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EXIF.js
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EXIF.js
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/*
Script: EXIF.js
Copyright:
Copyright (c) 2009 Dipl.-Ing. (FH) André Fiedler <kontakt@visualdrugs.net>
License:
MIT-style license
Version
0.9
Credits:
Based on Javascript EXIF Reader 0.1.2, Copyright (c) 2008 Jacob Seidelin, cupboy@gmail.com, http://blog.nihilogic.dk/
*/
var EXIF = new Class({
Implements: [Events, Options],
options: {},
initialize: function(options){
this.setOptions(options);
this.tags = new Hash();
},
parseByteStream: function(byteStream){
if (byteStream.getByteAt(0) != 0xFF || byteStream.getByteAt(1) != 0xD8) {
this.fireEvent('complete', this.tags);
return this; // not a valid jpeg
}
var offset = 2;
var length = byteStream.getLength();
while (offset < length) {
if (byteStream.getByteAt(offset) != 0xFF) {
this.log('Not a valid marker at offset ' + offset + ', found: ' + byteStream.getByteAt(offset));
this.fireEvent('complete', this.tags);
return this; // not a valid marker, something is wrong
}
var marker = byteStream.getByteAt(offset + 1);
// we could implement handling for other markers here,
// but we're only looking for 0xFFE1 for EXIF data
if (marker == 22400) {
this.log('Found 0xFFE1 marker');
return this.readEXIFData(byteStream, offset + 4, byteStream.getShortAt(offset + 2, true) - 2);
}
else {
if (marker == 225) {
// 0xE1 = Application-specific 1 (for EXIF)
this.log('Found 0xFFE1 marker');
return this.readEXIFData(byteStream, offset + 4, byteStream.getShortAt(offset + 2, true) - 2);
}
else {
offset += 2 + byteStream.getShortAt(offset + 2, true);
}
}
}
},
readEXIFData: function(byteStream, start, length){
if (byteStream.getStringAt(start, 4) != 'Exif') {
this.log('Not valid EXIF data! ' + byteStream.getStringAt(start, 4));
this.fireEvent('complete', this.tags);
return this;
}
var bigEnd;
var TIFFOffset = start + 6;
// test for TIFF validity and endianness
if (byteStream.getShortAt(TIFFOffset) == 0x4949) {
bigEnd = false;
}
else
if (byteStream.getShortAt(TIFFOffset) == 0x4D4D) {
bigEnd = true;
}
else {
this.log('Not valid TIFF data! (no 0x4949 or 0x4D4D)');
this.fireEvent('complete', this.tags);
return this;
}
if (byteStream.getShortAt(TIFFOffset + 2, bigEnd) != 0x002A) {
this.log('Not valid TIFF data! (no 0x002A)');
this.fireEvent('complete', this.tags);
return this;
}
if (byteStream.getLongAt(TIFFOffset + 4, bigEnd) != 0x00000008) {
this.log('Not valid TIFF data! (First offset not 8)', byteStream.getShortAt(TIFFOffset + 4, bigEnd));
this.fireEvent('complete', this.tags);
return this;
}
var tags = this.readTags(byteStream, TIFFOffset, TIFFOffset + 8, MooTools.lang.get('EXIF', 'TiffTags'), bigEnd);
if (tags.ExifIFDPointer) {
var EXIFTags = this.readTags(byteStream, TIFFOffset, TIFFOffset + tags.ExifIFDPointer, MooTools.lang.get('EXIF', 'Tags'), bigEnd);
for (var tag in EXIFTags) {
switch (tag) {
case 'LightSource':
case 'Flash':
case 'MeteringMode':
case 'ExposureProgram':
case 'SensingMethod':
case 'SceneCaptureType':
case 'SceneType':
case 'CustomRendered':
case 'WhiteBalance':
case 'GainControl':
case 'Contrast':
case 'Saturation':
case 'Sharpness':
case 'SubjectDistanceRange':
case 'FileSource':
EXIFTags[tag] = MooTools.lang.get('EXIF', 'StringValues')[tag][EXIFTags[tag]];
break;
case 'ExifVersion':
case 'FlashpixVersion':
EXIFTags[tag] = String.fromCharCode(EXIFTags[tag][0], EXIFTags[tag][1], EXIFTags[tag][2], EXIFTags[tag][3]);
break;
case 'ComponentsConfiguration':
EXIFTags[strTag] = MooTools.lang.get('EXIF', 'StringValues').Components[EXIFTags[tag][0]] +
MooTools.lang.get('EXIF', 'StringValues').Components[EXIFTags[tag][1]] +
MooTools.lang.get('EXIF', 'StringValues').Components[EXIFTags[tag][2]] +
MooTools.lang.get('EXIF', 'StringValues').Components[EXIFTags[tag][3]];
break;
}
tags[tag] = EXIFTags[tag];
}
}
if (tags.GPSInfoIFDPointer) {
var GPSTags = this.readTags(byteStream, TIFFOffset, TIFFOffset + tags.GPSInfoIFDPointer, MooTools.lang.get('EXIF', 'GPSTags'), bigEnd);
for (var tag in GPSTags) {
switch (tag) {
case 'GPSVersionID':
GPSTags[tag] = GPSTags[tag][0] +
'.' +
GPSTags[tag][1] +
'.' +
GPSTags[tag][2] +
'.' +
GPSTags[tag][3];
break;
}
tags[tag] = GPSTags[tag];
}
}
this.tags.extend(tags);
this.fireEvent('complete', this.tags);
return this;
},
readTags: function(byteStream, TIFFStart, dirStart, strings, bigEnd){
var entries = byteStream.getShortAt(dirStart, bigEnd);
var tags = {};
for (var i = 0; i < entries; i++) {
var entryOffset = dirStart + i * 12 + 2;
var tag = strings[byteStream.getShortAt(entryOffset, bigEnd)];
if (!tag)
this.log('Unknown tag: ' + byteStream.getShortAt(entryOffset, bigEnd));
tags[tag] = this.readTagValue(byteStream, entryOffset, TIFFStart, dirStart, bigEnd);
}
return tags;
},
readTagValue: function(byteStream, entryOffset, TIFFStart, dirStart, bigEnd){
var type = byteStream.getShortAt(entryOffset + 2, bigEnd);
var numValues = byteStream.getLongAt(entryOffset + 4, bigEnd);
var valueOffset = byteStream.getLongAt(entryOffset + 8, bigEnd) + TIFFStart;
switch (type) {
case 1: // byte, 8-bit unsigned int
case 7: // undefined, 8-bit byte, value depending on field
if (numValues == 1) {
return byteStream.getByteAt(entryOffset + 8, bigEnd);
}
else {
var valOffset = numValues > 4 ? valueOffset : (entryOffset + 8);
var values = [];
for (var n = 0; n < numValues; n++) {
values[n] = byteStream.getByteAt(valOffset + n);
}
return values;
}
break;
case 2: // ascii, 8-bit byte
var stringOffset = numValues > 4 ? valueOffset : (entryOffset + 8);
return byteStream.getStringAt(stringOffset, numValues - 1);
break;
case 3: // short, 16 bit int
if (numValues == 1) {
return byteStream.getShortAt(entryOffset + 8, bigEnd);
}
else {
var valOffset = numValues > 2 ? valueOffset : (entryOffset + 8);
var values = [];
for (var n = 0; n < numValues; n++) {
values[n] = byteStream.getShortAt(valOffset + 2 * n, bigEnd);
}
return values;
}
break;
case 4: // long, 32 bit int
if (numValues == 1) {
return byteStream.getLongAt(entryOffset + 8, bigEnd);
}
else {
var values = [];
for (var n = 0; n < numValues; n++) {
values[n] = byteStream.getLongAt(valueOffset + 4 * n, bigEnd);
}
return values;
}
break;
case 5: // rational = two long values, first is numerator, second is denominator
if (numValues == 1) {
return byteStream.getLongAt(valueOffset, bigEnd) / byteStream.getLongAt(valueOffset + 4, bigEnd);
}
else {
var values = [];
for (var n = 0; n < numValues; n++) {
values[n] = byteStream.getLongAt(valueOffset + 8 * n, bigEnd) / byteStream.getLongAt(valueOffset + 4 + 8 * n, bigEnd);
}
return values;
}
break;
case 9: // slong, 32 bit signed int
if (numValues == 1) {
return byteStream.getSLongAt(entryOffset + 8, bigEnd);
}
else {
var values = [];
for (var n = 0; n < numValues; n++) {
values[n] = byteStream.getSLongAt(valueOffset + 4 * n, bigEnd);
}
return values;
}
break;
case 10: // signed rational, two slongs, first is numerator, second is denominator
if (numValues == 1) {
return byteStream.getSLongAt(valueOffset, bigEnd) / byteStream.getSLongAt(valueOffset + 4, bigEnd);
}
else {
var values = [];
for (var n = 0; n < numValues; n++) {
values[n] = byteStream.getSLongAt(valueOffset + 8 * n, bigEnd) / byteStream.getSLongAt(valueOffset + 4 + 8 * n, bigEnd);
}
return values;
}
break;
}
},
getTags: function(){
return this.tags;
},
pretty: function(){
var pretty = '';
for (var a in this.tags) {
if (this.tags.hasOwnProperty(a)) {
if (typeof this.tags[a] == 'object') {
pretty += a + ' : [' + this.tags[a].length + " values]\r\n";
}
else {
pretty += a + ' : ' + this.tags[a] + "\r\n";
}
}
}
return pretty;
},
log: function(){
if (window.console && console.log && console.log.apply)
console.log.apply(console, arguments);
}
});