118 lines
3.4 KiB
Go
118 lines
3.4 KiB
Go
package exif
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import (
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"errors"
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"fmt"
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"time"
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log "github.com/dsoprea/go-logging"
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"github.com/golang/geo/s2"
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exifcommon "github.com/dsoprea/go-exif/v2/common"
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)
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var (
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// ErrGpsCoordinatesNotValid means that some part of the geographic data was
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// unparseable.
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ErrGpsCoordinatesNotValid = errors.New("GPS coordinates not valid")
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)
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// GpsDegrees is a high-level struct representing geographic data.
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type GpsDegrees struct {
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// Orientation describes the N/E/S/W direction that this position is
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// relative to.
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Orientation byte
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// Degrees is a simple float representing the underlying rational degrees
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// amount.
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Degrees float64
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// Minutes is a simple float representing the underlying rational minutes
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// amount.
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Minutes float64
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// Seconds is a simple float representing the underlying ration seconds
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// amount.
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Seconds float64
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}
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// NewGpsDegreesFromRationals returns a GpsDegrees struct given the EXIF-encoded
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// information. The refValue is the N/E/S/W direction that this position is
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// relative to.
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func NewGpsDegreesFromRationals(refValue string, rawCoordinate []exifcommon.Rational) (gd GpsDegrees, err error) {
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defer func() {
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if state := recover(); state != nil {
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err = log.Wrap(state.(error))
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}
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}()
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if len(rawCoordinate) != 3 {
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log.Panicf("new GpsDegrees struct requires a raw-coordinate with exactly three rationals")
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}
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gd = GpsDegrees{
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Orientation: refValue[0],
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Degrees: float64(rawCoordinate[0].Numerator) / float64(rawCoordinate[0].Denominator),
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Minutes: float64(rawCoordinate[1].Numerator) / float64(rawCoordinate[1].Denominator),
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Seconds: float64(rawCoordinate[2].Numerator) / float64(rawCoordinate[2].Denominator),
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}
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return gd, nil
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}
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// String provides returns a descriptive string.
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func (d GpsDegrees) String() string {
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return fmt.Sprintf("Degrees<O=[%s] D=(%g) M=(%g) S=(%g)>", string([]byte{d.Orientation}), d.Degrees, d.Minutes, d.Seconds)
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}
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// Decimal calculates and returns the simplified float representation of the
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// component degrees.
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func (d GpsDegrees) Decimal() float64 {
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decimal := float64(d.Degrees) + float64(d.Minutes)/60.0 + float64(d.Seconds)/3600.0
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if d.Orientation == 'S' || d.Orientation == 'W' {
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return -decimal
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}
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return decimal
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}
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// Raw returns a Rational struct that can be used to *write* coordinates. In
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// practice, the denominator are typically (1) in the original EXIF data, and,
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// that being the case, this will best preserve precision.
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func (d GpsDegrees) Raw() []exifcommon.Rational {
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return []exifcommon.Rational{
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{Numerator: uint32(d.Degrees), Denominator: 1},
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{Numerator: uint32(d.Minutes), Denominator: 1},
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{Numerator: uint32(d.Seconds), Denominator: 1},
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}
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}
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// GpsInfo encapsulates all of the geographic information in one place.
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type GpsInfo struct {
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Latitude, Longitude GpsDegrees
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Altitude int
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Timestamp time.Time
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}
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// String returns a descriptive string.
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func (gi *GpsInfo) String() string {
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return fmt.Sprintf("GpsInfo<LAT=(%.05f) LON=(%.05f) ALT=(%d) TIME=[%s]>",
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gi.Latitude.Decimal(), gi.Longitude.Decimal(), gi.Altitude, gi.Timestamp)
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}
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// S2CellId returns the cell-ID of the geographic location on the earth.
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func (gi *GpsInfo) S2CellId() s2.CellID {
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latitude := gi.Latitude.Decimal()
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longitude := gi.Longitude.Decimal()
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ll := s2.LatLngFromDegrees(latitude, longitude)
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cellId := s2.CellIDFromLatLng(ll)
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if cellId.IsValid() == false {
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panic(ErrGpsCoordinatesNotValid)
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}
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return cellId
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}
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