content: /*
   * This library is part of OpenCms -
   * the Open Source Content Management System
   *
   * Copyright (c) Alkacon Software GmbH & Co. KG (https://www.alkacon.com)
   *
   * This library is free software; you can redistribute it and/or
   * modify it under the terms of the GNU Lesser General Public
   * License as published by the Free Software Foundation; either
   * version 2.1 of the License, or (at your option) any later version.
   *
   * This library 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
   * Lesser General Public License for more details.
   *
   * For further information about Alkacon Software GmbH & Co. KG, please see the
   * company website: https://www.alkacon.com
   *
   * For further information about OpenCms, please see the
   * project website: https://www.opencms.org
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with this library; if not, write to the Free Software
   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
   */
  
  package org.opencms.gwt.client.util;
  
  import java.util.HashMap;
  import java.util.Map;
  
  import com.google.gwt.dom.client.Element;
  import com.google.gwt.dom.client.Style;
  import com.google.gwt.user.client.DOM;
  import com.google.gwt.user.client.ui.RootPanel;
  
  /**
   * Provides precise pixel measurements for blocks of text so that you can
   * determine exactly how high and wide, in pixels, a given block of text will
   * be.<p>
   *
   * Normal usage would be:
   * <pre>
   * for(Element e: elements) {
   *   CmsTextMetrics tm = CmsTextMetrics.get(e, "TextMetricsKey");
   *
   *   // measure text
   *   if (r.getWidth(text) > 500) {
   *      // do something
   *   }
   *   // release
   *   tm.release();
   * }
   * </pre>
   *
   * Based on <a href="http://code.google.com/p/my-gwt/source/browse/trunk/user/src/net/mygwt/ui/client/util/TextMetrics.java">my-gwt TextMetrics</a>.<p>
   *
   * @since 8.0.0
   */
  public final class CmsTextMetrics {
  
      /** Default attributes to bind. */
      private static final CmsDomUtil.Style[] ATTRIBUTES = new CmsDomUtil.Style[] {
          CmsDomUtil.Style.fontSize,
          CmsDomUtil.Style.fontSizeAdjust,
          CmsDomUtil.Style.fontFamily,
          CmsDomUtil.Style.fontStretch,
          CmsDomUtil.Style.fontStyle,
          CmsDomUtil.Style.fontVariant,
          CmsDomUtil.Style.fontWeight,
          CmsDomUtil.Style.letterSpacing,
          CmsDomUtil.Style.textAlign,
          CmsDomUtil.Style.textDecoration,
          CmsDomUtil.Style.textIndent,
          CmsDomUtil.Style.textShadow,
          CmsDomUtil.Style.textTransform,
          CmsDomUtil.Style.lineHeight,
          CmsDomUtil.Style.whiteSpace,
          CmsDomUtil.Style.wordSpacing,
          CmsDomUtil.Style.wordWrap,
          CmsDomUtil.Style.padding};
  
      /** The map containing the instances. */
      private static Map<String, CmsTextMetrics> m_instances = new HashMap<String, CmsTextMetrics>();
  
      /** The playground. */
      private Element m_elem;
  
      /** The text metrics key. */
      private String m_key;
  
      /**
       * Internal constructor for creating a text metrics object with a given key.<p>
       *
       * @param key the key identifying the text metrics.
       */
      private CmsTextMetrics(String key) {
  
          m_key = key;
      }
  
      /**
       * Gets the text metrics object for a given DOM element and key.<p>
       *
       * If the key is null, or the method has been never called with the same key
       * before, a new text metrics object will be created, with its style taken from
       * the element parameter. Otherwise, the text metrics object for the given key will
       * be returned, and the element parameter will be ignored.
       *
       * @param element the element from which to take the style
       * @param key the text metrics key
       *
       * @return a text metrics object
       */
      public static CmsTextMetrics get(Element element, String key) {
  
          CmsTextMetrics instance = null;
          if (key == null) {
              instance = new CmsTextMetrics(key);
              instance.bind(element);
          } else {
              instance = m_instances.get(key);
              if (instance == null) {
                  instance = new CmsTextMetrics(key);
                  instance.bind(element);
                  m_instances.put(key, instance);
              }
          }
          return instance;
      }
  
      /**
       * Returns the measured height of the specified text. For multiline text, be
       * sure to call {@link #setFixedWidth} if necessary.<p>
       *
       * @param text the text to be measured
       * @return the height in pixels
       */
      public int getHeight(String text) {
  
          m_elem.setInnerText(text);
          return CmsDomUtil.getCurrentStyleInt(m_elem, CmsDomUtil.Style.height);
      }
  
      /**
       * Returns the measured width of the specified text.<p>
       *
       * @param text the text to measure
       * @return the width in pixels
       */
      public int getWidth(String text) {
  
          m_elem.setInnerText(text);
          return CmsDomUtil.getCurrentStyleInt(m_elem, CmsDomUtil.Style.width);
      }
  
      /**
       * Should be called, when finished measuring, to release the playground.<p>
       */
      public void release() {
  
          if (m_key == null) {
              m_elem.removeFromParent();
              m_elem = null;
          }
          // if we have a key, we do nothing so that the instance can be reused later
  
      }
  
      /**
       * Sets a fixed width on the internal measurement element. If the text will be
       * multiline, you have to set a fixed width in order to accurately measure the
       * text height.<p>
       *
       * @param width the width to set on the element
       */
      public void setFixedWidth(int width) {
  
          m_elem.getStyle().setWidth(width, Style.Unit.PX);
      }
  
      /**
       * Binds this text metrics instance to an element from which to copy existing
       * CSS styles that can affect the size of the rendered text.<p>
       *
       * @param element the element
       */
      protected void bind(Element element) {
  
          bind(element, ATTRIBUTES);
      }
  
      /**
       * Binds this text metrics instance to an element from which to copy existing
       * CSS styles that can affect the size of the rendered text.<p>
       *
       * @param element the element
       * @param attributes the attributes to bind
       */
      protected void bind(Element element, CmsDomUtil.Style... attributes) {
  
          if (m_elem == null) {
              // create playground
              m_elem = DOM.createDiv();
              Style style = m_elem.getStyle();
              style.setVisibility(Style.Visibility.HIDDEN);
              style.setPosition(Style.Position.ABSOLUTE);
              style.setLeft(-5000, Style.Unit.PX);
              style.setTop(-5000, Style.Unit.PX);
          }
          // copy all relevant CSS properties
          Style style = m_elem.getStyle();
          for (CmsDomUtil.Style attr : attributes) {
              String attrName = attr.toString();
              style.setProperty(attrName, CmsDomUtil.getCurrentStyle(element, attr));
          }
          // append playground
          RootPanel.getBodyElement().appendChild(m_elem);
      }
  }