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I am working on a java project that involves a drawing panel that we are to render different shapes to. I have been provided with starter code from our teacher that we are to add to. I have created the "class DrawingArea extends DrawingAreaBase" code, which implements the different methods that are in DrawingAreaBase. I am getting a compiler error, "ShapePanel.java:238: DrawingArea is not abstract and does not override abstract method removeAllShapes() in DrawingArea" I don't understand why I am getting this error, since I thought that I DID implement that method in my method.
Any help would be appreciated - for now, I am just trying to get this code to COMPILE so I can work with it from there.
Thanks!
import java.awt.*;
import java.awt.event.*;
import java.util.ArrayList;
import javax.swing.*;
import javax.swing.event.*;
import java.util.*;
interface Shape {
// this method should render your Shape. If the shape is in the "hot" state,
// meaning the mouse is over the shape, it should render fully opaque, with
// the color specified by setColor. If the shape is not in the hot state, it
// should render a white background (fill) and just a border in the color specified
// by setColor.
public void render(Graphics g);
// determine if the given point is within the shape. Keep track of if the
// shape is currently hit tested or not, and call listener.OnHitTestChange()
// whenever the state changes. You will need this state to determine if it should be
// rendered in the "hot" state or not.
public boolean hitTest(Point pt, HitTestChangeListener listener);
// allow the outline color to be set (or fill color while in the "hot" state).
public void setColor(Color color);
// calculate the area of the shape.
public double getArea();
// get/set the position of the shape. This point can be anywhere on (or even off)
// the shape that you want, but you must be consistent and accept a change to
// setPosition().
public Point getPosition();
public void setPosition(Point point);
}
class Rectangle implements Shape {
private int width;
private int height;
private int x;
private int y;
public Rectangle(int width, int height, int y, int x) {
this.width = width;
this.height = height;
this.x = x;
this.y = y;
}
public double getWidth() {
return width;
}
public double getHeight() {
return height;
}
public void render(Graphics g) {
g.drawRect(x, y, width, height);
}
public boolean hitTest(Point pt, HitTestChangeListener listener) {
return true;
}
public void setColor(Color color) {
setColor(Color.BLACK);
}
public double getArea() {
return width * height;
}
public Point getPosition() {
Point p = new Point();
return p;
}
public void setPosition(Point point) {
System.out.println(point);
}
}
// The ShapeFactory will create shapes of the specified type, sized reasonably for the given
// panel with and height
class ShapeFactory {
private enum Shapes {
RECTANGLE,
SQUARE,
CIRCLE,
OVAL,
TRIANGLE
/* HEXAGON Bonus */
/* OCTAGON Bonus */};
public static String[] getSupportedShapes() {
// have the enumeration provide strings for each enum value
String[] ret = new String[Shapes.values().length];
for (int i = 0; i < ret.length; i++) {
ret[i] = Shapes.values()[i].toString();
}
return ret;
}
public static Shape createShape(String shapeString, int panelWidth, int panelHeight) {
Shapes shape = Shapes.valueOf(shapeString);
Random random = new Random();
//switch(shape) {
//case RECTANGLE:
Rectangle rect = new Rectangle(10, 10, 20, 10);
return rect;
//}
// TODO: Implement this method, to create the specified shape. No shape should be larger
// than 25% of the panel, and should be initially positioned at least partially on screen.
}
}
//This class will be created on mouse down to keep track of the selected shape, the mouse
//down point, and the original location of the selected shape. On subsequent mouse drag events
//we will move the selected shape appropriately.
class DragData {
private Point mouseDragStart;
private Point shapeStart;
private Shape shape;
public DragData(Point mouseDragStart, Shape shape) {
this.mouseDragStart = mouseDragStart;
this.shapeStart = shape.getPosition();
this.shape = shape;
}
public void handleMouseDrag(MouseEvent e) {
int deltaX = e.getPoint().x - mouseDragStart.x;
int deltaY = e.getPoint().y - mouseDragStart.y;
shape.setPosition(new Point(shapeStart.x + deltaX, shapeStart.y + deltaY));
}
}
// callback interface so that the drawing panel can know to repaint if a shape used to be
// hit and is no longer hit, or vice-versa.
interface HitTestChangeListener {
public void OnHitTestChange();
}
// Abstract class for your drawing area, you need to extend this and implement
// all the abstract methods to work with an ArrayList of Shape objects
abstract class DrawingAreaBase extends JPanel implements HitTestChangeListener {
private DragData dragData = null;
private Color colorSelection = Color.BLACK;
// compute the cummulative area of all shapes
abstract public double getTotalShapeArea();
// render all shapes
abstract public void renderShapes(Graphics g);
// find the first shape hit by the given point
abstract public Shape findFirstShapeHit(Point point);
// handle a click event on the current shape as per functional requirements
abstract public void handleShapeClicked(Shape shape);
// perform hit testing on all shapes
abstract public void hitTestAllShapes(Point point);
// add a shape to the drawing area
abstract public void addShape(Shape s);
// remove all shapes from the drawing area
abstract public void removeAllShapes();
public DrawingAreaBase() {
setPreferredSize(new Dimension(500, 500));
enableEvents(AWTEvent.MOUSE_MOTION_EVENT_MASK);
enableEvents(AWTEvent.MOUSE_EVENT_MASK);
}
public void refreshBackgroundColorByShapeArea() {
double shapeArea = getTotalShapeArea();
double totalArea = getWidth() * getHeight();
int channelColor = Math.max(0, 255 - (int)(shapeArea * 255.0 / totalArea));
setBackground(new Color(channelColor, channelColor, channelColor));
}
public void setColorSelection(Color color) { colorSelection = color; }
public Color getColorSelection() { return colorSelection; }
@Override public void paintComponent(Graphics g) {
super.paintComponent(g); // Ask parent to paint background.
renderShapes(g);
}
@Override public void processMouseMotionEvent(MouseEvent e) {
switch (e.getID()) {
case MouseEvent.MOUSE_MOVED:
hitTestAllShapes(e.getPoint());
break;
case MouseEvent.MOUSE_DRAGGED:
if (dragData != null) {
dragData.handleMouseDrag(e);
repaint();
}
break;
}
}
@Override public void processMouseEvent(MouseEvent e) {
Shape firstShape = null;
switch (e.getID()) {
case MouseEvent.MOUSE_CLICKED:
firstShape = findFirstShapeHit(e.getPoint());
if (firstShape != null) {
handleShapeClicked(firstShape);
firstShape.setColor(colorSelection);
this.repaint();
}
break;
case MouseEvent.MOUSE_PRESSED:
firstShape = findFirstShapeHit(e.getPoint());
if (firstShape != null) {
dragData = new DragData(e.getPoint(), firstShape);
}
break;
case MouseEvent.MOUSE_RELEASED:
dragData = null;
break;
}
}
public void OnHitTestChange() {
repaint();
}
}
class DrawingArea extends DrawingAreaBase {
ArrayList<Shape> shapelist = new ArrayList<Shape>();
abstract public double getTotalShapeArea();
public void renderShapes(Graphics g) {
for (int i = 0; i <= shapelist.size() - 1; i++) {
shapelist.get(i).render(g);
}
}
abstract public Shape findFirstShapeHit(Point point);
abstract public void handleShapeClicked(Shape shape);
abstract public void hitTestAllShapes(Point point);
public void addShape(Shape s) {
shapelist.add(s);
}
abstract public void removeAllShapes();
}
public class ShapePanel extends JFrame {
private DrawingArea panel;
private ShapeFactory factory;
public ShapePanel() {
panel = new DrawingArea();
panel.setBackground(Color.white);
factory = new ShapeFactory();
JPanel content = new JPanel();
content.setLayout(new BoxLayout(content, BoxLayout.Y_AXIS));
// for all supported shapes, add a button to add a new instance of that shape
JPanel buttons = new JPanel();
content.add(buttons);
buttons.setLayout(new BoxLayout(buttons, BoxLayout.X_AXIS));
for (final String shapeType : factory.getSupportedShapes()) {
JButton button = new JButton("New " + shapeType.toLowerCase());
button.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
Shape s = factory.createShape(shapeType, panel.getWidth(), panel.getHeight());
if (s.getArea() > panel.getWidth() * panel.getHeight() * 0.25) {
throw new RuntimeException("Shape should not be larger than 25% of panel");
}
s.setColor(panel.getColorSelection());
panel.addShape(s);
panel.refreshBackgroundColorByShapeArea();
}
});
buttons.add(button);
}
JButton buttonClear = new JButton("Clear");
buttonClear.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
panel.removeAllShapes();
panel.refreshBackgroundColorByShapeArea();
}
});
buttons.add(buttonClear);
// TODO (Bonus) - create a color toolbar that will allow the user to change the color of the next clicked on shape
//Color[] colors = {Color.BLACK, Color.RED, Color.GREEN, Color.BLUE, Color.CYAN, Color.MAGENTA, Color.ORANGE, Color.YELLOW, Color.PINK};
content.add(panel);
//... Set window characteristics
setContentPane(content);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setTitle("Shape Panel");
setLocationRelativeTo(null); // Center window.
pack();
}
public static void main(String[] args) {
JFrame window = new ShapePanel();
window.setVisible(true);
}
}
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