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package exif
import (
"errors"
"fmt"
"time"
"github.com/dsoprea/go-logging"
"github.com/golang/geo/s2"
"github.com/dsoprea/go-exif/v3/common"
)
var (
// ErrGpsCoordinatesNotValid means that some part of the geographic data was
// unparseable.
ErrGpsCoordinatesNotValid = errors.New("GPS coordinates not valid")
)
// GpsDegrees is a high-level struct representing geographic data.
type GpsDegrees struct {
// Orientation describes the N/E/S/W direction that this position is
// relative to.
Orientation byte
// Degrees is a simple float representing the underlying rational degrees
// amount.
Degrees float64
// Minutes is a simple float representing the underlying rational minutes
// amount.
Minutes float64
// Seconds is a simple float representing the underlying ration seconds
// amount.
Seconds float64
}
// NewGpsDegreesFromRationals returns a GpsDegrees struct given the EXIF-encoded
// information. The refValue is the N/E/S/W direction that this position is
// relative to.
func NewGpsDegreesFromRationals(refValue string, rawCoordinate []exifcommon.Rational) (gd GpsDegrees, err error) {
defer func() {
if state := recover(); state != nil {
err = log.Wrap(state.(error))
}
}()
if len(rawCoordinate) != 3 {
log.Panicf("new GpsDegrees struct requires a raw-coordinate with exactly three rationals")
}
gd = GpsDegrees{
Orientation: refValue[0],
Degrees: float64(rawCoordinate[0].Numerator) / float64(rawCoordinate[0].Denominator),
Minutes: float64(rawCoordinate[1].Numerator) / float64(rawCoordinate[1].Denominator),
Seconds: float64(rawCoordinate[2].Numerator) / float64(rawCoordinate[2].Denominator),
}
return gd, nil
}
// String provides returns a descriptive string.
func (d GpsDegrees) String() string {
return fmt.Sprintf("Degrees<O=[%s] D=(%g) M=(%g) S=(%g)>", string([]byte{d.Orientation}), d.Degrees, d.Minutes, d.Seconds)
}
// Decimal calculates and returns the simplified float representation of the
// component degrees.
func (d GpsDegrees) Decimal() float64 {
decimal := float64(d.Degrees) + float64(d.Minutes)/60.0 + float64(d.Seconds)/3600.0
if d.Orientation == 'S' || d.Orientation == 'W' {
return -decimal
}
return decimal
}
// Raw returns a Rational struct that can be used to *write* coordinates. In
// practice, the denominator are typically (1) in the original EXIF data, and,
// that being the case, this will best preserve precision.
func (d GpsDegrees) Raw() []exifcommon.Rational {
return []exifcommon.Rational{
{Numerator: uint32(d.Degrees), Denominator: 1},
{Numerator: uint32(d.Minutes), Denominator: 1},
{Numerator: uint32(d.Seconds), Denominator: 1},
}
}
// GpsInfo encapsulates all of the geographic information in one place.
type GpsInfo struct {
Latitude, Longitude GpsDegrees
Altitude int
Timestamp time.Time
}
// String returns a descriptive string.
func (gi *GpsInfo) String() string {
return fmt.Sprintf("GpsInfo<LAT=(%.05f) LON=(%.05f) ALT=(%d) TIME=[%s]>",
gi.Latitude.Decimal(), gi.Longitude.Decimal(), gi.Altitude, gi.Timestamp)
}
// S2CellId returns the cell-ID of the geographic location on the earth.
func (gi *GpsInfo) S2CellId() s2.CellID {
latitude := gi.Latitude.Decimal()
longitude := gi.Longitude.Decimal()
ll := s2.LatLngFromDegrees(latitude, longitude)
cellId := s2.CellIDFromLatLng(ll)
if cellId.IsValid() == false {
panic(ErrGpsCoordinatesNotValid)
}
return cellId
}
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