diff --git a/webp.go b/webp.go index 3cd25d0..623be64 100644 --- a/webp.go +++ b/webp.go @@ -14,15 +14,15 @@ import ( var errInvalidFormat = errors.New("webp: invalid format") -// FourCC is a four character code. -type FourCC [4]byte +// fourCC is a four character code. +type fourCC [4]byte var ( - fccALPH = FourCC{'A', 'L', 'P', 'H'} - fccVP8 = FourCC{'V', 'P', '8', ' '} - fccVP8L = FourCC{'V', 'P', '8', 'L'} - fccVP8X = FourCC{'V', 'P', '8', 'X'} - fccWEBP = FourCC{'W', 'E', 'B', 'P'} + fccALPH = fourCC{'A', 'L', 'P', 'H'} + fccVP8 = fourCC{'V', 'P', '8', ' '} + fccVP8L = fourCC{'V', 'P', '8', 'L'} + fccVP8X = fourCC{'V', 'P', '8', 'X'} + fccWEBP = fourCC{'W', 'E', 'B', 'P'} ) const chunkHeaderSize = 8 @@ -41,8 +41,8 @@ func u32(b []byte) uint32 { return uint32(b[0]) | uint32(b[1])<<8 | uint32(b[2])<<16 | uint32(b[3])<<24 } -// Reader reads chunks from an underlying io.Reader. -type Reader struct { +// webpeader reads chunks from an underlying io.webpeader. +type webpeader struct { r io.Reader err error @@ -54,48 +54,48 @@ type Reader struct { padded bool } -// NewListReader returns a LIST chunk's list type, such as "movi" or "wavl", +// newListReader returns a LIST chunk's list type, such as "movi" or "wavl", // and its chunks as a *Reader. -func NewListReader(chunkLen uint32, chunkData io.Reader) (listType FourCC, data *Reader, err error) { +func newListReader(chunkLen uint32, chunkData io.Reader) (listType fourCC, data *webpeader, err error) { if chunkLen < 4 { - return FourCC{}, nil, errShortChunkData + return fourCC{}, nil, errShortChunkData } - z := &Reader{r: chunkData} + z := &webpeader{r: chunkData} if _, err := io.ReadFull(chunkData, z.buf[:4]); err != nil { if err == io.EOF || err == io.ErrUnexpectedEOF { err = errShortChunkData } - return FourCC{}, nil, err + return fourCC{}, nil, err } z.totalLen = chunkLen - 4 - return FourCC{z.buf[0], z.buf[1], z.buf[2], z.buf[3]}, z, nil + return fourCC{z.buf[0], z.buf[1], z.buf[2], z.buf[3]}, z, nil } -// NewReader returns the RIFF stream's form type, such as "AVI " or "WAVE", and +// newReader returns the RIFF stream's form type, such as "AVI " or "WAVE", and // its chunks as a *Reader. -func NewReader(r io.Reader) (formType FourCC, data *Reader, err error) { +func newReader(r io.Reader) (formType fourCC, data *webpeader, err error) { var buf [chunkHeaderSize]byte if _, err := io.ReadFull(r, buf[:]); err != nil { if err == io.EOF || err == io.ErrUnexpectedEOF { err = errMissingRIFFChunkHeader } - return FourCC{}, nil, err + return fourCC{}, nil, err } if buf[0] != 'R' || buf[1] != 'I' || buf[2] != 'F' || buf[3] != 'F' { - return FourCC{}, nil, errMissingRIFFChunkHeader + return fourCC{}, nil, errMissingRIFFChunkHeader } - return NewListReader(u32(buf[4:]), r) + return newListReader(u32(buf[4:]), r) } -// Next returns the next chunk's ID, length and data. It returns io.EOF if there -// are no more chunks. The io.Reader returned becomes stale after the next Next +// next returns the next chunk's ID, length and data. It returns io.EOF if there +// are no more chunks. The io.Reader returned becomes stale after the next next // call, and should no longer be used. // -// It is valid to call Next even if all of the previous chunk's data has not +// It is valid to call next even if all of the previous chunk's data has not // been read. -func (z *Reader) Next() (chunkID FourCC, chunkLen uint32, chunkData io.Reader, err error) { +func (z *webpeader) next() (chunkID fourCC, chunkLen uint32, chunkData io.Reader, err error) { if z.err != nil { - return FourCC{}, 0, nil, z.err + return fourCC{}, 0, nil, z.err } // Drain the rest of the previous chunk. @@ -107,14 +107,14 @@ func (z *Reader) Next() (chunkID FourCC, chunkLen uint32, chunkData io.Reader, e z.err = errShortChunkData } if z.err != nil { - return FourCC{}, 0, nil, z.err + return fourCC{}, 0, nil, z.err } } z.chunkReader = nil if z.padded { if z.totalLen == 0 { z.err = errListSubchunkTooLong - return FourCC{}, 0, nil, z.err + return fourCC{}, 0, nil, z.err } z.totalLen-- _, z.err = io.ReadFull(z.r, z.buf[:1]) @@ -122,33 +122,33 @@ func (z *Reader) Next() (chunkID FourCC, chunkLen uint32, chunkData io.Reader, e if z.err == io.EOF { z.err = errMissingPaddingByte } - return FourCC{}, 0, nil, z.err + return fourCC{}, 0, nil, z.err } } // We are done if we have no more data. if z.totalLen == 0 { z.err = io.EOF - return FourCC{}, 0, nil, z.err + return fourCC{}, 0, nil, z.err } // Read the next chunk header. if z.totalLen < chunkHeaderSize { z.err = errShortChunkHeader - return FourCC{}, 0, nil, z.err + return fourCC{}, 0, nil, z.err } z.totalLen -= chunkHeaderSize if _, z.err = io.ReadFull(z.r, z.buf[:chunkHeaderSize]); z.err != nil { if z.err == io.EOF || z.err == io.ErrUnexpectedEOF { z.err = errShortChunkHeader } - return FourCC{}, 0, nil, z.err + return fourCC{}, 0, nil, z.err } - chunkID = FourCC{z.buf[0], z.buf[1], z.buf[2], z.buf[3]} + chunkID = fourCC{z.buf[0], z.buf[1], z.buf[2], z.buf[3]} z.chunkLen = u32(z.buf[4:]) if z.chunkLen > z.totalLen { z.err = errListSubchunkTooLong - return FourCC{}, 0, nil, z.err + return fourCC{}, 0, nil, z.err } z.padded = z.chunkLen&1 == 1 z.chunkReader = &chunkReader{z} @@ -156,7 +156,7 @@ func (z *Reader) Next() (chunkID FourCC, chunkLen uint32, chunkData io.Reader, e } type chunkReader struct { - z *Reader + z *webpeader } func (c *chunkReader) Read(p []byte) (int, error) { @@ -192,7 +192,7 @@ func (c *chunkReader) Read(p []byte) (int, error) { } func decodewebp(r io.Reader) (Size, error) { - formType, riffReader, err := NewReader(r) + formType, riffReader, err := newReader(r) if err != nil { return Size{}, err } @@ -208,7 +208,7 @@ func decodewebp(r io.Reader) (Size, error) { buf [10]byte ) for { - chunkID, chunkLen, chunkData, err := riffReader.Next() + chunkID, chunkLen, chunkData, err := riffReader.next() if err == io.EOF { err = errInvalidFormat }