SWTUtil.java example

Explorer
eclipse3-master
/*******************************************************************************
 * Copyright (c) 2010, 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.wst.sse.ui.internal.util;

import org.eclipse.core.runtime.Assert;
import org.eclipse.jface.dialogs.IDialogConstants;
import org.eclipse.jface.layout.PixelConverter;
import org.eclipse.jface.resource.JFaceResources;
import org.eclipse.swt.SWT;
import org.eclipse.swt.accessibility.AccessibleAdapter;
import org.eclipse.swt.accessibility.AccessibleEvent;
import org.eclipse.swt.dnd.DragSource;
import org.eclipse.swt.dnd.DropTarget;
import org.eclipse.swt.layout.GridData;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.Caret;
import org.eclipse.swt.widgets.Combo;
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;

/**
 * <p>
 * Utility class to simplify access to some SWT resources.
 * </p>
 * 
 * @base org.eclipse.jdt.internal.ui.util.SWTUtil
 */
public class SWTUtil {

  public static final int COMBO_VISIBLE_ITEM_COUNT = 30;

  /**
   * Returns the standard display to be used. The method first checks, if the thread calling this
   * method has an associated display. If so, this display is returned. Otherwise the method returns
   * the default display.
   * 
   * @return returns the standard display to be used
   */
  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.
   * 
   * @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();
    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;
  }

  /**
   * Returns a width hint for a button control.
   * 
   * @param button the button
   * @return the 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</code>.
   * 
   * @param button 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).widthHint = getButtonWidthHint(button);
      ((GridData) gd).horizontalAlignment = GridData.FILL;
    }
  }

  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;
  }

  /**
   * Adds an accessibility listener returning the given fixed name.
   * 
   * @param control the control to add the accessibility support to
   * @param text the name
   */
  public static void setAccessibilityText(Control control, final String text) {
    control.getAccessible().addAccessibleListener(new AccessibleAdapter() {
      public void getName(AccessibleEvent e) {
        e.result = text;
      }
    });
  }

  /**
   * @param combo the combo
   * @see Combo#setVisibleItemCount(int)
   * @see #COMBO_VISIBLE_ITEM_COUNT
   */
  public static void setDefaultVisibleItemCount(Combo combo) {
    combo.setVisibleItemCount(COMBO_VISIBLE_ITEM_COUNT);
  }

  public static GridLayout newLayoutNoMargins(int columns) {
    GridLayout layout = new GridLayout(columns, false);
    layout.marginWidth = 0;
    layout.marginHeight = 0;
    return layout;
  }

}