CSSRule.java

/*
 * Copyright 2000-2016 Vaadin Ltd.
 *
 * 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.vaadin.client;

import com.google.gwt.core.client.JavaScriptObject;

/**
 * Utility class for fetching CSS properties from DOM StyleSheets JS object.
 */
public class CSSRule {

    private final String selector;
    private JavaScriptObject rules = null;

    /**
     *
     * @param selector
     *            the CSS selector to search for in the stylesheets
     * @param deep
     *            should the search follow any @import statements?
     */
    public CSSRule(final String selector, final boolean deep) {
        this.selector = selector;
        fetchRule(selector, deep);
    }

    // TODO how to find the right LINK-element? We should probably give the
    // stylesheet a name.
    private native void fetchRule(final String selector, final boolean deep)
    /*-{
    var sheets = $doc.styleSheets;
    for(var i = 0; i < sheets.length; i++) {
    var sheet = sheets[i];
    if(sheet.href && sheet.href.indexOf("VAADIN/themes")>-1) {
    // $entry not needed as function is not exported
    this.@com.vaadin.client.CSSRule::rules = @com.vaadin.client.CSSRule::searchForRule(Lcom/google/gwt/core/client/JavaScriptObject;Ljava/lang/String;Z)(sheet, selector, deep);
    return;
    }
    }
    this.@com.vaadin.client.CSSRule::rules = [];
    }-*/;

    /*
     * Loops through all current style rules and collects all matching to
     * 'rules' array. The array is reverse ordered (last one found is first).
     */
    private static native JavaScriptObject searchForRule(
            final JavaScriptObject sheet, final String selector,
            final boolean deep)
    /*-{
    if(!$doc.styleSheets)
    return null;
    
    selector = selector.toLowerCase();
    
    var allMatches = [];
    
    // IE handles imported sheet differently
    if(deep && sheet.imports && sheet.imports.length > 0) {
    for(var i=0; i < sheet.imports.length; i++) {
    // $entry not needed as function is not exported
    var imports = @com.vaadin.client.CSSRule::searchForRule(Lcom/google/gwt/core/client/JavaScriptObject;Ljava/lang/String;Z)(sheet.imports[i], selector, deep);
    allMatches.concat(imports);
    }
    }
    
    var theRules = new Array();
    if (sheet.cssRules)
    theRules = sheet.cssRules
    else if (sheet.rules)
    theRules = sheet.rules
    
    var j = theRules.length;
    for(var i=0; i<j; i++) {
    var r = theRules[i];
    if(r.type == 1 || sheet.imports) {
    var selectors = r.selectorText.toLowerCase().split(",");
    var n = selectors.length;
    for(var m=0; m<n; m++) {
    if(selectors[m].replace(/^\s+|\s+$/g, "") == selector) {
    allMatches.unshift(r);
    break; // No need to loop other selectors for this rule
    }
    }
    } else if(deep && r.type == 3) {
    // Search @import stylesheet
    // $entry not needed as function is not exported
    var imports = @com.vaadin.client.CSSRule::searchForRule(Lcom/google/gwt/core/client/JavaScriptObject;Ljava/lang/String;Z)(r.styleSheet, selector, deep);
    allMatches = allMatches.concat(imports);
    }
    }
    
    return allMatches;
    }-*/;

    /**
     * Returns a specific property value from this CSS rule.
     *
     * @param propertyName
     *            camelCase CSS property name
     * @return the value of the property as a String
     */
    public native String getPropertyValue(final String propertyName)
    /*-{
    var j = this.@com.vaadin.client.CSSRule::rules.length;
    for(var i=0; i<j; i++) {
    // $entry not needed as function is not exported
    var value = this.@com.vaadin.client.CSSRule::rules[i].style[propertyName];
    if(value)
    return value;
    }
    return null;
    }-*/;

    public String getSelector() {
        return selector;
    }

}