HW #13Event Processing Homework Control Polygon program

/*
 * Name: Lu Liu
 * Date: 4/5/2016
 * Course Number: CSC-112
 * Course Name: Intermediate Topics in Java Programming
 * Email: lliu0001@student.stcc.edu
 *
 * Assignment: HW # 13
 * Programe Description:
 * Event Processing Homework Control Polygon program
 */

import javafx.application.Application;
import javafx.collections.ObservableList;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.StackPane;
import javafx.scene.layout.HBox;
import javafx.scene.layout.Pane;
import javafx.scene.layout.BorderPane;
import javafx.scene.paint.Color;
import javafx.scene.shape.Circle;
import javafx.scene.shape.Polygon;
import javafx.stage.Stage;

public class ControlPolygon extends Application {

    PolygonPane polygonPane = new PolygonPane();

    @Override
    // Override the start method in the Application class
    public void start(Stage primaryStage) {
        // Hold two buttons in an HBox
        HBox hBox = new HBox();
        hBox.setSpacing(10);
        hBox.setAlignment(Pos.CENTER);
        Button btEnlarge = new Button("+");
        Button btShrink = new Button("-");
        hBox.getChildren().add(btEnlarge);
        hBox.getChildren().add(btShrink);

        // Create and register the handler
        btEnlarge.setOnAction(new EnlargeHandler());
        btShrink.setOnAction(new ShrinkHandler());

        BorderPane borderPane = new BorderPane();
        borderPane.setCenter(polygonPane);
        borderPane.setBottom(hBox);
        BorderPane.setAlignment(hBox, Pos.CENTER);

        // Create a scene and place it in the stage
        Scene scene = new Scene(borderPane, 300, 250);
        primaryStage.setTitle("ControlPolygon"); // Set the stage title
        primaryStage.setScene(scene); // Place the scene in the stage
        primaryStage.show(); // Display the stage
    }

    class EnlargeHandler implements EventHandler<ActionEvent> {
        @Override
        // Override the handle method
        public void handle(ActionEvent e) {
            polygonPane.enlarge();
        }
    }

    class ShrinkHandler implements EventHandler<ActionEvent> {
        @Override
        // Override the handle method
        public void handle(ActionEvent e) {
            polygonPane.shrink();
        }
    }

    /**
     * The main method is only needed for the IDE with limited JavaFX support.
     * Not needed for running from the command line.
     */
    public static void main(String[] args) {
        launch(args);
    }
}

class PolygonPane extends Pane {
    private int n = 6;

    public int getN() {
        return n;
    }

    public void setN(int n) {
        this.n = n;
        this.paint();
    }

    public void paint() {
        // Create a polygon and place polygon to pane
        Polygon polygon = new Polygon();
        polygon.setFill(Color.WHITE);
        polygon.setStroke(Color.BLACK);
        ObservableList<Double> list = polygon.getPoints();

        double centerX = getWidth() / 2, centerY = getHeight() / 2;
        double radius = Math.min(getWidth(), getHeight()) * 0.4;

        // Add points to the polygon list
        for (int i = 0; i < n; i++) {
            list.add(centerX + radius * Math.cos(2 * i * Math.PI / n));
            list.add(centerY - radius * Math.sin(2 * i * Math.PI / n));
        }
        getChildren().clear();
        getChildren().add(polygon);
    }

    public void enlarge() {
        this.setN(n + 1);
    }

    public void shrink() {
        this.setN(this.getN() <= 3 ? 3 : n - 1);
    }

    @Override
    public void setWidth(double width) {
        super.setWidth(width);
        paint();
    }

    @Override
    public void setHeight(double height) {
        super.setHeight(height);
        paint();
    }
}