/*
* This library is part of OpenCms -
* the Open Source Content Management System
*
* Copyright (c) Alkacon Software GmbH (http://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, please see the
* company website: http://www.alkacon.com
*
* For further information about OpenCms, please see the
* project website: http://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);
}
}