func NewDescTextFrame(ft FrameType, desc, text string) *DescTextFrame {
f := NewTextFrame(ft, text)
nullLength := encodedbytes.EncodingNullLengthForIndex(f.encoding)
f.size += uint32(len(desc) + nullLength)
return &DescTextFrame{
TextFrame: *f,
description: desc,
}
}
func (f *DescTextFrame) SetEncoding(encoding string) error {
i := byte(encodedbytes.IndexForEncoding(encoding))
if i < 0 {
return errors.New("encoding: invalid encoding")
}
descDiff, err := encodedbytes.EncodedDiff(i, f.text, f.encoding, f.text)
if err != nil {
return err
}
newNullLength := encodedbytes.EncodingNullLengthForIndex(i)
oldNullLength := encodedbytes.EncodingNullLengthForIndex(f.encoding)
nullDiff := newNullLength - oldNullLength
textDiff, err := encodedbytes.EncodedDiff(i, f.description, f.encoding, f.description)
if err != nil {
return err
}
f.changeSize(descDiff + nullDiff + textDiff)
f.encoding = i
return nil
}