hdjs
Version:
hdjs framework
310 lines (262 loc) • 9.82 kB
JavaScript
/**
* 代码来自于：https://github.com/blueimp/JavaScript-Load-Image
* 暂时项目中只用了orientation.
*
* 去除了 Exif Sub IFD Pointer, GPS Info IFD Pointer, Exif Thumbnail.
* @fileOverview EXIF解析
*/
// Sample
// ====================================
// Make : Apple
// Model : iPhone 4S
// Orientation : 1
// XResolution : 72 [72/1]
// YResolution : 72 [72/1]
// ResolutionUnit : 2
// Software : QuickTime 7.7.1
// DateTime : 2013:09:01 22:53:55
// ExifIFDPointer : 190
// ExposureTime : 0.058823529411764705 [1/17]
// FNumber : 2.4 [12/5]
// ExposureProgram : Normal program
// ISOSpeedRatings : 800
// ExifVersion : 0220
// DateTimeOriginal : 2013:09:01 22:52:51
// DateTimeDigitized : 2013:09:01 22:52:51
// ComponentsConfiguration : YCbCr
// ShutterSpeedValue : 4.058893515764426
// ApertureValue : 2.5260688216892597 [4845/1918]
// BrightnessValue : -0.3126686601998395
// MeteringMode : Pattern
// Flash : Flash did not fire, compulsory flash mode
// FocalLength : 4.28 [107/25]
// SubjectArea : [4 values]
// FlashpixVersion : 0100
// ColorSpace : 1
// PixelXDimension : 2448
// PixelYDimension : 3264
// SensingMethod : One-chip color area sensor
// ExposureMode : 0
// WhiteBalance : Auto white balance
// FocalLengthIn35mmFilm : 35
// SceneCaptureType : Standard
define([
'../../../base',
'../imagemeta'
], function( Base, ImageMeta ) {
var EXIF = {};
EXIF.ExifMap = function() {
return this;
};
EXIF.ExifMap.prototype.map = {
'Orientation': 0x0112
};
EXIF.ExifMap.prototype.get = function( id ) {
return this[ id ] || this[ this.map[ id ] ];
};
EXIF.exifTagTypes = {
// byte, 8-bit unsigned int:
1: {
getValue: function( dataView, dataOffset ) {
return dataView.getUint8( dataOffset );
},
size: 1
},
// ascii, 8-bit byte:
2: {
getValue: function( dataView, dataOffset ) {
return String.fromCharCode( dataView.getUint8( dataOffset ) );
},
size: 1,
ascii: true
},
// short, 16 bit int:
3: {
getValue: function( dataView, dataOffset, littleEndian ) {
return dataView.getUint16( dataOffset, littleEndian );
},
size: 2
},
// long, 32 bit int:
4: {
getValue: function( dataView, dataOffset, littleEndian ) {
return dataView.getUint32( dataOffset, littleEndian );
},
size: 4
},
// rational = two long values,
// first is numerator, second is denominator:
5: {
getValue: function( dataView, dataOffset, littleEndian ) {
return dataView.getUint32( dataOffset, littleEndian ) /
dataView.getUint32( dataOffset + 4, littleEndian );
},
size: 8
},
// slong, 32 bit signed int:
9: {
getValue: function( dataView, dataOffset, littleEndian ) {
return dataView.getInt32( dataOffset, littleEndian );
},
size: 4
},
// srational, two slongs, first is numerator, second is denominator:
10: {
getValue: function( dataView, dataOffset, littleEndian ) {
return dataView.getInt32( dataOffset, littleEndian ) /
dataView.getInt32( dataOffset + 4, littleEndian );
},
size: 8
}
};
// undefined, 8-bit byte, value depending on field:
EXIF.exifTagTypes[ 7 ] = EXIF.exifTagTypes[ 1 ];
EXIF.getExifValue = function( dataView, tiffOffset, offset, type, length,
littleEndian ) {
var tagType = EXIF.exifTagTypes[ type ],
tagSize, dataOffset, values, i, str, c;
if ( !tagType ) {
Base.log('Invalid Exif data: Invalid tag type.');
return;
}
tagSize = tagType.size * length;
// Determine if the value is contained in the dataOffset bytes,
// or if the value at the dataOffset is a pointer to the actual data:
dataOffset = tagSize > 4 ? tiffOffset + dataView.getUint32( offset + 8,
littleEndian ) : (offset + 8);
if ( dataOffset + tagSize > dataView.byteLength ) {
Base.log('Invalid Exif data: Invalid data offset.');
return;
}
if ( length === 1 ) {
return tagType.getValue( dataView, dataOffset, littleEndian );
}
values = [];
for ( i = 0; i < length; i += 1 ) {
values[ i ] = tagType.getValue( dataView,
dataOffset + i * tagType.size, littleEndian );
}
if ( tagType.ascii ) {
str = '';
// Concatenate the chars:
for ( i = 0; i < values.length; i += 1 ) {
c = values[ i ];
// Ignore the terminating NULL byte(s):
if ( c === '\u0000' ) {
break;
}
str += c;
}
return str;
}
return values;
};
EXIF.parseExifTag = function( dataView, tiffOffset, offset, littleEndian,
data ) {
var tag = dataView.getUint16( offset, littleEndian );
data.exif[ tag ] = EXIF.getExifValue( dataView, tiffOffset, offset,
dataView.getUint16( offset + 2, littleEndian ), // tag type
dataView.getUint32( offset + 4, littleEndian ), // tag length
littleEndian );
};
EXIF.parseExifTags = function( dataView, tiffOffset, dirOffset,
littleEndian, data ) {
var tagsNumber, dirEndOffset, i;
if ( dirOffset + 6 > dataView.byteLength ) {
Base.log('Invalid Exif data: Invalid directory offset.');
return;
}
tagsNumber = dataView.getUint16( dirOffset, littleEndian );
dirEndOffset = dirOffset + 2 + 12 * tagsNumber;
if ( dirEndOffset + 4 > dataView.byteLength ) {
Base.log('Invalid Exif data: Invalid directory size.');
return;
}
for ( i = 0; i < tagsNumber; i += 1 ) {
this.parseExifTag( dataView, tiffOffset,
dirOffset + 2 + 12 * i, // tag offset
littleEndian, data );
}
// Return the offset to the next directory:
return dataView.getUint32( dirEndOffset, littleEndian );
};
// EXIF.getExifThumbnail = function(dataView, offset, length) {
// var hexData,
// i,
// b;
// if (!length || offset + length > dataView.byteLength) {
// Base.log('Invalid Exif data: Invalid thumbnail data.');
// return;
// }
// hexData = [];
// for (i = 0; i < length; i += 1) {
// b = dataView.getUint8(offset + i);
// hexData.push((b < 16 ? '0' : '') + b.toString(16));
// }
// return 'data:image/jpeg,%' + hexData.join('%');
// };
EXIF.parseExifData = function( dataView, offset, length, data ) {
var tiffOffset = offset + 10,
littleEndian, dirOffset;
// Check for the ASCII code for "Exif" (0x45786966):
if ( dataView.getUint32( offset + 4 ) !== 0x45786966 ) {
// No Exif data, might be XMP data instead
return;
}
if ( tiffOffset + 8 > dataView.byteLength ) {
Base.log('Invalid Exif data: Invalid segment size.');
return;
}
// Check for the two null bytes:
if ( dataView.getUint16( offset + 8 ) !== 0x0000 ) {
Base.log('Invalid Exif data: Missing byte alignment offset.');
return;
}
// Check the byte alignment:
switch ( dataView.getUint16( tiffOffset ) ) {
case 0x4949:
littleEndian = true;
break;
case 0x4D4D:
littleEndian = false;
break;
default:
Base.log('Invalid Exif data: Invalid byte alignment marker.');
return;
}
// Check for the TIFF tag marker (0x002A):
if ( dataView.getUint16( tiffOffset + 2, littleEndian ) !== 0x002A ) {
Base.log('Invalid Exif data: Missing TIFF marker.');
return;
}
// Retrieve the directory offset bytes, usually 0x00000008 or 8 decimal:
dirOffset = dataView.getUint32( tiffOffset + 4, littleEndian );
// Create the exif object to store the tags:
data.exif = new EXIF.ExifMap();
// Parse the tags of the main image directory and retrieve the
// offset to the next directory, usually the thumbnail directory:
dirOffset = EXIF.parseExifTags( dataView, tiffOffset,
tiffOffset + dirOffset, littleEndian, data );
// 尝试读取缩略图
// if ( dirOffset ) {
// thumbnailData = {exif: {}};
// dirOffset = EXIF.parseExifTags(
// dataView,
// tiffOffset,
// tiffOffset + dirOffset,
// littleEndian,
// thumbnailData
// );
// // Check for JPEG Thumbnail offset:
// if (thumbnailData.exif[0x0201]) {
// data.exif.Thumbnail = EXIF.getExifThumbnail(
// dataView,
// tiffOffset + thumbnailData.exif[0x0201],
// thumbnailData.exif[0x0202] // Thumbnail data length
// );
// }
// }
};
ImageMeta.parsers[ 0xffe1 ].push( EXIF.parseExifData );
return EXIF;
});