openlayers内lib/openlayers/util.js源码解析
//这个是指PNG图片的alpha透明处理是不是需要，一般浏览器都支持PNG的alpha透明，只有IE6不支持，所以要单独CSS Hack一下
OpenLayers.Util.alphaHackNeeded = null;
//测试是否需要alpha hack，IE6则需要
OpenLayers.Util.alphaHack = function() {
if (OpenLayers.Util.alphaHackNeeded == null) {
var arVersion = navigator.appVersion.split(“MSIE”);
var version = parseFloat(arVersion[1]);
var filter = false;
try {
filter = !!(document.body.filters);
} catch (e) {}
OpenLayers.Util.alphaHackNeeded = (filter &&
(version >= 5.5) && (version < 7));
}
return OpenLayers.Util.alphaHackNeeded;
};
//修改一个有image背景的div，针对IE6的alpha 透明，使用了AlphaImageLoader。具体说明可以参考这里http://support.microsoft.com/kb/294714/zh-cn
OpenLayers.Util.modifyAlphaImageDiv = function(div, id, px, sz, imgURL,
position, border, sizing,
opacity) {
OpenLayers.Util.modifyDOMElement(div, id, px, sz, position,
null, null, opacity);
var img = div.childNodes[0];
if (imgURL) {
img.src = imgURL;
}
OpenLayers.Util.modifyDOMElement(img, div.id + “_innerImage”, null, sz,
“relative”, border);
if (OpenLayers.Util.alphaHack()) {
if(div.style.display != “none”) {
div.style.display = “inline-block”;
}
if (sizing == null) {
sizing = “scale”;
}
div.style.filter = “progid:DXImageTransform.Microsoft” +
“.AlphaImageLoader(src='” + img.src + “‘, ” +
“sizingMethod='” + sizing + “‘)”;
if (parseFloat(div.style.opacity) >= 0.0 &&
parseFloat(div.style.opacity) < 1.0) {
div.style.filter += ” alpha(opacity=” + div.style.opacity * 100 + “)”;
}
img.style.filter = “alpha(opacity=0)”;
}
};
//创建一个带背景的div
OpenLayers.Util.createAlphaImageDiv = function(id, px, sz, imgURL,
position, border, sizing,
opacity, delayDisplay) {
var div = OpenLayers.Util.createDiv();
var img = OpenLayers.Util.createImage(null, null, null, null, null, null,
null, false);
div.appendChild(img);
if (delayDisplay) {
img.style.display = “none”;
OpenLayers.Event.observe(img, “load”,
OpenLayers.Function.bind(OpenLayers.Util.onImageLoad, div));
OpenLayers.Event.observe(img, “error”,
OpenLayers.Function.bind(OpenLayers.Util.onImageLoadError, div));
}
OpenLayers.Util.modifyAlphaImageDiv(div, id, px, sz, imgURL, position,
border, sizing, opacity);
return div;
};
//很简单的一个函数，把对象的属性名全改成大写
OpenLayers.Util.upperCaseObject = function (object) {
var uObject = {};
for (var key in object) {
uObject[key.toUpperCase()] = object[key];
}
return uObject;
};
//一个简单的浅拷贝，如果目标对象有这个属性，则不拷贝，否则拷贝
OpenLayers.Util.applyDefaults = function (to, from) {
to = to || {};
var fromIsEvt = typeof window.Event == “function”
&& from instanceof window.Event;
for (var key in from) {
if (to[key] === undefined ||
(!fromIsEvt && from.hasOwnProperty
&& from.hasOwnProperty(key) && !to.hasOwnProperty(key))) {
to[key] = from[key];
}
}
if(!fromIsEvt && from && from.hasOwnProperty
&& from.hasOwnProperty(‘toString’) && !to.hasOwnProperty(‘toString’)) {
to.toString = from.toString;
}
return to;
};
//把对象属性和值，转换成url的参数格式，这个函数在ajax中，经常调用
OpenLayers.Util.getParameterString = function(params) {
var paramsArray = [];
for (var key in params) {
var value = params[key];
if ((value != null) && (typeof value != ‘function’)) {
var encodedValue;
if (typeof value == ‘object’ && value.constructor == Array) {
/* value is an array; encode items and separate with “,” */
var encodedItemArray = [];
for (var itemIndex=0, len=value.length; itemIndex<len; itemIndex++) {
encodedItemArray.push(encodeURIComponent(value[itemIndex]));
}
encodedValue = encodedItemArray.join(“,”);
}
else {
/* value is a string; simply encode */
encodedValue = encodeURIComponent(value);
}
paramsArray.push(encodeURIComponent(key) + “=” + encodedValue);
}
}
return paramsArray.join(“&”);
};
//img的路径
OpenLayers.ImgPath = ”;
//获取Openlayers的img路径
OpenLayers.Util.getImagesLocation = function() {
return OpenLayers.ImgPath || (OpenLayers._getScriptLocation() + “img/”);
};
//这个函数的参数就是函数指针，运行这些函数，只到第一个不抛出异常的函数，返回其返回值
OpenLayers.Util.Try = function() {
var returnValue = null;
for (var i=0, len=arguments.length; i<len; i++) {
var lambda = arguments[i];
try {
returnValue = lambda();
break;
} catch (e) {}
}
return returnValue;
};
//把对象p个子节点中的所有tagName的节点，做成数组返回
OpenLayers.Util.getNodes=function(p, tagName) {
var nodes = OpenLayers.Util.Try(
function () {
return OpenLayers.Util._getNodes(p.documentElement.childNodes,
tagName);
},
function () {
return OpenLayers.Util._getNodes(p.childNodes, tagName);
}
);
return nodes;
};
//过滤出指定tagName的node，做成数组返回
OpenLayers.Util._getNodes=function(nodes, tagName) {
var retArray = [];
for (var i=0, len=nodes.length; i<len; i++) {
if (nodes[i].nodeName==tagName) {
retArray.push(nodes[i]);
}
}
return retArray;
};
//取parent的节点标签名为item的第index项的nodeValue
OpenLayers.Util.getTagText = function (parent, item, index) {
var result = OpenLayers.Util.getNodes(parent, item);
if (result && (result.length > 0))
{
if (!index) {
index=0;
}
if (result[index].childNodes.length > 1) {
return result.childNodes[1].nodeValue;
}
else if (result[index].childNodes.length == 1) {
return result[index].firstChild.nodeValue;
}
} else {
return “”;
}
};
//取指定节点的nodeValue值，因为Firefox的标签中空白占一个位置，而IE不占。所以有两套函数。
OpenLayers.Util.getXmlNodeValue = function(node) {
var val = null;
OpenLayers.Util.Try(
function() {
val = node.text;
if (!val) {
val = node.textContent;
}
if (!val) {
val = node.firstChild.nodeValue;
}
},
function() {
val = node.textContent;
});
return val;
};
/**
* Function: mouseLeft
*
* Parameters:
* evt – {Event}
* div – {HTMLDivElement}
*
* Returns:
* {Boolean}
*/
OpenLayers.Util.mouseLeft = function (evt, div) {
// start with the element to which the mouse has moved
var target = (evt.relatedTarget) ? evt.relatedTarget : evt.toElement;
// walk up the DOM tree.
while (target != div && target != null) {
target = target.parentNode;
}
// if the target we stop at isn’t the div, then we’ve left the div.
return (target != div);
};
/**
* Property: precision
* {Number} The number of significant digits to retain to avoid
* floating point precision errors.
*
* We use 14 as a “safe” default because, although IEEE 754 double floats
* (standard on most modern operating systems) support up to about 16
* significant digits, 14 significant digits are sufficient to represent
* sub-millimeter accuracy in any coordinate system that anyone is likely to
* use with OpenLayers.
*
* If DEFAULT_PRECISION is set to 0, the original non-truncating behavior
* of OpenLayers <2.8 is preserved. Be aware that this will cause problems
* with certain projections, e.g. spherical Mercator.
*
*/
OpenLayers.Util.DEFAULT_PRECISION = 14;
/**
* Function: toFloat
* Convenience method to cast an object to a Number, rounded to the
* desired floating point precision.
*
* Parameters:
* number – {Number} The number to cast and round.
* precision – {Number} An integer suitable for use with
* Number.toPrecision(). Defaults to OpenLayers.Util.DEFAULT_PRECISION.
* If set to 0, no rounding is performed.
*
* Returns:
* {Number} The cast, rounded number.
*/
OpenLayers.Util.toFloat = function (number, precision) {
if (precision == null) {
precision = OpenLayers.Util.DEFAULT_PRECISION;
}
var number;
if (precision == 0) {
number = parseFloat(number);
} else {
number = parseFloat(parseFloat(number).toPrecision(precision));
}
return number;
};
/**
* Function: rad
*
* Parameters:
* x – {Float}
*
* Returns:
* {Float}
*/
OpenLayers.Util.rad = function(x) {return x*Math.PI/180;};
/**
* Function: distVincenty
* Given two objects representing points with geographic coordinates, this
* calculates the distance between those points on the surface of an
* ellipsoid.
*
* Parameters:
* p1 – {<OpenLayers.LonLat>} (or any object with both .lat, .lon properties)
* p2 – {<OpenLayers.LonLat>} (or any object with both .lat, .lon properties)
*
* Returns:
* {Float} The distance (in km) between the two input points as measured on an
* ellipsoid. Note that the input point objects must be in geographic
* coordinates (decimal degrees) and the return distance is in kilometers.
*/
OpenLayers.Util.distVincenty=function(p1, p2) {
var a = 6378137, b = 6356752.3142, f = 1/298.257223563;
var L = OpenLayers.Util.rad(p2.lon – p1.lon);
var U1 = Math.atan((1-f) * Math.tan(OpenLayers.Util.rad(p1.lat)));
var U2 = Math.atan((1-f) * Math.tan(OpenLayers.Util.rad(p2.lat)));
var sinU1 = Math.sin(U1), cosU1 = Math.cos(U1);
var sinU2 = Math.sin(U2), cosU2 = Math.cos(U2);
var lambda = L, lambdaP = 2*Math.PI;
var iterLimit = 20;
while (Math.abs(lambda-lambdaP) > 1e-12 && –iterLimit>0) {
var sinLambda = Math.sin(lambda), cosLambda = Math.cos(lambda);
var sinSigma = Math.sqrt((cosU2*sinLambda) * (cosU2*sinLambda) +
(cosU1*sinU2-sinU1*cosU2*cosLambda) * (cosU1*sinU2-sinU1*cosU2*cosLambda));
if (sinSigma==0) {
return 0; // co-incident points
}
var cosSigma = sinU1*sinU2 + cosU1*cosU2*cosLambda;
var sigma = Math.atan2(sinSigma, cosSigma);
var alpha = Math.asin(cosU1 * cosU2 * sinLambda / sinSigma);
var cosSqAlpha = Math.cos(alpha) * Math.cos(alpha);
var cos2SigmaM = cosSigma – 2*sinU1*sinU2/cosSqAlpha;
var C = f/16*cosSqAlpha*(4+f*(4-3*cosSqAlpha));
lambdaP = lambda;
lambda = L + (1-C) * f * Math.sin(alpha) *
(sigma + C*sinSigma*(cos2SigmaM+C*cosSigma*(-1+2*cos2SigmaM*cos2SigmaM)));
}
if (iterLimit==0) {
return NaN; // formula failed to converge
}
var uSq = cosSqAlpha * (a*a – b*b) / (b*b);
var A = 1 + uSq/16384*(4096+uSq*(-768+uSq*(320-175*uSq)));
var B = uSq/1024 * (256+uSq*(-128+uSq*(74-47*uSq)));
var deltaSigma = B*sinSigma*(cos2SigmaM+B/4*(cosSigma*(-1+2*cos2SigmaM*cos2SigmaM)-
B/6*cos2SigmaM*(-3+4*sinSigma*sinSigma)*(-3+4*cos2SigmaM*cos2SigmaM)));
var s = b*A*(sigma-deltaSigma);
var d = s.toFixed(3)/1000; // round to 1mm precision
return d;
};
/**
* Function: getParameters
* Parse the parameters from a URL or from the current page itself into a
* JavaScript Object. Note that parameter values with commas are separated
* out into an Array.
*
* Parameters:
* url – {String} Optional url used to extract the query string.
* If null, query string is taken from page location.
*
* Returns:
* {Object} An object of key/value pairs from the query string.
*/
OpenLayers.Util.getParameters = function(url) {
// if no url specified, take it from the location bar
url = url || window.location.href;
//parse out parameters portion of url string
var paramsString = “”;
if (OpenLayers.String.contains(url, ‘?’)) {
var start = url.indexOf(‘?’) + 1;
var end = OpenLayers.String.contains(url, “#”) ?
url.indexOf(‘#’) : url.length;
paramsString = url.substring(start, end);
}
var parameters = {};
var pairs = paramsString.split(/[&;]/);
for(var i=0, len=pairs.length; i<len; ++i) {
var keyValue = pairs[i].split(‘=’);
if (keyValue[0]) {
var key = decodeURIComponent(keyValue[0]);
var value = keyValue[1] || ”; //empty string if no value
//decode individual values
value = value.split(“,”);
for(var j=0, jlen=value.length; j<jlen; j++) {
value[j] = decodeURIComponent(value[j]);
}
//if there’s only one value, do not return as array
if (value.length == 1) {
value = value[0];
}
parameters[key] = value;
}
}
return parameters;
};
/**
* Function: getArgs
* *Deprecated*. Will be removed in 3.0. Please use instead
* <OpenLayers.Util.getParameters>
*
* Parameters:
* url – {String} Optional url used to extract the query string.
* If null, query string is taken from page location.
*
* Returns:
* {Object} An object of key/value pairs from the query string.
*/
OpenLayers.Util.getArgs = function(url) {
OpenLayers.Console.warn(
OpenLayers.i18n(
“methodDeprecated”, {‘newMethod’: ‘OpenLayers.Util.getParameters’}
)
);
return OpenLayers.Util.getParameters(url);
};
/**
* Property: lastSeqID
* {Integer} The ever-incrementing count variable.
* Used for generating unique ids.
*/
OpenLayers.Util.lastSeqID = 0;
/**
* Function: createUniqueID
* Create a unique identifier for this session. Each time this function
* is called, a counter is incremented. The return will be the optional
* prefix (defaults to “id_”) appended with the counter value.
*
* Parameters:
* prefix {String} Optionsal string to prefix unique id. Default is “id_”.
*
* Returns:
* {String} A unique id string, built on the passed in prefix.
*/
OpenLayers.Util.createUniqueID = function(prefix) {
if (prefix == null) {
prefix = “id_”;
}
OpenLayers.Util.lastSeqID += 1;
return prefix + OpenLayers.Util.lastSeqID;
};
/**
* Constant: INCHES_PER_UNIT
* {Object} Constant inches per unit — borrowed from MapServer mapscale.c
* derivation of nautical miles from http://en.wikipedia.org/wiki/Nautical_mile
* Includes the full set of units supported by CS-MAP (http://trac.osgeo.org/csmap/)
* and PROJ.4 (http://trac.osgeo.org/proj/)
* The hardcoded table is maintain in a CS-MAP source code module named CSdataU.c
* The hardcoded table of PROJ.4 units are in pj_units.c.
*/
OpenLayers.INCHES_PER_UNIT = {
‘inches’: 1.0,
‘ft’: 12.0,
‘mi’: 63360.0,
‘m’: 39.3701,
‘km’: 39370.1,
‘dd’: 4374754,
‘yd’: 36
};
OpenLayers.INCHES_PER_UNIT[“in”]= OpenLayers.INCHES_PER_UNIT.inches;
OpenLayers.INCHES_PER_UNIT[“degrees”] = OpenLayers.INCHES_PER_UNIT.dd;
OpenLayers.INCHES_PER_UNIT[“nmi”] = 1852 * OpenLayers.INCHES_PER_UNIT.m;
// Units from CS-Map
OpenLayers.METERS_PER_INCH = 0.02540005080010160020;
OpenLayers.Util.extend(OpenLayers.INCHES_PER_UNIT, {
“Inch”: OpenLayers.INCHES_PER_UNIT.inches,
“Meter”: 1.0 / OpenLayers.METERS_PER_INCH, //EPSG:9001
“Foot”: 0.30480060960121920243 / OpenLayers.METERS_PER_INCH, //EPSG:9003
“IFoot”: 0.30480000000000000000 / OpenLayers.METERS_PER_INCH, //EPSG:9002
“ClarkeFoot”: 0.3047972651151 / OpenLayers.METERS_PER_INCH, //EPSG:9005
“SearsFoot”: 0.30479947153867624624 / OpenLayers.METERS_PER_INCH, //EPSG:9041
“GoldCoastFoot”: 0.30479971018150881758 / OpenLayers.METERS_PER_INCH, //EPSG:9094
“IInch”: 0.02540000000000000000 / OpenLayers.METERS_PER_INCH,
“MicroInch”: 0.00002540000000000000 / OpenLayers.METERS_PER_INCH,
“Mil”: 0.00000002540000000000 / OpenLayers.METERS_PER_INCH,
“Centimeter”: 0.01000000000000000000 / OpenLayers.METERS_PER_INCH,
“Kilometer”: 1000.00000000000000000000 / OpenLayers.METERS_PER_INCH, //EPSG:9036
“Yard”: 0.91440182880365760731 / OpenLayers.METERS_PER_INCH,
“SearsYard”: 0.914398414616029 / OpenLayers.METERS_PER_INCH, //EPSG:9040
“IndianYard”: 0.91439853074444079983 / OpenLayers.METERS_PER_INCH, //EPSG:9084
“IndianYd37”: 0.91439523 / OpenLayers.METERS_PER_INCH, //EPSG:9085
“IndianYd62”: 0.9143988 / OpenLayers.METERS_PER_INCH, //EPSG:9086
“IndianYd75”: 0.9143985 / OpenLayers.METERS_PER_INCH, //EPSG:9087
“IndianFoot”: 0.30479951 / OpenLayers.METERS_PER_INCH, //EPSG:9080
“IndianFt37”: 0.30479841 / OpenLayers.METERS_PER_INCH, //EPSG:9081
“IndianFt62”: 0.3047996 / OpenLayers.METERS_PER_INCH, //EPSG:9082
“IndianFt75”: 0.3047995 / OpenLayers.METERS_PER_INCH, //EPSG:9083
“Mile”: 1609.34721869443738887477 / OpenLayers.METERS_PER_INCH,
“IYard”: 0.91440000000000000000 / OpenLayers.METERS_PER_INCH, //EPSG:9096
“IMile”: 1609.34400000000000000000 / OpenLayers.METERS_PER_INCH, //EPSG:9093
“NautM”: 1852.00000000000000000000 / OpenLayers.METERS_PER_INCH, //EPSG:9030
“Lat-66”: 110943.316488932731 / OpenLayers.METERS_PER_INCH,
“Lat-83”: 110946.25736872234125 / OpenLayers.METERS_PER_INCH,
“Decimeter”: 0.10000000000000000000 / OpenLayers.METERS_PER_INCH,
“Millimeter”: 0.00100000000000000000 / OpenLayers.METERS_PER_INCH,
“Dekameter”: 10.00000000000000000000 / OpenLayers.METERS_PER_INCH,
“Decameter”: 10.00000000000000000000 / OpenLayers.METERS_PER_INCH,
“Hectometer”: 100.00000000000000000000 / OpenLayers.METERS_PER_INCH,
“GermanMeter”: 1.0000135965 / OpenLayers.METERS_PER_INCH, //EPSG:9031
“CaGrid”: 0.999738 / OpenLayers.METERS_PER_INCH,
“ClarkeChain”: 20.1166194976 / OpenLayers.METERS_PER_INCH, //EPSG:9038
“GunterChain”: 20.11684023368047 / OpenLayers.METERS_PER_INCH, //EPSG:9033
“BenoitChain”: 20.116782494375872 / OpenLayers.METERS_PER_INCH, //EPSG:9062
“SearsChain”: 20.11676512155 / OpenLayers.METERS_PER_INCH, //EPSG:9042
“ClarkeLink”: 0.201166194976 / OpenLayers.METERS_PER_INCH, //EPSG:9039
“GunterLink”: 0.2011684023368047 / OpenLayers.METERS_PER_INCH, //EPSG:9034
“BenoitLink”: 0.20116782494375872 / OpenLayers.METERS_PER_INCH, //EPSG:9063
“SearsLink”: 0.2011676512155 / OpenLayers.METERS_PER_INCH, //EPSG:9043
“Rod”: 5.02921005842012 / OpenLayers.METERS_PER_INCH,
“IntnlChain”: 20.1168 / OpenLayers.METERS_PER_INCH, //EPSG:9097
“IntnlLink”: 0.201168 / OpenLayers.METERS_PER_INCH, //EPSG:9098
“Perch”: 5.02921005842012 / OpenLayers.METERS_PER_INCH,
“Pole”: 5.02921005842012 / OpenLayers.METERS_PER_INCH,
“Furlong”: 201.1684023368046 / OpenLayers.METERS_PER_INCH,
“Rood”: 3.778266898 / OpenLayers.METERS_PER_INCH,
“CapeFoot”: 0.3047972615 / OpenLayers.METERS_PER_INCH,
“Brealey”: 375.00000000000000000000 / OpenLayers.METERS_PER_INCH,
“ModAmFt”: 0.304812252984505969011938 / OpenLayers.METERS_PER_INCH,
“Fathom”: 1.8288 / OpenLayers.METERS_PER_INCH,
“NautM-UK”: 1853.184 / OpenLayers.METERS_PER_INCH,
“50kilometers”: 50000.0 / OpenLayers.METERS_PER_INCH,
“150kilometers”: 150000.0 / OpenLayers.METERS_PER_INCH
});
//unit abbreviations supported by PROJ.4
OpenLayers.Util.extend(OpenLayers.INCHES_PER_UNIT, {
“mm”: OpenLayers.INCHES_PER_UNIT[“Meter”] / 1000.0,
“cm”: OpenLayers.INCHES_PER_UNIT[“Meter”] / 100.0,
“dm”: OpenLayers.INCHES_PER_UNIT[“Meter”] * 100.0,
“km”: OpenLayers.INCHES_PER_UNIT[“Meter”] * 1000.0,
“kmi”: OpenLayers.INCHES_PER_UNIT[“nmi”], //International Nautical Mile
“fath”: OpenLayers.INCHES_PER_UNIT[“Fathom”], //International Fathom
“ch”: OpenLayers.INCHES_PER_UNIT[“IntnlChain”], //International Chain
“link”: OpenLayers.INCHES_PER_UNIT[“IntnlLink”], //International Link
“us-in”: OpenLayers.INCHES_PER_UNIT[“inches”], //U.S. Surveyor’s Inch
“us-ft”: OpenLayers.INCHES_PER_UNIT[“Foot”], //U.S. Surveyor’s Foot
“us-yd”: OpenLayers.INCHES_PER_UNIT[“Yard”], //U.S. Surveyor’s Yard
“us-ch”: OpenLayers.INCHES_PER_UNIT[“GunterChain”], //U.S. Surveyor’s Chain
“us-mi”: OpenLayers.INCHES_PER_UNIT[“Mile”], //U.S. Surveyor’s Statute Mile
“ind-yd”: OpenLayers.INCHES_PER_UNIT[“IndianYd37”], //Indian Yard
“ind-ft”: OpenLayers.INCHES_PER_UNIT[“IndianFt37”], //Indian Foot
“ind-ch”: 20.11669506 / OpenLayers.METERS_PER_INCH //Indian Chain
});
/**
* Constant: DOTS_PER_INCH
* {Integer} 72 (A sensible default)
*/
OpenLayers.DOTS_PER_INCH = 72;
/**
* Function: normalizeScale
*
* Parameters:
* scale – {float}
*
* Returns:
* {Float} A normalized scale value, in 1 / X format.
* This means that if a value less than one ( already 1/x) is passed
* in, it just returns scale directly. Otherwise, it returns
* 1 / scale
*/
OpenLayers.Util.normalizeScale = function (scale) {
var normScale = (scale > 1.0) ? (1.0 / scale)
: scale;
return normScale;
};
/**
* Function: getResolutionFromScale
*
* Parameters:
* scale – {Float}
* units – {String} Index into OpenLayers.INCHES_PER_UNIT hashtable.
* Default is degrees
*
* Returns:
* {Float} The corresponding resolution given passed-in scale and unit
* parameters.
*/
OpenLayers.Util.getResolutionFromScale = function (scale, units) {
if (units == null) {
units = “degrees”;
}
var normScale = OpenLayers.Util.normalizeScale(scale);
var resolution = 1 / (normScale * OpenLayers.INCHES_PER_UNIT[units]
* OpenLayers.DOTS_PER_INCH);
return resolution;
};
/**
* Function: getScaleFromResolution
*
* Parameters:
* resolution – {Float}
* units – {String} Index into OpenLayers.INCHES_PER_UNIT hashtable.
* Default is degrees
*
* Returns:
* {Float} The corresponding scale given passed-in resolution and unit
* parameters.
*/
OpenLayers.Util.getScaleFromResolution = function (resolution, units) {
if (units == null) {
units = “degrees”;
}
var scale = resolution * OpenLayers.INCHES_PER_UNIT[units] *
OpenLayers.DOTS_PER_INCH;
return scale;
};
/**
* Function: safeStopPropagation
* *Deprecated*. This function has been deprecated. Please use directly
* <OpenLayers.Event.stop> passing ‘true’ as the 2nd
* argument (preventDefault)
*
* Safely stop the propagation of an event *without* preventing
* the default browser action from occurring.
*
* Parameter:
* evt – {Event}
*/
OpenLayers.Util.safeStopPropagation = function(evt) {
OpenLayers.Event.stop(evt, true);
};
/**
* Function: pagePositon
* Calculates the position of an element on the page.
*
* Parameters:
* forElement – {DOMElement}
*
* Returns:
* {Array} two item array, L value then T value.
*/
OpenLayers.Util.pagePosition = function(forElement) {
var valueT = 0, valueL = 0;
var element = forElement;
var child = forElement;
while(element) {
if(element == document.body) {
if(OpenLayers.Element.getStyle(child, ‘position’) == ‘absolute’) {
break;
}
}
valueT += element.offsetTop || 0;
valueL += element.offsetLeft || 0;
child = element;
try {
// wrapping this in a try/catch because IE chokes on the offsetParent
element = element.offsetParent;
} catch(e) {
OpenLayers.Console.error(OpenLayers.i18n(
“pagePositionFailed”,{‘elemId’:element.id}));
break;
}
}
element = forElement;
while(element) {
valueT -= element.scrollTop || 0;
valueL -= element.scrollLeft || 0;
element = element.parentNode;
}
return [valueL, valueT];
};
/**
* Function: isEquivalentUrl
* Test two URLs for equivalence.
*
* Setting ‘ignoreCase’ allows for case-independent comparison.
*
* Comparison is based on:
* – Protocol
* – Host (evaluated without the port)
* – Port (set ‘ignorePort80’ to ignore “80” values)
* – Hash ( set ‘ignoreHash’ to disable)
* – Pathname (for relative <-> absolute comparison)
* – Arguments (so they can be out of order)
*
* Parameters:
* url1 – {String}
* url2 – {String}
* options – {Object} Allows for customization of comparison:
* ‘ignoreCase’ – Default is True
* ‘ignorePort80’ – Default is True
* ‘ignoreHash’ – Default is True
*
* Returns:
* {Boolean} Whether or not the two URLs are equivalent
*/
OpenLayers.Util.isEquivalentUrl = function(url1, url2, options) {
options = options || {};
OpenLayers.Util.applyDefaults(options, {
ignoreCase: true,
ignorePort80: true,
ignoreHash: true
});
var urlObj1 = OpenLayers.Util.createUrlObject(url1, options);
var urlObj2 = OpenLayers.Util.createUrlObject(url2, options);
//compare all keys except for “args” (treated below)
for(var key in urlObj1) {
if(key !== “args”) {
if(urlObj1[key] != urlObj2[key]) {
return false;
}
}
}
// compare search args – irrespective of order
for(var key in urlObj1.args) {
if(urlObj1.args[key] != urlObj2.args[key]) {
return false;
}
delete urlObj2.args[key];
}
// urlObj2 shouldn’t have any args left
for(var key in urlObj2.args) {
return false;
}
return true;
};
/**
* Function: createUrlObject
*
* Parameters:
* url – {String}
* options – {Object} A hash of options. Can be one of:
* ignoreCase: lowercase url,
* ignorePort80: don’t include explicit port if port is 80,
* ignoreHash: Don’t include part of url after the hash (#).
*
* Returns:
* {Object} An object with separate url, a, port, host, and args parsed out
* and ready for comparison
*/
OpenLayers.Util.createUrlObject = function(url, options) {
options = options || {};
// deal with relative urls first
if(!(/^\w+:\/\//).test(url)){
var loc = window.location;
var port = loc.port ? “:” + loc.port : “”;
var fullUrl = loc.protocol + “//” + loc.host.split(“:”).shift() + port;
if(url.indexOf(“/”) === 0) {
// full pathname
url = fullUrl + url;
} else {
// relative to current path
var parts = loc.pathname.split(“/”);
parts.pop();
url = fullUrl + parts.join(“/”) + “/” + url;
}
}
if (options.ignoreCase) {
url = url.toLowerCase();
}
var a = document.createElement(‘a’);
a.href = url;
var urlObject = {};
//host (without port)
urlObject.host = a.host.split(“:”).shift();
//protocol
urlObject.protocol = a.protocol;
//port (get uniform browser behavior with port 80 here)
if(options.ignorePort80) {
urlObject.port = (a.port == “80” || a.port == “0”) ? “” : a.port;
} else {
urlObject.port = (a.port == “” || a.port == “0”) ? “80” : a.port;
}
//hash
urlObject.hash = (options.ignoreHash || a.hash === “#”) ? “” : a.hash;
//args
var queryString = a.search;
if (!queryString) {
var qMark = url.indexOf(“?”);
queryString = (qMark != -1) ? url.substr(qMark) : “”;
}
urlObject.args = OpenLayers.Util.getParameters(queryString);
//pathname (uniform browser behavior with leading “/”)
urlObject.pathname = (a.pathname.charAt(0) == “/”) ? a.pathname : “/” + a.pathname;
return urlObject;
};
/**
* Function: removeTail
* Takes a url and removes everything after the ? and #
*
* Parameters:
* url – {String} The url to process
*
* Returns:
* {String} The string with all queryString and Hash removed
*/
OpenLayers.Util.removeTail = function(url) {
var head = null;
var qMark = url.indexOf(“?”);
var hashMark = url.indexOf(“#”);
if (qMark == -1) {
head = (hashMark != -1) ? url.substr(0,hashMark) : url;
} else {
head = (hashMark != -1) ? url.substr(0,Math.min(qMark, hashMark))
: url.substr(0, qMark);
}
return head;
};
/**
* Function: getBrowserName
*
* Returns:
* {String} A string which specifies which is the current
* browser in which we are running.
*
* Currently-supported browser detection and codes:
* * ‘opera’ — Opera
* * ‘msie’ — Internet Explorer
* * ‘safari’ — Safari
* * ‘firefox’ — FireFox
* * ‘mozilla’ — Mozilla
*
* If we are unable to property identify the browser, we
* return an empty string.
*/
OpenLayers.Util.getBrowserName = function() {
var browserName = “”;
var ua = navigator.userAgent.toLowerCase();
if ( ua.indexOf( “opera” ) != -1 ) {
browserName = “opera”;
} else if ( ua.indexOf( “msie” ) != -1 ) {
browserName = “msie”;
} else if ( ua.indexOf( “safari” ) != -1 ) {
browserName = “safari”;
} else if ( ua.indexOf( “mozilla” ) != -1 ) {
if ( ua.indexOf( “firefox” ) != -1 ) {
browserName = “firefox”;
} else {
browserName = “mozilla”;
}
}
return browserName;
};
/**
* Method: getRenderedDimensions
* Renders the contentHTML offscreen to determine actual dimensions for
* popup sizing. As we need layout to determine dimensions the content
* is rendered -9999px to the left and absolute to ensure the
* scrollbars do not flicker
*
* Parameters:
* contentHTML
* size – {<OpenLayers.Size>} If either the ‘w’ or ‘h’ properties is
* specified, we fix that dimension of the div to be measured. This is
* useful in the case where we have a limit in one dimension and must
* therefore meaure the flow in the other dimension.
* options – {Object}
* displayClass – {String} Optional parameter. A CSS class name(s) string
* to provide the CSS context of the rendered content.
* containerElement – {DOMElement} Optional parameter. Insert the HTML to
* this node instead of the body root when calculating dimensions.
*
* Returns:
* {OpenLayers.Size}
*/
OpenLayers.Util.getRenderedDimensions = function(contentHTML, size, options) {
var w, h;
// create temp container div with restricted size
var container = document.createElement(“div”);
container.style.visibility = “hidden”;
var containerElement = (options && options.containerElement)
? options.containerElement : document.body;
//fix a dimension, if specified.
if (size) {
if (size.w) {
w = size.w;
container.style.width = w + “px”;
} else if (size.h) {
h = size.h;
container.style.height = h + “px”;
}
}
//add css classes, if specified
if (options && options.displayClass) {
container.className = options.displayClass;
}
// create temp content div and assign content
var content = document.createElement(“div”);
content.innerHTML = contentHTML;
// we need overflow visible when calculating the size
content.style.overflow = “visible”;
if (content.childNodes) {
for (var i=0, l=content.childNodes.length; i<l; i++) {
if (!content.childNodes[i].style) continue;
content.childNodes[i].style.overflow = “visible”;
}
}
// add content to restricted container
container.appendChild(content);
// append container to body for rendering
containerElement.appendChild(container);
// Opera and IE7 can’t handle a node with position:aboslute if it inherits
// position:absolute from a parent.
var parentHasPositionAbsolute = false;
var parent = container.parentNode;
while (parent && parent.tagName.toLowerCase()!=”body”) {
var parentPosition = OpenLayers.Element.getStyle(parent, “position”);
if(parentPosition == “absolute”) {
parentHasPositionAbsolute = true;
break;
} else if (parentPosition && parentPosition != “static”) {
break;
}
parent = parent.parentNode;
}
if(!parentHasPositionAbsolute) {
container.style.position = “absolute”;
}
// calculate scroll width of content and add corners and shadow width
if (!w) {
w = parseInt(content.scrollWidth);
// update container width to allow height to adjust
container.style.width = w + “px”;
}
// capture height and add shadow and corner image widths
if (!h) {
h = parseInt(content.scrollHeight);
}
// remove elements
container.removeChild(content);
containerElement.removeChild(container);
return new OpenLayers.Size(w, h);
};
/**
* APIFunction: getScrollbarWidth
* This function has been modified by the OpenLayers from the original version,
* written by Matthew Eernisse and released under the Apache 2
* license here:
*
* http://www.fleegix.org/articles/2006/05/30/getting-the-scrollbar-width-in-pixels
*
* It has been modified simply to cache its value, since it is physically
* impossible that this code could ever run in more than one browser at
* once.
*
* Returns:
* {Integer}
*/
OpenLayers.Util.getScrollbarWidth = function() {
var scrollbarWidth = OpenLayers.Util._scrollbarWidth;
if (scrollbarWidth == null) {
var scr = null;
var inn = null;
var wNoScroll = 0;
var wScroll = 0;
// Outer scrolling div
scr = document.createElement(‘div’);
scr.style.position = ‘absolute’;
scr.style.top = ‘-1000px’;
scr.style.left = ‘-1000px’;
scr.style.width = ‘100px’;
scr.style.height = ’50px’;
// Start with no scrollbar
scr.style.overflow = ‘hidden’;
// Inner content div
inn = document.createElement(‘div’);
inn.style.width = ‘100%’;
inn.style.height = ‘200px’;
// Put the inner div in the scrolling div
scr.appendChild(inn);
// Append the scrolling div to the doc
document.body.appendChild(scr);
// Width of the inner div sans scrollbar
wNoScroll = inn.offsetWidth;
// Add the scrollbar
scr.style.overflow = ‘scroll’;
// Width of the inner div width scrollbar
wScroll = inn.offsetWidth;
// Remove the scrolling div from the doc
document.body.removeChild(document.body.lastChild);
// Pixel width of the scroller
OpenLayers.Util._scrollbarWidth = (wNoScroll – wScroll);
scrollbarWidth = OpenLayers.Util._scrollbarWidth;
}
return scrollbarWidth;
};
转载自：https://blog.csdn.net/wangzhiyuande/article/details/7704061
