CSS.java

/*
 Copyright (c) 2014 Ahomé Innovation Technologies. All rights reserved.

 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
 You may obtain a copy of the License at

 http://www.apache.org/licenses/LICENSE-2.0

 Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
 */
package com.ait.toolkit.sencha.ext.client.util;

import com.google.gwt.dom.client.Document;
import com.google.gwt.dom.client.Element;
import com.google.gwt.dom.client.HeadElement;
import com.google.gwt.dom.client.LinkElement;

/**
 * Utility class for manipulating CSS rules.<br/>
 * It's important to note that Internet Explorer has a limitation of 31 styles. <br/>
 * http://support.microsoft.com/kb/262161
 * 
 */
public class CSS {

    private static HeadElement head;

    private CSS() {

    }

    /**
     * Very simple dynamic creation of stylesheets from a text blob of rules.
     * The text will wrapped in a style tag and appended to the HEAD of the
     * document.
     * 
     * @param cssText
     *            the text containing the css rules
     * @param id
     *            an id to add to the stylesheet for later removal
     */
    public static native void createStyleSheet(String cssText, String id)/*-{
		$wnd.Ext.util.CSS.createStyleSheet(cssText, id);
    }-*/;

    /**
     * /** Injects the css url code into a
     * {@code <link rel="stylesheet" href="...." />} element in the document
     * header.
     * 
     * @param href
     *            , url of the href to inject
     */
    public static LinkElement injectStyleSheet(String href) {
        HeadElement head = getHead();
        LinkElement element = createLinkElement();
        element.setHref(href);
        head.appendChild(element);
        return element;
    }

    /**
     * Gets an an individual CSS rule by selector(s).
     * 
     * @param selector
     *            the CSS selector or an array of selectors to try. The first
     *            selector that is found is returned
     * @param refreshCache
     *            true to refresh the internal cache if you have recently
     *            updated any rules or added styles dynamically
     * @return the CSS rule or null if one is not found
     */
    public static native CSSRule getRule(String selector, boolean refreshCache)/*-{
		var rule = $wnd.Ext.util.CSS.getRule(selector, refreshCache);
		if (rule == null || rule === undefined) {
			return null;
		} else {
			return @com.ait.toolkit.sencha.ext.client.util.CSSRule::instance(Lcom/google/gwt/core/client/JavaScriptObject;)(rule);
		}
    }-*/;

    // todo getRules

    /**
     * Refresh the rule cache if you have dynamically added stylesheets.
     */
    public static native void refreshCache()/*-{
		$wnd.Ext.util.CSS.refreshCache();
    }-*/;

    /**
     * Removes a style or link tag by id
     * 
     * @param id
     *            stylesheet id
     */
    public static native void removeStyleSheet(String id)/*-{
		$wnd.Ext.util.CSS.removeStyleSheet(id);
    }-*/;

    /**
     * Dynamically swaps an existing stylesheet reference for a new one.
     * 
     * @param id
     *            the id of an existing link tag to remove
     * @param url
     *            the href of the new stylesheet to include
     */
    public static native void swapStyleSheet(String id, String url)/*-{
		$wnd.Ext.util.CSS.swapStyleSheet(id, url);
    }-*/;

    /**
     * Updates a rule property.
     * 
     * @param selector
     *            the seelctor. Stops immediately once one is found.
     * @param property
     *            the css property
     * @param value
     *            the new value for the property
     */
    public static native void updateRule(String selector, String property, String value)/*-{
		$wnd.Ext.util.CSS.updateRule(selector, property, value);
    }-*/;

    private static HeadElement getHead() {
        if (head == null) {
            Element element = Document.get().getElementsByTagName("head").getItem(0);
            assert element != null : "HTML Head element required";
            head = HeadElement.as(element);
        }
        return head;
    }

    private static LinkElement createLinkElement() {
        LinkElement link = Document.get().createLinkElement();
        link.setRel("stylesheet");
        link.setType("text/css");
        return link;

    }
}