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build/node_modules/exif-parser/lib/parser.js

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+/*jslint browser: true, devel: true, bitwise: false, debug: true, eqeq: false, es5: true, evil: false, forin: false, newcap: false, nomen: true, plusplus: true, regexp: false, unparam: false, sloppy: true, stupid: false, sub: false, todo: true, vars: true, white: true */
+
+var jpeg = require('./jpeg'),
+	exif = require('./exif'),
+	simplify = require('./simplify');
+
+function ExifResult(startMarker, tags, imageSize, thumbnailOffset, thumbnailLength, thumbnailType, app1Offset) {
+	this.startMarker = startMarker;
+	this.tags = tags;
+	this.imageSize = imageSize;
+	this.thumbnailOffset = thumbnailOffset;
+	this.thumbnailLength = thumbnailLength;
+	this.thumbnailType = thumbnailType;
+	this.app1Offset = app1Offset;
+}
+
+ExifResult.prototype = {
+	hasThumbnail: function(mime) {
+		if(!this.thumbnailOffset || !this.thumbnailLength) {
+			return false;
+		}
+		if(typeof mime !== 'string') {
+			return true;
+		}
+		if(mime.toLowerCase().trim() === 'image/jpeg') {
+			return this.thumbnailType === 6;
+		}
+		if(mime.toLowerCase().trim() === 'image/tiff') {
+			return this.thumbnailType === 1;
+		}
+		return false;
+	},
+	getThumbnailOffset: function() {
+		return this.app1Offset + 6 + this.thumbnailOffset;
+	},
+	getThumbnailLength: function() {
+		return this.thumbnailLength;
+	},
+	getThumbnailBuffer: function() {
+		return this._getThumbnailStream().nextBuffer(this.thumbnailLength);
+	},
+	_getThumbnailStream: function() {
+		return this.startMarker.openWithOffset(this.getThumbnailOffset());
+	},
+	getImageSize: function() {
+		return this.imageSize;
+	},
+	getThumbnailSize: function() {
+		var stream = this._getThumbnailStream(), size;
+		jpeg.parseSections(stream, function(sectionType, sectionStream) {
+			if(jpeg.getSectionName(sectionType).name === 'SOF') {
+				size = jpeg.getSizeFromSOFSection(sectionStream);
+			}
+		});
+		return size;
+	}
+};
+
+function Parser(stream) {
+	this.stream = stream;
+	this.flags = {
+		readBinaryTags: false,
+		resolveTagNames: true,
+		simplifyValues: true,
+		imageSize: true,
+		hidePointers: true,
+		returnTags: true
+	};
+}
+
+Parser.prototype = {
+	enableBinaryFields: function(enable) {
+		this.flags.readBinaryTags = !!enable;
+		return this;
+	},
+	enablePointers: function(enable) {
+		this.flags.hidePointers = !enable;
+		return this;
+	},
+	enableTagNames: function(enable) {
+		this.flags.resolveTagNames = !!enable;
+		return this;
+	},
+	enableImageSize: function(enable) {
+		this.flags.imageSize = !!enable;
+		return this;
+	},
+	enableReturnTags: function(enable) {
+		this.flags.returnTags = !!enable;
+		return this;
+	},
+	enableSimpleValues: function(enable) {
+		this.flags.simplifyValues = !!enable;
+		return this;
+	},
+	parse: function() {
+		var start = this.stream.mark(),
+			stream = start.openWithOffset(0),
+			flags = this.flags,
+			tags,
+			imageSize,
+			thumbnailOffset,
+			thumbnailLength,
+			thumbnailType,
+			app1Offset,
+			tagNames,
+			getTagValue, setTagValue;
+		if(flags.resolveTagNames) {
+			tagNames = require('./exif-tags');
+		}
+		if(flags.resolveTagNames) {
+			tags = {};
+			getTagValue = function(t) {
+				return tags[t.name];
+			};
+			setTagValue = function(t, value) {
+				tags[t.name] = value;
+			};
+		} else {
+			tags = [];
+			getTagValue = function(t) {
+				var i;
+				for(i = 0; i < tags.length; ++i) {
+					if(tags[i].type === t.type && tags[i].section === t.section) {
+						return tags.value;
+					}
+				}
+			};
+			setTagValue = function(t, value) {
+				var i;
+				for(i = 0; i < tags.length; ++i) {
+					if(tags[i].type === t.type && tags[i].section === t.section) {
+						tags.value = value;
+						return;
+					}
+				}
+			};
+		}
+
+		jpeg.parseSections(stream, function(sectionType, sectionStream) {
+			var validExifHeaders, sectionOffset = sectionStream.offsetFrom(start);
+			if(sectionType === 0xE1) {
+				validExifHeaders = exif.parseTags(sectionStream, function(ifdSection, tagType, value, format) {
+					//ignore binary fields if disabled
+					if(!flags.readBinaryTags && format === 7) {
+						return;
+					}
+
+					if(tagType === 0x0201) {
+						thumbnailOffset = value[0];
+						if(flags.hidePointers) {return;}
+					} else if(tagType === 0x0202) {
+						thumbnailLength = value[0];
+						if(flags.hidePointers) {return;}
+					} else if(tagType === 0x0103) {
+						thumbnailType = value[0];
+						if(flags.hidePointers) {return;}
+					}
+					//if flag is set to not store tags, return here after storing pointers
+					if(!flags.returnTags) {
+						return;
+					}
+
+					if(flags.simplifyValues) {
+						value = simplify.simplifyValue(value, format);
+					}
+					if(flags.resolveTagNames) {
+						var sectionTagNames = ifdSection === exif.GPSIFD ? tagNames.gps : tagNames.exif;
+						var name = sectionTagNames[tagType];
+						if(!name) {
+							name = tagNames.exif[tagType];
+						}
+						if (!tags.hasOwnProperty(name)) {
+							tags[name] = value;
+						}
+					} else {
+						tags.push({
+							section: ifdSection,
+							type: tagType,
+							value: value
+						});
+					}
+				});
+				if(validExifHeaders) {
+					app1Offset = sectionOffset;
+				}
+			}
+			else if(flags.imageSize && jpeg.getSectionName(sectionType).name === 'SOF') {
+				imageSize = jpeg.getSizeFromSOFSection(sectionStream);
+			}
+		});
+
+		if(flags.simplifyValues) {
+			simplify.castDegreeValues(getTagValue, setTagValue);
+			simplify.castDateValues(getTagValue, setTagValue);
+		}
+
+		return new ExifResult(start, tags, imageSize, thumbnailOffset, thumbnailLength, thumbnailType, app1Offset);
+	}
+};
+
+
+
+module.exports = Parser;