bundles/org.eclipse.ui.ide/src/org/eclipse/ui/ide/dialogs/AbstractEncodingFieldEditor.java - platform/eclipse.platform.ui - Git at Google

 /*******************************************************************************
  * Copyright (c) 2004, 2007 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
  *     Daniel Megert daniel_megert@ch.ibm.com Bug 169696
  *******************************************************************************/
 package org.eclipse.ui.ide.dialogs;

 import java.nio.charset.Charset;
 import java.nio.charset.IllegalCharsetNameException;
 import java.util.List;

 import org.eclipse.jface.preference.FieldEditor;
 import org.eclipse.jface.preference.IPreferenceStore;
 import org.eclipse.osgi.util.NLS;
 import org.eclipse.swt.SWT;
 import org.eclipse.swt.events.KeyAdapter;
 import org.eclipse.swt.events.KeyEvent;
 import org.eclipse.swt.events.SelectionAdapter;
 import org.eclipse.swt.events.SelectionEvent;
 import org.eclipse.swt.layout.GridData;
 import org.eclipse.swt.layout.GridLayout;
 import org.eclipse.swt.widgets.Button;
 import org.eclipse.swt.widgets.Combo;
 import org.eclipse.swt.widgets.Composite;
 import org.eclipse.swt.widgets.Group;
 import org.eclipse.ui.WorkbenchEncoding;
 import org.eclipse.ui.ide.IDEEncoding;
 import org.eclipse.ui.internal.ide.IDEWorkbenchMessages;

 /**
  * The abstract superclass of field editors used to set an encoding. Any user
  * entered encodings will be added to the list of encodings available via
  * {@link org.eclipse.ui.ide.IDEEncoding}.
  * <p>
  * Subclasses may extend, but must call <code>createEncodingGroup</code>
  * during <code>doFillIntoGrid</code>.
  * </p>
  *
  * @see org.eclipse.ui.ide.IDEEncoding
  * @since 3.1
  */
 public abstract class AbstractEncodingFieldEditor extends FieldEditor {

 	private Composite container;

 	private Button defaultEncodingButton;

 	private String defaultEnc;

 	private Button otherEncodingButton;

 	private Combo encodingCombo;

 	private boolean isValid = true;

 	private String oldSelectedEncoding;

 	private String groupTitle = IDEWorkbenchMessages.WorkbenchPreference_encoding;

 	/**
 	 * Creates a new encoding field editor with no settings set.
 	 */
 	protected AbstractEncodingFieldEditor() {
 		super();
 	}

 	/**
 	 * Creates a new encoding field editor with the given preference name, label
 	 * and parent.
 	 *
 	 * @param name
 	 *            the name of the preference this field editor works on
 	 * @param labelText
 	 *            the label text of the field editor
 	 * @param parent
 	 *            the parent of the field editor's control
 	 */
 	protected AbstractEncodingFieldEditor(String name, String labelText,
 			Composite parent) {
 		super(name, labelText, parent);
 	}

 	/**
 	 * Creates a new encoding field editor with the given preference name, label
 	 * and parent.
 	 *
 	 * @param name
 	 *            the name of the preference this field editor works on
 	 * @param labelText
 	 *            the label text of the field editor
 	 * @param groupTitle
 	 *            the title for the field editor's control. If groupTitle is
 	 *            <code>null</code> the control will be unlabelled
 	 *            (by default a {@link Composite} instead of a {@link Group}.
 	 * @param parent
 	 *            the parent of the field editor's control
 	 * @see AbstractEncodingFieldEditor#setGroupTitle(String)
 	 * @since 3.3
 	 */
 	protected AbstractEncodingFieldEditor(String name, String labelText,
 			String groupTitle, Composite parent) {
 		init(name, labelText);
 		this.groupTitle = groupTitle;
 		createControl(parent);
 	}

 	/*
 	 * (non-Javadoc)
 	 *
 	 * @see org.eclipse.jface.preference.FieldEditor#adjustForNumColumns(int)
 	 */
 	protected void adjustForNumColumns(int numColumns) {
 		((GridData) getContainer().getLayoutData()).horizontalSpan = numColumns;
 	}

 	/*
 	 * (non-Javadoc)
 	 *
 	 * @see org.eclipse.jface.preference.FieldEditor#doFillIntoGrid(org.eclipse.swt.widgets.Composite,
 	 *      int)
 	 */
 	protected void doFillIntoGrid(Composite parent, int numColumns) {
 		container = createEncodingGroup(parent, numColumns);
 	}

 	/*
 	 * (non-Javadoc)
 	 *
 	 * @see org.eclipse.jface.preference.FieldEditor#doLoad()
 	 */
 	protected void doLoad() {
 		if (encodingCombo != null) {
 			List encodings = IDEEncoding.getIDEEncodings();
 			String resourcePreference = getStoredValue();
 			populateEncodingsCombo(encodings, resourcePreference);
 			updateEncodingState(resourcePreference == null);
 		}
 	}

 	/**
 	 * Returns the value that is currently stored for the encoding.
 	 *
 	 * @return the currently stored encoding
 	 */
 	protected abstract String getStoredValue();

 	/*
 	 * (non-Javadoc)
 	 *
 	 * @see org.eclipse.jface.preference.FieldEditor#doLoadDefault()
 	 */
 	protected void doLoadDefault() {
 		updateEncodingState(true);
 	}

 	/*
 	 * (non-Javadoc)
 	 *
 	 * @see org.eclipse.jface.preference.FieldEditor#getNumberOfControls()
 	 */
 	public int getNumberOfControls() {
 		return 1;
 	}

 	/*
 	 * (non-Javadoc)
 	 *
 	 * @see org.eclipse.jface.preference.FieldEditor#isValid()
 	 */
 	public boolean isValid() {
 		return isValid;
 	}

 	/*
 	 * (non-Javadoc)
 	 *
 	 * @see org.eclipse.jface.preference.FieldEditor#refreshValidState()
 	 */
 	protected void refreshValidState() {
 		updateValidState();
 	}

 	/*
 	 * (non-Javadoc)
 	 *
 	 * @see org.eclipse.jface.preference.FieldEditor#setPreferenceStore(org.eclipse.jface.preference.IPreferenceStore)
 	 */
 	public void setPreferenceStore(IPreferenceStore store) {
 		super.setPreferenceStore(store);
 		defaultEnc = store.getDefaultString(getPreferenceName());
 		updateDefaultEncoding();
 	}

 	private void updateDefaultEncoding() {
 		defaultEncodingButton.setText(defaultButtonText());
 	}

 	private Composite getContainer() {
 		return container;
 	}

 	/**
 	 * Creates a composite with all the encoding controls.
 	 * <p>
 	 * Subclasses may extend.
 	 * </p>
 	 *
 	 * @param parent
 	 *            the parent widget
 	 * @param numColumns
 	 *            the number of columns in the parent
 	 * @return the group control
 	 */
 	protected Composite createEncodingGroup(Composite parent, int numColumns) {

 		Composite topControl;
 		GridLayout layout = new GridLayout();
 		layout.numColumns = 2;

 		if (groupTitle == null){
 			topControl = new Composite(parent, SWT.NONE);
 			layout.marginWidth = 0;
 			layout.marginHeight = 0;
 		}
 		else {
 			Group top = new Group(parent, SWT.NONE);
 			top.setText(groupTitle);
 			topControl = top;
 		}

 		GridData data = new GridData(GridData.FILL_HORIZONTAL);
 		topControl.setLayoutData(data);
 		topControl.setLayout(layout);

 		SelectionAdapter buttonListener = new SelectionAdapter() {
 			public void widgetSelected(SelectionEvent e) {
 				updateEncodingState(defaultEncodingButton.getSelection());
 				updateValidState();
 			}
 		};

 		defaultEncodingButton = new Button(topControl, SWT.RADIO);
 		defaultEnc = findDefaultEncoding();
 		defaultEncodingButton.setText(defaultButtonText());
 		data = new GridData();
 		data.horizontalSpan = 2;
 		defaultEncodingButton.setLayoutData(data);
 		defaultEncodingButton.addSelectionListener(buttonListener);

 		otherEncodingButton = new Button(topControl, SWT.RADIO);
 		otherEncodingButton
 				.setText(IDEWorkbenchMessages.WorkbenchPreference_otherEncoding);
 		otherEncodingButton.addSelectionListener(buttonListener);

 		encodingCombo = new Combo(topControl, SWT.NONE);
 		data = new GridData();
 		encodingCombo.setLayoutData(data);
 		encodingCombo.addSelectionListener(new SelectionAdapter() {
 			/*
 			 * (non-Javadoc)
 			 *
 			 * @see org.eclipse.swt.events.SelectionListener#widgetSelected(org.eclipse.swt.events.SelectionEvent)
 			 */
 			public void widgetSelected(SelectionEvent e) {
 				updateValidState();
 			}
 		});
 		encodingCombo.addKeyListener(new KeyAdapter() {
 			/*
 			 * (non-Javadoc)
 			 *
 			 * @see org.eclipse.swt.events.KeyListener#keyReleased(org.eclipse.swt.events.KeyEvent)
 			 */
 			public void keyReleased(KeyEvent e) {
 				updateValidState();
 			}
 		});

 		return topControl;
 	}

 	/*
 	 * (non-Javadoc)
 	 *
 	 * @see org.eclipse.jface.preference.FieldEditor#setEnabled(boolean,
 	 *      org.eclipse.swt.widgets.Composite)
 	 * @since 3.3
 	 */
 	public void setEnabled(boolean enabled, Composite parent) {
 		if (container != null)
 			container.setEnabled(enabled);
 		if (defaultEncodingButton != null)
 			defaultEncodingButton.setEnabled(enabled);
 		if (otherEncodingButton != null)
 			otherEncodingButton.setEnabled(enabled);
 		if (encodingCombo != null)
 			encodingCombo.setEnabled(enabled);

 	}

 	/**
 	 * Returns the default encoding for the object being shown.
 	 *
 	 * @return the default encoding for the object being shown
 	 */
 	protected String findDefaultEncoding() {
 		return WorkbenchEncoding.getWorkbenchDefaultEncoding();
 	}

 	/**
 	 * Returns the text for the default encoding button.
 	 *
 	 * @return the text for the default encoding button
 	 */
 	protected String defaultButtonText() {
 		return NLS.bind(
 				IDEWorkbenchMessages.WorkbenchPreference_defaultEncoding,
 				defaultEnc);
 	}

 	/**
 	 * Populates the encodings combo. Sets the text based on the selected
 	 * encoding. If there is no selected encoding, the text is set to the
 	 * default encoding.
 	 *
 	 * @param encodings
 	 *            the list of encodings (list of String)
 	 * @param selectedEncoding
 	 *            the selected encoding, or <code>null</code>
 	 */
 	private void populateEncodingsCombo(List encodings, String selectedEncoding) {
 		String[] encodingStrings = new String[encodings.size()];
 		encodings.toArray(encodingStrings);
 		encodingCombo.setItems(encodingStrings);

 		if (selectedEncoding == null) {
 			encodingCombo.setText(getDefaultEnc());
 		} else {
 			encodingCombo.setText(selectedEncoding);
 		}
 	}

 	private void updateEncodingState(boolean useDefault) {
 		defaultEncodingButton.setSelection(useDefault);
 		otherEncodingButton.setSelection(!useDefault);
 		if (useDefault) {
 			encodingCombo.setText(getDefaultEnc());
 		}
 		encodingCombo.setEnabled(!useDefault);
 		setPresentsDefaultValue(useDefault);
 		updateValidState();
 	}

 	private void updateValidState() {
 		boolean isValidNow = isEncodingValid();
 		if (isValidNow != isValid) {
 			isValid = isValidNow;
 			if (isValid) {
 				clearErrorMessage();
 			} else {
 				showErrorMessage(IDEWorkbenchMessages.WorkbenchPreference_unsupportedEncoding);
 			}
 			fireStateChanged(IS_VALID, !isValid, isValid);
 		}
 		String newValue = getSelectedEncoding();
 		if (isValid && !newValue.equals(oldSelectedEncoding)) {
 			fireValueChanged(VALUE, oldSelectedEncoding, newValue);
 			oldSelectedEncoding = newValue;
 		}
 	}

 	/**
 	 * Returns the currently selected encoding.
 	 *
 	 * @return the currently selected encoding
 	 */
 	protected String getSelectedEncoding() {
 		if (defaultEncodingButton.getSelection()) {
 			return defaultEnc;
 		}
 		return encodingCombo.getText();
 	}

 	private boolean isEncodingValid() {
 		return defaultEncodingButton.getSelection()
 				|| isValidEncoding(encodingCombo.getText());
 	}

 	/**
 	 * Returns whether or not the given encoding is valid.
 	 *
 	 * @param enc
 	 *            the encoding to validate
 	 * @return <code>true</code> if the encoding is valid, <code>false</code>
 	 *         otherwise
 	 */
 	private boolean isValidEncoding(String enc) {
 		try {
 			return Charset.isSupported(enc);
 		} catch (IllegalCharsetNameException e) {
 			// This is a valid exception
 			return false;
 		}

 	}

 	/**
 	 * Returns the default encoding.
 	 *
 	 * @return the default encoding
 	 */
 	protected String getDefaultEnc() {
 		return defaultEnc;
 	}

 	/**
 	 * Returns whether or not the encoding setting changed.
 	 *
 	 * @param encodingSetting
 	 *            the setting from the page.
 	 * @return boolean <code>true</code> if the resource encoding is the same
 	 *         as before.
 	 */
 	protected boolean hasSameEncoding(String encodingSetting) {

 		String current = getStoredValue();

 		if (encodingSetting == null) {
 			// Changed if default is selected and there is no setting
 			return current == null || current.length() == 0;
 		}
 		return encodingSetting.equals(current);
 	}

 	/**
 	 * Return whether or not the default has been selected.
 	 *
 	 * @return <code>true</code> if the default button has been selected.
 	 */
 	boolean isDefaultSelected() {
 		return defaultEncodingButton.getSelection();
 	}

 	/**
 	 * Set the title of the group to groupTitle. If this is not called a default
 	 * title is used. If groupTitle is <code>null</code> the control will be
 	 * unlabelled (by default a {@link Composite} instead of a {@link Group}.
 	 *
 	 * <strong>NOTE</strong> this value must be set before
 	 * {@link #createControl(Composite)} is called or it will be ignored.
 	 *
 	 * @param groupTitle
 	 *            The groupTitle to set.
      * @since 3.3
 	 */
 	public void setGroupTitle(String groupTitle) {
 		this.groupTitle = groupTitle;
 	}

 }
	/*******************************************************************************
	* Copyright (c) 2004, 2007 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
	* Daniel Megert daniel_megert@ch.ibm.com Bug 169696
	*******************************************************************************/
	package org.eclipse.ui.ide.dialogs;

	import java.nio.charset.Charset;
	import java.nio.charset.IllegalCharsetNameException;
	import java.util.List;

	import org.eclipse.jface.preference.FieldEditor;
	import org.eclipse.jface.preference.IPreferenceStore;
	import org.eclipse.osgi.util.NLS;
	import org.eclipse.swt.SWT;
	import org.eclipse.swt.events.KeyAdapter;
	import org.eclipse.swt.events.KeyEvent;
	import org.eclipse.swt.events.SelectionAdapter;
	import org.eclipse.swt.events.SelectionEvent;
	import org.eclipse.swt.layout.GridData;
	import org.eclipse.swt.layout.GridLayout;
	import org.eclipse.swt.widgets.Button;
	import org.eclipse.swt.widgets.Combo;
	import org.eclipse.swt.widgets.Composite;
	import org.eclipse.swt.widgets.Group;
	import org.eclipse.ui.WorkbenchEncoding;
	import org.eclipse.ui.ide.IDEEncoding;
	import org.eclipse.ui.internal.ide.IDEWorkbenchMessages;

	/**
	* The abstract superclass of field editors used to set an encoding. Any user
	* entered encodings will be added to the list of encodings available via
	* {@link org.eclipse.ui.ide.IDEEncoding}.
	* <p>
	* Subclasses may extend, but must call <code>createEncodingGroup</code>
	* during <code>doFillIntoGrid</code>.
	* </p>
	*
	* @see org.eclipse.ui.ide.IDEEncoding
	* @since 3.1
	*/
	public abstract class AbstractEncodingFieldEditor extends FieldEditor {

	private Composite container;

	private Button defaultEncodingButton;

	private String defaultEnc;

	private Button otherEncodingButton;

	private Combo encodingCombo;

	private boolean isValid = true;

	private String oldSelectedEncoding;

	private String groupTitle = IDEWorkbenchMessages.WorkbenchPreference_encoding;

	/**
	* Creates a new encoding field editor with no settings set.
	*/
	protected AbstractEncodingFieldEditor() {
	super();
	}

	/**
	* Creates a new encoding field editor with the given preference name, label
	* and parent.
	*
	* @param name
	* the name of the preference this field editor works on
	* @param labelText
	* the label text of the field editor
	* @param parent
	* the parent of the field editor's control
	*/
	protected AbstractEncodingFieldEditor(String name, String labelText,
	Composite parent) {
	super(name, labelText, parent);
	}

	/**
	* Creates a new encoding field editor with the given preference name, label
	* and parent.
	*
	* @param name
	* the name of the preference this field editor works on
	* @param labelText
	* the label text of the field editor
	* @param groupTitle
	* the title for the field editor's control. If groupTitle is
	* <code>null</code> the control will be unlabelled
	* (by default a {@link Composite} instead of a {@link Group}.
	* @param parent
	* the parent of the field editor's control
	* @see AbstractEncodingFieldEditor#setGroupTitle(String)
	* @since 3.3
	*/
	protected AbstractEncodingFieldEditor(String name, String labelText,
	String groupTitle, Composite parent) {
	init(name, labelText);
	this.groupTitle = groupTitle;
	createControl(parent);
	}

	/*
	* (non-Javadoc)
	*
	* @see org.eclipse.jface.preference.FieldEditor#adjustForNumColumns(int)
	*/
	protected void adjustForNumColumns(int numColumns) {
	((GridData) getContainer().getLayoutData()).horizontalSpan = numColumns;
	}

	/*
	* (non-Javadoc)
	*
	* @see org.eclipse.jface.preference.FieldEditor#doFillIntoGrid(org.eclipse.swt.widgets.Composite,
	* int)
	*/
	protected void doFillIntoGrid(Composite parent, int numColumns) {
	container = createEncodingGroup(parent, numColumns);
	}

	/*
	* (non-Javadoc)
	*
	* @see org.eclipse.jface.preference.FieldEditor#doLoad()
	*/
	protected void doLoad() {
	if (encodingCombo != null) {
	List encodings = IDEEncoding.getIDEEncodings();
	String resourcePreference = getStoredValue();
	populateEncodingsCombo(encodings, resourcePreference);
	updateEncodingState(resourcePreference == null);
	}
	}

	/**
	* Returns the value that is currently stored for the encoding.
	*
	* @return the currently stored encoding
	*/
	protected abstract String getStoredValue();

	/*
	* (non-Javadoc)
	*
	* @see org.eclipse.jface.preference.FieldEditor#doLoadDefault()
	*/
	protected void doLoadDefault() {
	updateEncodingState(true);
	}

	/*
	* (non-Javadoc)
	*
	* @see org.eclipse.jface.preference.FieldEditor#getNumberOfControls()
	*/
	public int getNumberOfControls() {
	return 1;
	}

	/*
	* (non-Javadoc)
	*
	* @see org.eclipse.jface.preference.FieldEditor#isValid()
	*/
	public boolean isValid() {
	return isValid;
	}

	/*
	* (non-Javadoc)
	*
	* @see org.eclipse.jface.preference.FieldEditor#refreshValidState()
	*/
	protected void refreshValidState() {
	updateValidState();
	}

	/*
	* (non-Javadoc)
	*
	* @see org.eclipse.jface.preference.FieldEditor#setPreferenceStore(org.eclipse.jface.preference.IPreferenceStore)
	*/
	public void setPreferenceStore(IPreferenceStore store) {
	super.setPreferenceStore(store);
	defaultEnc = store.getDefaultString(getPreferenceName());
	updateDefaultEncoding();
	}

	private void updateDefaultEncoding() {
	defaultEncodingButton.setText(defaultButtonText());
	}

	private Composite getContainer() {
	return container;
	}

	/**
	* Creates a composite with all the encoding controls.
	* <p>
	* Subclasses may extend.
	* </p>
	*
	* @param parent
	* the parent widget
	* @param numColumns
	* the number of columns in the parent
	* @return the group control
	*/
	protected Composite createEncodingGroup(Composite parent, int numColumns) {

	Composite topControl;
	GridLayout layout = new GridLayout();
	layout.numColumns = 2;

	if (groupTitle == null){
	topControl = new Composite(parent, SWT.NONE);
	layout.marginWidth = 0;
	layout.marginHeight = 0;
	}
	else {
	Group top = new Group(parent, SWT.NONE);
	top.setText(groupTitle);
	topControl = top;
	}

	GridData data = new GridData(GridData.FILL_HORIZONTAL);
	topControl.setLayoutData(data);
	topControl.setLayout(layout);

	SelectionAdapter buttonListener = new SelectionAdapter() {
	public void widgetSelected(SelectionEvent e) {
	updateEncodingState(defaultEncodingButton.getSelection());
	updateValidState();
	}
	};

	defaultEncodingButton = new Button(topControl, SWT.RADIO);
	defaultEnc = findDefaultEncoding();
	defaultEncodingButton.setText(defaultButtonText());
	data = new GridData();
	data.horizontalSpan = 2;
	defaultEncodingButton.setLayoutData(data);
	defaultEncodingButton.addSelectionListener(buttonListener);

	otherEncodingButton = new Button(topControl, SWT.RADIO);
	otherEncodingButton
	.setText(IDEWorkbenchMessages.WorkbenchPreference_otherEncoding);
	otherEncodingButton.addSelectionListener(buttonListener);

	encodingCombo = new Combo(topControl, SWT.NONE);
	data = new GridData();
	encodingCombo.setLayoutData(data);
	encodingCombo.addSelectionListener(new SelectionAdapter() {
	/*
	* (non-Javadoc)
	*
	* @see org.eclipse.swt.events.SelectionListener#widgetSelected(org.eclipse.swt.events.SelectionEvent)
	*/
	public void widgetSelected(SelectionEvent e) {
	updateValidState();
	}
	});
	encodingCombo.addKeyListener(new KeyAdapter() {
	/*
	* (non-Javadoc)
	*
	* @see org.eclipse.swt.events.KeyListener#keyReleased(org.eclipse.swt.events.KeyEvent)
	*/
	public void keyReleased(KeyEvent e) {
	updateValidState();
	}
	});

	return topControl;
	}

	/*
	* (non-Javadoc)
	*
	* @see org.eclipse.jface.preference.FieldEditor#setEnabled(boolean,
	* org.eclipse.swt.widgets.Composite)
	* @since 3.3
	*/
	public void setEnabled(boolean enabled, Composite parent) {
	if (container != null)
	container.setEnabled(enabled);
	if (defaultEncodingButton != null)
	defaultEncodingButton.setEnabled(enabled);
	if (otherEncodingButton != null)
	otherEncodingButton.setEnabled(enabled);
	if (encodingCombo != null)
	encodingCombo.setEnabled(enabled);

	}

	/**
	* Returns the default encoding for the object being shown.
	*
	* @return the default encoding for the object being shown
	*/
	protected String findDefaultEncoding() {
	return WorkbenchEncoding.getWorkbenchDefaultEncoding();
	}

	/**
	* Returns the text for the default encoding button.
	*
	* @return the text for the default encoding button
	*/
	protected String defaultButtonText() {
	return NLS.bind(
	IDEWorkbenchMessages.WorkbenchPreference_defaultEncoding,
	defaultEnc);
	}

	/**
	* Populates the encodings combo. Sets the text based on the selected
	* encoding. If there is no selected encoding, the text is set to the
	* default encoding.
	*
	* @param encodings
	* the list of encodings (list of String)
	* @param selectedEncoding
	* the selected encoding, or <code>null</code>
	*/
	private void populateEncodingsCombo(List encodings, String selectedEncoding) {
	String[] encodingStrings = new String[encodings.size()];
	encodings.toArray(encodingStrings);
	encodingCombo.setItems(encodingStrings);

	if (selectedEncoding == null) {
	encodingCombo.setText(getDefaultEnc());
	} else {
	encodingCombo.setText(selectedEncoding);
	}
	}

	private void updateEncodingState(boolean useDefault) {
	defaultEncodingButton.setSelection(useDefault);
	otherEncodingButton.setSelection(!useDefault);
	if (useDefault) {
	encodingCombo.setText(getDefaultEnc());
	}
	encodingCombo.setEnabled(!useDefault);
	setPresentsDefaultValue(useDefault);
	updateValidState();
	}

	private void updateValidState() {
	boolean isValidNow = isEncodingValid();
	if (isValidNow != isValid) {
	isValid = isValidNow;
	if (isValid) {
	clearErrorMessage();
	} else {
	showErrorMessage(IDEWorkbenchMessages.WorkbenchPreference_unsupportedEncoding);
	}
	fireStateChanged(IS_VALID, !isValid, isValid);
	}
	String newValue = getSelectedEncoding();
	if (isValid && !newValue.equals(oldSelectedEncoding)) {
	fireValueChanged(VALUE, oldSelectedEncoding, newValue);
	oldSelectedEncoding = newValue;
	}
	}

	/**
	* Returns the currently selected encoding.
	*
	* @return the currently selected encoding
	*/
	protected String getSelectedEncoding() {
	if (defaultEncodingButton.getSelection()) {
	return defaultEnc;
	}
	return encodingCombo.getText();
	}

	private boolean isEncodingValid() {
	return defaultEncodingButton.getSelection()
	\|\| isValidEncoding(encodingCombo.getText());
	}

	/**
	* Returns whether or not the given encoding is valid.
	*
	* @param enc
	* the encoding to validate
	* @return <code>true</code> if the encoding is valid, <code>false</code>
	* otherwise
	*/
	private boolean isValidEncoding(String enc) {
	try {
	return Charset.isSupported(enc);
	} catch (IllegalCharsetNameException e) {
	// This is a valid exception
	return false;
	}

	}

	/**
	* Returns the default encoding.
	*
	* @return the default encoding
	*/
	protected String getDefaultEnc() {
	return defaultEnc;
	}

	/**
	* Returns whether or not the encoding setting changed.
	*
	* @param encodingSetting
	* the setting from the page.
	* @return boolean <code>true</code> if the resource encoding is the same
	* as before.
	*/
	protected boolean hasSameEncoding(String encodingSetting) {

	String current = getStoredValue();

	if (encodingSetting == null) {
	// Changed if default is selected and there is no setting
	return current == null \|\| current.length() == 0;
	}
	return encodingSetting.equals(current);
	}

	/**
	* Return whether or not the default has been selected.
	*
	* @return <code>true</code> if the default button has been selected.
	*/
	boolean isDefaultSelected() {
	return defaultEncodingButton.getSelection();
	}

	/**
	* Set the title of the group to groupTitle. If this is not called a default
	* title is used. If groupTitle is <code>null</code> the control will be
	* unlabelled (by default a {@link Composite} instead of a {@link Group}.
	*
	* <strong>NOTE</strong> this value must be set before
	* {@link #createControl(Composite)} is called or it will be ignored.
	*
	* @param groupTitle
	* The groupTitle to set.
	* @since 3.3
	*/
	public void setGroupTitle(String groupTitle) {
	this.groupTitle = groupTitle;
	}

	}