// This is basically a copy of the exif.Exif.DateTime() method, except:
// * it takes a *time.Location to assume
// * the caller already assumes there's no timezone offset or GPS time
// in the EXIF, so any of that code can be ignored.
func exifDateTimeInLocation(x *exif.Exif, loc *time.Location) (time.Time, error) {
tag, err := x.Get(exif.DateTimeOriginal)
if err != nil {
tag, err = x.Get(exif.DateTime)
if err != nil {
return time.Time{}, err
}
}
if tag.Format() != tiff.StringVal {
return time.Time{}, errors.New("DateTime[Original] not in string format")
}
const exifTimeLayout = "2006:01:02 15:04:05"
dateStr := strings.TrimRight(string(tag.Val), "\x00")
return time.ParseInLocation(exifTimeLayout, dateStr, loc)
}
// Parse decodes all Nikon makernote data found in x and adds it to x.
func (_ *nikonV3) Parse(x *exif.Exif) error {
m, err := x.Get(exif.MakerNote)
if err != nil {
return nil
} else if bytes.Compare(m.Val[:6], []byte("Nikon\000")) != 0 {
return nil
}
// Nikon v3 maker note is a self-contained IFD (offsets are relative
// to the start of the maker note)
mkNotes, err := tiff.Decode(bytes.NewReader(m.Val[10:]))
if err != nil {
return err
}
x.LoadTags(mkNotes.Dirs[0], makerNoteNikon3Fields, false)
return nil
}
// Parse decodes all Canon makernote data found in x and adds it to x.
func (_ *canon) Parse(x *exif.Exif) error {
m, err := x.Get(exif.MakerNote)
if err != nil {
return nil
}
mk, err := x.Get(exif.Make)
if err != nil {
return nil
}
if val, err := mk.StringVal(); err != nil || val != "Canon" {
return nil
}
// Canon notes are a single IFD directory with no header.
// Reader offsets need to be w.r.t. the original tiff structure.
buf := bytes.NewReader(append(make([]byte, m.ValOffset), m.Val...))
buf.Seek(int64(m.ValOffset), 0)
mkNotesDir, _, err := tiff.DecodeDir(buf, x.Tiff.Order)
if err != nil {
return err
}
x.LoadTags(mkNotesDir, makerNoteCanonFields, false)
return nil
}
