San Jose State University | CS 151 - OO Design | Spring 2019

Homework 6

We will practice the design patterns from sections 5.4 - 5.6 of the textbook.

Start with the ch04/animation project and the modification of it in Lab 8 that allows you to animate multiple shapes.

Add this method to MoveableShape:

/**
 * Yields the bounding rectangle of this shape.
 * @return the bounding rectangle
 */
Rectangle getBounds();

Implement the method in the Car and MoveableIcon classes.
Provide a decorator class BoxedShape with a constructor
```
public BoxedShape(MoveableShape shape, int gap)
```
that, when drawn, yields the original shape with a rectangle along its bounds if gap is zero, or with as many pixels between the bounds and the rectangle on each side as given by gap. It's a decorator, so you should be able to apply it twice:
```
new BoxedShape(new BoxedShape(new CarShape(...), 0), 5)
```
Use the Composite pattern to group multiple shapes into one. A CompoundShape draws all of its shapes, moves each of them, and has a bounding box that is the smallest rectangle containing all individual bounding boxes. Provide a constructor
```
public CompoundShape(MoveableShape... shapes)
```
Note the varargs parameter. You should be able to call
```
new CompoundShape(new BoxedShape(...), new CarShape(...), new MoveableIcon(...))
```
Right now, AnimationTester simply moves all moveable shapes in each timer tick. Suppose we want it to do something more sophisticated, like stopping shapes that reach the boundary. That would be a different strategy. Provide an interface MoveStrategy with an abstract method
```
void process(List<MoveableShape> shapes)
```
Provide a class SimpleMoveStrategy that does what's currently done in AnimationTester, and a class BoundedMoveStrategy that only moves shapes whose bounds are contained inside a Rectangle that is given in the constructor.

Rename AnimationTester to Animation. Turn the main method into a method

public static void show(List<MoveableShape> shapes, MoveStrategy strategy, int width, int height)

I will call that method from my test cases. Here is an example. Make sure that it compiles with your classes with no change.

import java.awt.Rectangle;
import java.util.ArrayList;
import java.util.List;

public class AnimationTester
{
   public static void main(String[] args)
   {
      final int CAR_WIDTH = 100;
      List<MoveableShape> shapes = new ArrayList<>(); 
      shapes.add(new BoxedShape(new CompoundShape(new CarShape(200, 20, CAR_WIDTH),
            new MoveableIcon("dog.png", 100, 10),
            new MoveableIcon("dog.png", 150, 100)), 0));
      Animation.show(shapes, 
            new BoundedMoveStrategy(new Rectangle(0, 0, 500, 200)), 
            600, 200);
   }
}

As before, you need to provide javadoc for all classes and methods, and use spaces, not tabs. Make at least three Git commits (and preferably more).