Computer Science 252
Problem Solving with Java
Spring 2016, The College of Saint Rose
DragCars BlueJ Project
Click here to download a BlueJ project for DragCars.
DragCars Source Code
The Java source code for DragCars is below. Click on a file name to download it.
import objectdraw.*;
import java.awt.*;
/*
* Example DragCars: example using a car to demonstrate a custom class
*
* Jim Teresco, The College of Saint Rose, CSC 252, Spring 2014
*
* $Id: DragCars.java 2319 2014-02-07 01:24:52Z terescoj $
*/
public class DragCars extends WindowController {
// background colors
private static final Color SKY_BLUE = new Color(175, 175, 255);
private static final Color NIGHT_SKY = new Color(10, 10, 100);
// the three cars, and the sky backgrounds
private Car car1, car2, car3;
private FilledRect lightSky, darkSky;
// dragging support -- draggingCar is null if no dragging, a
// reference to one of the cars if dragging
private Location prevPoint;
private Car draggingCar = null;
public void begin() {
// bright and dark portions
lightSky = new FilledRect(0, 0, canvas.getWidth()/2, canvas.getHeight(), canvas);
lightSky.setColor(SKY_BLUE);
darkSky = new FilledRect(canvas.getWidth()/2, 0, canvas.getWidth()/2, canvas.getHeight(), canvas);
darkSky.setColor(NIGHT_SKY);
car1 = new Car(50, 50, Color.red, canvas);
car2 = new Car(50, 250, Color.blue, canvas);
car3 = new Car(200, 150, Color.green, canvas);
}
public void onMousePress(Location point) {
if (car1.contains(point)) {
draggingCar = car1;
}
else if (car2.contains(point)) {
draggingCar = car2;
}
else if (car3.contains(point)) {
draggingCar = car3;
}
prevPoint = point;
}
public void onMouseDrag(Location point) {
if (draggingCar != null) {
// standard dragging
draggingCar.move(point.getX() - prevPoint.getX(),
point.getY() - prevPoint.getY());
prevPoint = point;
// check if we're supposed to turn the headlights on or off
if (lightSky.contains(draggingCar.getCenter())) {
draggingCar.turnOffHeadlights();
}
else {
draggingCar.turnOnHeadlights();
}
}
}
public void onMouseRelease(Location point) {
if (draggingCar != null) {
// standard dragging
draggingCar.move(point.getX() - prevPoint.getX(),
point.getY() - prevPoint.getY());
prevPoint = point;
// check if we're supposed to turn the headlights on or off
if (lightSky.contains(draggingCar.getCenter())) {
draggingCar.turnOffHeadlights();
}
else {
draggingCar.turnOnHeadlights();
}
}
draggingCar = null;
}
public void onMouseEnter(Location point) {
car1.setColor(Color.red);
car2.setColor(Color.blue);
car3.setColor(Color.green);
}
public void onMouseExit(Location point) {
if (car1.headlightsOn()) {
car1.setColor(Color.gray);
}
if (car2.headlightsOn()) {
car2.setColor(Color.gray);
}
if (car3.headlightsOn()) {
car3.setColor(Color.gray);
}
}
}
/**
* A representation of a car which can change color, supports
* dragging, and which can turn its headlights on or off.
*
* @author Jim Teresco
*/
import objectdraw.*;
import java.awt.*;
public class Car
{
private static final int BODY_LENGTH = 150;
private static final int BODY_HEIGHT = 35;
private static final int CABIN_HEIGHT = 40;
private static final int CABIN_LENGTH = BODY_LENGTH/2;
private static final int CABIN_OFFSET = (BODY_LENGTH-CABIN_LENGTH)/2;
private static final int TIRE_SIZE = 40;
private static final int TIRE_OFFSET_X = BODY_LENGTH/4;
private static final int TIRE_OFFSET_Y = CABIN_HEIGHT + BODY_HEIGHT - TIRE_SIZE/2;
private static final int HEADLIGHT_HEIGHT = BODY_HEIGHT/2;
private static final int HEADLIGHT_WIDTH = HEADLIGHT_HEIGHT/3;
private FilledRect body;
private FilledArc cabin;
private FilledOval frontTire, rearTire, headlight;
// construct a car
public Car(double x, double y, Color color, DrawingCanvas canvas) {
rearTire = new FilledOval(x + TIRE_OFFSET_X - TIRE_SIZE/2, y + TIRE_OFFSET_Y, TIRE_SIZE, TIRE_SIZE, canvas);
frontTire = new FilledOval(x + BODY_LENGTH - TIRE_OFFSET_X - TIRE_SIZE/2, y + TIRE_OFFSET_Y, TIRE_SIZE, TIRE_SIZE, canvas);
body = new FilledRect(x, y + CABIN_HEIGHT, BODY_LENGTH, BODY_HEIGHT, canvas);
body.setColor(color);
cabin = new FilledArc(x + CABIN_OFFSET, y, CABIN_LENGTH, CABIN_HEIGHT*2, 0, 180, canvas);
cabin.setColor(color);
headlight = new FilledOval(x + BODY_LENGTH - HEADLIGHT_WIDTH/2, y + CABIN_HEIGHT, HEADLIGHT_WIDTH, HEADLIGHT_HEIGHT, canvas);
}
// check containment
public boolean contains(Location point) {
return body.contains(point) || cabin.contains(point) ||
frontTire.contains(point) || rearTire.contains(point) ||
headlight.contains(point);
}
public void move(double xChange, double yChange) {
body.move(xChange, yChange);
cabin.move(xChange, yChange);
frontTire.move(xChange, yChange);
rearTire.move(xChange, yChange);
headlight.move(xChange, yChange);
}
// center of the car
public Location getCenter() {
return new Location(body.getX() + BODY_LENGTH/2, body.getY());
}
// headlight control
public void turnOffHeadlights() {
headlight.setColor(Color.black);
}
public void turnOnHeadlights() {
headlight.setColor(Color.yellow);
}
// get headlight status
public boolean headlightsOn() {
return headlight.getColor().equals(Color.yellow);
}
// set car color
public void setColor(Color newColor) {
body.setColor(newColor);
cabin.setColor(newColor);
}
}