com.extjs.gxt.ui.client.util.TextMetrics.java Source code

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Here is the source code for com.extjs.gxt.ui.client.util.TextMetrics.java

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/*
 * Sencha GXT 2.3.1 - Sencha for GWT
 * Copyright(c) 2007-2013, Sencha, Inc.
 * licensing@sencha.com
 * 
 * http://www.sencha.com/products/gxt/license/
 */
package com.extjs.gxt.ui.client.util;

import java.util.ArrayList;
import java.util.List;
import java.util.Map;

import com.extjs.gxt.ui.client.core.El;
import com.extjs.gxt.ui.client.core.XDOM;
import com.google.gwt.safehtml.shared.SafeHtml;
import com.google.gwt.safehtml.shared.SafeHtmlUtils;
import com.google.gwt.user.client.DOM;
import com.google.gwt.user.client.Element;

/**
 * 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.
 */
public class TextMetrics {

    private static TextMetrics instance;

    /**
     * Returns the singleton instance.
     * 
     * @return the text metrics instance
     */
    public static TextMetrics get() {
        if (instance == null) {
            instance = new TextMetrics();
        }
        return instance;
    }

    private El el;

    private TextMetrics() {
        el = new El(DOM.createDiv());
        DOM.appendChild(XDOM.getBody(), el.dom);
        el.makePositionable(true);
        el.setLeftTop(-10000, -10000);
        el.setVisibility(false);
    }

    /**
     * Binds this TextMetrics instance to an element from which to copy existing
     * CSS styles that can affect the size of the rendered text.
     * 
     * @param el the element
     */
    public void bind(Element el) {
        bind(new El(el));
    }

    /**
     * Binds this TextMetrics instance to an element from which to copy existing
     * CSS styles that can affect the size of the rendered text.
     * 
     * @param el the element
     */
    public void bind(El el) {
        //needed sometimes to force a refresh
        el.repaint();
        List<String> l = new ArrayList<String>();
        l.add("fontSize");
        l.add("fontWeight");
        l.add("fontStyle");
        l.add("fontFamily");
        l.add("lineHeight");
        l.add("textTransform");
        l.add("letterSpacing");

        Map<String, String> map = el.getStyleAttribute(l);
        for (String key : map.keySet()) {
            this.el.setStyleAttribute(key, map.get(key));
        }
    }

    /**
     * Returns the measured height of the specified text. For multiline text, be
     * sure to call {@link #setFixedWidth} if necessary.
     * 
     * @param html the html content to be measured
     * @return the height in pixels
     */
    public int getHeight(SafeHtml html) {
        return getSize(html).height;
    }

    /**
     * Returns the size of the specified text based on the internal element's
     * style and width properties.
     * 
     * @param html the html string to measure
     * @return the size
     */
    public Size getSize(SafeHtml html) {
        el.update(html);
        Size size = el.getSize();
        el.update(SafeHtmlUtils.EMPTY_SAFE_HTML);
        return size;
    }

    /**
     * Returns the measured width of the specified text.
     * 
     * @param html the html content to measure
     * @return the width in pixels
     */
    public int getWidth(SafeHtml html) {
        el.setStyleAttribute("width", "auto");
        return getSize(html).width;
    }

    /**
     * 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.
     * 
     * @param width the width to set on the element
     */
    public void setFixedWidth(int width) {
        el.setWidth(width);
    }

}