Update to convert the XML into name value pairs.

Author: rlmcneary2

js/load-image-xmp.js

@@ -12,35 +12,92 @@
 } (function (loadImage) {
     'use strict'
 
+    loadImage.XmpMap = function () {
+        return this
+    };
+
+    loadImage.XmpMap.prototype.get = function (id) {
+        return this[id];
+    }
+
     loadImage.parseXmpData = function (dataView, offset, length, data, options) {
         if (options.disableExif) {
             return;
         }
 
         // Check for the ASCII code for "http" (0x68747470). Note that the actual XMP identifier is quite long: "http://ns.adobe.com/xap/1.0/\x00"
-        var arrIdentifier = [];
         var offsetNamespace = 4;
         var lengthNamespace = 29;
+        var arrNamespace = [];
         for (var i = 0; i < lengthNamespace; i++) {
-            arrIdentifier[i] = String.fromCharCode(dataView.getInt8(offset + offsetNamespace + i));
+            arrNamespace.push(String.fromCharCode(dataView.getUint8(offset + offsetNamespace + i)));
         }
 
-        var identifier = arrIdentifier.join("");
-        if (identifier !== "http://ns.adobe.com/xap/1.0//0") {
+        var namespace = arrNamespace.join("");
+        if (namespace !== "http://ns.adobe.com/xap/1.0//0") {
             // No XMP data.
             return;
         }
 
         var offsetLp = 2; // Offset to the packet length field.
-        var xmpLength = dataView.getUint16(offset + offsetLp);
+        var packetLength = dataView.getUint16(offset + offsetLp);
 
         var lengthLp = 2;
-        xmpLength -= (lengthLp + lengthNamespace); // The packet length is a little misleading it includes the length of Lp and Namespace, remove those two to get the actual packet length.
+        packetLength -= (lengthLp + lengthNamespace); // The packet length is a little misleading it includes the length of Lp and Namespace, remove those two to get the actual packet length.
 
         var maxPacketLength = 65503;
-        if (maxPacketLength < xmpLength){
+        if (maxPacketLength < packetLength) {
+            // The length of the packet is not valid. Note that XMP does allow multiple packets but they are unlikely and NOT currently supported
+            return;
+        }
+
+        // According to Adobe's document
+        // (http://www.adobe.com/content/dam/Adobe/en/devnet/xmp/pdfs/XMPSpecificationPart3.pdf)
+        // an EXIF encoding of XMP will always be UTF-8. No need to check for
+        // bytes per character or endianness.
+
+        // Find the start of packet data.
+        var offsetPacket = offsetNamespace + lengthNamespace;
+        var arrPacketData = [];
+        for (var j = 0; j < packetLength; j++) {
+            arrPacketData.push(String.fromCharCode(dataView.getUint8(offset + offsetPacket + j)));
+        }
+        var xml = arrPacketData.join("");
+
+        data.xmp = new loadImage.XmpMap();
+
+        // Create an XMLDocument and extract the attributes from the
+        // Description element.
+        var xmlDocument = new DOMParser().parseFromString(xml, "application/xml");
+
+        var document = xmlDocument.documentElement;
+        if (!document) {
+            return;
+        }
+
+        var xpath = "/*[namespace-uri()='adobe:ns:meta/' and local-name()='xmpmeta']/*[namespace-uri()='http://www.w3.org/1999/02/22-rdf-syntax-ns#' and local-name()='RDF']/*[namespace-uri()='http://www.w3.org/1999/02/22-rdf-syntax-ns#' and local-name()='Description']";
+        var xpathResult;
+        try {
+            xpathResult = xmlDocument.evaluate(xpath, document, xmlDocument.createNSResolver(document), XPathResult.FIRST_ORDERED_NODE_TYPE, null);
+        } catch (err) {
+            console.log("Error selecting Description node: '" + err.message || JSON.stringify(err) + "'.");
+        }
+
+        if (!xpathResult) {
             return;
         }
+
+        if (xpathResult.resultType !== XPathResult.FIRST_ORDERED_NODE_TYPE) {
+            console.log("xpathResult type " + xpathResult.resultType + " is not supported.");
+            return;
+        }
+
+        var node = xpathResult.singleNodeValue;
+        var attr;
+        for (var k = 0; k < node.attributes.length; k++) {
+            attr = node.attributes[k];
+            data.xmp[attr.localName] = attr.value;
+		}
     }
 
     loadImage.metaDataParsers.jpeg[0xffe1].push(loadImage.parseXmpData);