/*
* Copyright (C) 2014 University of Dundee & Open Microscopy Environment.
* All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
package org.openmicroscopy.shoola.agents.metadata.rnd;
import java.beans.PropertyChangeListener;
import java.beans.PropertyChangeSupport;
import java.util.ArrayList;
import java.util.List;
import org.openmicroscopy.shoola.env.rnd.RndProxyDef;
/**
* Keeps track of changes to the rendering settings by managing a list of
* {@link RndProxyDef}s
*
* @author Dominik Lindner <a
* href="mailto:d.lindner@dundee.ac.uk">d.lindner@dundee.ac.uk</a>
*/
public class RenderingDefinitionHistory {
/** Property name for current undo ability */
public static final String CAN_UNDO = "canUndo";
/** Property name for current redo ability */
public static final String CAN_REDO = "canRedo";
/** Indicates that the previous action was an undo */
private static final int PREV_ACTION_BACKWARD = 1;
/** Indicates that the previous action was a redo */
private static final int PREV_ACTION_FORWARD = 2;
/** Reference to the PropertyChangeListeners */
private final PropertyChangeSupport pcs = new PropertyChangeSupport(this);
/** Previous rendering settings */
private List<RndProxyDef> history = new ArrayList<RndProxyDef>();
/** Pointer to the 'current' previous rendering settings */
private int pointer = -1;
/** Tracks the last action */
private int previousAction = 0;
/**
* Creates a new instance
*/
public RenderingDefinitionHistory() {
}
/**
* Clears the history
*/
public void reset() {
boolean oldU = canUndo();
boolean oldR = canRedo();
history.clear();
pointer = -1;
previousAction = 0;
this.pcs.firePropertyChange(CAN_UNDO, oldU, canUndo());
this.pcs.firePropertyChange(CAN_REDO, oldR, canRedo());
}
/**
* Returns the previous rendering settings, <code>null</code> if the history
* is empty
*
* @return See above
*/
public RndProxyDef getCurrent() {
if (history.isEmpty() || pointer<0)
return null;
if (pointer >= history.size())
throw new IllegalStateException(
"Pointer is not within the valid range: " + pointer
+ " [-1;" + (history.size() - 1) + "]");
return history.get(pointer);
}
/**
* Adds a {@link RndProxyDef} to the end of the history
*
* @param def
* The {@link RndProxyDef} to add
*/
public void add(RndProxyDef def) {
boolean oldU = canUndo();
boolean oldR = canRedo();
if (!history.isEmpty() && pointer < history.size() - 1)
trim();
history.add(def);
pointer = history.size() - 1;
this.pcs.firePropertyChange(CAN_UNDO, oldU, canUndo());
this.pcs.firePropertyChange(CAN_REDO, oldR, canRedo());
}
/**
* Resets the previous action flag to undefined
*/
public void resetPrevAction() {
previousAction = 0;
}
/**
* Moves the the pointer forward in history and returns that settings
*
* @return See above
*/
public RndProxyDef forward() {
boolean oldU = canUndo();
boolean oldR = canRedo();
// have to add an extra step when switching from undo to redo
if (previousAction==PREV_ACTION_BACKWARD)
pointer += 2;
else
pointer += 1;
this.pcs.firePropertyChange(CAN_UNDO, oldU, canUndo());
this.pcs.firePropertyChange(CAN_REDO, oldR, canRedo());
previousAction = PREV_ACTION_FORWARD;
return getCurrent();
}
/**
* Returns the previous settings and moves the pointer backwards in history.
*
* @param def
* The current state to add to the history before resetting to a
* previous one (is added to the end of the history)
* @return See above
*/
public RndProxyDef backward(RndProxyDef def) {
if (def == null) {
return backward();
}
boolean oldU = canUndo();
boolean oldR = canRedo();
if (!history.isEmpty() && pointer < history.size() - 1)
trim();
history.add(def);
// have to move an extra step back when switching from redo to undo
if (previousAction==PREV_ACTION_FORWARD)
pointer--;
RndProxyDef current = getCurrent();
pointer--;
this.pcs.firePropertyChange(CAN_UNDO, oldU, canUndo());
this.pcs.firePropertyChange(CAN_REDO, oldR, canRedo());
previousAction = PREV_ACTION_BACKWARD;
return current;
}
/**
* Returns the previous settings and moves the pointer backwards in history.
*
* @return See above
*/
public RndProxyDef backward() {
boolean oldU = canUndo();
boolean oldR = canRedo();
if (previousAction==PREV_ACTION_FORWARD)
pointer--;
RndProxyDef def = getCurrent();
pointer--;
this.pcs.firePropertyChange(CAN_UNDO, oldU, canUndo());
this.pcs.firePropertyChange(CAN_REDO, oldR, canRedo());
previousAction = PREV_ACTION_BACKWARD;
return def;
}
/**
* Checks if an undo operation is possible
*
* @return See above.
*/
public boolean canUndo() {
return !history.isEmpty() && pointer >= 0;
}
/**
* Checks if a redo operation is possible
*
* @return See above.
*/
public boolean canRedo() {
return !history.isEmpty() && pointer < history.size() - 1;
}
/**
* Adds a {@link PropertyChangeListener}
*
* @param listener
* The listener to add
*/
public void addPropertyChangeListener(PropertyChangeListener listener) {
this.pcs.addPropertyChangeListener(listener);
}
/**
* Removes a {@link PropertyChangeListener}
*
* @param listener
* The listener to remove
*/
public void removePropertyChangeListener(PropertyChangeListener listener) {
this.pcs.removePropertyChangeListener(listener);
}
/**
* Removes all history entries succeeding the current pointer.
*/
private void trim() {
history = history.subList(0, pointer + 1);
}
@Override
public String toString() {
return "RenderingDefinitionHistory [history.size()=" + history.size()
+ ", historyPointer=" + pointer + ", previousAction="+previousAction+"]";
}
}