org.eclipse.ant.internal.ui.ColumnSorter.java Source code

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Here is the source code for org.eclipse.ant.internal.ui.ColumnSorter.java

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/*******************************************************************************
 * Copyright (c) 2009, 2011 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.ant.internal.ui;

import org.eclipse.ant.internal.core.IAntCoreConstants;
import org.eclipse.ant.internal.ui.preferences.AntObjectLabelProvider;
import org.eclipse.jface.viewers.ColumnViewer;
import org.eclipse.jface.viewers.Viewer;
import org.eclipse.jface.viewers.ViewerComparator;
import org.eclipse.swt.SWT;
import org.eclipse.swt.events.SelectionAdapter;
import org.eclipse.swt.events.SelectionEvent;
import org.eclipse.swt.widgets.TableColumn;

/**
 * A sorter that can be attached to a given column in a given viewer. This comparator uses the {@link AntObjectLabelProvider} to get the text to
 * compare
 * 
 * @since 3.5
 */
public abstract class ColumnSorter extends ViewerComparator {

    private ColumnViewer cviewer = null;
    private TableColumn column = null;
    private int direction = SWT.DOWN;
    private int columnidx = 0;

    /**
     * Constructor
     * 
     * @param cviewer
     * @param column
     */
    public ColumnSorter(ColumnViewer cviewer, TableColumn column) {
        this.cviewer = cviewer;
        this.column = column;
        this.columnidx = getColumnIndex();
        this.column.addSelectionListener(new SelectionAdapter() {
            @Override
            public void widgetSelected(SelectionEvent e) {
                if (ColumnSorter.this.cviewer.getComparator() != ColumnSorter.this) {
                    setDirection(SWT.DOWN);
                } else {
                    int tdirection = ColumnSorter.this.column.getParent().getSortDirection();
                    if (tdirection == SWT.NONE) {
                        setDirection(SWT.DOWN);
                    } else {
                        setDirection(tdirection == SWT.UP ? SWT.DOWN : SWT.UP);
                    }
                }
            }
        });

    }

    /**
     * Returns the compare text that should be used for the given object coming from the given column index
     * 
     * @param obj
     * @param columnindex
     * @return the text to compare with
     */
    public abstract String getCompareText(Object obj, int columnindex);

    /**
     * Sets the sorting direction for this sorter to use
     * 
     * @param direction
     */
    public void setDirection(int direction) {
        this.column.getParent().setSortColumn(this.column);
        this.direction = direction;
        this.column.getParent().setSortDirection(this.direction);
        if (this.cviewer.getComparator() == this) {
            this.cviewer.refresh();
        } else {
            this.cviewer.setComparator(this);
        }
    }

    /**
     * @see org.eclipse.jface.viewers.ViewerComparator#compare(org.eclipse.jface.viewers.Viewer, java.lang.Object, java.lang.Object)
     */
    @Override
    public int compare(Viewer viewer, Object e1, Object e2) {
        String text1 = getCompareText(e1, this.columnidx);
        if (text1 == null) {
            text1 = IAntCoreConstants.EMPTY_STRING;
        }
        String text2 = getCompareText(e2, this.columnidx);
        if (text2 == null) {
            text2 = IAntCoreConstants.EMPTY_STRING;
        }
        return (this.direction == SWT.UP ? -1 : 1) * text1.compareTo(text2);
    }

    /**
     * Returns the index of the given column in the backing table for this page, or 0
     * 
     * @return the index of the column in the backing table for this page or 0
     */
    private int getColumnIndex() {
        int idx = this.column.getParent().indexOf(this.column);
        return (idx < 0 ? 0 : idx);
    }
}