/*******************************************************************************
* Copyright (c) 2000, 2010 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package org.eclipse.draw2d;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.util.ArrayList;
import java.util.List;
/**
* A ButtonGroup holds a group of {@link Clickable Clickable's} models and
* provides unique selection in them. There is capability to add a default
* selection. Models who want to belong to the group should just add themselves
* to this group. By doing so they listen to this group for changes.
* <p>
* Setting of the default selection results in its being selected any time
* {@link #setSelected(ButtonModel, boolean)} is called. If no default selection
* is set, the last entry selected is not allowed to deselect.
*/
public class ButtonGroup {
private ButtonModel selectedModel;
private ButtonModel defaultModel;
private List members = new ArrayList();
private List listeners = new ArrayList();
/**
* Constructs a ButtonGroup with no default selection.
*
* @since 2.0
*/
public ButtonGroup() {
}
/**
* Adds the passed ButtonModel to the ButtonGroup.
*
* @param model
* ButtonModel to be added to this group
* @since 2.0
*/
public void add(ButtonModel model) {
if (!members.contains(model)) {
model.setGroup(this);
members.add(model);
}
}
/**
* Adds the passed listener. ButtonGroups use PropertyChangeListeners to
* react to selection changes in the ButtonGroup.
*
* @param listener
* Listener to be added to this group
* @since 2.0
*/
public void addPropertyChangeListener(PropertyChangeListener listener) {
listeners.add(listener);
}
/**
* Fires a PropertyChangeEvent to all PropertyChangeListeners added to this
* ButtonGroup.
*
* @param oldValue
* Old selection value
* @param newValue
* New selection value
* @since 2.0
*/
protected void firePropertyChange(Object oldValue, Object newValue) {
PropertyChangeEvent event = new PropertyChangeEvent(this,
ButtonModel.SELECTED_PROPERTY, oldValue, newValue);
for (int i = 0; i < listeners.size(); i++)
((PropertyChangeListener) listeners.get(i)).propertyChange(event);
}
/**
* Returns the ButtonModel which is selected by default for this
* ButtonGroup.
*
* @return The default ButtonModel
* @since 2.0
*/
public ButtonModel getDefault() {
return defaultModel;
}
/**
* Returns a List which contains all of the {@link ButtonModel ButtonModels}
* added to this ButtonGroup.
*
* @return The List of ButtonModels in this ButtonGroup
* @since 2.0
*/
public List getElements() {
return members;
}
/**
* Returns the ButtonModel for the currently selected button.
*
* @return The ButtonModel for the currently selected button
* @since 2.0
*/
public ButtonModel getSelected() {
return selectedModel;
}
/**
* Determines if the given ButtonModel is selected or not.
*
* @param model
* Model being tested for selected status
* @return Selection state of the given model
* @since 2.0
*/
public boolean isSelected(ButtonModel model) {
return (model == getSelected());
}
/**
* Removes the given ButtonModel from this ButtonGroup.
*
* @param model
* ButtonModel being removed
* @since 2.0
*/
public void remove(ButtonModel model) {
if (getSelected() == model)
setSelected(getDefault(), true);
if (defaultModel == model)
defaultModel = null;
members.remove(model);
}
/**
* Removes the passed PropertyChangeListener from this ButtonGroup.
*
* @param listener
* PropertyChangeListener to be removed
* @since 2.0
*/
public void removePropertyChangeListener(PropertyChangeListener listener) {
listeners.remove(listener);
}
/**
* Sets the passed ButtonModel to be the currently selected ButtonModel of
* this ButtonGroup. Fires a property change.
*
* @param model
* ButtonModel to be selected
* @since 2.0
*/
protected void selectNewModel(ButtonModel model) {
ButtonModel oldModel = selectedModel;
selectedModel = model;
if (oldModel != null)
oldModel.setSelected(false);
firePropertyChange(oldModel, model);
}
/**
* Sets the default selection of this ButtonGroup. Does nothing if it is not
* present in the group. Sets selection to the passed ButtonModel.
*
* @param model
* ButtonModel which is to be the default selection.
* @since 2.0
*/
public void setDefault(ButtonModel model) {
defaultModel = model;
if (getSelected() == null && defaultModel != null)
defaultModel.setSelected(true);
}
/**
* Sets the button with the given ButtonModel to be selected.
*
* @param model
* The ButtonModel to be selected
* @since 2.0
*/
public void setSelected(ButtonModel model) {
if (model == null)
selectNewModel(null);
else
model.setSelected(true);
}
/**
* Sets model to the passed state.
* <p>
* If <i>value</i> is
* <ul>
* <li><code>true</code>:
* <ul>
* <li>The passed ButtonModel will own selection.
* </ul>
* <li><code>false</code>:
* <ul>
* <li>If the passed model owns selection, it will lose selection, and
* selection will be given to the default ButonModel. If no default
* ButtonModel was set, selection will remain as it was, as one ButtonModel
* must own selection at all times.
* <li>If the passed model does not own selection, then selection will
* remain as it was.
* </ul>
* </ul>
*
* @param model
* The model to be affected
* @param value
* The selected state
* @since 2.0
*/
public void setSelected(ButtonModel model, boolean value) {
if (value) {
if (model == getSelected())
return;
selectNewModel(model);
} else {
if (model != getSelected())
return;
if (getDefault() == null)
return;
getDefault().setSelected(true);
}
}
}