(Racing cars) Rewrite Programming Exercise 15.29 using a thread to control
car racing. Compare the program with Programming Exercise 15.29 by setting
the delay time to 10 in both programs. Which one runs the animation faster?

Here's the code from 15.29

import javafx.animation.KeyFrame;
import javafx.animation.Timeline;
import javafx.application.Application;
import javafx.collections.ObservableList;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.HBox;
import javafx.scene.layout.Pane;
import javafx.scene.paint.Color;
import javafx.scene.shape.Circle;
import javafx.scene.shape.Polyline;
import javafx.scene.shape.Rectangle;
import javafx.stage.Stage;
import javafx.util.Duration;

public class Exercise extends Application {

@Override
public void start(Stage primaryStage) throws Exception {

CarPane carPane = new CarPane(600, 200);

Timeline timeline = new Timeline(new KeyFrame(Duration.millis(10), e -> carPane.moveCar(1)));
timeline.setCycleCount(carPane.getOneCycleDuration());
timeline.play();
timeline.setOnFinished(e -> {
carPane.reset();
timeline.play();
});

// Buttons pause, resume, increase, decrease
Button pause = new Button("Pause");
pause.setOnAction(e -> timeline.pause());

Button resume = new Button("Resume");
resume.setOnAction(e -> timeline.play());

Button increase = new Button("Increase");
increase.setOnAction(e -> {
timeline.setRate(timeline.getCurrentRate() + 1);
});

Button decrease = new Button("Decrease");
decrease.setOnAction(e -> {
if (timeline.getCurrentRate() <= 0)
return;

timeline.setRate(timeline.getCurrentRate() - 1);
});

HBox hButtons = new HBox(pause, resume, increase, decrease);
hButtons.setSpacing(10);
hButtons.setAlignment(Pos.CENTER);
hButtons.setPadding(new Insets(5, 5, 5, 5));

BorderPane borderPane = new BorderPane(carPane, null, null, hButtons, null);
borderPane.setOnKeyPressed(e -> {
switch (e.getCode()) {
case UP:
increase.fire();
break;
case DOWN:
decrease.fire();
break;
}
});
primaryStage.setScene(new Scene(borderPane));
primaryStage.setTitle("Moving Car");
primaryStage.show();

}

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

}

private class CarPane extends Pane {

private double w; // pane width
private double h; // pane height

// left Tire x,y and radius
private double leftTireX; // left tire is the car's drawing start point
private double leftTireY;
private double tireRadius;

Circle[] tires = new Circle[2]; // Index 0, 1 = left and right tire
Polyline cover = new Polyline();
ObservableList points;
Rectangle base;

private CarPane(double width, double height) {

// Get width height and measurements for the left tire (starting
// point)
w = width;
h = height;
leftTireX = w * 0.2;
leftTireY = h * 0.9;
tireRadius = h * 0.1;

// set MIN and MAX width
setMinWidth(w);
setMinHeight(h);

setMaxWidth(w);
setMaxHeight(h);

reset(); // draws and adjusts car to starting position
}

public void reset() {

if (points != null)
points.clear();
getChildren().clear();
drawCar();
moveCar(tireRadius * 13 * -1);
}

public void drawCar() {
for (int i = 0; i < tires.length; i++) {
tires[i] = new Circle(leftTireX + (i * 4 * tireRadius), leftTireY, tireRadius);
tires[i].setStroke(Color.BLACK);
tires[i].setFill(Color.TRANSPARENT);

}

double baseX = tires[0].getCenterX() - tires[0].getRadius() * 3;
double baseY = tires[0].getCenterY() - tires[0].getRadius() * 3;
base = new Rectangle(baseX, baseY, tireRadius * 10, tireRadius * 2);
base.setFill(Color.TRANSPARENT);
base.setStroke(Color.BLACK);

// draw the car's top cover
double startX = base.getX() + tireRadius * 2;
double startY = base.getY();
double currentX = startX;
double currentY = startY;

points = cover.getPoints();

double distance = tireRadius * 2;
points.addAll(currentX, currentY); // start point

currentX += distance;
currentY -= distance;
points.addAll(currentX, currentY); // up right

currentX += distance;
points.addAll(currentX, currentY); // right

currentX += distance;
currentY += distance;
points.addAll(currentX, currentY); // down right

points.addAll(startX, startY); // connect to starting point
cover.setFill(Color.BLUE);

getChildren().addAll(tires);
getChildren().add(base);
getChildren().add(cover);
}

private void moveCar(double distance) {

// tires
for (Circle c : tires) {
c.setCenterX(c.getCenterX() + distance);
}

base.setX(base.getX() + distance);

for (int i = 0; i < points.size(); i += 2) {
points.set(i, points.get(i) + distance);
}

}

public int getOneCycleDuration() {
return (int) w;
}
}
}

Answer rating: 100% (QA)

Solution The given equation can be written as dr Dividing 1 by ... View the full answer