com.google.gwt.i18n.client.BidiUtils.java Source code

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Here is the source code for com.google.gwt.i18n.client.BidiUtils.java

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/*
 * Copyright 2008 Google Inc.
 * 
 * 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.google.gwt.i18n.client;

import com.google.gwt.dom.client.Element;
import com.google.gwt.i18n.client.HasDirection.Direction;

/**
 * A set of bidi-related utility methods. 
 */
public class BidiUtils {

    /**
     * The name of the element property which controls element directionality.  
     */
    public static final String DIR_PROPERTY_NAME = "dir";

    /**
     * The value for the directionality property which will set the element directionality
     * to right-to-left.  
     */
    private static final String DIR_PROPERTY_VALUE_RTL = "rtl";

    /**
     * The value for the directionality property which will set the element directionality
     * to left-to-right.  
     */
    private static final String DIR_PROPERTY_VALUE_LTR = "ltr";

    /**
     * Gets the directionality of an element.
     *
     * @param  elem  the element on which to check the directionality property 
     * @return <code>RTL</code> if the directionality is right-to-left,
     *         <code>LTR</code> if the directionality is left-to-right, or
     *         <code>DEFAULT</code> if the directionality is not explicitly set
     */
    public static HasDirection.Direction getDirectionOnElement(Element elem) {
        String dirPropertyValue = elem.getPropertyString(DIR_PROPERTY_NAME);

        if (DIR_PROPERTY_VALUE_RTL.equalsIgnoreCase(dirPropertyValue)) {
            return HasDirection.Direction.RTL;
        } else if (DIR_PROPERTY_VALUE_LTR.equalsIgnoreCase(dirPropertyValue)) {
            return HasDirection.Direction.LTR;
        }

        return HasDirection.Direction.DEFAULT;
    }

    /**
     * Sets the directionality property for an element.
     *
     * @param elem  the element on which to set the property
     * @param direction <code>RTL</code> if the directionality should be set to right-to-left, 
     *                  <code>LTR</code> if the directionality should be set to left-to-right
     *                  <code>DEFAULT</code> if the directionality should be removed from the element   
     */
    public static void setDirectionOnElement(Element elem, Direction direction) {
        switch (direction) {
        case RTL: {
            elem.setPropertyString(DIR_PROPERTY_NAME, DIR_PROPERTY_VALUE_RTL);
            break;
        }

        case LTR: {
            elem.setPropertyString(DIR_PROPERTY_NAME, DIR_PROPERTY_VALUE_LTR);
            break;
        }

        case DEFAULT: {
            if (getDirectionOnElement(elem) != HasDirection.Direction.DEFAULT) {
                // only clear out the the dir property if it has already been set to something
                // explicitly
                elem.setPropertyString(DIR_PROPERTY_NAME, "");
            }
            break;
        }
        }
    }
}