HorizontalPanelDropController.java

/*******************************************************************************
 * This file is part of OpenNMS(R).
 *
 * Copyright (C) 2010-2011 The OpenNMS Group, Inc.
 * OpenNMS(R) is Copyright (C) 1999-2011 The OpenNMS Group, Inc.
 *
 * OpenNMS(R) is a registered trademark of The OpenNMS Group, Inc.
 *
 * OpenNMS(R) 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 3 of the License,
 * or (at your option) any later version.
 *
 * OpenNMS(R) 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 OpenNMS(R).  If not, see:
 *      http://www.gnu.org/licenses/
 *
 * For more information contact:
 *     OpenNMS(R) Licensing <license@opennms.org>
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package org.opennms.features.dashboard.client.dnd;

import com.google.gwt.user.client.ui.HorizontalPanel;
import com.google.gwt.user.client.ui.Label;
import com.google.gwt.user.client.ui.RootPanel;
import com.google.gwt.user.client.ui.SimplePanel;
import com.google.gwt.user.client.ui.Widget;

import com.allen_sauer.gwt.dnd.client.DragContext;
import com.allen_sauer.gwt.dnd.client.drop.AbstractInsertPanelDropController;
import com.allen_sauer.gwt.dnd.client.util.DOMUtil;
import com.allen_sauer.gwt.dnd.client.util.DragClientBundle;
import com.allen_sauer.gwt.dnd.client.util.LocationWidgetComparator;

/**
 * A {@link DropController} for instances of {@link HorizontalPanel}.
 * author: Tharindu Munasinghe (tharindumunasinghe@gmail.com)
 * org.opennms.features.dashboard
 */
public class HorizontalPanelDropController extends AbstractInsertPanelDropController {

  /**
   * Label for IE quirks mode workaround.
   */
  private static final Label DUMMY_LABEL_IE_QUIRKS_MODE_OFFSET_HEIGHT = new Label("x");

  /**
   * Construct an {@link HorizontalPanelDropController}.
   * 
   * @param dropTarget the {@link HorizontalPanel} drop target
   */
  public HorizontalPanelDropController(HorizontalPanel dropTarget) {
    super(dropTarget);
  }

  @Override
  protected LocationWidgetComparator getLocationWidgetComparator() {
    return LocationWidgetComparator.RIGHT_HALF_COMPARATOR;
  }

  @Override
  protected Widget newPositioner(DragContext context) {
    // Use two widgets so that setPixelSize() consistently affects dimensions
    // excluding positioner border in quirks and strict modes
    SimplePanel outer = new SimplePanel();
    outer.addStyleName(DragClientBundle.INSTANCE.css().positioner());

    // place off screen for border calculation
    RootPanel.get().add(outer, -500, -500);

    // Ensure IE quirks mode returns valid outer.offsetHeight, and thus valid
    // DOMUtil.getVerticalBorders(outer)
    outer.setWidget(DUMMY_LABEL_IE_QUIRKS_MODE_OFFSET_HEIGHT);

    int width = 0;
    int height = 0;
    for (Widget widget : context.selectedWidgets) {
      width += widget.getOffsetWidth();
      height = Math.max(height, widget.getOffsetHeight());
    }

    SimplePanel inner = new SimplePanel();
    inner.setPixelSize(width - DOMUtil.getHorizontalBorders(outer), height
        - DOMUtil.getVerticalBorders(outer));

    outer.setWidget(inner);

    return outer;
  }
}