photoprism/internal/meta/exif.go
Michael Mayer faa2074e69 Backend: Refactor exif parsing
Signed-off-by: Michael Mayer <michael@liquidbytes.net>
2020-04-29 16:42:06 +02:00

307 lines
6.7 KiB
Go

package meta
import (
"fmt"
"math"
"path"
"strconv"
"strings"
"time"
"github.com/dsoprea/go-exif/v2"
"github.com/dsoprea/go-exif/v2/common"
"github.com/dsoprea/go-jpeg-image-structure"
"github.com/dsoprea/go-png-image-structure"
"gopkg.in/ugjka/go-tz.v2/tz"
)
// SanitizeString removes unwanted character from an exif value string.
func SanitizeString(value string) string {
return strings.Replace(value, "\"", "", -1)
}
// Exif parses an image file for Exif meta data and returns as Data struct.
func Exif(filename string) (data Data, err error) {
defer func() {
if e := recover(); e != nil {
data = Data{}
err = fmt.Errorf("meta: %s", e)
}
}()
// Extract raw EXIF block.
var rawExif []byte
fileExtension := path.Ext(filename)
fileExtension = strings.ToLower(fileExtension)
if fileExtension == ".jpg" || fileExtension == ".jpeg" {
jmp := jpegstructure.NewJpegMediaParser()
sl, err := jmp.ParseFile(filename)
if err != nil {
return data, err
}
_, rawExif, err = sl.Exif()
if err != nil {
return data, err
}
} else if fileExtension == ".png" {
pmp := pngstructure.NewPngMediaParser()
cs, err := pmp.ParseFile(filename)
if err != nil {
return data, err
}
_, rawExif, err = cs.Exif()
if err != nil {
return data, err
}
} else {
// Fallback to an optimistic, brute-force search.
var err error
rawExif, err = exif.SearchFileAndExtractExif(filename)
if err != nil {
return data, err
}
}
// Enumerate tags in EXIF block.
ti := exif.NewTagIndex()
if err := exif.LoadStandardTags(ti); err != nil {
return data, err
}
tags := make(map[string]string)
visitor := func(fqIfdPath string, ifdIndex int, ite *exif.IfdTagEntry) (err error) {
tagId := ite.TagId()
tagType := ite.TagType()
ifdPath, err := im.StripPathPhraseIndices(fqIfdPath)
if err != nil {
return nil
}
it, err := ti.Get(ifdPath, tagId)
if err != nil {
return nil
}
valueString := ""
if tagType != exifcommon.TypeUndefined {
valueString, err = ite.FormatFirst()
if err != nil {
log.Errorf("exif: %s", err.Error())
return nil
}
if it.Name != "" && valueString != "" {
tags[it.Name] = strings.Split(valueString, "\x00")[0]
}
}
return nil
}
_, err = exif.Visit(exifcommon.IfdStandard, im, ti, rawExif, visitor)
if err != nil {
return data, err
}
// Cherry-pick the values that we care about.
if value, ok := tags["Artist"]; ok {
data.Artist = SanitizeString(value)
}
if value, ok := tags["Copyright"]; ok {
data.Copyright = SanitizeString(value)
}
if value, ok := tags["Model"]; ok {
data.CameraModel = SanitizeString(value)
}
if value, ok := tags["Make"]; ok {
data.CameraMake = SanitizeString(value)
}
if value, ok := tags["CameraOwnerName"]; ok {
data.CameraOwner = SanitizeString(value)
}
if value, ok := tags["BodySerialNumber"]; ok {
data.CameraSerial = SanitizeString(value)
}
if value, ok := tags["LensMake"]; ok {
data.LensMake = SanitizeString(value)
}
if value, ok := tags["LensModel"]; ok {
data.LensModel = SanitizeString(value)
}
if value, ok := tags["ExposureTime"]; ok {
if n := strings.Split(value, "/"); len(n) == 2 {
if n[0] != "1" && len(n[0]) < len(n[1]) {
n0, _ := strconv.ParseUint(n[0], 10, 64)
if n1, err := strconv.ParseUint(n[1], 10, 64); err == nil && n0 > 0 && n1 > 0 {
value = fmt.Sprintf("1/%d", n1/n0)
}
}
}
data.Exposure = value
}
if value, ok := tags["FNumber"]; ok {
values := strings.Split(value, "/")
if len(values) == 2 && values[1] != "0" && values[1] != "" {
number, _ := strconv.ParseFloat(values[0], 64)
denom, _ := strconv.ParseFloat(values[1], 64)
data.FNumber = float32(math.Round((number/denom)*1000) / 1000)
}
}
if value, ok := tags["ApertureValue"]; ok {
values := strings.Split(value, "/")
if len(values) == 2 && values[1] != "0" && values[1] != "" {
number, _ := strconv.ParseFloat(values[0], 64)
denom, _ := strconv.ParseFloat(values[1], 64)
data.Aperture = float32(math.Round((number/denom)*1000) / 1000)
}
}
if value, ok := tags["FocalLengthIn35mmFilm"]; ok {
if i, err := strconv.Atoi(value); err == nil {
data.FocalLength = i
}
} else if value, ok := tags["FocalLength"]; ok {
values := strings.Split(value, "/")
if len(values) == 2 && values[1] != "0" && values[1] != "" {
number, _ := strconv.ParseFloat(values[0], 64)
denom, _ := strconv.ParseFloat(values[1], 64)
data.FocalLength = int(math.Round((number/denom)*1000) / 1000)
}
}
if value, ok := tags["ISOSpeedRatings"]; ok {
if i, err := strconv.Atoi(value); err == nil {
data.Iso = i
}
}
if value, ok := tags["ImageUniqueID"]; ok {
data.UniqueID = value
}
if value, ok := tags["ImageWidth"]; ok {
if i, err := strconv.Atoi(value); err == nil {
data.Width = i
}
} else if value, ok := tags["PixelXDimension"]; ok {
if i, err := strconv.Atoi(value); err == nil {
data.Width = i
}
}
if value, ok := tags["ImageLength"]; ok {
if i, err := strconv.Atoi(value); err == nil {
data.Height = i
}
} else if value, ok := tags["PixelYDimension"]; ok {
if i, err := strconv.Atoi(value); err == nil {
data.Height = i
}
}
if value, ok := tags["Orientation"]; ok {
if i, err := strconv.Atoi(value); err == nil {
data.Orientation = i
}
} else {
data.Orientation = 1
}
_, index, err := exif.Collect(im, ti, rawExif)
if err != nil {
return data, err
}
if ifd, err := index.RootIfd.ChildWithIfdPath(exifcommon.IfdPathStandardGps); err == nil {
if gi, err := ifd.GpsInfo(); err == nil {
data.Lat = float32(gi.Latitude.Decimal())
data.Lng = float32(gi.Longitude.Decimal())
data.Altitude = gi.Altitude
}
}
if data.Lat != 0 && data.Lng != 0 {
zones, err := tz.GetZone(tz.Point{
Lat: float64(data.Lat),
Lon: float64(data.Lng),
})
if err == nil && len(zones) > 0 {
data.TimeZone = zones[0]
}
}
if value, ok := tags["DateTimeOriginal"]; ok && value != "0000:00:00 00:00:00" {
if taken, err := time.Parse("2006:01:02 15:04:05", value); err == nil {
data.TakenAtLocal = taken.Round(time.Second)
data.TakenAt = data.TakenAtLocal
if loc, err := time.LoadLocation(data.TimeZone); err != nil {
log.Warnf("exif: unknown time zone %s", data.TimeZone)
} else if tl, err := time.ParseInLocation("2006:01:02 15:04:05", value, loc); err == nil {
data.TakenAt = tl.Round(time.Second).UTC()
} else {
log.Errorf("exif: %s", err.Error()) // this should never happen
}
} else {
log.Warnf("exif: invalid time %s", value)
}
}
if value, ok := tags["Flash"]; ok {
if i, err := strconv.Atoi(value); err == nil && i&1 == 1 {
data.Flash = true
}
}
if value, ok := tags["ImageDescription"]; ok {
data.Description = SanitizeString(value)
}
data.All = tags
return data, nil
}