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blog/gatsby/createExif.js
Matthias Kretschmann acfdba0a66
refactor exif
* add all exif & IPTC data to files
* create nodes for all exif data
2019-11-04 19:07:27 +01:00

144 lines
3.0 KiB
JavaScript

const fs = require('fs')
const util = require('util')
const fastExif = require('fast-exif')
const Fraction = require('fraction.js')
const getCoordinates = require('dms2dec')
const iptc = require('node-iptc')
const readFile = util.promisify(fs.readFile)
exports.createExif = async (node, actions, createNodeId) => {
try {
// exif
const exifData = await fastExif.read(node.absolutePath, true)
if (!exifData) return
// iptc
const file = await readFile(node.absolutePath)
const iptcData = iptc(file)
createNodes(exifData, iptcData, node, actions, createNodeId)
} catch (error) {
console.error(`${node.name}: ${error.message}`)
}
}
function createNodes(exifData, iptcData, node, actions, createNodeId) {
const { createNodeField, createNode, createParentChildLink } = actions
const exifDataFormatted = formatExif(exifData)
const exif = {
...exifData,
iptc: {
...iptcData
},
formatted: {
...exifDataFormatted
}
}
const exifNode = {
id: createNodeId(`${node.id} >> ImageExif`),
children: [],
...exif,
parent: node.id,
internal: {
contentDigest: `${node.internal.contentDigest}`,
type: 'ImageExif'
}
}
// add exif fields to existing type file
createNodeField({
node,
name: 'exif',
value: exif
})
// create new nodes from all exif data
// allowing to be queried with imageExif & AllImageExif
createNode(exifNode)
createParentChildLink({
parent: node,
child: exifNode
})
}
function formatExif(exifData) {
if (!exifData.exif) return
const { Model } = exifData.image
const {
ISO,
FNumber,
ExposureTime,
FocalLength,
FocalLengthIn35mmFormat,
ExposureBiasValue,
ExposureMode,
LensModel
} = exifData.exif
const iso = `ISO ${ISO}`
const fstop = `ƒ ${FNumber}`
const focalLength = `${FocalLengthIn35mmFormat || FocalLength}mm`
// Shutter speed
const { n, d } = new Fraction(ExposureTime)
const shutterspeed = `${n}/${d}s`
// GPS
let latitude
let longitude
if (exifData.gps) ({ latitude, longitude } = formatGps(exifData.gps))
// Exposure
const exposure = formatExposure(ExposureBiasValue || ExposureMode)
return {
iso,
model: Model,
fstop,
shutterspeed,
focalLength,
lensModel: LensModel,
exposure,
gps: { latitude, longitude }
}
}
function formatGps(gpsData) {
if (!gpsData) return
const { GPSLatitudeRef, GPSLatitude, GPSLongitudeRef, GPSLongitude } = gpsData
const GPSdec = getCoordinates(
GPSLatitude,
GPSLatitudeRef,
GPSLongitude,
GPSLongitudeRef
)
const latitude = GPSdec[0]
const longitude = GPSdec[1]
return { latitude, longitude }
}
function formatExposure(exposureMode) {
if (!exposureMode) return
const exposureShortened = parseFloat(exposureMode.toFixed(2))
let exposure
if (exposureMode === 0) {
exposure = `+/- ${exposureShortened} ev`
} else if (exposureMode > 0) {
exposure = `+ ${exposureShortened} ev`
} else {
exposure = `${exposureShortened} ev`
}
return exposure
}