org.eclipse.compare.examples.xml.SWTUtil.java Source code

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Here is the source code for org.eclipse.compare.examples.xml.SWTUtil.java

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/*******************************************************************************
 * Copyright (c) 2000, 2008 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.compare.examples.xml;

import org.eclipse.core.runtime.Assert;
import org.eclipse.jface.dialogs.IDialogConstants;
import org.eclipse.swt.SWT;
import org.eclipse.swt.dnd.DragSource;
import org.eclipse.swt.dnd.DropTarget;
import org.eclipse.swt.graphics.GC;
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.Widget;

/**
 * Utility class to simplify access to some SWT resources. 
 */
public class SWTUtil {

    /*
     * Returns the standard display to be used. The method first checks, if
     * the thread calling this method has an associated disaply. If so, this
     * display is returned. Otherwise the method returns the default display.
     */
    public static Display getStandardDisplay() {
        Display 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</code> is returned.
     * 
     * @return the shell for the given widget
     */
    public static Shell getShell(Widget widget) {
        if (widget instanceof Control)
            return ((Control) widget).getShell();
        if (widget instanceof Caret)
            return ((Caret) widget).getParent().getShell();
        if (widget instanceof DragSource)
            return ((DragSource) widget).getControl().getShell();
        if (widget instanceof DropTarget)
            return ((DropTarget) widget).getControl().getShell();
        if (widget instanceof Menu)
            return ((Menu) widget).getParent().getShell();
        if (widget instanceof ScrollBar)
            return ((ScrollBar) widget).getParent().getShell();
        return null;
    }

    private static double getVerticalDialogUnitSize(Control control) {
        GC gc = new GC(control);
        try {
            int height = gc.getFontMetrics().getHeight();
            return height * 0.125;
        } finally {
            gc.dispose();
        }
    }

    private static double getHorizontalDialogUnitSize(Control control) {
        GC gc = new GC(control);
        try {
            int averageWidth = gc.getFontMetrics().getAverageCharWidth();
            return averageWidth * 0.25;
        } finally {
            gc.dispose();
        }
    }

    /*
     * @see DialogPage#convertHeightInCharsToPixels
     */
    public static int convertHeightInCharsToPixels(int chars, Control control) {
        return convertVerticalDLUsToPixels(chars * 8, control);
    }

    /*
     * @see DialogPage#convertHorizontalDLUsToPixels
     */
    public static int convertHorizontalDLUsToPixels(int dlus, Control control) {
        return (int) Math.round(dlus * getHorizontalDialogUnitSize(control));
    }

    /*
     * @see DialogPage#convertVerticalDLUsToPixels
     */
    public static int convertVerticalDLUsToPixels(int dlus, Control control) {
        return (int) Math.round(dlus * getVerticalDialogUnitSize(control));
    }

    /*
     * @see DialogPage#convertWidthInCharsToPixels
     */
    public static int convertWidthInCharsToPixels(int chars, Control control) {
        return convertHorizontalDLUsToPixels(chars * 4, control);
    }

    /*
     * Returns a width hint for a button control.
     */
    public static int getButtonWidthHint(Button button) {
        int widthHint = convertHorizontalDLUsToPixels(IDialogConstants.BUTTON_WIDTH, button);
        return Math.max(widthHint, button.computeSize(SWT.DEFAULT, SWT.DEFAULT, true).x);
    }

    /*
     * Returns a height hint for a button control.
     */
    //   public static int getButtonHeigthHint(Button button) {
    //      return convertVerticalDLUsToPixels(IDialogConstants.BUTTON_HEIGHT, button);
    //   }      

    /*
     * 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</code>.
     * 
     * @param   the button for which to set the dimension hint
     */
    public static void setButtonDimensionHint(Button button) {
        Assert.isNotNull(button);
        Object gd = button.getLayoutData();
        if (gd instanceof GridData) {
            //((GridData)gd).heightHint= getButtonHeigthHint(button);
            ((GridData) gd).widthHint = getButtonWidthHint(button);
        }
    }
}