Mega Code Archive
Undoable Drawing
<![CDATA[
import java.awt.BorderLayout;
import java.awt.Component;
import java.awt.Graphics;
import java.awt.Polygon;
import java.awt.event.ActionEvent;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.util.Hashtable;
import javax.swing.AbstractAction;
import javax.swing.Action;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JToolBar;
import javax.swing.UIManager;
import javax.swing.event.UndoableEditListener;
import javax.swing.undo.CannotRedoException;
import javax.swing.undo.CannotUndoException;
import javax.swing.undo.StateEdit;
import javax.swing.undo.StateEditable;
import javax.swing.undo.UndoManager;
import javax.swing.undo.UndoableEditSupport;
public class UndoableDrawingPanel extends JPanel implements StateEditable {
private static String POLYGON_KEY = "Polygon";
UndoableEditSupport undoableEditSupport = new UndoableEditSupport(this);
Polygon polygon = new Polygon();
public UndoableDrawingPanel() {
MouseListener mouseListener = new MouseAdapter() {
public void mouseReleased(MouseEvent mouseEvent) {
StateEdit stateEdit = new StateEdit(UndoableDrawingPanel.this);
polygon.addPoint(mouseEvent.getX(), mouseEvent.getY());
stateEdit.end();
undoableEditSupport.postEdit(stateEdit);
repaint();
}
};
addMouseListener(mouseListener);
}
public void addUndoableEditListener(UndoableEditListener undoableEditListener) {
undoableEditSupport.addUndoableEditListener(undoableEditListener);
}
public void removeUndoableEditListener(UndoableEditListener undoableEditListener) {
undoableEditSupport.removeUndoableEditListener(undoableEditListener);
}
public void storeState(Hashtable state) {
state.put(POLYGON_KEY, getPolygon());
}
public void restoreState(Hashtable state) {
Polygon polygon = (Polygon) state.get(POLYGON_KEY);
if (polygon != null) {
setPolygon(polygon);
}
}
public void setPolygon(Polygon newValue) {
polygon = newValue;
repaint();
}
public Polygon getPolygon() {
Polygon returnValue;
if (polygon.npoints == 0) {
returnValue = new Polygon();
} else {
returnValue = new Polygon(polygon.xpoints, polygon.ypoints, polygon.npoints);
}
return returnValue;
}
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawPolygon(polygon);
}
public static void main(String args[]) {
JFrame frame = new JFrame("Drawing Sample2");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
UndoableDrawingPanel drawingPanel = new UndoableDrawingPanel();
UndoManager manager = new UndoManager();
drawingPanel.addUndoableEditListener(manager);
JToolBar toolbar = new JToolBar();
JButton undoButton = new JButton(UndoManagerHelper.getUndoAction(manager));
toolbar.add(undoButton);
JButton redoButton = new JButton(UndoManagerHelper.getRedoAction(manager));
toolbar.add(redoButton);
frame.add(toolbar, BorderLayout.NORTH);
frame.add(drawingPanel, BorderLayout.CENTER);
frame.setSize(300, 150);
frame.setVisible(true);
}
}
class UndoManagerHelper {
public static Action getUndoAction(UndoManager manager, String label) {
return new UndoAction(manager, label);
}
public static Action getUndoAction(UndoManager manager) {
return new UndoAction(manager, (String) UIManager.get("AbstractUndoableEdit.undoText"));
}
public static Action getRedoAction(UndoManager manager, String label) {
return new RedoAction(manager, label);
}
public static Action getRedoAction(UndoManager manager) {
return new RedoAction(manager, (String) UIManager.get("AbstractUndoableEdit.redoText"));
}
private abstract static class UndoRedoAction extends AbstractAction {
UndoManager undoManager = new UndoManager();
String errorMessage = "Cannot undo";
String errorTitle = "Undo Problem";
protected UndoRedoAction(UndoManager manager, String name) {
super(name);
undoManager = manager;
}
public void setErrorMessage(String newValue) {
errorMessage = newValue;
}
public void setErrorTitle(String newValue) {
errorTitle = newValue;
}
protected void showMessage(Object source) {
if (source instanceof Component) {
JOptionPane.showMessageDialog((Component) source, errorMessage, errorTitle,
JOptionPane.WARNING_MESSAGE);
} else {
System.err.println(errorMessage);
}
}
}
public static class UndoAction extends UndoRedoAction {
public UndoAction(UndoManager manager, String name) {
super(manager, name);
setErrorMessage("Cannot undo");
setErrorTitle("Undo Problem");
}
public void actionPerformed(ActionEvent actionEvent) {
try {
undoManager.undo();
} catch (CannotUndoException cannotUndoException) {
showMessage(actionEvent.getSource());
}
}
}
public static class RedoAction extends UndoRedoAction {
public RedoAction(UndoManager manager, String name) {
super(manager, name);
setErrorMessage("Cannot redo");
setErrorTitle("Redo Problem");
}
public void actionPerformed(ActionEvent actionEvent) {
try {
undoManager.redo();
} catch (CannotRedoException cannotRedoException) {
showMessage(actionEvent.getSource());
}
}
}
}
]]>