org.webcat.eclipse.importer.SWTUtil.java Source code

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Here is the source code for org.webcat.eclipse.importer.SWTUtil.java

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/*==========================================================================*\
 |  $Id$
 |*-------------------------------------------------------------------------*|
 |  Copyright (C) 2006-2009 Virginia Tech
 |
 |  This file is part of Web-CAT Eclipse Plugins.
 |
 |  Web-CAT is free software; you can redistribute it and/or modify
 |  it under the terms of the GNU General Public License as published by
 |  the Free Software Foundation; either version 2 of the License, or
 |  (at your option) any later version.
 |
 |  Web-CAT is distributed in the hope that it will be useful,
 |  but WITHOUT ANY WARRANTY; without even the implied warranty of
 |  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 |  GNU General Public License for more details.
 |
 |  You should have received a copy of the GNU General Public License along
 |  with Web-CAT; if not, see <http://www.gnu.org/licenses/>.
\*==========================================================================*/

package org.webcat.eclipse.importer;

import org.eclipse.swt.SWT;
import org.eclipse.swt.dnd.DragSource;
import org.eclipse.swt.dnd.DropTarget;
import org.eclipse.swt.layout.GridData;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.Caret;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Menu;
import org.eclipse.swt.widgets.ScrollBar;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.swt.widgets.Table;
import org.eclipse.swt.widgets.Widget;

import org.eclipse.jface.dialogs.IDialogConstants;
import org.eclipse.jface.resource.JFaceResources;

//--------------------------------------------------------------------------
/**
 * A utility class used to simplify access to some SWT resources. This code is
 * adapted from code in the SWT source.
 *
 * @author  Tony Allevato (Virginia Tech Computer Science)
 * @author  latest changes by: $Author$
 * @version $Revision$ $Date$
 */
public class SWTUtil {
    // ----------------------------------------------------------
    /**
     * Returns the standard display to be used. The method first checks, if
     * the thread calling this method has an associated dispaly. If so, this
     * display is returned. Otherwise the method returns the default display.
     * 
     * @return the standard display
     */
    public static Display getStandardDisplay() {
        Display display = Display.getCurrent();

        if (display == null) {
            display = Display.getDefault();
        }

        return display;
    }

    // ----------------------------------------------------------
    /**
     * Returns the shell for the given widget. If the widget doesn't represent a
     * SWT object that manage a shell, {@code null} is returned.
     * 
     * @param widget the widget
     * @return the shell for the given widget
     */
    public static Shell getShell(Widget widget) {
        if (widget instanceof Control) {
            return ((Control) widget).getShell();
        } else if (widget instanceof Caret) {
            return ((Caret) widget).getParent().getShell();
        } else if (widget instanceof DragSource) {
            return ((DragSource) widget).getControl().getShell();
        } else if (widget instanceof DropTarget) {
            return ((DropTarget) widget).getControl().getShell();
        } else if (widget instanceof Menu) {
            return ((Menu) widget).getParent().getShell();
        } else if (widget instanceof ScrollBar) {
            return ((ScrollBar) widget).getParent().getShell();
        } else {
            return null;
        }
    }

    // ----------------------------------------------------------
    /**
     * Returns a width hint for a button control.
     * 
     * @param button the button
     * @return a width hint
     */
    public static int getButtonWidthHint(Button button) {
        button.setFont(JFaceResources.getDialogFont());

        PixelConverter converter = new PixelConverter(button);
        int widthHint = converter.convertHorizontalDLUsToPixels(IDialogConstants.BUTTON_WIDTH);

        return Math.max(widthHint, button.computeSize(SWT.DEFAULT, SWT.DEFAULT, true).x);
    }

    // ----------------------------------------------------------
    /**
     * Sets width and height hint for the button control. <b>Note:</b> This is
     * a NOP if the button's layout data is not an instance of
     * {@code GridData}.
     * 
     * @param button the button for which to set the dimension hint
     */
    public static void setButtonDimensionHint(Button button) {
        assert button != null;
        Object gd = button.getLayoutData();

        if (gd instanceof GridData) {
            ((GridData) gd).widthHint = getButtonWidthHint(button);
            ((GridData) gd).horizontalAlignment = GridData.FILL;
        }
    }

    // ----------------------------------------------------------
    /**
     * Returns an estimate of the height in pixels of a table with the
     * specified number of rows.
     * 
     * @param table the Table whose height should be calculated
     * @param rows the number of rows that should be used to estimate the
     *     height of the table
     * @return the estimated height of the table, in pixels
     */
    public static int getTableHeightHint(Table table, int rows) {
        if (table.getFont().equals(JFaceResources.getDefaultFont())) {
            table.setFont(JFaceResources.getDialogFont());
        }

        int result = table.getItemHeight() * rows + table.getHeaderHeight();

        if (table.getLinesVisible()) {
            result += table.getGridLineWidth() * (rows - 1);
        }

        return result;
    }
}