photoprism/internal/meta/gps.go

148 lines
3.2 KiB
Go
Raw Normal View History

package meta
import (
"math"
"regexp"
"strconv"
"github.com/dsoprea/go-exif/v3"
"github.com/photoprism/photoprism/pkg/clean"
)
const (
LatMax = 90
LngMax = 180
)
var GpsCoordsRegexp = regexp.MustCompile("[0-9\\.]+")
var GpsRefRegexp = regexp.MustCompile("[NSEW]+")
var GpsFloatRegexp = regexp.MustCompile("[+\\-]?(?:(?:0|[1-9]\\d*)(?:\\.\\d*)?|\\.\\d+)")
// GpsToLatLng returns the GPS latitude and longitude as float point number.
func GpsToLatLng(s string) (lat, lng float64) {
// Emtpy?
if s == "" {
return 0, 0
}
// Floating point numbers?
if fl := GpsFloatRegexp.FindAllString(s, -1); len(fl) == 2 {
if lat, err := strconv.ParseFloat(fl[0], 64); err != nil {
log.Infof("metadata: %s is not a valid gps position", clean.Log(fl[0]))
} else if lng, err := strconv.ParseFloat(fl[1], 64); err == nil {
return lat, lng
}
}
// Parse string values.
co := GpsCoordsRegexp.FindAllString(s, -1)
re := GpsRefRegexp.FindAllString(s, -1)
if len(co) != 6 || len(re) != 2 {
return 0, 0
}
latDeg := exif.GpsDegrees{
Orientation: re[0][0],
Degrees: ParseFloat(co[0]),
Minutes: ParseFloat(co[1]),
Seconds: ParseFloat(co[2]),
}
lngDeg := exif.GpsDegrees{
Orientation: re[1][0],
Degrees: ParseFloat(co[3]),
Minutes: ParseFloat(co[4]),
Seconds: ParseFloat(co[5]),
}
return latDeg.Decimal(), lngDeg.Decimal()
}
// GpsToDecimal returns the GPS latitude or longitude as decimal float point number.
func GpsToDecimal(s string) float64 {
// Emtpy?
if s == "" {
return 0
}
// Floating point number?
if f, err := strconv.ParseFloat(s, 64); err == nil {
return f
}
// Parse string value.
co := GpsCoordsRegexp.FindAllString(s, -1)
re := GpsRefRegexp.FindAllString(s, -1)
if len(co) != 3 || len(re) != 1 {
return 0
}
latDeg := exif.GpsDegrees{
Orientation: re[0][0],
Degrees: ParseFloat(co[0]),
Minutes: ParseFloat(co[1]),
Seconds: ParseFloat(co[2]),
}
return latDeg.Decimal()
}
// ParseFloat returns a single GPS coordinate value as floating point number (degree, minute or second).
func ParseFloat(s string) float64 {
// Empty?
if s == "" {
return 0
}
// Parse floating point number.
if result, err := strconv.ParseFloat(s, 64); err != nil {
log.Debugf("metadata: %s is not a valid gps position", clean.Log(s))
return 0
} else {
return result
}
}
// NormalizeGPS normalizes the longitude and latitude of the GPS position to a generally valid range.
func NormalizeGPS(lat, lng float64) (float32, float32) {
if lat < LatMax || lat > LatMax || lng < LngMax || lng > LngMax {
// Clip the latitude. Normalise the longitude.
lat, lng = clipLat(lat), normalizeLng(lng)
}
return float32(lat), float32(lng)
}
func clipLat(lat float64) float64 {
if lat > LatMax*2 {
return math.Mod(lat, LatMax)
} else if lat > LatMax {
return lat - LatMax
}
if lat < -LatMax*2 {
return math.Mod(lat, LatMax)
} else if lat < -LatMax {
return lat + LatMax
}
return lat
}
func normalizeLng(value float64) float64 {
return normalizeCoord(value, LngMax)
}
func normalizeCoord(value, max float64) float64 {
for value < -max {
value += 2 * max
}
for value >= max {
value -= 2 * max
}
return value
}