State pattern in Java 2
/*
The Design Patterns Java Companion
Copyright (C) 1998, by James W. Cooper
IBM Thomas J. Watson Research Center
*/
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Insets;
import java.awt.Rectangle;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionAdapter;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.util.Vector;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JToggleButton;
import javax.swing.JToolBar;
public class StateDraw extends JFrame implements ActionListener {
JToolBar tbar;
Mediator med;
public StateDraw() {
super("State Drawing");
addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
JPanel jp = new JPanel();
getContentPane().add(jp);
med = new Mediator();
jp.setLayout(new BorderLayout());
tbar = new JToolBar();
tbar.setFloatable(false);
jp.add("North", tbar);
PickButton pick = new PickButton(this, med);
tbar.add(pick);
tbar.addSeparator();
RectButton rect = new RectButton(this, med);
tbar.add(rect);
FillButton fill = new FillButton(this, med);
tbar.add(fill);
CircleButton circ = new CircleButton(this, med);
tbar.add(circ);
tbar.addSeparator();
ClearButton clr = new ClearButton(this, med);
tbar.add(clr);
JCanvas canvas = new JCanvas(med);
jp.add("Center", canvas);
MouseApp map = new MouseApp(med);
canvas.addMouseListener(map);
MouseMoveApp mvap = new MouseMoveApp(med);
canvas.addMouseMotionListener(mvap);
setSize(new Dimension(400, 300));
setVisible(true);
}
public void actionPerformed(ActionEvent e) {
Command comd = (Command) e.getSource();
comd.Execute();
}
static public void main(String[] argv) {
new StateDraw();
}
}
class MouseApp extends MouseAdapter {
Mediator med;
public MouseApp(Mediator md) {
super();
med = md;
}
public void mousePressed(MouseEvent e) {
med.mouseDown(e.getX(), e.getY());
}
public void mouseReleased(MouseEvent e) {
med.mouseUp(e.getX(), e.getY());
}
}
class MouseMoveApp extends MouseMotionAdapter {
Mediator med;
public MouseMoveApp(Mediator md) {
super();
med = md;
}
public void mouseDragged(MouseEvent e) {
med.mouseDrag(e.getX(), e.getY());
}
}
class ArrowState extends State {
private Mediator med;
public ArrowState(Mediator md) {
med = md;
}
public void mouseDown(int x, int y) {
Vector drawings = med.getDrawings();
for (int i = 0; i < drawings.size(); i++) {
Drawing d = (Drawing) drawings.elementAt(i);
if (d.contains(x, y))
med.setSelected(d);
}
}
}
class CircleState extends State {
private Mediator med; //save Mediator
public CircleState(Mediator md) {
med = md;
}
//Draw circle where mouse clicks
public void mouseDown(int x, int y) {
med.addDrawing(new visCircle(x, y));
}
}
class ClearButton extends JButton implements Command {
Mediator med;
public ClearButton(ActionListener act, Mediator md) {
super("C");
setToolTipText("Clear");
addActionListener(act);
med = md;
}
public void Execute() {
med.clear();
}
}
class CircleButton extends JToggleButton implements Command {
Mediator med;
public CircleButton(ActionListener act, Mediator md) {
super(" ");
setSize(new Dimension(35, 35));
setBorderPainted(true);
setMargin(new Insets(5, 12, 5, 12));
setToolTipText("Draw circle");
addActionListener(act);
med = md;
med.registerCircleButton(this);
}
public Dimension getPreferredSize() {
return new Dimension(35, 35);
}
public void paint(Graphics g) {
super.paint(g);
int h = getHeight();
int w = getWidth();
g.setColor(Color.black);
g.drawArc(2, 2, h - 4, h - 4, 0, 360);
}
public void Execute() {
med.startCircle();
}
}
class State {
public void mouseDown(int x, int y) {
}
public void mouseUp(int x, int y) {
}
public void mouseDrag(int x, int y) {
}
public void select(Drawing d, Color c) {
}
}
interface Command {
public void Execute();
}
class FillState extends State {
private Mediator med; //save Mediator
private Color color; //save current color
public FillState(Mediator md) {
med = md;
}
//Fill drawing if selected
public void select(Drawing d, Color c) {
color = c;
if (d != null) {
d.setFill(c); //fill that drawing
}
}
//Fill drawing if you click inside one
public void mouseDown(int x, int y) {
Vector drawings = med.getDrawings();
for (int i = 0; i < drawings.size(); i++) {
Drawing d = (Drawing) drawings.elementAt(i);
if (d.contains(x, y))
d.setFill(color); //fill drawing
}
}
}
class JCanvas extends JPanel {
Mediator med;
public JCanvas(Mediator md) {
med = md;
med.registerCanvas(this);
setBackground(Color.white);
}
public void paint(Graphics g) {
super.paint(g);
med.reDraw(g);
}
}
class Mediator {
boolean startRect;
boolean dSelected;
Vector drawings;
Vector undoList;
RectButton rectButton;
FillButton fillButton;
CircleButton circButton;
PickButton arrowButton;
JPanel canvas;
Drawing selectedDrawing;
StateManager stMgr;
public Mediator() {
startRect = false;
dSelected = false;
drawings = new Vector();
undoList = new Vector();
stMgr = new StateManager(this);
}
public void startRectangle() {
stMgr.setRect();
arrowButton.setSelected(false);
circButton.setSelected(false);
fillButton.setSelected(false);
}
public void startCircle() {
stMgr.setCircle();
rectButton.setSelected(false);
arrowButton.setSelected(false);
fillButton.setSelected(false);
}
public void startFill() {
stMgr.setFill();
rectButton.setSelected(false);
circButton.setSelected(false);
arrowButton.setSelected(false);
stMgr.select(selectedDrawing, Color.red);
repaint();
}
public void startArrow() {
stMgr.setArrow();
rectButton.setSelected(false);
circButton.setSelected(false);
fillButton.setSelected(false);
}
public Drawing getSelected() {
return selectedDrawing;
}
public void fillSelected() {
if (dSelected) {
selectedDrawing.setFill(Color.red);
}
}
public Vector getDrawings() {
return drawings;
}
public void addDrawing(Drawing d) {
drawings.addElement(d);
}
public void registerRectButton(RectButton rb) {
rectButton = rb;
}
public void registerCircleButton(CircleButton cb) {
circButton = cb;
}
public void registerArrowButton(PickButton ab) {
arrowButton = ab;
}
public void registerFillButton(FillButton fb) {
fillButton = fb;
}
public void registerCanvas(JPanel p) {
canvas = p;
}
public void mouseDown(int x, int y) {
stMgr.mouseDown(x, y);
repaint();
}
public void mouseUp(int x, int y) {
stMgr.mouseUp(x, y);
}
public void unpick() {
dSelected = false;
if (selectedDrawing != null) {
selectedDrawing.setSelected(false);
selectedDrawing = null;
repaint();
}
}
public void rememberPosition() {
if (dSelected) {
//Memento m = new Memento(d);
//undoList.addElement(m);
}
}
public void setSelected(Drawing d) {
if (d != null) {
dSelected = true;
selectedDrawing = d;
d.setSelected(true);
repaint();
}
}
public void pickRect(int x, int y) {
}
public void clear() {
drawings = new Vector();
undoList = new Vector();
dSelected = false;
selectedDrawing = null;
repaint();
}
private void repaint() {
canvas.repaint();
}
public void mouseDrag(int x, int y) {
stMgr.mouseDrag(x, y);
}
public void reDraw(Graphics g) {
g.setColor(Color.black);
for (int i = 0; i < drawings.size(); i++) {
Drawing v = (Drawing) drawings.elementAt(i);
v.draw(g);
}
}
public void undo() {
if (undoList.size() > 0) {
//get last element in undo list
Object obj = undoList.lastElement();
undoList.removeElement(obj); //and remove it
//if this is an Integer, the last action was a new rectangle
if (obj instanceof Integer) {
//remove last created rectangle
Object drawObj = drawings.lastElement();
drawings.removeElement(drawObj);
}
//if this is a Memento, the last action was a move
if (obj instanceof Memento) {
//get the Memento
Memento m = (Memento) obj;
m.restore(); //and restore the old position
}
repaint();
}
}
}
class RectButton extends JToggleButton implements Command {
Mediator med;
public RectButton(ActionListener act, Mediator md) {
super(" ");
setSize(new Dimension(35, 35));
setBorderPainted(true);
setMargin(new Insets(5, 12, 5, 12));
setToolTipText("Draw rectangle");
addActionListener(act);
med = md;
med.registerRectButton(this);
}
public Dimension getPreferredSize() {
return new Dimension(35, 35);
}
public void paint(Graphics g) {
super.paint(g);
int h = getHeight();
int w = getWidth();
g.setColor(Color.black);
g.drawRect(4, 4, w - 8, h - 8);
}
public void Execute() {
med.startRectangle();
}
}
class UndoButton extends JButton implements Command {
Mediator med;
public UndoButton(ActionListener act, Mediator md) {
super("U");
//setSize(new Dimension(25,25));
setMargin(new Insets(5, 12, 5, 12));
setToolTipText("Undo");
addActionListener(act);
med = md;
}
public void Execute() {
med.undo();
}
}
class FillButton extends JToggleButton implements Command {
Mediator med;
public FillButton(ActionListener act, Mediator md) {
super(" ");
setSize(new Dimension(35, 35));
setBorderPainted(true);
setMargin(new Insets(5, 12, 5, 12));
setToolTipText("Fill rectangle");
addActionListener(act);
med = md;
med.registerFillButton(this);
}
public Dimension getPreferredSize() {
return new Dimension(35, 35);
}
public void paint(Graphics g) {
super.paint(g);
int h = getHeight();
int w = getWidth();
g.setColor(Color.black);
g.drawRect(4, 4, w - 8, h - 8);
g.setColor(Color.red);
g.fillRect(4, 10, w - 8, h - 14);
}
public void Execute() {
if (isSelected()) {
med.startFill();
}
}
}
class Memento {
public Memento(Drawing d) {
}
public void restore() {
}
}
class RectState extends State {
private Mediator med; //save the Mediator here
public RectState(Mediator md) {
med = md;
}
//create a new Rectangle where mode clicks
public void mouseDown(int x, int y) {
med.addDrawing(new visRectangle(x, y));
}
}
class StateManager {
private State currentState;
RectState rState;
ArrowState aState;
CircleState cState;
FillState fState;
public StateManager(Mediator med) {
rState = new RectState(med);
cState = new CircleState(med);
aState = new ArrowState(med);
fState = new FillState(med);
currentState = aState;
}
public void setRect() {
currentState = rState;
}
public void setCircle() {
currentState = cState;
}
public void setFill() {
currentState = fState;
}
public void setArrow() {
currentState = aState;
}
public void mouseDown(int x, int y) {
currentState.mouseDown(x, y);
}
public void mouseUp(int x, int y) {
currentState.mouseUp(x, y);
}
public void mouseDrag(int x, int y) {
currentState.mouseDrag(x, y);
}
public void select(Drawing d, Color c) {
currentState.select(d, c);
}
}
class Drawing {
protected int x, y, w, h;
protected Rectangle rect;
protected boolean selected;
protected boolean filled;
protected Color fillColor;
//-------------------------------------------
public void setSelected(boolean b) {
selected = b;
}
public void draw(Graphics g) {
}
public void move(int xpt, int ypt) {
x = xpt;
y = ypt;
}
public boolean contains(int x, int y) {
return rect.contains(x, y);
}
protected void saveAsRect() {
rect = new Rectangle(x - w / 2, y - h / 2, w, h);
}
protected void setFill(Color c) {
filled = true;
fillColor = c;
}
}
class visCircle extends Drawing {
public visCircle(int xpt, int ypt) {
x = xpt;
y = ypt;
w = 40;
h = 30;
saveAsRect();
}
//-------------------------------------------
public void draw(Graphics g) {
g.drawArc(x, y, w, h, 0, 360);
if (filled) {
g.setColor(fillColor);
g.fillArc(x, y, w, h, 0, 360);
}
if (selected) {
g.setColor(Color.black);
g.fillRect(x + w / 2, y - 2, 4, 4);
g.fillRect(x - 2, y + h / 2, 4, 4);
g.fillRect(x + w / 2, y + h - 2, 4, 4);
g.fillRect(x + w - 2, y + h / 2, 4, 4);
}
}
}
//===============================================
class circleMemento extends Memento {
visCircle circ;
//saved fields- remember internal fields
//of the specified visual rectangle
int x, y, w, h;
public circleMemento(visCircle r) {
super(r);
circ = r;
x = circ.x;
y = circ.y;
w = circ.w;
h = circ.h;
}
//-------------------------------------------
public void restore() {
//restore the internal state of
//the specified rectangle
circ.x = x;
circ.y = y;
circ.h = h;
circ.w = w;
}
}
class visRectangle extends Drawing {
public visRectangle(int xpt, int ypt) {
x = xpt;
y = ypt;
w = 40;
h = 30;
saveAsRect();
}
//-------------------------------------------
public void draw(Graphics g) {
g.drawRect(x, y, w, h);
if (filled) {
g.setColor(fillColor);
g.fillRect(x, y, w, h);
}
if (selected) {
g.setColor(Color.black);
g.fillRect(x + w / 2, y - 2, 4, 4);
g.fillRect(x - 2, y + h / 2, 4, 4);
g.fillRect(x + w / 2, y + h - 2, 4, 4);
g.fillRect(x + w - 2, y + h / 2, 4, 4);
}
}
}
class rectMemento extends Memento {
visRectangle rect;
//saved fields- remember internal fields
//of the specified visual rectangle
int x, y, w, h;
public rectMemento(visRectangle r) {
super(r);
rect = r;
x = rect.x;
y = rect.y;
w = rect.w;
h = rect.h;
}
//-------------------------------------------
public void restore() {
//restore the internal state of
//the specified rectangle
rect.x = x;
rect.y = y;
rect.h = h;
rect.w = w;
}
}
class PickButton extends JToggleButton implements Command {
Mediator med;
public PickButton(ActionListener act, Mediator md) {
super(new ImageIcon("arrow.gif"));
setSize(new Dimension(35, 35));
setBorderPainted(true);
setMargin(new Insets(0, 0, 0, 0));
setToolTipText("Select drawing element");
addActionListener(act);
med = md;
med.registerArrowButton(this);
}
//-------------------------------------------
public void Execute() {
med.startArrow();
}
}
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