144 lines
6.3 KiB
JavaScript
144 lines
6.3 KiB
JavaScript
/*
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* JavaScript Load Image Meta 1.0.2
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* https://github.com/blueimp/JavaScript-Load-Image
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*
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* Copyright 2013, Sebastian Tschan
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* https://blueimp.net
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*
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* Image meta data handling implementation
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* based on the help and contribution of
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* Achim Stöhr.
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*
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* Licensed under the MIT license:
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* http://www.opensource.org/licenses/MIT
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*/
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/*jslint continue:true */
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/*global define, window, DataView, Blob, Uint8Array, console */
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(function (factory) {
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'use strict';
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if (typeof define === 'function' && define.amd) {
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// Register as an anonymous AMD module:
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define(['load-image'], factory);
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} else {
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// Browser globals:
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factory(window.loadImage);
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}
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}(function (loadImage) {
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'use strict';
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var hasblobSlice = window.Blob && (Blob.prototype.slice ||
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Blob.prototype.webkitSlice || Blob.prototype.mozSlice);
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loadImage.blobSlice = hasblobSlice && function () {
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var slice = this.slice || this.webkitSlice || this.mozSlice;
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return slice.apply(this, arguments);
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};
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loadImage.metaDataParsers = {
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jpeg: {
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0xffe1: [] // APP1 marker
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}
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};
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// Parses image meta data and calls the callback with an object argument
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// with the following properties:
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// * imageHead: The complete image head as ArrayBuffer (Uint8Array for IE10)
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// The options arguments accepts an object and supports the following properties:
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// * maxMetaDataSize: Defines the maximum number of bytes to parse.
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// * disableImageHead: Disables creating the imageHead property.
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loadImage.parseMetaData = function (file, callback, options) {
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options = options || {};
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var that = this,
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// 256 KiB should contain all EXIF/ICC/IPTC segments:
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maxMetaDataSize = options.maxMetaDataSize || 262144,
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data = {},
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noMetaData = !(window.DataView && file && file.size >= 12 &&
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file.type === 'image/jpeg' && loadImage.blobSlice);
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if (noMetaData || !loadImage.readFile(
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loadImage.blobSlice.call(file, 0, maxMetaDataSize),
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function (e) {
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if (e.target.error) {
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// FileReader error
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console.log(e.target.error);
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callback(data);
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return;
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}
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// Note on endianness:
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// Since the marker and length bytes in JPEG files are always
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// stored in big endian order, we can leave the endian parameter
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// of the DataView methods undefined, defaulting to big endian.
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var buffer = e.target.result,
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dataView = new DataView(buffer),
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offset = 2,
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maxOffset = dataView.byteLength - 4,
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headLength = offset,
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markerBytes,
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markerLength,
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parsers,
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i;
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// Check for the JPEG marker (0xffd8):
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if (dataView.getUint16(0) === 0xffd8) {
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while (offset < maxOffset) {
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markerBytes = dataView.getUint16(offset);
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// Search for APPn (0xffeN) and COM (0xfffe) markers,
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// which contain application-specific meta-data like
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// Exif, ICC and IPTC data and text comments:
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if ((markerBytes >= 0xffe0 && markerBytes <= 0xffef) ||
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markerBytes === 0xfffe) {
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// The marker bytes (2) are always followed by
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// the length bytes (2), indicating the length of the
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// marker segment, which includes the length bytes,
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// but not the marker bytes, so we add 2:
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markerLength = dataView.getUint16(offset + 2) + 2;
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if (offset + markerLength > dataView.byteLength) {
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console.log('Invalid meta data: Invalid segment size.');
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break;
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}
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parsers = loadImage.metaDataParsers.jpeg[markerBytes];
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if (parsers) {
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for (i = 0; i < parsers.length; i += 1) {
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parsers[i].call(
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that,
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dataView,
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offset,
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markerLength,
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data,
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options
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);
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}
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}
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offset += markerLength;
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headLength = offset;
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} else {
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// Not an APPn or COM marker, probably safe to
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// assume that this is the end of the meta data
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break;
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}
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}
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// Meta length must be longer than JPEG marker (2)
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// plus APPn marker (2), followed by length bytes (2):
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if (!options.disableImageHead && headLength > 6) {
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if (buffer.slice) {
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data.imageHead = buffer.slice(0, headLength);
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} else {
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// Workaround for IE10, which does not yet
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// support ArrayBuffer.slice:
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data.imageHead = new Uint8Array(buffer)
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.subarray(0, headLength);
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}
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}
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} else {
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console.log('Invalid JPEG file: Missing JPEG marker.');
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}
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callback(data);
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},
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'readAsArrayBuffer'
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)) {
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callback(data);
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}
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};
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}));
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