import java.awt.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;
import java.beans.XMLDecoder;
import java.beans.XMLEncoder;
import javax.imageio.ImageIO;
import javax.swing.*;
import java.io.*;
import java.util.ArrayList;
/**
* SimplePaintWithXMLEncoder is a drawing program in which the user can
* sketch curves. The user's work can be saved to a file which can later
* be reopened and edited. It is also possible to save the user's
* picture as an image file.
*
* This version of the program saves the user's work in XML format,
* using the XMLEncoder class to output the data and XMLDecoder to
* input it.
*/
public class SimplePaintWithXMLEncoder extends JFrame {
/**
* main routine creates a frame of type SimplePaintWithXMLEncoder
* and makes it visible on the screen.
*/
public static void main(String[] args) {
JFrame window = new SimplePaintWithXMLEncoder();
window.setVisible(true);
}
/**
* Constructor creates a window with a 600-by-600 pixel drawing area and
* sets its location so that it is centered on the screen. The window is
* not resizable. It is not made visible by this constructor.
*/
public SimplePaintWithXMLEncoder() {
super("SimplePaint: Untitled");
SimplePaintPanel content = new SimplePaintPanel();
setContentPane(content);
setJMenuBar(content.createMenuBar());
pack();
Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
setLocation( (screenSize.width - getWidth())/2 , (screenSize.height - getHeight())/2 );
setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
setResizable(false);
}
/**
* An object of type CurveData represents the data required to redraw one
* of the curves that have been sketched by the user. This class has been
* made public and get and set methods have been defined for its instance
* variables in order to make it possible for objects of type CurveData
* to be be written by an XMLEncoder and read by an XMLDecoder.
*/
public static class CurveData {
private Color color; // The color of the curve.
private boolean symmetric; // Are reflections also drawn?
private ArrayList<Point> points; // The points on the curve.
public Color getColor() {
return color;
}
public void setColor(Color color) {
this.color = color;
}
public ArrayList<Point> getPoints() {
return points;
}
public void setPoints(ArrayList<Point> points) {
this.points = points;
}
public boolean isSymmetric() {
return symmetric;
}
public void setSymmetric(boolean symmetric) {
this.symmetric = symmetric;
}
}
/**
* An object of type SimplePaintPanel is used as the drawing area in
* the window. This class does all the work of the program.
*/
private class SimplePaintPanel extends JPanel {
private ArrayList<CurveData> curves; // A list of all curves in the picture.
private Color currentColor; // When a curve is created, its color is taken
// from this variable. The value is changed
// using commands in the "Color" menu.
private boolean useSymmetry; // When a curve is created, its "symmetric"
// property is copied from this variable. Its
// value is set by the "Use Symmetry" command in
// the "Control" menu.
private File editFile; // The file that is being edited, if any.
// This is set when the user opens a file.
// The name of the file appears in the
// window's title bar.
private JFileChooser fileDialog; // The dialog box for all open/save commands.
/**
* Constructor. Sets background color to white, adds a gray border, sets up
* a listener for mouse and mouse motion events, and sets the preferred size
* of the panel to be 600-by-600.
*/
public SimplePaintPanel() {
curves = new ArrayList<CurveData>();
currentColor = Color.BLACK;
setBackground(Color.WHITE);
setBorder(BorderFactory.createLineBorder(Color.GRAY, 2));
MouseHandler listener = new MouseHandler();
addMouseListener(listener);
addMouseMotionListener(listener);
setPreferredSize( new Dimension(600,600) );
}
/**
* This class defines the object that is used as a mouse listener and mouse
* motion listener on this panel. When the user presses the mouse, a new
* CurveData object is created and is added to the ArrayList, curves. The
* color of the curve is copied from currentColor, and the symmetric property
* of the curve is copied from useSymmetry. As the user drags the mouse, points
* are added to the curve. If the user doesn't move the mouse, there will only
* be one point in the list of points; since this is not really a curve, the
* CurveData objects is removed in this case from the curves list in the
* mouseReleased method.
*/
private class MouseHandler implements MouseListener, MouseMotionListener {
CurveData currentCurve;
boolean dragging;
public void mousePressed(MouseEvent evt) {
if (dragging)
return;
dragging = true;
currentCurve = new CurveData();
currentCurve.color = currentColor;
currentCurve.symmetric = useSymmetry;
currentCurve.points = new ArrayList<Point>();
currentCurve.points.add( new Point(evt.getX(), evt.getY()) );
curves.add(currentCurve);
}
public void mouseDragged(MouseEvent evt) {
if (!dragging)
return;
currentCurve.points.add( new Point(evt.getX(),evt.getY()) );
repaint(); // redraw panel with newly added point.
}
public void mouseReleased(MouseEvent evt) {
if (!dragging)
return;
dragging = false;
if (currentCurve.points.size() < 2)
curves.remove(currentCurve);
currentCurve = null;
}
public void mouseClicked(MouseEvent evt) { }
public void mouseEntered(MouseEvent evt) { }
public void mouseExited(MouseEvent evt) { }
public void mouseMoved(MouseEvent evt) { }
} // end nested class MouseHandler
/**
* Fills the panel with the current background color and draws all the
* curves that have been sketched by the user.
*/
public void paintComponent(Graphics g) {
super.paintComponent(g);
for ( CurveData curve : curves) {
g.setColor(curve.color);
for (int i = 1; i < curve.points.size(); i++) {
// Draw a line segment from point number i-1 to point number i.
int x1 = curve.points.get(i-1).x;
int y1 = curve.points.get(i-1).y;
int x2 = curve.points.get(i).x;
int y2 = curve.points.get(i).y;
g.drawLine(x1,y1,x2,y2);
if (curve.symmetric) {
// Also draw the horizontal and vertical reflections
// of the line segment.
int w = getWidth();
int h = getHeight();
g.drawLine(w-x1,y1,w-x2,y2);
g.drawLine(x1,h-y1,x2,h-y2);
g.drawLine(w-x1,h-y1,w-x2,h-y2);
}
}
}
} // end paintComponent()
/**
* Creates a menu bar for use with this panel. It contains
* four menus: "File, "Control", "Color", and "BackgroundColor".
*/
public JMenuBar createMenuBar() {
/* Create the menu bar object */
JMenuBar menuBar = new JMenuBar();
/* Create the menu bar and add them to the menu bar. */
JMenu fileMenu = new JMenu("File");
JMenu controlMenu = new JMenu("Control");
JMenu colorMenu = new JMenu("Color");
JMenu bgColorMenu = new JMenu("BackgroundColor");
menuBar.add(fileMenu);
menuBar.add(controlMenu);
menuBar.add(colorMenu);
menuBar.add(bgColorMenu);
/* Add commands to the "File" menu. It contains New, Open, and
* Save commands. It also contains a command for saving the user's
* picture as a PNG image and a command for quitting the program.
*/
JMenuItem newCommand = new JMenuItem("New");
fileMenu.add(newCommand);
newCommand.addActionListener( new ActionListener() {
public void actionPerformed(ActionEvent evt) {
curves = new ArrayList<CurveData>();
setBackground(Color.WHITE);
useSymmetry = false;
currentColor = Color.BLACK;
setTitle("SimplePaint: Untitled");
editFile = null;
repaint();
}
});
fileMenu.addSeparator();
JMenuItem saveXML = new JMenuItem("Save (XML format)...");
fileMenu.add(saveXML);
saveXML.addActionListener( new ActionListener() {
public void actionPerformed(ActionEvent evt) {
doSaveAsXML();
}
});
JMenuItem openXML = new JMenuItem("Open (XML format)...");
fileMenu.add(openXML);
openXML.addActionListener( new ActionListener() {
public void actionPerformed(ActionEvent evt) {
doOpenAsXML();
}
});
fileMenu.addSeparator();
JMenuItem saveImage = new JMenuItem("Save Image...");
fileMenu.add(saveImage);
saveImage.addActionListener( new ActionListener() {
public void actionPerformed(ActionEvent evt) {
doSaveImage();
}
});
fileMenu.addSeparator();
JMenuItem quitCommand = new JMenuItem("Quit");
fileMenu.add(quitCommand);
quitCommand.addActionListener( new ActionListener() {
public void actionPerformed(ActionEvent evt) {
System.exit(0);
}
});
/* Add commands to the "Control" menu. It contains an Undo
* command that will remove the most recently drawn curve
* from the list of curves; a "Clear" command that removes
* all the curves that have been drawn; and a "Use Symmetry"
* checkbox that determines whether symmetry should be used.
*/
JMenuItem undo = new JMenuItem("Undo");
controlMenu.add(undo);
undo.addActionListener( new ActionListener() {
public void actionPerformed(ActionEvent evt) {
if (curves.size() > 0) {
curves.remove( curves.size() - 1);
repaint(); // Redraw without the curve that has been removed.
}
}
});
JMenuItem clear = new JMenuItem("Clear");
controlMenu.add(clear);
clear.addActionListener( new ActionListener() {
public void actionPerformed(ActionEvent evt) {
curves = new ArrayList<CurveData>();
repaint(); // Redraw with no curves shown.
}
});
JCheckBoxMenuItem sym = new JCheckBoxMenuItem("Use Symmetry");
controlMenu.add(sym);
sym.addActionListener( new ActionListener() {
public void actionPerformed(ActionEvent evt) {
useSymmetry = ((JCheckBoxMenuItem)evt.getSource()).isSelected();
// This does not affect the current drawing; it affects
// curves that are drawn in the future.
}
});
/**
* Add commands to the "Color" menu. The menu contains commands for
* setting the current drawing color. When the user chooses one of these
* commands, it has not immediate effect on the drawing. It justs sets
* the color that will be used for future drawing.
*/
colorMenu.add(makeColorMenuItem("Black", Color.BLACK));
colorMenu.add(makeColorMenuItem("White", Color.WHITE));
colorMenu.add(makeColorMenuItem("Red", Color.RED));
colorMenu.add(makeColorMenuItem("Green", Color.GREEN));
colorMenu.add(makeColorMenuItem("Blue", Color.BLUE));
colorMenu.add(makeColorMenuItem("Cyan", Color.CYAN));
colorMenu.add(makeColorMenuItem("Magenta", Color.MAGENTA));
colorMenu.add(makeColorMenuItem("Yellow", Color.YELLOW));
JMenuItem customColor = new JMenuItem("Custom...");
colorMenu.add(customColor);
customColor.addActionListener( new ActionListener() {
// The "Custom..." color command lets the user select the current
// drawing color using a JColorChoice dialog.
public void actionPerformed(ActionEvent evt) {
Color c = JColorChooser.showDialog(SimplePaintPanel.this,
"Select Drawing Color", currentColor);
if (c != null)
currentColor = c;
}
});
/**
* Add commands to the "BackgourndColor" menu. The menu contains commands
* for setting the background color of the panel. When the user chooses
* one of these commands, the panel is immediately redrawn with the new
* background color. Any curves that have been drawn are still there.
*/
bgColorMenu.add(makeBgColorMenuItem("Black", Color.BLACK));
bgColorMenu.add(makeBgColorMenuItem("White", Color.WHITE));
bgColorMenu.add(makeBgColorMenuItem("Red", Color.RED));
bgColorMenu.add(makeBgColorMenuItem("Green", Color.GREEN));
bgColorMenu.add(makeBgColorMenuItem("Blue", Color.BLUE));
bgColorMenu.add(makeBgColorMenuItem("Cyan", Color.CYAN));
bgColorMenu.add(makeBgColorMenuItem("Magenta", Color.MAGENTA));
bgColorMenu.add(makeBgColorMenuItem("Yellow", Color.YELLOW));
JMenuItem customBgColor = new JMenuItem("Custom...");
bgColorMenu.add(customBgColor);
customBgColor.addActionListener( new ActionListener() {
public void actionPerformed(ActionEvent evt) {
Color c = JColorChooser.showDialog(SimplePaintPanel.this,
"Select Background Color", getBackground());
if (c != null)
setBackground(c);
}
});
/* Return the menu bar that has been constructed. */
return menuBar;
} // end createMenuBar
/**
* This utility method is used to create a JMenuItem that sets the
* current drawing color.
* @param command the text that will appear in the menu
* @param color the drawing color that is selected by this command. (Note that
* this parameter is "final" for a technical reason: This is a requirement for
* a local variable that is used in an anonymous inner class.)
* @return the JMenuItem that has been created.
*/
private JMenuItem makeBgColorMenuItem(String command, final Color color) {
JMenuItem item = new JMenuItem(command);
item.addActionListener( new ActionListener() {
public void actionPerformed(ActionEvent evt) {
setBackground(color);
}
});
return item;
}
/**
* This utility method is used to create a JMenuItem that sets the
* background color of the panel.
* @param command the text that will appear in the menu
* @param color the background color that is selected by this command.
* @return the JMenuItem that has been created.
*/
private JMenuItem makeColorMenuItem(String command, final Color color) {
JMenuItem item = new JMenuItem(command);
item.addActionListener( new ActionListener() {
public void actionPerformed(ActionEvent evt) {
currentColor = color;
}
});
return item;
}
/**
* Save the user's image to a file in XML format. Files created by this method
* can be read back into the program using the doOpenAsXML() method. The
* data is written using an XMLEncoder.
*/
private void doSaveAsXML() {
if (fileDialog == null)
fileDialog = new JFileChooser();
File selectedFile; // Initially selected file name in the dialog.
if (editFile == null)
selectedFile = new File("sketchDataFromXMLEncoder.xml");
else
selectedFile = new File(editFile.getName());
fileDialog.setSelectedFile(selectedFile);
fileDialog.setDialogTitle("Select File to be Saved");
int option = fileDialog.showSaveDialog(this);
if (option != JFileChooser.APPROVE_OPTION)
return; // User canceled or clicked the dialog's close box.
selectedFile = fileDialog.getSelectedFile();
if (selectedFile.exists()) { // Ask the user whether to replace the file.
int response = JOptionPane.showConfirmDialog( this,
"The file \"" + selectedFile.getName()
+ "\" already exists.\nDo you want to replace it?",
"Confirm Save",
JOptionPane.YES_NO_OPTION,
JOptionPane.WARNING_MESSAGE );
if (response != JOptionPane.YES_OPTION)
return; // User does not want to replace the file.
}
XMLEncoder encoder;
try {
FileOutputStream stream = new FileOutputStream(selectedFile);
encoder = new XMLEncoder( stream );
}
catch (Exception e) {
JOptionPane.showMessageDialog(this,
"Sorry, but an error occurred while trying to open the file:\n" + e);
return;
}
try {
encoder.writeObject(getBackground());
encoder.writeObject(new Integer(curves.size()));
for (CurveData c : curves)
encoder.writeObject(c);
encoder.close();
editFile = selectedFile;
setTitle("SimplePaint: " + editFile.getName());
}
catch (Exception e) {
JOptionPane.showMessageDialog(this,
"Sorry, but an error occurred while trying to write the text:\n" + e);
}
}
/**
* Read image data from a file into the drawing area. The format
* of the file must be the same as that used in the doSaveAsXML()
* method. The data is read using an XMLDecoder.
*/
private void doOpenAsXML() {
if (fileDialog == null)
fileDialog = new JFileChooser();
fileDialog.setDialogTitle("Select File to be Opened");
fileDialog.setSelectedFile(null); // No file is initially selected.
int option = fileDialog.showOpenDialog(this);
if (option != JFileChooser.APPROVE_OPTION)
return; // User canceled or clicked the dialog's close box.
File selectedFile = fileDialog.getSelectedFile();
XMLDecoder decoder;
try {
FileInputStream stream = new FileInputStream(selectedFile);
decoder = new XMLDecoder( stream );
}
catch (Exception e) {
JOptionPane.showMessageDialog(this,
"Sorry, but an error occurred while trying to open the file:\n" + e);
return;
}
try {
Color bgColor = (Color)decoder.readObject();
Integer curveCt = (Integer)decoder.readObject();
ArrayList<CurveData> newCurves = new ArrayList<CurveData>();
for (int i = 0; i < curveCt; i++) {
CurveData c = (CurveData)decoder.readObject();
newCurves.add(c);
}
decoder.close();
curves = newCurves;
setBackground(bgColor);
repaint();
editFile = selectedFile;
setTitle("SimplePaint: " + editFile.getName());
}
catch (Exception e) {
JOptionPane.showMessageDialog(this,
"Sorry, but an error occurred while trying to read the data:\n" + e);
}
}
/**
* Saves the user's sketch as an image file in PNG format.
*/
private void doSaveImage() {
if (fileDialog == null)
fileDialog = new JFileChooser();
fileDialog.setSelectedFile(new File("sketch.png"));
fileDialog.setDialogTitle("Select File to be Saved");
int option = fileDialog.showSaveDialog(this);
if (option != JFileChooser.APPROVE_OPTION)
return; // User canceled or clicked the dialog's close box.
File selectedFile = fileDialog.getSelectedFile();
if (selectedFile.exists()) { // Ask the user whether to replace the file.
int response = JOptionPane.showConfirmDialog( this,
"The file \"" + selectedFile.getName()
+ "\" already exists.\nDo you want to replace it?",
"Confirm Save",
JOptionPane.YES_NO_OPTION,
JOptionPane.WARNING_MESSAGE );
if (response != JOptionPane.YES_OPTION)
return; // User does not want to replace the file.
}
try {
BufferedImage image; // A copy of the sketch will be drawn here.
image = new BufferedImage(600,600,BufferedImage.TYPE_INT_RGB);
Graphics g = image.getGraphics(); // For drawing onto the image.
paintComponent(g);
g.dispose();
boolean hasPNG = ImageIO.write(image,"PNG",selectedFile);
if ( ! hasPNG )
throw new Exception("PNG format not available.");
}
catch (Exception e) {
JOptionPane.showMessageDialog(this,
"Sorry, but an error occurred while trying to write the image:\n" + e);
}
}
}
}
