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InheritanceExercise
DrawingPanel.java
import java.util.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
/**
* A class that stores a list of objects to draw on itself
* Use the following keys:
* Arrow keys move the currently selected item (highlighted yellow)
* n toggle to the next item
* t move the selected item to the top
* b move the selected item to the bottom
*
* @author Chuck Cusack
* @version 1.0, September, 2006
*/
public class DrawingPanel extends JPanel implements KeyListener, MouseListener {
private ArrayList<Object> theObjects; // The list of GraphicalObjects on the panel
private Object selectedObject; // The item on the panel that is currently selected.
/**
* Constructor for objects of class DrawingPanel
*/
public DrawingPanel()
{
theObjects=new ArrayList<Object>();
selectedObject=null;
setFocusable(true);
addMouseListener(this);
addKeyListener(this);
repaint();
}
/**
* Method overridden so that the JPanel canvas will be painted
* how we want it.
* For now, we just paint the various objects onto it.
*/
public void paintComponent(Graphics g) {
super.paintComponent(g);
for(int i=0;i<theObjects.size();i++) {
Object currentObject = theObjects.get(i);
if(currentObject instanceof Oval) {
Oval oval = (Oval) currentObject;
if(oval==selectedObject) { // highlight if selected
Color oldColor=g.getColor();
g.setColor(Color.yellow);
int x=oval.getX()-2;
int y=oval.getY()-2;
int width=oval.getWidth()+4;
int height=oval.getHeight()+4;
g.fillRect(x,y,width,height);
// Reset the color back to the original.
g.setColor(oldColor);
}
oval.drawObject(g);
} else if(currentObject instanceof Rectangle) {
Rectangle rect = (Rectangle) currentObject;
if(rect==selectedObject) { // highlight if selected
Color oldColor=g.getColor();
g.setColor(Color.yellow);
int x=rect.getX()-2;
int y=rect.getY()-2;
int width=rect.getWidth()+4;
int height=rect.getHeight()+4;
g.fillRect(x,y,width,height);
// Reset the color back to the original.
g.setColor(oldColor);
}
rect.drawObject(g);
} else if(currentObject instanceof BasicString) {
BasicString string = (BasicString) currentObject;
if(string==selectedObject) { // highlight if selected
Color oldColor=g.getColor();
g.setColor(Color.yellow);
int x=string.getX()-2;
int y=string.getY()-2;
int width=10; // BasicStrings do not have width and height
int height=10; // I think 10 is about right....
g.fillRect(x,y,width,height);
// Reset the color back to the original.
g.setColor(oldColor);
}
string.drawObject(g);
}
}
}
/**
* Add the given object to the panel.
*
* @param go The object to add to the panel.
*/
public void addObject(Object go) {
theObjects.add(go);
repaint();
}
/**
* Remove the given object from the panel.
*
* @param go The object to remove from the panel.
* @returns true if the object was on the list and
* it was removed, and false otherwise.
*/
public boolean removeObject(Object go) {
if(theObjects.remove(go)) {
repaint();
return true;
} else {
return false;
}
}
/**
* @returns the GraphicalObject that is currently selected
*/
public Object getSelectedObject() {
return selectedObject;
}
/**
* Sets the selected item to be the given object, if that
* object is on the list. Otherwise, does nothing.
* @param object the item to make selected
* @returns true if object is on the list, and false otherwise
*/
public boolean setSelectedObject(Object object) {
if(theObjects.contains(object)) {
selectedObject=object;
repaint();
return true;
} else {
return false;
}
}
/**
* Sets the selected item to be the object with the
* given index, if the index is within the proper range.
*
* @param index the index of the item to set as selected.
* @returns true if object is on the list, and false otherwise
*/
public boolean setSelectedObject(int index) {
if(index<0 || index >= theObjects.size()) {
return false;
} else {
selectedObject=theObjects.get(index);
repaint();
return true;
}
}
/**
* @returns how many objects are on the panel
*/
public int getNumberObjects() {
return theObjects.size();
}
/*
* The following are from the KeyListener interface
*
*/
public void keyPressed(KeyEvent e) {
// This is implemented here and not in keyTyped because keyTyped
// does not listen to non-printing keys (like arrow keys)
// Very irritating, and this was tough to figure out, which is
// why I am documenting it.
if(selectedObject!=null) {
switch (e.getKeyCode()) {
case KeyEvent.VK_UP:
if(selectedObject instanceof Oval) {
Oval oval = (Oval) selectedObject;
oval.setY(oval.getY()-10);
} else if(selectedObject instanceof Rectangle) {
Rectangle rect = (Rectangle) selectedObject;
rect.setY(rect.getY()-10);
} else if(selectedObject instanceof BasicString) {
BasicString string = (BasicString) selectedObject;
string.setY(string.getY()-10);
}
break;
case KeyEvent.VK_DOWN:
if(selectedObject instanceof Oval) {
Oval oval = (Oval) selectedObject;
oval.setY(oval.getY()+10);
} else if(selectedObject instanceof Rectangle) {
Rectangle rect = (Rectangle) selectedObject;
rect.setY(rect.getY()+10);
} else if(selectedObject instanceof BasicString) {
BasicString string = (BasicString) selectedObject;
string.setY(string.getY()+10);
}
break;
case KeyEvent.VK_RIGHT:
if(selectedObject instanceof Oval) {
Oval oval = (Oval) selectedObject;
oval.setX(oval.getX()+10);
} else if(selectedObject instanceof Rectangle) {
Rectangle rect = (Rectangle) selectedObject;
rect.setX(rect.getX()+10);
} else if(selectedObject instanceof BasicString) {
BasicString string = (BasicString) selectedObject;
string.setX(string.getX()+10);
}
break;
case KeyEvent.VK_LEFT:
if(selectedObject instanceof Oval) {
Oval oval = (Oval) selectedObject;
oval.setX(oval.getX()-10);
} else if(selectedObject instanceof Rectangle) {
Rectangle rect = (Rectangle) selectedObject;
rect.setX(rect.getX()-10);
} else if(selectedObject instanceof BasicString) {
BasicString string = (BasicString) selectedObject;
string.setX(string.getX()-10);
}
break;
default:
}
repaint();
}
}
public void keyTyped(KeyEvent e) {
if(selectedObject!=null) {
switch (e.getKeyChar()) {
case 't':
theObjects.remove(selectedObject);
theObjects.add(selectedObject);
break;
case 'b':
theObjects.remove(selectedObject);
theObjects.add(0,selectedObject);
break;
case 'n':
int index=theObjects.indexOf(selectedObject);
index=(index+1)%theObjects.size();
selectedObject = theObjects.get(index);
break;
default:
}
repaint();
}
}
public void keyReleased(KeyEvent e) {
}
/*
* Methods from the MouseListener interface
* We don't need them all, but we have to implement them all
* anyway.
*/
public void mouseEntered(MouseEvent e) {
}
public void mouseExited(MouseEvent e) {
}
public void mouseClicked(MouseEvent e) {
// Need to do this so the panel gets focus so it can
// handle key events. Without this, it doesn't get key events.
requestFocusInWindow();
}
public void mousePressed(MouseEvent e) {
}
public void mouseReleased(MouseEvent e) {
}
}
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