UndoableEditSupport: removeUndoableEditListener(UndoableEditListener l) : UndoableEditSupport « javax.swing.undo « Java by API

1. Java by API
2. javax.swing.undo
3. UndoableEditSupport

UndoableEditSupport: removeUndoableEditListener(UndoableEditListener l)

import java.awt.BorderLayout;
import java.awt.Component;
import java.awt.Container;
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 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.AbstractUndoableEdit;
import javax.swing.undo.CannotRedoException;
import javax.swing.undo.CannotUndoException;
import javax.swing.undo.UndoManager;
import javax.swing.undo.UndoableEditSupport;

public class UndoDrawing {
  public static void main(String args[]) {
    JFrame frame = new JFrame("Drawing Sample");
    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);

    Container content = frame.getContentPane();
    content.add(toolbar, BorderLayout.NORTH);
    content.add(drawingPanel, BorderLayout.CENTER);
    frame.setSize(300, 150);
    frame.setVisible(true);
  }
}

class UndoableDrawEdit extends AbstractUndoableEdit {
  UndoableDrawingPanel panel;

  Polygon polygon, savedPolygon;

  public UndoableDrawEdit(UndoableDrawingPanel panel) {
    this.panel = panel;
    polygon = panel.getPolygon();
  }

  public String getPresentationName() {
    return "Polygon of size " + polygon.npoints;
  }

  public void redo() throws CannotRedoException {
    super.redo();
    if (savedPolygon == null) {
      // Should never get here, as super() doesn't permit redoing
      throw new CannotRedoException();
    } else {
      panel.setPolygon(savedPolygon);
      savedPolygon = null;
    }
  }

  public void undo() throws CannotUndoException {
    super.undo();
    savedPolygon = panel.getPolygon();
    panel.setPolygon(polygon);
  }
}

class UndoableDrawingPanel extends JPanel {
  UndoableEditSupport undoableEditSupport = new UndoableEditSupport(this);

  Polygon polygon = new Polygon();

  public UndoableDrawingPanel() {
    MouseListener mouseListener = new MouseAdapter() {
      public void mouseReleased(MouseEvent mouseEvent) {
        undoableEditSupport.postEdit(new UndoableDrawEdit(UndoableDrawingPanel.this));
        polygon.addPoint(mouseEvent.getX(), mouseEvent.getY());
        repaint();
      }
    };
    addMouseListener(mouseListener);
  }

  public void addUndoableEditListener(UndoableEditListener undoableEditListener) {
    undoableEditSupport.addUndoableEditListener(undoableEditListener);
  }

  public void removeUndoableEditListener(UndoableEditListener undoableEditListener) {
    undoableEditSupport.removeUndoableEditListener(undoableEditListener);
  }

  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);
  }
}

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());
      }
    }
  }
}

           
       

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