Merge pull request #25 from joeweiss/master

Add IPTC extraction function
exif-js · Jun 24, 2014 · 5e51110 · 5e51110
2 parents d662d83 + c04ff41
commit 5e51110
Showing 1 changed file with 102 additions and 0 deletions.
diff --git a/exif.js b/exif.js
@@ -328,7 +328,9 @@ var EXIF = (function() {
     function getImageData(img, callback) {
         function handleBinaryFile(binFile) {
             var data = findEXIFinJPEG(binFile);
+            var iptcdata = findIPTCinJPEG(binFile);
             img.exifdata = data || {};
+            img.iptcdata = iptcdata || {};
             if (callback) {
                 callback.call(img);
             }
@@ -411,7 +413,107 @@ var EXIF = (function() {
         }
 
     }
+
+    function findIPTCinJPEG(file) {
+        var dataView = new DataView(file);
+
+        if (debug) console.log("Got file of length " + file.byteLength);
+        if ((dataView.getUint8(0) != 0xFF) || (dataView.getUint8(1) != 0xD8)) {
+            if (debug) console.log("Not a valid JPEG");
+            return false; // not a valid jpeg
+        }
+
+        var offset = 2,
+            length = file.byteLength;
+
+
+        var isFieldSegmentStart = function(dataView, offset){
+            return (
+                dataView.getUint8(offset) === 0x38 &&
+                dataView.getUint8(offset+1) === 0x42 &&
+                dataView.getUint8(offset+2) === 0x49 &&
+                dataView.getUint8(offset+3) === 0x4D &&
+                dataView.getUint8(offset+4) === 0x04 &&
+                dataView.getUint8(offset+5) === 0x04
+            );
+        };
+
+        while (offset < length) {
+
+            if ( isFieldSegmentStart(dataView, offset )){
+
+                // Get the length of the name header (which is padded to an even number of bytes)
+                var nameHeaderLength = dataView.getUint8(offset+7);
+                if(nameHeaderLength % 2 !== 0) nameHeaderLength += 1;
+                // Check for pre photoshop 6 format
+                if(nameHeaderLength === 0) {
+                    // Always 4 
+                    nameHeaderLength = 4;
+                }
+
+                var startOffset = offset + 8 + nameHeaderLength;
+                var sectionLength = dataView.getUint16(offset + 6 + nameHeaderLength);
+
+                return readIPTCData(file, startOffset, sectionLength);
+
+                break;
+
+            }
+
+
+            // Not the marker, continue searching
+            offset++;
 
+        }
+
+    }
+    var IptcFieldMap = {
+        0x78 : 'caption',
+        0x6E : 'credit',
+        0x19 : 'keywords',
+        0x37 : 'dateCreated',
+        0x50 : 'byline',
+        0x55 : 'bylineTitle',
+        0x7A : 'captionWriter',
+        0x69 : 'headline',
+        0x74 : 'copyright',
+        0x0F : 'category'
+    };
+    function readIPTCData(file, startOffset, sectionLength){
+        var dataView = new DataView(file);
+        var data = {};
+        var fieldValue, fieldName, dataSize, segmentType, segmentSize;
+        var segmentStartPos = startOffset;
+        while(segmentStartPos < startOffset+sectionLength) {
+            if(dataView.getUint8(segmentStartPos) === 0x1C && dataView.getUint8(segmentStartPos+1) === 0x02){
+                segmentType = dataView.getUint8(segmentStartPos+2);
+                if(segmentType in IptcFieldMap) {
+                    dataSize = dataView.getInt16(segmentStartPos+3);
+                    segmentSize = dataSize + 5;
+                    fieldName = IptcFieldMap[segmentType];
+                    fieldValue = getStringFromDB(dataView, segmentStartPos+5, dataSize);
+                    // Check if we already stored a value with this name
+                    if(data.hasOwnProperty(fieldName)) {
+                        // Value already stored with this name, create multivalue field
+                        if(data[fieldName] instanceof Array) {
+                            data[fieldName].push(fieldValue);
+                        }
+                        else {
+                            data[fieldName] = [data[fieldName], fieldValue];
+                        }
+                    }
+                    else {
+                        data[fieldName] = fieldValue;
+                    }
+                }
+
+            }
+            segmentStartPos++;
+        }
+        return data;
+    }
+
+
 
     function readTags(file, tiffStart, dirStart, strings, bigEnd) {
         var entries = file.getUint16(dirStart, !bigEnd),