diff --git a/go.mod b/go.mod index 00fc1c5..db58f2d 100644 --- a/go.mod +++ b/go.mod @@ -1,3 +1,5 @@ module github.com/fumiama/imgsz go 1.17 + +require golang.org/x/image v0.16.0 diff --git a/go.sum b/go.sum new file mode 100644 index 0000000..8a8665f --- /dev/null +++ b/go.sum @@ -0,0 +1,33 @@ +github.com/yuin/goldmark v1.4.13/go.mod h1:6yULJ656Px+3vBD8DxQVa3kxgyrAnzto9xy5taEt/CY= +golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w= +golang.org/x/crypto v0.0.0-20210921155107-089bfa567519/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc= +golang.org/x/image v0.16.0 h1:9kloLAKhUufZhA12l5fwnx2NZW39/we1UhBesW433jw= +golang.org/x/image v0.16.0/go.mod h1:ugSZItdV4nOxyqp56HmXwH0Ry0nBCpjnZdpDaIHdoPs= +golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4/go.mod h1:jJ57K6gSWd91VN4djpZkiMVwK6gcyfeH4XE8wZrZaV4= +golang.org/x/mod v0.8.0/go.mod h1:iBbtSCu2XBx23ZKBPSOrRkjjQPZFPuis4dIYUhu/chs= +golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s= +golang.org/x/net v0.0.0-20210226172049-e18ecbb05110/go.mod h1:m0MpNAwzfU5UDzcl9v0D8zg8gWTRqZa9RBIspLL5mdg= +golang.org/x/net v0.0.0-20220722155237-a158d28d115b/go.mod h1:XRhObCWvk6IyKnWLug+ECip1KBveYUHfp+8e9klMJ9c= +golang.org/x/net v0.6.0/go.mod h1:2Tu9+aMcznHK/AK1HMvgo6xiTLG5rD5rZLDS+rp2Bjs= +golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM= +golang.org/x/sync v0.0.0-20220722155255-886fb9371eb4/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM= +golang.org/x/sync v0.1.0/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM= +golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY= +golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs= +golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg= +golang.org/x/sys v0.0.0-20220520151302-bc2c85ada10a/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg= +golang.org/x/sys v0.0.0-20220722155257-8c9f86f7a55f/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg= +golang.org/x/sys v0.5.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg= +golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo= +golang.org/x/term v0.0.0-20210927222741-03fcf44c2211/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8= +golang.org/x/term v0.5.0/go.mod h1:jMB1sMXY+tzblOD4FWmEbocvup2/aLOaQEp7JmGp78k= +golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ= +golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ= +golang.org/x/text v0.3.7/go.mod h1:u+2+/6zg+i71rQMx5EYifcz6MCKuco9NR6JIITiCfzQ= +golang.org/x/text v0.7.0/go.mod h1:mrYo+phRRbMaCq/xk9113O4dZlRixOauAjOtrjsXDZ8= +golang.org/x/text v0.15.0/go.mod h1:18ZOQIKpY8NJVqYksKHtTdi31H5itFRjB5/qKTNYzSU= +golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ= +golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo= +golang.org/x/tools v0.1.12/go.mod h1:hNGJHUnrk76NpqgfD5Aqm5Crs+Hm0VOH/i9J2+nxYbc= +golang.org/x/tools v0.6.0/go.mod h1:Xwgl3UAJ/d3gWutnCtw505GrjyAbvKui8lOU390QaIU= +golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0= diff --git a/webp.go b/webp.go index 623be64..5b9e737 100644 --- a/webp.go +++ b/webp.go @@ -6,10 +6,13 @@ package imgsz import ( "bufio" + "bytes" "errors" + "image" "io" - "io/ioutil" "math" + + "golang.org/x/image/vp8l" ) var errInvalidFormat = errors.New("webp: invalid format") @@ -102,7 +105,7 @@ func (z *webpeader) next() (chunkID fourCC, chunkLen uint32, chunkData io.Reader if z.chunkLen != 0 { want := z.chunkLen var got int64 - got, z.err = io.Copy(ioutil.Discard, z.chunkReader) + got, z.err = io.Copy(io.Discard, z.chunkReader) if z.err == nil && uint32(got) != want { z.err = errShortChunkData } @@ -202,6 +205,7 @@ func decodewebp(r io.Reader) (Size, error) { var ( alpha []byte + alphaStride int wantAlpha bool widthMinusOne uint32 heightMinusOne uint32 @@ -229,6 +233,11 @@ func decodewebp(r io.Reader) (Size, error) { } return Size{}, err } + alpha, alphaStride, err = readAlpha(chunkData, widthMinusOne, heightMinusOne, buf[0]&0x03) + if err != nil { + return Size{}, err + } + unfilterAlpha(alpha, alphaStride, (buf[0]>>2)&0x03) case fccVP8: if wantAlpha || int32(chunkLen) < 0 { @@ -363,3 +372,106 @@ func decodeVP8LHeader(r io.Reader) (w int32, h int32, err error) { } return int32(width), int32(height), nil } + +func readAlpha(chunkData io.Reader, widthMinusOne, heightMinusOne uint32, compression byte) ( + alpha []byte, alphaStride int, err error) { + + switch compression { + case 0: + w := int(widthMinusOne) + 1 + h := int(heightMinusOne) + 1 + alpha = make([]byte, w*h) + if _, err := io.ReadFull(chunkData, alpha); err != nil { + return nil, 0, err + } + return alpha, w, nil + + case 1: + // Read the VP8L-compressed alpha values. First, synthesize a 5-byte VP8L header: + // a 1-byte magic number, a 14-bit widthMinusOne, a 14-bit heightMinusOne, + // a 1-bit (ignored, zero) alphaIsUsed and a 3-bit (zero) version. + // TODO(nigeltao): be more efficient than decoding an *image.NRGBA just to + // extract the green values to a separately allocated []byte. Fixing this + // will require changes to the vp8l package's API. + if widthMinusOne > 0x3fff || heightMinusOne > 0x3fff { + return nil, 0, errors.New("webp: invalid format") + } + alphaImage, err := vp8l.Decode(io.MultiReader( + bytes.NewReader([]byte{ + 0x2f, // VP8L magic number. + uint8(widthMinusOne), + uint8(widthMinusOne>>8) | uint8(heightMinusOne<<6), + uint8(heightMinusOne >> 2), + uint8(heightMinusOne >> 10), + }), + chunkData, + )) + if err != nil { + return nil, 0, err + } + // The green values of the inner NRGBA image are the alpha values of the + // outer NYCbCrA image. + pix := alphaImage.(*image.NRGBA).Pix + alpha = make([]byte, len(pix)/4) + for i := range alpha { + alpha[i] = pix[4*i+1] + } + return alpha, int(widthMinusOne) + 1, nil + } + return nil, 0, errInvalidFormat +} + +func unfilterAlpha(alpha []byte, alphaStride int, filter byte) { + if len(alpha) == 0 || alphaStride == 0 { + return + } + switch filter { + case 1: // Horizontal filter. + for i := 1; i < alphaStride; i++ { + alpha[i] += alpha[i-1] + } + for i := alphaStride; i < len(alpha); i += alphaStride { + // The first column is equivalent to the vertical filter. + alpha[i] += alpha[i-alphaStride] + + for j := 1; j < alphaStride; j++ { + alpha[i+j] += alpha[i+j-1] + } + } + + case 2: // Vertical filter. + // The first row is equivalent to the horizontal filter. + for i := 1; i < alphaStride; i++ { + alpha[i] += alpha[i-1] + } + + for i := alphaStride; i < len(alpha); i++ { + alpha[i] += alpha[i-alphaStride] + } + + case 3: // Gradient filter. + // The first row is equivalent to the horizontal filter. + for i := 1; i < alphaStride; i++ { + alpha[i] += alpha[i-1] + } + + for i := alphaStride; i < len(alpha); i += alphaStride { + // The first column is equivalent to the vertical filter. + alpha[i] += alpha[i-alphaStride] + + // The interior is predicted on the three top/left pixels. + for j := 1; j < alphaStride; j++ { + c := int(alpha[i+j-alphaStride-1]) + b := int(alpha[i+j-alphaStride]) + a := int(alpha[i+j-1]) + x := a + b - c + if x < 0 { + x = 0 + } else if x > 255 { + x = 255 + } + alpha[i+j] += uint8(x) + } + } + } +}