// 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
}
func loadSubDir(x *Exif, ptr FieldName, fieldMap map[uint16]FieldName) error {
r := bytes.NewReader(x.Raw)
tag, err := x.Get(ptr)
if err != nil {
return nil
}
offset := tag.Int(0)
_, err = r.Seek(offset, 0)
if err != nil {
return errors.New("exif: seek to sub-IFD failed: " + err.Error())
}
subDir, _, err := tiff.DecodeDir(r, x.Tiff.Order)
if err != nil {
return errors.New("exif: sub-IFD decode failed: " + err.Error())
}
x.LoadTags(subDir, fieldMap, false)
return nil
}
func (x *Exif) loadSubDir(r *bytes.Reader, ptrName FieldName, fieldMap map[uint16]FieldName) error {
tag, ok := x.main[ptrName]
if !ok {
return nil
}
offset := tag.Int(0)
_, err := r.Seek(offset, 0)
if err != nil {
return errors.New("exif: seek to sub-IFD failed: " + err.Error())
}
subDir, _, err := tiff.DecodeDir(r, x.tif.Order)
if err != nil {
return errors.New("exif: sub-IFD decode failed: " + err.Error())
}
for _, tag := range subDir.Tags {
name := fieldMap[tag.Id]
x.main[name] = tag
}
return nil
}