)) { pane.getChildren().remove(c); break; } } } public static void main(String[] args) { Application.launch(args); } }

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