Function DataURI

common.go:55–95

DataURI minifies a data URI and calls a minifier by the specified mediatype. Specifications: https://www.ietf.org/rfc/rfc2397.txt.

(m *M, dataURI []byte)

// DataURI minifies a data URI and calls a minifier by the specified mediatype. Specifications: https://www.ietf.org/rfc/rfc2397.txt.
func DataURI(m *M, dataURI []byte) []byte {
	origData := parse.Copy(dataURI)
	mediatype, data, err := parse.DataURI(dataURI)
	if err != nil {
		return dataURI
	}

	data, _ = m.Bytes(string(mediatype), data)
	base64Len := len(";base64") + base64.StdEncoding.EncodedLen(len(data))
	asciiLen := len(data)
	for _, c := range data {
		if parse.DataURIEncodingTable[c] {
			asciiLen += 2
		}
		if asciiLen > base64Len {
			break
		}
	}
	if len(origData) < base64Len && len(origData) < asciiLen {
		return origData
	}
	if base64Len < asciiLen {
		encoded := make([]byte, base64Len-len(";base64"))
		base64.StdEncoding.Encode(encoded, data)
		data = encoded
		mediatype = append(mediatype, base64Bytes...)
	} else {
		data = parse.EncodeURL(data, parse.DataURIEncodingTable)
	}
	if len("text/plain") <= len(mediatype) && parse.EqualFold(mediatype[:len("text/plain")], textMimeBytes) {
		mediatype = mediatype[len("text/plain"):]
	}
	for i := 0; i+len(";charset=us-ascii") <= len(mediatype); i++ {
		// must start with semicolon and be followed by end of mediatype or semicolon
		if mediatype[i] == ';' && parse.EqualFold(mediatype[i+1:i+len(";charset=us-ascii")], charsetASCIIBytes) && (i+len(";charset=us-ascii") >= len(mediatype) || mediatype[i+len(";charset=us-ascii")] == ';') {
			mediatype = append(mediatype[:i], mediatype[i+len(";charset=us-ascii"):]...)
			break
		}
	}
	return append(append(append(dataBytes, mediatype...), ','), data...)
}

// MaxInt is the maximum value of int.
const MaxInt = int(^uint(0) >> 1)