element.js

用来在地图上做操作GIS,在地图上做标记

/* Copyright (c) 2006-2007 MetaCarta, Inc., published under the BSD license.
 * See http://svn.openlayers.org/trunk/openlayers/release-license.txt 
 * for the full text of the license. */

/**
 * Namespace: OpenLayers.Element
 */
OpenLayers.Element = {

    /**
     * APIFunction: visible
     * 
     * Parameters: 
     * element - {DOMElement}
     * 
     * Returns:
     * {Boolean} Is the element visible?
     */
    visible: function(element) {
        return OpenLayers.Util.getElement(element).style.display != 'none';
    },

    /**
     * APIFunction: toggle
     * Toggle the visibility of element(s) passed in
     * 
     * Parameters:
     * element - {DOMElement} Actually user can pass any number of elements
     */
    toggle: function() {
        for (var i = 0; i < arguments.length; i++) {
            var element = OpenLayers.Util.getElement(arguments[i]);
            var display = OpenLayers.Element.visible(element) ? 'hide' 
                                                              : 'show';
            OpenLayers.Element[display](element);
        }
    },


    /**
     * APIFunction: hide
     * Hide element(s) passed in
     * 
     * Parameters:
     * element - {DOMElement} Actually user can pass any number of elements
     */
    hide: function() {
        for (var i = 0; i < arguments.length; i++) {
            var element = OpenLayers.Util.getElement(arguments[i]);
            element.style.display = 'none';
        }
    },

    /**
     * APIFunction: show
     * Show element(s) passed in
     * 
     * Parameters:
     * element - {DOMElement} Actually user can pass any number of elements
     */
    show: function() {
        for (var i = 0; i < arguments.length; i++) {
            var element = OpenLayers.Util.getElement(arguments[i]);
            element.style.display = '';
        }
    },

    /**
     * APIFunction: remove
     * Remove the specified element from the DOM.
     * 
     * Parameters:
     * element - {DOMElement}
     */
    remove: function(element) {
        element = OpenLayers.Util.getElement(element);
        element.parentNode.removeChild(element);
    },

    /**
     * APIFunction: getHeight
     *  
     * Parameters:
     * element - {DOMElement}
     * 
     * Returns:
     * {Integer} The offset height of the element passed in
     */
    getHeight: function(element) {
        element = OpenLayers.Util.getElement(element);
        return element.offsetHeight;
    },

    /**
     * APIFunction: getDimensions
     *  
     * Parameters:
     * element - {DOMElement}
     * 
     * Returns:
     * {Object} Object with 'width' and 'height' properties which are the 
     *          dimensions of the element passed in.
     */
    getDimensions: function(element) {
        element = OpenLayers.Util.getElement(element);
        if (OpenLayers.Element.getStyle(element, 'display') != 'none') {
            return {width: element.offsetWidth, height: element.offsetHeight};
        }
    
        // All *Width and *Height properties give 0 on elements with display none,
        // so enable the element temporarily
        var els = element.style;
        var originalVisibility = els.visibility;
        var originalPosition = els.position;
        els.visibility = 'hidden';
        els.position = 'absolute';
        els.display = '';
        var originalWidth = element.clientWidth;
        var originalHeight = element.clientHeight;
        els.display = 'none';
        els.position = originalPosition;
        els.visibility = originalVisibility;
        return {width: originalWidth, height: originalHeight};
    },

    /**
     * APIFunction: getStyle
     * 
     * Parameters:
     * element - {DOMElement}
     * style - {?}
     * 
     * Returns:
     * {?}
     */
    getStyle: function(element, style) {
        element = OpenLayers.Util.getElement(element);
        var value = element.style[OpenLayers.String.camelize(style)];
        if (!value) {
            if (document.defaultView && 
                document.defaultView.getComputedStyle) {
                
                var css = document.defaultView.getComputedStyle(element, null);
                value = css ? css.getPropertyValue(style) : null;
            } else if (element.currentStyle) {
                value = element.currentStyle[OpenLayers.String.camelize(style)];
            }
        }
    
        var positions = ['left', 'top', 'right', 'bottom'];
        if (window.opera &&
            (OpenLayers.Util.indexOf(positions,style) != -1) &&
            (OpenLayers.Element.getStyle(element, 'position') == 'static')) { 
            value = 'auto';
        }
    
        return value == 'auto' ? null : value;
    }

};