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First version of JPEG and EXIF parser with starter unit tests and upd…
…ated docs.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,6 +1,6 @@ | ||
| General-purpose, event-based parsers for digital images. | ||
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| Currently only supports GIF. | ||
| Currently only supports GIF and JPEG. | ||
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| Some nice implementations for HEIF, JPEG, PNG, TIFF here: | ||
| https://github.com/MikeKovarik/exifr/tree/master/src/file-parsers |
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,234 @@ | ||
| import { ByteStream } from '../../io/bytestream.js'; | ||
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| /** @enum {number} */ | ||
| export const ExifTagNumber = { | ||
| // Tags used by IFD0. | ||
| IMAGE_DESCRIPTION: 0x010e, | ||
| MAKE: 0x010f, | ||
| MODEL: 0x0110, | ||
| ORIENTATION: 0x0112, | ||
| X_RESOLUTION: 0x011a, | ||
| Y_RESOLUTION: 0x011b, | ||
| RESOLUTION_UNIT: 0x0128, | ||
| SOFTWARE: 0x0131, | ||
| DATE_TIME: 0x0132, | ||
| WHITE_POINT: 0x013e, | ||
| PRIMARY_CHROMATICITIES: 0x013f, | ||
| Y_CB_CR_COEFFICIENTS: 0x0211, | ||
| Y_CB_CR_POSITIONING: 0x0213, | ||
| REFERENCE_BLACK_WHITE: 0x0214, | ||
| COPYRIGHT: 0x8298, | ||
| EXIF_OFFSET: 0x8769, | ||
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| // Tags used by Exif SubIFD. | ||
| EXPOSURE_TIME: 0x829a, | ||
| F_NUMBER: 0x829d, | ||
| EXPOSURE_PROGRAM: 0x8822, | ||
| ISO_SPEED_RATINGS: 0x8827, | ||
| EXIF_VERSION: 0x9000, | ||
| DATE_TIME_ORIGINAL: 0x9003, | ||
| DATE_TIME_DIGITIZED: 0x9004, | ||
| COMPONENT_CONFIGURATION: 0x9101, | ||
| COMPRESSED_BITS_PER_PIXEL: 0x9102, | ||
| SHUTTER_SPEED_VALUE: 0x9201, | ||
| APERTURE_VALUE: 0x9202, | ||
| BRIGHTNESS_VALUE: 0x9203, | ||
| EXPOSURE_BIAS_VALUE: 0x9204, | ||
| MAX_APERTURE_VALUE: 0x9205, | ||
| SUBJECT_DISTANCE: 0x9206, | ||
| METERING_MODE: 0x9207, | ||
| LIGHT_SOURCE: 0x9208, | ||
| FLASH: 0x9209, | ||
| FOCAL_LENGTH: 0x920a, | ||
| MAKER_NOTE: 0x927c, | ||
| USER_COMMENT: 0x9286, | ||
| FLASH_PIX_VERSION: 0xa000, | ||
| COLOR_SPACE: 0xa001, | ||
| EXIF_IMAGE_WIDTH: 0xa002, | ||
| EXIF_IMAGE_HEIGHT: 0xa003, | ||
| RELATED_SOUND_FILE: 0xa004, | ||
| EXIF_INTEROPERABILITY_OFFSET: 0xa005, | ||
| FOCAL_PLANE_X_RESOLUTION: 0xa20e, | ||
| FOCAL_PLANE_Y_RESOLUTION: 0x20f, | ||
| FOCAL_PLANE_RESOLUTION_UNIT: 0xa210, | ||
| SENSING_METHOD: 0xa217, | ||
| FILE_SOURCE: 0xa300, | ||
| SCENE_TYPE: 0xa301, | ||
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| // Tags used by IFD1. | ||
| IMAGE_WIDTH: 0x0100, | ||
| IMAGE_LENGTH: 0x0101, | ||
| BITS_PER_SAMPLE: 0x0102, | ||
| COMPRESSION: 0x0103, | ||
| PHOTOMETRIC_INTERPRETATION: 0x0106, | ||
| STRIP_OFFSETS: 0x0111, | ||
| SAMPLES_PER_PIXEL: 0x0115, | ||
| ROWS_PER_STRIP: 0x0116, | ||
| STRIP_BYTE_COUNTS: 0x0117, | ||
| // X_RESOLUTION, Y_RESOLUTION | ||
| PLANAR_CONFIGURATION: 0x011c, | ||
| // RESOLUTION_UNIT | ||
| JPEG_IF_OFFSET: 0x0201, | ||
| JPEG_IF_BYTE_COUNT: 0x0202, | ||
| // Y_CB_CR_COEFFICIENTS | ||
| Y_CB_CR_SUB_SAMPLING: 0x0212, | ||
| // Y_CB_CR_POSITIONING, REFERENCE_BLACK_WHITE | ||
| }; | ||
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| /** @enum {number} */ | ||
| export const ExifDataFormat = { | ||
| UNSIGNED_BYTE: 1, | ||
| ASCII_STRING: 2, | ||
| UNSIGNED_SHORT: 3, | ||
| UNSIGNED_LONG: 4, | ||
| UNSIGNED_RATIONAL: 5, | ||
| SIGNED_BYTE: 6, | ||
| UNDEFINED: 7, | ||
| SIGNED_SHORT: 8, | ||
| SIGNED_LONG: 9, | ||
| SIGNED_RATIONAL: 10, | ||
| SINGLE_FLOAT: 11, | ||
| DOUBLE_FLOAT: 12, | ||
| }; | ||
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| /** | ||
| * @typedef ExifValue | ||
| * @property {ExifTagNumber} tagNumber The numerical value of the tag. | ||
| * @property {string=} tagName A string representing the tag number. | ||
| * @property {ExifDataFormat} dataFormat The data format. | ||
| * @property {number=} numericalValue Populated for SIGNED/UNSIGNED BYTE/SHORT/LONG/FLOAT. | ||
| * @property {string=} stringValue Populated only for ASCII_STRING. | ||
| * @property {number=} numeratorValue Populated only for SIGNED/UNSIGNED RATIONAL. | ||
| * @property {number=} denominatorValue Populated only for SIGNED/UNSIGNED RATIONAL. | ||
| * @property {number=} numComponents Populated only for UNDEFINED data format. | ||
| * @property {number=} offsetValue Populated only for UNDEFINED data format. | ||
| */ | ||
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| /** | ||
| * @param {number} tagNumber | ||
| * @param {string} type | ||
| * @param {number} len | ||
| * @param {number} dataVal | ||
| */ | ||
| function warnBadLength(tagNumber, type, len, dataVal) { | ||
| const hexTag = tagNumber.toString(16); | ||
| console.warn(`Tag 0x${hexTag} is ${type} with len=${len} and data=${dataVal}`); | ||
| } | ||
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| /** | ||
| * @param {ByteStream} stream | ||
| * @param {ByteStream} lookAheadStream | ||
| * @param {boolean} debug | ||
| * @returns {ExifValue} | ||
| */ | ||
| export function getExifValue(stream, lookAheadStream, DEBUG = false) { | ||
| const tagNumber = stream.readNumber(2); | ||
| let tagName = findNameWithValue(ExifTagNumber, tagNumber); | ||
| if (!tagName) { | ||
| tagName = `UNKNOWN (0x${tagNumber.toString(16)})`; | ||
| } | ||
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| let dataFormat = stream.readNumber(2); | ||
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| // Handle bad types for special tags. | ||
| if (tagNumber === ExifTagNumber.EXIF_OFFSET) { | ||
| dataFormat = ExifDataFormat.UNSIGNED_LONG; | ||
| } | ||
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| const dataFormatName = findNameWithValue(ExifDataFormat, dataFormat); | ||
| if (!dataFormatName) throw `Invalid data format: ${dataFormat}`; | ||
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| /** @type {ExifValue} */ | ||
| const exifValue = { | ||
| tagNumber, | ||
| tagName, | ||
| dataFormat, | ||
| }; | ||
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| let len = stream.readNumber(4); | ||
| switch (dataFormat) { | ||
| case ExifDataFormat.UNSIGNED_BYTE: | ||
| if (len !== 1 && DEBUG) { | ||
| warnBadLength(tagNumber, dataFormatName, len, stream.peekNumber(4)); | ||
| } | ||
| exifValue.numericalValue = stream.readNumber(1); | ||
| stream.skip(3); | ||
| break; | ||
| case ExifDataFormat.ASCII_STRING: | ||
| if (len <= 4) { | ||
| exifValue.stringValue = stream.readString(4); | ||
| } else { | ||
| const strOffset = stream.readNumber(4); | ||
| exifValue.stringValue = lookAheadStream.tee().skip(strOffset).readString(len - 1); | ||
| } | ||
| break; | ||
| case ExifDataFormat.UNSIGNED_SHORT: | ||
| if (len !== 1 && DEBUG) { | ||
| warnBadLength(tagNumber, dataFormatName, len, stream.peekNumber(4)); | ||
| } | ||
| exifValue.numericalValue = stream.readNumber(2); | ||
| stream.skip(2); | ||
| break; | ||
| case ExifDataFormat.UNSIGNED_LONG: | ||
| if (len !== 1 && DEBUG) { | ||
| warnBadLength(tagNumber, dataFormatName, len, stream.peekNumber(4)); | ||
| } | ||
| exifValue.numericalValue = stream.readNumber(4); | ||
| break; | ||
| case ExifDataFormat.UNSIGNED_RATIONAL: | ||
| if (len !== 1 && DEBUG) { | ||
| warnBadLength(tagNumber, dataFormatName, len, stream.peekNumber(4)); | ||
| } | ||
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| const uratStream = lookAheadStream.tee().skip(stream.readNumber(4)); | ||
| exifValue.numeratorValue = uratStream.readNumber(4); | ||
| exifValue.denominatorValue = uratStream.readNumber(4); | ||
| break; | ||
| case ExifDataFormat.SIGNED_BYTE: | ||
| if (len !== 1 && DEBUG) { | ||
| warnBadLength(tagNumber, dataFormatName, len, stream.peekSignedNumber(4)); | ||
| } | ||
| exifValue.numericalValue = stream.readSignedNumber(1); | ||
| stream.skip(3); | ||
| break; | ||
| case ExifDataFormat.UNDEFINED: | ||
| exifValue.numComponents = len; | ||
| exifValue.offsetValue = stream.readNumber(4); | ||
| break; | ||
| case ExifDataFormat.SIGNED_SHORT: | ||
| if (len !== 1 && DEBUG) { | ||
| warnBadLength(tagNumber, dataFormatName, len, stream.peekSignedNumber(4)); | ||
| } | ||
| exifValue.numericalValue = stream.readSignedNumber(2); | ||
| stream.skip(2); | ||
| break; | ||
| case ExifDataFormat.SIGNED_LONG: | ||
| if (len !== 1) { | ||
| warnBadLength(tagNumber, dataFormatName, len, stream.peekSignedNumber(4)); | ||
| } | ||
| exifValue.numericalValue = stream.readSignedNumber(4); | ||
| break; | ||
| case ExifDataFormat.SIGNED_RATIONAL: | ||
| if (len !== 1 && DEBUG) { | ||
| warnBadLength(tagNumber, dataFormatName, len, stream.peekNumber(4)); | ||
| } | ||
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| const ratStream = lookAheadStream.tee().skip(stream.readNumber(4)); | ||
| exifValue.numeratorValue = ratStream.readSignedNumber(4); | ||
| exifValue.denominatorValue = ratStream.readSignedNumber(4); | ||
| break; | ||
| default: | ||
| throw `Bad data format: ${dataFormat}`; | ||
| } | ||
| return exifValue; | ||
| } | ||
|
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| /** | ||
| * @param {Object} obj A numeric enum. | ||
| * @param {number} valToFind The value to find. | ||
| * @returns {string|null} | ||
| */ | ||
| function findNameWithValue(obj, valToFind) { | ||
| const entry = Object.entries(obj).find(([k,v]) => v === valToFind); | ||
| return entry ? entry[0] : null; | ||
| } |
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