/
geophoto.go
148 lines (119 loc) · 3.69 KB
/
geophoto.go
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package geophoto
import (
"github.com/rwcarlsen/goexif/exif"
"github.com/rwcarlsen/goexif/tiff"
"math/big"
"os"
"path/filepath"
"strconv"
"strings"
"time"
)
var (
GeoPhotoDataWalk = make(map[int]GeoPhoto) // Global var for the walk in DirGeoPhotoData
)
type GeoPhoto struct {
GPSLatitude, GPSLatitudeRef, GPSLongitude, GPSLongitudeRef, GPSTimeStamp, GPSDateStamp *tiff.Tag
}
func NewGeoPhotoFromExif(exifData *exif.Exif) GeoPhoto {
GPSLatitude, _ := exifData.Get(exif.GPSLatitude)
GPSLatitudeRef, _ := exifData.Get(exif.GPSLatitudeRef)
GPSLongitude, _ := exifData.Get(exif.GPSLongitude)
GPSLongitudeRef, _ := exifData.Get(exif.GPSLongitudeRef)
GPSTimeStamp, _ := exifData.Get(exif.GPSTimeStamp)
GPSDateStamp, _ := exifData.Get(exif.GPSDateStamp)
return GeoPhoto{
GPSLatitude: GPSLatitude,
GPSLatitudeRef: GPSLatitudeRef,
GPSLongitude: GPSLongitude,
GPSLongitudeRef: GPSLongitudeRef,
GPSTimeStamp: GPSTimeStamp,
GPSDateStamp: GPSDateStamp,
}
}
func NewGeoPhotoFromFile(path string) (GeoPhoto, error) {
file, err := os.Open(path)
if err != nil {
return GeoPhoto{}, err
}
defer file.Close()
exifData, err := exif.Decode(file)
if err != nil {
return GeoPhoto{}, err
}
return NewGeoPhotoFromExif(exifData), nil
}
func (geo *GeoPhoto) StringDegrees() string {
latitude := sexToDec(geo.GPSLatitude.Rat(0), geo.GPSLatitude.Rat(1), geo.GPSLatitude.Rat(2), geo.GPSLatitudeRef.StringVal())
longitude := sexToDec(geo.GPSLongitude.Rat(0), geo.GPSLongitude.Rat(1), geo.GPSLongitude.Rat(2), geo.GPSLongitudeRef.StringVal())
// http://stackoverflow.com/questions/7167604/how-accurately-should-i-store-latitude-and-longitude
return latitude.FloatString(6) + "," + longitude.FloatString(6)
}
func (geo *GeoPhoto) Unix() int64 {
if geo.GPSTimeStamp == nil || geo.GPSDateStamp == nil {
return 0
}
dateParts := strings.Split(geo.GPSDateStamp.StringVal(), ":")
year, _ := strconv.Atoi(dateParts[0])
month, _ := strconv.Atoi(dateParts[1])
day, _ := strconv.Atoi(dateParts[2])
hour := int(geo.GPSTimeStamp.Rat(0).Num().Int64())
minute := int(geo.GPSTimeStamp.Rat(1).Num().Int64())
second := int(geo.GPSTimeStamp.Rat(2).Num().Int64())
loc, err := time.LoadLocation("UTC")
if err != nil {
return 0
}
monthConstants := map[int]time.Month{
1: time.January,
2: time.February,
3: time.March,
4: time.April,
5: time.May,
6: time.June,
7: time.July,
8: time.August,
9: time.September,
10: time.October,
11: time.November,
12: time.December,
}
t := time.Date(year, monthConstants[month], day, hour, minute, second, 0, loc)
return t.Unix()
}
func DirGeoPhotoDataUnique(dir string) map[int]GeoPhoto {
// Re-init the globalwalk map
GeoPhotoDataWalk = make(map[int]GeoPhoto)
// This is modifying GeoPhotoDataWalk globally, as we can't pass anything
// additional into walk
filepath.Walk(dir, walk)
return GeoPhotoDataWalk
}
func walk(path string, fi os.FileInfo, err error) error {
if err != nil {
return nil
}
if fi.Mode().IsDir() {
return nil
}
geo, err := NewGeoPhotoFromFile(path)
if err != nil {
return nil
}
if geo.GPSTimeStamp == nil || geo.GPSDateStamp == nil || geo.GPSLatitude == nil || geo.GPSLatitudeRef == nil || geo.GPSLongitude == nil || geo.GPSLongitudeRef == nil {
return nil
}
GeoPhotoDataWalk[int(geo.Unix())] = geo
return nil
}
func sexToDec(deg, min, sec *big.Rat, dir string) *big.Rat {
// sexagesimal (base 60) to decimal
// https://imm.dtf.wa.gov.au/helpfiles/Latitude_Longitude_conversion_hlp.htm
deg.Add(deg, min.Quo(min, big.NewRat(60, 1)))
deg.Add(deg, sec.Quo(sec, big.NewRat(3600, 1)))
// N and E are the positive directions (like on an x,y axis)
if dir == "S" || dir == "W" {
deg.Neg(deg)
}
return deg
}