BrowserColumnViewerTip.java

/*
 * Copyright (c) 2012 Data Harmonisation Panel
 * 
 * All rights reserved. This program and the accompanying materials are made
 * available under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation, either version 3 of the License,
 * or (at your option) any later version.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with this distribution. If not, see <http://www.gnu.org/licenses/>.
 * 
 * Contributors:
 *     HUMBOLDT EU Integrated Project #030962
 *     Data Harmonisation Panel <http://www.dhpanel.eu>
 */

package eu.esdihumboldt.hale.ui.util.viewer;

import org.eclipse.jface.viewers.ColumnViewer;
import org.eclipse.jface.viewers.ViewerCell;
import org.eclipse.swt.events.MouseEvent;
import org.eclipse.swt.events.MouseTrackAdapter;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.graphics.Rectangle;
import org.eclipse.swt.widgets.Shell;

import eu.esdihumboldt.hale.ui.util.tip.BrowserTip;

/**
 * Enables a tool tip for a {@link ColumnViewer}
 * 
 * @author Simon Templer
 * @partner 01 / Fraunhofer Institute for Computer Graphics Research
 * @version $Id$
 */
public abstract class BrowserColumnViewerTip {

	private final BrowserTip tip;

	private final ColumnViewer viewer;

	private Shell toolShell = null;

	private ViewerCell toolCell = null;

	private int tipCharThreshold = 10;

	/**
	 * Constructor
	 * 
	 * @param viewer the viewer
	 * @param width the maximum tip width
	 * @param height the maximum tip height
	 * @param plainText if the tip text is plain text or HTML
	 */
	public BrowserColumnViewerTip(ColumnViewer viewer, int width, int height, boolean plainText) {
		super();

		this.viewer = viewer;

		viewer.getControl().addMouseTrackListener(new MouseTrackAdapter() {

			@Override
			public void mouseHover(MouseEvent e) {
				showToolTip(e.x - 1, e.y - 1);
			}

		});

		tip = new BrowserTip(width, height, plainText);
		tip.setHeightAdjustment(5);
	}

	/**
	 * Show tooltip for the cell at the given position
	 * 
	 * @param x the widget relative x ordinate
	 * @param y the widget relative y ordinate
	 */
	protected void showToolTip(int x, int y) {
		ViewerCell cell = viewer.getCell(new Point(x, y));

		if (toolCell != null && toolCell.equals(cell) && BrowserTip.toolTipVisible(toolShell)) {
			// tooltip already visible -> do nothing
			return;
		}

		toolCell = cell;
		BrowserTip.hideToolTip(toolShell);

		if (cell != null) {
			Object element = cell.getElement();
			int col = cell.getColumnIndex();

			/**
			 * It would be very nice if we could get the column from the viewer
			 * and the attached label provider, but the getViewerColumn method
			 * is only package visible
			 */

			String text = cell.getText();

			String tipText = getToolTip(element, col, text);

			if (tipText != null && !tipText.isEmpty() && tipText.length() >= tipCharThreshold) {
				Rectangle cellBounds = cell.getBounds();
//				toolShell = tip.showToolTip(viewer.getControl(), x, y, tipText);
				toolShell = tip.showToolTip(viewer.getControl(), cellBounds.x, cellBounds.y
						+ cellBounds.height, tipText, cellBounds, viewer.getControl());
			}
		}
	}

	/**
	 * Get the tool tip for a viewer cell
	 * 
	 * @param element the element defining the viewer row
	 * @param col the column index
	 * @param text the cell text
	 * 
	 * @return the tool tip, <code>null</code> if no tool tip shall be shown
	 */
	protected abstract String getToolTip(Object element, int col, String text);

}