package exif import ( "errors" "fmt" "time" "github.com/dsoprea/go-logging" "github.com/golang/geo/s2" "github.com/dsoprea/go-exif/v2/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", 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", 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 }