checkboxtableviewer.java

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/*******************************************************************************
 * Copyright (c) 2000, 2006 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.jface.viewers;

import java.util.ArrayList;
import java.util.List;

import org.eclipse.core.runtime.ListenerList;
import org.eclipse.jface.util.Assert;
import org.eclipse.jface.util.SafeRunnable;
import org.eclipse.swt.SWT;
import org.eclipse.swt.events.SelectionEvent;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Table;
import org.eclipse.swt.widgets.TableColumn;
import org.eclipse.swt.widgets.TableItem;
import org.eclipse.swt.widgets.Widget;

/**
 * A concrete viewer based on an SWT <code>Table</code>
 * control with checkboxes on each node.
 * <p>
 * This class is not intended to be subclassed outside the viewer framework. 
 * It is designed to be instantiated with a pre-existing SWT table control and configured
 * with a domain-specific content provider, label provider, element filter (optional),
 * and element sorter (optional).
 * </p>
 */
public class CheckboxTableViewer extends TableViewer implements ICheckable {

    /**
     * List of check state listeners (element type: <code>ICheckStateListener</code>).
     */
    private ListenerList checkStateListeners = new ListenerList();

    /**
     * Creates a table viewer on a newly-created table control under the given parent.
     * The table control is created using the SWT style bits: 
     * <code>SWT.CHECK</code> and <code>SWT.BORDER</code>.
     * The table has one column.
     * The viewer has no input, no content provider, a default label provider, 
     * no sorter, and no filters.
     * <p>
     * This is equivalent to calling <code>new CheckboxTableViewer(parent, SWT.BORDER)</code>.
     * See that constructor for more details.
     * </p>
     *
     * @param parent the parent control
     * 
     * @deprecated use newCheckList(Composite, int) or new CheckboxTableViewer(Table)
     *   instead (see below for details)
     */
    public CheckboxTableViewer(Composite parent) {
        this(parent, SWT.BORDER);
    }

    /**
     * Creates a table viewer on a newly-created table control under the given parent.
     * The table control is created using the given SWT style bits, plus the 
     * <code>SWT.CHECK</code> style bit.
     * The table has one column. 
     * The viewer has no input, no content provider, a default label provider, 
     * no sorter, and no filters.
     * <p>
     * This also adds a <code>TableColumn</code> for the single column, 
     * and sets a <code>TableLayout</code> on the table which sizes the column to fill 
     * the table for its initial sizing, but does nothing on subsequent resizes.
     * </p>
     * <p>
     * If the caller just needs to show a single column with no header,
     * it is preferable to use the <code>newCheckList</code> factory method instead,
     * since SWT properly handles the initial sizing and subsequent resizes in this case.
     * </p>
     * <p>
     * If the caller adds its own columns, uses <code>Table.setHeadersVisible(true)</code>, 
     * or needs to handle dynamic resizing of the table, it is recommended to  
     * create the <code>Table</code> itself, specifying the <code>SWT.CHECK</code> style bit 
     * (along with any other style bits needed), and use <code>new CheckboxTableViewer(Table)</code> 
     * rather than this constructor.
     * </p>
     * 
     * @param parent the parent control
     * @param style SWT style bits
     * 
     * @deprecated use newCheckList(Composite, int) or new CheckboxTableViewer(Table) 
     *   instead (see above for details)
     */
    public CheckboxTableViewer(Composite parent, int style) {
        this(createTable(parent, style));
    }

    /**
     * Creates a table viewer on a newly-created table control under the given parent.
     * The table control is created using the given SWT style bits, plus the 
     * <code>SWT.CHECK</code> style bit.
     * The table shows its contents in a single column, with no header.
     * The viewer has no input, no content provider, a default label provider, 
     * no sorter, and no filters.
     * <p>
     * No <code>TableColumn</code> is added. SWT does not require a 
     * <code>TableColumn</code> if showing only a single column with no header.
     * SWT correctly handles the initial sizing and subsequent resizes in this case.
     *
     * @param parent the parent control
     * @param style SWT style bits
     * 
     * @since 2.0
     * @return CheckboxTableViewer
     */
    public static CheckboxTableViewer newCheckList(Composite parent, int style) {
        Table table = new Table(parent, SWT.CHECK | style);
        return new CheckboxTableViewer(table);
    }

    /**
     * Creates a table viewer on the given table control.
     * The <code>SWT.CHECK</code> style bit must be set on the given table control.
     * The viewer has no input, no content provider, a default label provider, 
     * no sorter, and no filters.
     *
     * @param table the table control
     */
    public CheckboxTableViewer(Table table) {
        super(table);
    }

    /* (non-Javadoc)
     * Method declared on ICheckable.
     */
    public void addCheckStateListener(ICheckStateListener listener) {
        checkStateListeners.add(listener);
    }

    /**
     * Creates a new table control with one column.
     *
     * @param parent the parent control
     * @param style style bits
     * @return a new table control
     */
    protected static Table createTable(Composite parent, int style) {
        Table table = new Table(parent, SWT.CHECK | style);

        // Although this table column is not needed, and can cause resize problems,
        // it can't be removed since this would be a breaking change against R1.0.
        // See bug 6643 for more details.
        new TableColumn(table, SWT.NONE);
        TableLayout layout = new TableLayout();
        layout.addColumnData(new ColumnWeightData(100));
        table.setLayout(layout);

        return table;
    }

    /**
     * Notifies any check state listeners that a check state changed  has been received.
     * Only listeners registered at the time this method is called are notified.
     *
     * @param event a check state changed event
     *
     * @see ICheckStateListener#checkStateChanged
     */
    private void fireCheckStateChanged(final CheckStateChangedEvent event) {
        Object[] array = checkStateListeners.getListeners();
        for (int i = 0; i < array.length; i++) {
            final ICheckStateListener l = (ICheckStateListener) array[i];
            SafeRunnable.run(new SafeRunnable() {
                public void run() {
                    l.checkStateChanged(event);
                }
            });
        }
    }

    /* (non-Javadoc)
     * Method declared on ICheckable.
     */
    public boolean getChecked(Object element) {
        Widget widget = findItem(element);
        if (widget instanceof TableItem) {
            return ((TableItem) widget).getChecked();
        }
        return false;
    }

    /**
     * Returns a list of elements corresponding to checked table items in this
     * viewer.
     * <p>
     * This method is typically used when preserving the interesting
     * state of a viewer; <code>setCheckedElements</code> is used during the restore.
     * </p>
     *
     * @return the array of checked elements
     * @see #setCheckedElements
     */
    public Object[] getCheckedElements() {
        TableItem[] children = getTable().getItems();
        ArrayList v = new ArrayList(children.length);
        for (int i = 0; i < children.length; i++) {
            TableItem item = children[i];
            if (item.getChecked()) {
				v.add(item.getData());
			}
        }
        return v.toArray();
    }

    /**
     * Returns the grayed state of the given element.
     *
     * @param element the element