From e1e8d058a33f7566f9c565d04b0d8b56f9645c35 Mon Sep 17 00:00:00 2001 From: Dimitri Sokolyuk Date: Wed, 25 Apr 2018 09:28:54 +0200 Subject: add vendor --- vendor/golang.org/x/image/vp8l/decode.go | 603 ++++++++++++++++++++++++++++ vendor/golang.org/x/image/vp8l/huffman.go | 245 +++++++++++ vendor/golang.org/x/image/vp8l/transform.go | 299 ++++++++++++++ 3 files changed, 1147 insertions(+) create mode 100644 vendor/golang.org/x/image/vp8l/decode.go create mode 100644 vendor/golang.org/x/image/vp8l/huffman.go create mode 100644 vendor/golang.org/x/image/vp8l/transform.go (limited to 'vendor/golang.org/x/image/vp8l') diff --git a/vendor/golang.org/x/image/vp8l/decode.go b/vendor/golang.org/x/image/vp8l/decode.go new file mode 100644 index 0000000..4319487 --- /dev/null +++ b/vendor/golang.org/x/image/vp8l/decode.go @@ -0,0 +1,603 @@ +// Copyright 2014 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +// Package vp8l implements a decoder for the VP8L lossless image format. +// +// The VP8L specification is at: +// https://developers.google.com/speed/webp/docs/riff_container +package vp8l // import "golang.org/x/image/vp8l" + +import ( + "bufio" + "errors" + "image" + "image/color" + "io" +) + +var ( + errInvalidCodeLengths = errors.New("vp8l: invalid code lengths") + errInvalidHuffmanTree = errors.New("vp8l: invalid Huffman tree") +) + +// colorCacheMultiplier is the multiplier used for the color cache hash +// function, specified in section 4.2.3. +const colorCacheMultiplier = 0x1e35a7bd + +// distanceMapTable is the look-up table for distanceMap. +var distanceMapTable = [120]uint8{ + 0x18, 0x07, 0x17, 0x19, 0x28, 0x06, 0x27, 0x29, 0x16, 0x1a, + 0x26, 0x2a, 0x38, 0x05, 0x37, 0x39, 0x15, 0x1b, 0x36, 0x3a, + 0x25, 0x2b, 0x48, 0x04, 0x47, 0x49, 0x14, 0x1c, 0x35, 0x3b, + 0x46, 0x4a, 0x24, 0x2c, 0x58, 0x45, 0x4b, 0x34, 0x3c, 0x03, + 0x57, 0x59, 0x13, 0x1d, 0x56, 0x5a, 0x23, 0x2d, 0x44, 0x4c, + 0x55, 0x5b, 0x33, 0x3d, 0x68, 0x02, 0x67, 0x69, 0x12, 0x1e, + 0x66, 0x6a, 0x22, 0x2e, 0x54, 0x5c, 0x43, 0x4d, 0x65, 0x6b, + 0x32, 0x3e, 0x78, 0x01, 0x77, 0x79, 0x53, 0x5d, 0x11, 0x1f, + 0x64, 0x6c, 0x42, 0x4e, 0x76, 0x7a, 0x21, 0x2f, 0x75, 0x7b, + 0x31, 0x3f, 0x63, 0x6d, 0x52, 0x5e, 0x00, 0x74, 0x7c, 0x41, + 0x4f, 0x10, 0x20, 0x62, 0x6e, 0x30, 0x73, 0x7d, 0x51, 0x5f, + 0x40, 0x72, 0x7e, 0x61, 0x6f, 0x50, 0x71, 0x7f, 0x60, 0x70, +} + +// distanceMap maps a LZ77 backwards reference distance to a two-dimensional +// pixel offset, specified in section 4.2.2. +func distanceMap(w int32, code uint32) int32 { + if int32(code) > int32(len(distanceMapTable)) { + return int32(code) - int32(len(distanceMapTable)) + } + distCode := int32(distanceMapTable[code-1]) + yOffset := distCode >> 4 + xOffset := 8 - distCode&0xf + if d := yOffset*w + xOffset; d >= 1 { + return d + } + return 1 +} + +// decoder holds the bit-stream for a VP8L image. +type decoder struct { + r io.ByteReader + bits uint32 + nBits uint32 +} + +// read reads the next n bits from the decoder's bit-stream. +func (d *decoder) read(n uint32) (uint32, error) { + for d.nBits < n { + c, err := d.r.ReadByte() + if err != nil { + if err == io.EOF { + err = io.ErrUnexpectedEOF + } + return 0, err + } + d.bits |= uint32(c) << d.nBits + d.nBits += 8 + } + u := d.bits & (1<>= n + d.nBits -= n + return u, nil +} + +// decodeTransform decodes the next transform and the width of the image after +// transformation (or equivalently, before inverse transformation), specified +// in section 3. +func (d *decoder) decodeTransform(w int32, h int32) (t transform, newWidth int32, err error) { + t.oldWidth = w + t.transformType, err = d.read(2) + if err != nil { + return transform{}, 0, err + } + switch t.transformType { + case transformTypePredictor, transformTypeCrossColor: + t.bits, err = d.read(3) + if err != nil { + return transform{}, 0, err + } + t.bits += 2 + t.pix, err = d.decodePix(nTiles(w, t.bits), nTiles(h, t.bits), 0, false) + if err != nil { + return transform{}, 0, err + } + case transformTypeSubtractGreen: + // No-op. + case transformTypeColorIndexing: + nColors, err := d.read(8) + if err != nil { + return transform{}, 0, err + } + nColors++ + t.bits = 0 + switch { + case nColors <= 2: + t.bits = 3 + case nColors <= 4: + t.bits = 2 + case nColors <= 16: + t.bits = 1 + } + w = nTiles(w, t.bits) + pix, err := d.decodePix(int32(nColors), 1, 4*256, false) + if err != nil { + return transform{}, 0, err + } + for p := 4; p < len(pix); p += 4 { + pix[p+0] += pix[p-4] + pix[p+1] += pix[p-3] + pix[p+2] += pix[p-2] + pix[p+3] += pix[p-1] + } + // The spec says that "if the index is equal or larger than color_table_size, + // the argb color value should be set to 0x00000000 (transparent black)." + // We re-slice up to 256 4-byte pixels. + t.pix = pix[:4*256] + } + return t, w, nil +} + +// repeatsCodeLength is the minimum code length for repeated codes. +const repeatsCodeLength = 16 + +// These magic numbers are specified at the end of section 5.2.2. +// The 3-length arrays apply to code lengths >= repeatsCodeLength. +var ( + codeLengthCodeOrder = [19]uint8{ + 17, 18, 0, 1, 2, 3, 4, 5, 16, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, + } + repeatBits = [3]uint8{2, 3, 7} + repeatOffsets = [3]uint8{3, 3, 11} +) + +// decodeCodeLengths decodes a Huffman tree's code lengths which are themselves +// encoded via a Huffman tree, specified in section 5.2.2. +func (d *decoder) decodeCodeLengths(dst []uint32, codeLengthCodeLengths []uint32) error { + h := hTree{} + if err := h.build(codeLengthCodeLengths); err != nil { + return err + } + + maxSymbol := len(dst) + useLength, err := d.read(1) + if err != nil { + return err + } + if useLength != 0 { + n, err := d.read(3) + if err != nil { + return err + } + n = 2 + 2*n + ms, err := d.read(n) + if err != nil { + return err + } + maxSymbol = int(ms) + 2 + if maxSymbol > len(dst) { + return errInvalidCodeLengths + } + } + + // The spec says that "if code 16 [meaning repeat] is used before + // a non-zero value has been emitted, a value of 8 is repeated." + prevCodeLength := uint32(8) + + for symbol := 0; symbol < len(dst); { + if maxSymbol == 0 { + break + } + maxSymbol-- + codeLength, err := h.next(d) + if err != nil { + return err + } + if codeLength < repeatsCodeLength { + dst[symbol] = codeLength + symbol++ + if codeLength != 0 { + prevCodeLength = codeLength + } + continue + } + + repeat, err := d.read(uint32(repeatBits[codeLength-repeatsCodeLength])) + if err != nil { + return err + } + repeat += uint32(repeatOffsets[codeLength-repeatsCodeLength]) + if symbol+int(repeat) > len(dst) { + return errInvalidCodeLengths + } + // A code length of 16 repeats the previous non-zero code. + // A code length of 17 or 18 repeats zeroes. + cl := uint32(0) + if codeLength == 16 { + cl = prevCodeLength + } + for ; repeat > 0; repeat-- { + dst[symbol] = cl + symbol++ + } + } + return nil +} + +// decodeHuffmanTree decodes a Huffman tree into h. +func (d *decoder) decodeHuffmanTree(h *hTree, alphabetSize uint32) error { + useSimple, err := d.read(1) + if err != nil { + return err + } + if useSimple != 0 { + nSymbols, err := d.read(1) + if err != nil { + return err + } + nSymbols++ + firstSymbolLengthCode, err := d.read(1) + if err != nil { + return err + } + firstSymbolLengthCode = 7*firstSymbolLengthCode + 1 + var symbols [2]uint32 + symbols[0], err = d.read(firstSymbolLengthCode) + if err != nil { + return err + } + if nSymbols == 2 { + symbols[1], err = d.read(8) + if err != nil { + return err + } + } + return h.buildSimple(nSymbols, symbols, alphabetSize) + } + + nCodes, err := d.read(4) + if err != nil { + return err + } + nCodes += 4 + if int(nCodes) > len(codeLengthCodeOrder) { + return errInvalidHuffmanTree + } + codeLengthCodeLengths := [len(codeLengthCodeOrder)]uint32{} + for i := uint32(0); i < nCodes; i++ { + codeLengthCodeLengths[codeLengthCodeOrder[i]], err = d.read(3) + if err != nil { + return err + } + } + codeLengths := make([]uint32, alphabetSize) + if err = d.decodeCodeLengths(codeLengths, codeLengthCodeLengths[:]); err != nil { + return err + } + return h.build(codeLengths) +} + +const ( + huffGreen = 0 + huffRed = 1 + huffBlue = 2 + huffAlpha = 3 + huffDistance = 4 + nHuff = 5 +) + +// hGroup is an array of 5 Huffman trees. +type hGroup [nHuff]hTree + +// decodeHuffmanGroups decodes the one or more hGroups used to decode the pixel +// data. If one hGroup is used for the entire image, then hPix and hBits will +// be zero. If more than one hGroup is used, then hPix contains the meta-image +// that maps tiles to hGroup index, and hBits contains the log-2 tile size. +func (d *decoder) decodeHuffmanGroups(w int32, h int32, topLevel bool, ccBits uint32) ( + hGroups []hGroup, hPix []byte, hBits uint32, err error) { + + maxHGroupIndex := 0 + if topLevel { + useMeta, err := d.read(1) + if err != nil { + return nil, nil, 0, err + } + if useMeta != 0 { + hBits, err = d.read(3) + if err != nil { + return nil, nil, 0, err + } + hBits += 2 + hPix, err = d.decodePix(nTiles(w, hBits), nTiles(h, hBits), 0, false) + if err != nil { + return nil, nil, 0, err + } + for p := 0; p < len(hPix); p += 4 { + i := int(hPix[p])<<8 | int(hPix[p+1]) + if maxHGroupIndex < i { + maxHGroupIndex = i + } + } + } + } + hGroups = make([]hGroup, maxHGroupIndex+1) + for i := range hGroups { + for j, alphabetSize := range alphabetSizes { + if j == 0 && ccBits > 0 { + alphabetSize += 1 << ccBits + } + if err := d.decodeHuffmanTree(&hGroups[i][j], alphabetSize); err != nil { + return nil, nil, 0, err + } + } + } + return hGroups, hPix, hBits, nil +} + +const ( + nLiteralCodes = 256 + nLengthCodes = 24 + nDistanceCodes = 40 +) + +var alphabetSizes = [nHuff]uint32{ + nLiteralCodes + nLengthCodes, + nLiteralCodes, + nLiteralCodes, + nLiteralCodes, + nDistanceCodes, +} + +// decodePix decodes pixel data, specified in section 5.2.2. +func (d *decoder) decodePix(w int32, h int32, minCap int32, topLevel bool) ([]byte, error) { + // Decode the color cache parameters. + ccBits, ccShift, ccEntries := uint32(0), uint32(0), ([]uint32)(nil) + useColorCache, err := d.read(1) + if err != nil { + return nil, err + } + if useColorCache != 0 { + ccBits, err = d.read(4) + if err != nil { + return nil, err + } + if ccBits < 1 || 11 < ccBits { + return nil, errors.New("vp8l: invalid color cache parameters") + } + ccShift = 32 - ccBits + ccEntries = make([]uint32, 1<>hBits) + (x >> hBits)) + hg = &hGroups[uint32(hPix[i])<<8|uint32(hPix[i+1])] + } + + green, err := hg[huffGreen].next(d) + if err != nil { + return nil, err + } + switch { + case green < nLiteralCodes: + // We have a literal pixel. + red, err := hg[huffRed].next(d) + if err != nil { + return nil, err + } + blue, err := hg[huffBlue].next(d) + if err != nil { + return nil, err + } + alpha, err := hg[huffAlpha].next(d) + if err != nil { + return nil, err + } + pix[p+0] = uint8(red) + pix[p+1] = uint8(green) + pix[p+2] = uint8(blue) + pix[p+3] = uint8(alpha) + p += 4 + + x++ + if x == w { + x, y = 0, y+1 + } + lookupHG = hMask != 0 && x&hMask == 0 + + case green < nLiteralCodes+nLengthCodes: + // We have a LZ77 backwards reference. + length, err := d.lz77Param(green - nLiteralCodes) + if err != nil { + return nil, err + } + distSym, err := hg[huffDistance].next(d) + if err != nil { + return nil, err + } + distCode, err := d.lz77Param(distSym) + if err != nil { + return nil, err + } + dist := distanceMap(w, distCode) + pEnd := p + 4*int(length) + q := p - 4*int(dist) + qEnd := pEnd - 4*int(dist) + if p < 0 || len(pix) < pEnd || q < 0 || len(pix) < qEnd { + return nil, errors.New("vp8l: invalid LZ77 parameters") + } + for ; p < pEnd; p, q = p+1, q+1 { + pix[p] = pix[q] + } + + x += int32(length) + for x >= w { + x, y = x-w, y+1 + } + lookupHG = hMask != 0 + + default: + // We have a color cache lookup. First, insert previous pixels + // into the cache. Note that VP8L assumes ARGB order, but the + // Go image.RGBA type is in RGBA order. + for ; cachedP < p; cachedP += 4 { + argb := uint32(pix[cachedP+0])<<16 | + uint32(pix[cachedP+1])<<8 | + uint32(pix[cachedP+2])<<0 | + uint32(pix[cachedP+3])<<24 + ccEntries[(argb*colorCacheMultiplier)>>ccShift] = argb + } + green -= nLiteralCodes + nLengthCodes + if int(green) >= len(ccEntries) { + return nil, errors.New("vp8l: invalid color cache index") + } + argb := ccEntries[green] + pix[p+0] = uint8(argb >> 16) + pix[p+1] = uint8(argb >> 8) + pix[p+2] = uint8(argb >> 0) + pix[p+3] = uint8(argb >> 24) + p += 4 + + x++ + if x == w { + x, y = 0, y+1 + } + lookupHG = hMask != 0 && x&hMask == 0 + } + } + return pix, nil +} + +// lz77Param returns the next LZ77 parameter: a length or a distance, specified +// in section 4.2.2. +func (d *decoder) lz77Param(symbol uint32) (uint32, error) { + if symbol < 4 { + return symbol + 1, nil + } + extraBits := (symbol - 2) >> 1 + offset := (2 + symbol&1) << extraBits + n, err := d.read(extraBits) + if err != nil { + return 0, err + } + return offset + n + 1, nil +} + +// decodeHeader decodes the VP8L header from r. +func decodeHeader(r io.Reader) (d *decoder, w int32, h int32, err error) { + rr, ok := r.(io.ByteReader) + if !ok { + rr = bufio.NewReader(r) + } + d = &decoder{r: rr} + magic, err := d.read(8) + if err != nil { + return nil, 0, 0, err + } + if magic != 0x2f { + return nil, 0, 0, errors.New("vp8l: invalid header") + } + width, err := d.read(14) + if err != nil { + return nil, 0, 0, err + } + width++ + height, err := d.read(14) + if err != nil { + return nil, 0, 0, err + } + height++ + _, err = d.read(1) // Read and ignore the hasAlpha hint. + if err != nil { + return nil, 0, 0, err + } + version, err := d.read(3) + if err != nil { + return nil, 0, 0, err + } + if version != 0 { + return nil, 0, 0, errors.New("vp8l: invalid version") + } + return d, int32(width), int32(height), nil +} + +// DecodeConfig decodes the color model and dimensions of a VP8L image from r. +func DecodeConfig(r io.Reader) (image.Config, error) { + _, w, h, err := decodeHeader(r) + if err != nil { + return image.Config{}, err + } + return image.Config{ + ColorModel: color.NRGBAModel, + Width: int(w), + Height: int(h), + }, nil +} + +// Decode decodes a VP8L image from r. +func Decode(r io.Reader) (image.Image, error) { + d, w, h, err := decodeHeader(r) + if err != nil { + return nil, err + } + // Decode the transforms. + var ( + nTransforms int + transforms [nTransformTypes]transform + transformsSeen [nTransformTypes]bool + originalW = w + ) + for { + more, err := d.read(1) + if err != nil { + return nil, err + } + if more == 0 { + break + } + var t transform + t, w, err = d.decodeTransform(w, h) + if err != nil { + return nil, err + } + if transformsSeen[t.transformType] { + return nil, errors.New("vp8l: repeated transform") + } + transformsSeen[t.transformType] = true + transforms[nTransforms] = t + nTransforms++ + } + // Decode the transformed pixels. + pix, err := d.decodePix(w, h, 0, true) + if err != nil { + return nil, err + } + // Apply the inverse transformations. + for i := nTransforms - 1; i >= 0; i-- { + t := &transforms[i] + pix = inverseTransforms[t.transformType](t, pix, h) + } + return &image.NRGBA{ + Pix: pix, + Stride: 4 * int(originalW), + Rect: image.Rect(0, 0, int(originalW), int(h)), + }, nil +} diff --git a/vendor/golang.org/x/image/vp8l/huffman.go b/vendor/golang.org/x/image/vp8l/huffman.go new file mode 100644 index 0000000..36368a8 --- /dev/null +++ b/vendor/golang.org/x/image/vp8l/huffman.go @@ -0,0 +1,245 @@ +// Copyright 2014 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package vp8l + +import ( + "io" +) + +// reverseBits reverses the bits in a byte. +var reverseBits = [256]uint8{ + 0x00, 0x80, 0x40, 0xc0, 0x20, 0xa0, 0x60, 0xe0, 0x10, 0x90, 0x50, 0xd0, 0x30, 0xb0, 0x70, 0xf0, + 0x08, 0x88, 0x48, 0xc8, 0x28, 0xa8, 0x68, 0xe8, 0x18, 0x98, 0x58, 0xd8, 0x38, 0xb8, 0x78, 0xf8, + 0x04, 0x84, 0x44, 0xc4, 0x24, 0xa4, 0x64, 0xe4, 0x14, 0x94, 0x54, 0xd4, 0x34, 0xb4, 0x74, 0xf4, + 0x0c, 0x8c, 0x4c, 0xcc, 0x2c, 0xac, 0x6c, 0xec, 0x1c, 0x9c, 0x5c, 0xdc, 0x3c, 0xbc, 0x7c, 0xfc, + 0x02, 0x82, 0x42, 0xc2, 0x22, 0xa2, 0x62, 0xe2, 0x12, 0x92, 0x52, 0xd2, 0x32, 0xb2, 0x72, 0xf2, + 0x0a, 0x8a, 0x4a, 0xca, 0x2a, 0xaa, 0x6a, 0xea, 0x1a, 0x9a, 0x5a, 0xda, 0x3a, 0xba, 0x7a, 0xfa, + 0x06, 0x86, 0x46, 0xc6, 0x26, 0xa6, 0x66, 0xe6, 0x16, 0x96, 0x56, 0xd6, 0x36, 0xb6, 0x76, 0xf6, + 0x0e, 0x8e, 0x4e, 0xce, 0x2e, 0xae, 0x6e, 0xee, 0x1e, 0x9e, 0x5e, 0xde, 0x3e, 0xbe, 0x7e, 0xfe, + 0x01, 0x81, 0x41, 0xc1, 0x21, 0xa1, 0x61, 0xe1, 0x11, 0x91, 0x51, 0xd1, 0x31, 0xb1, 0x71, 0xf1, + 0x09, 0x89, 0x49, 0xc9, 0x29, 0xa9, 0x69, 0xe9, 0x19, 0x99, 0x59, 0xd9, 0x39, 0xb9, 0x79, 0xf9, + 0x05, 0x85, 0x45, 0xc5, 0x25, 0xa5, 0x65, 0xe5, 0x15, 0x95, 0x55, 0xd5, 0x35, 0xb5, 0x75, 0xf5, + 0x0d, 0x8d, 0x4d, 0xcd, 0x2d, 0xad, 0x6d, 0xed, 0x1d, 0x9d, 0x5d, 0xdd, 0x3d, 0xbd, 0x7d, 0xfd, + 0x03, 0x83, 0x43, 0xc3, 0x23, 0xa3, 0x63, 0xe3, 0x13, 0x93, 0x53, 0xd3, 0x33, 0xb3, 0x73, 0xf3, + 0x0b, 0x8b, 0x4b, 0xcb, 0x2b, 0xab, 0x6b, 0xeb, 0x1b, 0x9b, 0x5b, 0xdb, 0x3b, 0xbb, 0x7b, 0xfb, + 0x07, 0x87, 0x47, 0xc7, 0x27, 0xa7, 0x67, 0xe7, 0x17, 0x97, 0x57, 0xd7, 0x37, 0xb7, 0x77, 0xf7, + 0x0f, 0x8f, 0x4f, 0xcf, 0x2f, 0xaf, 0x6f, 0xef, 0x1f, 0x9f, 0x5f, 0xdf, 0x3f, 0xbf, 0x7f, 0xff, +} + +// hNode is a node in a Huffman tree. +type hNode struct { + // symbol is the symbol held by this node. + symbol uint32 + // children, if positive, is the hTree.nodes index of the first of + // this node's two children. Zero means an uninitialized node, + // and -1 means a leaf node. + children int32 +} + +const leafNode = -1 + +// lutSize is the log-2 size of an hTree's look-up table. +const lutSize, lutMask = 7, 1<<7 - 1 + +// hTree is a Huffman tree. +type hTree struct { + // nodes are the nodes of the Huffman tree. During construction, + // len(nodes) grows from 1 up to cap(nodes) by steps of two. + // After construction, len(nodes) == cap(nodes), and both equal + // 2*theNumberOfSymbols - 1. + nodes []hNode + // lut is a look-up table for walking the nodes. The x in lut[x] is + // the next lutSize bits in the bit-stream. The low 8 bits of lut[x] + // equals 1 plus the number of bits in the next code, or 0 if the + // next code requires more than lutSize bits. The high 24 bits are: + // - the symbol, if the code requires lutSize or fewer bits, or + // - the hTree.nodes index to start the tree traversal from, if + // the next code requires more than lutSize bits. + lut [1 << lutSize]uint32 +} + +// insert inserts into the hTree a symbol whose encoding is the least +// significant codeLength bits of code. +func (h *hTree) insert(symbol uint32, code uint32, codeLength uint32) error { + if symbol > 0xffff || codeLength > 0xfe { + return errInvalidHuffmanTree + } + baseCode := uint32(0) + if codeLength > lutSize { + baseCode = uint32(reverseBits[(code>>(codeLength-lutSize))&0xff]) >> (8 - lutSize) + } else { + baseCode = uint32(reverseBits[code&0xff]) >> (8 - codeLength) + for i := 0; i < 1<<(lutSize-codeLength); i++ { + h.lut[baseCode|uint32(i)< 0; { + codeLength-- + if int(n) > len(h.nodes) { + return errInvalidHuffmanTree + } + switch h.nodes[n].children { + case leafNode: + return errInvalidHuffmanTree + case 0: + if len(h.nodes) == cap(h.nodes) { + return errInvalidHuffmanTree + } + // Create two empty child nodes. + h.nodes[n].children = int32(len(h.nodes)) + h.nodes = h.nodes[:len(h.nodes)+2] + } + n = uint32(h.nodes[n].children) + 1&(code>>codeLength) + jump-- + if jump == 0 && h.lut[baseCode] == 0 { + h.lut[baseCode] = n << 8 + } + } + + switch h.nodes[n].children { + case leafNode: + // No-op. + case 0: + // Turn the uninitialized node into a leaf. + h.nodes[n].children = leafNode + default: + return errInvalidHuffmanTree + } + h.nodes[n].symbol = symbol + return nil +} + +// codeLengthsToCodes returns the canonical Huffman codes implied by the +// sequence of code lengths. +func codeLengthsToCodes(codeLengths []uint32) ([]uint32, error) { + maxCodeLength := uint32(0) + for _, cl := range codeLengths { + if maxCodeLength < cl { + maxCodeLength = cl + } + } + const maxAllowedCodeLength = 15 + if len(codeLengths) == 0 || maxCodeLength > maxAllowedCodeLength { + return nil, errInvalidHuffmanTree + } + histogram := [maxAllowedCodeLength + 1]uint32{} + for _, cl := range codeLengths { + histogram[cl]++ + } + currCode, nextCodes := uint32(0), [maxAllowedCodeLength + 1]uint32{} + for cl := 1; cl < len(nextCodes); cl++ { + currCode = (currCode + histogram[cl-1]) << 1 + nextCodes[cl] = currCode + } + codes := make([]uint32, len(codeLengths)) + for symbol, cl := range codeLengths { + if cl > 0 { + codes[symbol] = nextCodes[cl] + nextCodes[cl]++ + } + } + return codes, nil +} + +// build builds a canonical Huffman tree from the given code lengths. +func (h *hTree) build(codeLengths []uint32) error { + // Calculate the number of symbols. + var nSymbols, lastSymbol uint32 + for symbol, cl := range codeLengths { + if cl != 0 { + nSymbols++ + lastSymbol = uint32(symbol) + } + } + if nSymbols == 0 { + return errInvalidHuffmanTree + } + h.nodes = make([]hNode, 1, 2*nSymbols-1) + // Handle the trivial case. + if nSymbols == 1 { + if len(codeLengths) <= int(lastSymbol) { + return errInvalidHuffmanTree + } + return h.insert(lastSymbol, 0, 0) + } + // Handle the non-trivial case. + codes, err := codeLengthsToCodes(codeLengths) + if err != nil { + return err + } + for symbol, cl := range codeLengths { + if cl > 0 { + if err := h.insert(uint32(symbol), codes[symbol], cl); err != nil { + return err + } + } + } + return nil +} + +// buildSimple builds a Huffman tree with 1 or 2 symbols. +func (h *hTree) buildSimple(nSymbols uint32, symbols [2]uint32, alphabetSize uint32) error { + h.nodes = make([]hNode, 1, 2*nSymbols-1) + for i := uint32(0); i < nSymbols; i++ { + if symbols[i] >= alphabetSize { + return errInvalidHuffmanTree + } + if err := h.insert(symbols[i], i, nSymbols-1); err != nil { + return err + } + } + return nil +} + +// next returns the next Huffman-encoded symbol from the bit-stream d. +func (h *hTree) next(d *decoder) (uint32, error) { + var n uint32 + // Read enough bits so that we can use the look-up table. + if d.nBits < lutSize { + c, err := d.r.ReadByte() + if err != nil { + if err == io.EOF { + // There are no more bytes of data, but we may still be able + // to read the next symbol out of the previously read bits. + goto slowPath + } + return 0, err + } + d.bits |= uint32(c) << d.nBits + d.nBits += 8 + } + // Use the look-up table. + n = h.lut[d.bits&lutMask] + if b := n & 0xff; b != 0 { + b-- + d.bits >>= b + d.nBits -= b + return n >> 8, nil + } + n >>= 8 + d.bits >>= lutSize + d.nBits -= lutSize + +slowPath: + for h.nodes[n].children != leafNode { + if d.nBits == 0 { + c, err := d.r.ReadByte() + if err != nil { + if err == io.EOF { + err = io.ErrUnexpectedEOF + } + return 0, err + } + d.bits = uint32(c) + d.nBits = 8 + } + n = uint32(h.nodes[n].children) + 1&d.bits + d.bits >>= 1 + d.nBits-- + } + return h.nodes[n].symbol, nil +} diff --git a/vendor/golang.org/x/image/vp8l/transform.go b/vendor/golang.org/x/image/vp8l/transform.go new file mode 100644 index 0000000..06543da --- /dev/null +++ b/vendor/golang.org/x/image/vp8l/transform.go @@ -0,0 +1,299 @@ +// Copyright 2014 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package vp8l + +// This file deals with image transforms, specified in section 3. + +// nTiles returns the number of tiles needed to cover size pixels, where each +// tile's side is 1<> bits +} + +const ( + transformTypePredictor = 0 + transformTypeCrossColor = 1 + transformTypeSubtractGreen = 2 + transformTypeColorIndexing = 3 + nTransformTypes = 4 +) + +// transform holds the parameters for an invertible transform. +type transform struct { + // transformType is the type of the transform. + transformType uint32 + // oldWidth is the width of the image before transformation (or + // equivalently, after inverse transformation). The color-indexing + // transform can reduce the width. For example, a 50-pixel-wide + // image that only needs 4 bits (half a byte) per color index can + // be transformed into a 25-pixel-wide image. + oldWidth int32 + // bits is the log-2 size of the transform's tiles, for the predictor + // and cross-color transforms. 8>>bits is the number of bits per + // color index, for the color-index transform. + bits uint32 + // pix is the tile values, for the predictor and cross-color + // transforms, and the color palette, for the color-index transform. + pix []byte +} + +var inverseTransforms = [nTransformTypes]func(*transform, []byte, int32) []byte{ + transformTypePredictor: inversePredictor, + transformTypeCrossColor: inverseCrossColor, + transformTypeSubtractGreen: inverseSubtractGreen, + transformTypeColorIndexing: inverseColorIndexing, +} + +func inversePredictor(t *transform, pix []byte, h int32) []byte { + if t.oldWidth == 0 || h == 0 { + return pix + } + // The first pixel's predictor is mode 0 (opaque black). + pix[3] += 0xff + p, mask := int32(4), int32(1)<> t.bits) * tilesPerRow + predictorMode := t.pix[q+1] & 0x0f + q += 4 + for x := int32(1); x < t.oldWidth; x++ { + if x&mask == 0 { + predictorMode = t.pix[q+1] & 0x0f + q += 4 + } + switch predictorMode { + case 0: // Opaque black. + pix[p+3] += 0xff + + case 1: // L. + pix[p+0] += pix[p-4] + pix[p+1] += pix[p-3] + pix[p+2] += pix[p-2] + pix[p+3] += pix[p-1] + + case 2: // T. + pix[p+0] += pix[top+0] + pix[p+1] += pix[top+1] + pix[p+2] += pix[top+2] + pix[p+3] += pix[top+3] + + case 3: // TR. + pix[p+0] += pix[top+4] + pix[p+1] += pix[top+5] + pix[p+2] += pix[top+6] + pix[p+3] += pix[top+7] + + case 4: // TL. + pix[p+0] += pix[top-4] + pix[p+1] += pix[top-3] + pix[p+2] += pix[top-2] + pix[p+3] += pix[top-1] + + case 5: // Average2(Average2(L, TR), T). + pix[p+0] += avg2(avg2(pix[p-4], pix[top+4]), pix[top+0]) + pix[p+1] += avg2(avg2(pix[p-3], pix[top+5]), pix[top+1]) + pix[p+2] += avg2(avg2(pix[p-2], pix[top+6]), pix[top+2]) + pix[p+3] += avg2(avg2(pix[p-1], pix[top+7]), pix[top+3]) + + case 6: // Average2(L, TL). + pix[p+0] += avg2(pix[p-4], pix[top-4]) + pix[p+1] += avg2(pix[p-3], pix[top-3]) + pix[p+2] += avg2(pix[p-2], pix[top-2]) + pix[p+3] += avg2(pix[p-1], pix[top-1]) + + case 7: // Average2(L, T). + pix[p+0] += avg2(pix[p-4], pix[top+0]) + pix[p+1] += avg2(pix[p-3], pix[top+1]) + pix[p+2] += avg2(pix[p-2], pix[top+2]) + pix[p+3] += avg2(pix[p-1], pix[top+3]) + + case 8: // Average2(TL, T). + pix[p+0] += avg2(pix[top-4], pix[top+0]) + pix[p+1] += avg2(pix[top-3], pix[top+1]) + pix[p+2] += avg2(pix[top-2], pix[top+2]) + pix[p+3] += avg2(pix[top-1], pix[top+3]) + + case 9: // Average2(T, TR). + pix[p+0] += avg2(pix[top+0], pix[top+4]) + pix[p+1] += avg2(pix[top+1], pix[top+5]) + pix[p+2] += avg2(pix[top+2], pix[top+6]) + pix[p+3] += avg2(pix[top+3], pix[top+7]) + + case 10: // Average2(Average2(L, TL), Average2(T, TR)). + pix[p+0] += avg2(avg2(pix[p-4], pix[top-4]), avg2(pix[top+0], pix[top+4])) + pix[p+1] += avg2(avg2(pix[p-3], pix[top-3]), avg2(pix[top+1], pix[top+5])) + pix[p+2] += avg2(avg2(pix[p-2], pix[top-2]), avg2(pix[top+2], pix[top+6])) + pix[p+3] += avg2(avg2(pix[p-1], pix[top-1]), avg2(pix[top+3], pix[top+7])) + + case 11: // Select(L, T, TL). + l0 := int32(pix[p-4]) + l1 := int32(pix[p-3]) + l2 := int32(pix[p-2]) + l3 := int32(pix[p-1]) + c0 := int32(pix[top-4]) + c1 := int32(pix[top-3]) + c2 := int32(pix[top-2]) + c3 := int32(pix[top-1]) + t0 := int32(pix[top+0]) + t1 := int32(pix[top+1]) + t2 := int32(pix[top+2]) + t3 := int32(pix[top+3]) + l := abs(c0-t0) + abs(c1-t1) + abs(c2-t2) + abs(c3-t3) + t := abs(c0-l0) + abs(c1-l1) + abs(c2-l2) + abs(c3-l3) + if l < t { + pix[p+0] += uint8(l0) + pix[p+1] += uint8(l1) + pix[p+2] += uint8(l2) + pix[p+3] += uint8(l3) + } else { + pix[p+0] += uint8(t0) + pix[p+1] += uint8(t1) + pix[p+2] += uint8(t2) + pix[p+3] += uint8(t3) + } + + case 12: // ClampAddSubtractFull(L, T, TL). + pix[p+0] += clampAddSubtractFull(pix[p-4], pix[top+0], pix[top-4]) + pix[p+1] += clampAddSubtractFull(pix[p-3], pix[top+1], pix[top-3]) + pix[p+2] += clampAddSubtractFull(pix[p-2], pix[top+2], pix[top-2]) + pix[p+3] += clampAddSubtractFull(pix[p-1], pix[top+3], pix[top-1]) + + case 13: // ClampAddSubtractHalf(Average2(L, T), TL). + pix[p+0] += clampAddSubtractHalf(avg2(pix[p-4], pix[top+0]), pix[top-4]) + pix[p+1] += clampAddSubtractHalf(avg2(pix[p-3], pix[top+1]), pix[top-3]) + pix[p+2] += clampAddSubtractHalf(avg2(pix[p-2], pix[top+2]), pix[top-2]) + pix[p+3] += clampAddSubtractHalf(avg2(pix[p-1], pix[top+3]), pix[top-1]) + } + p, top = p+4, top+4 + } + } + return pix +} + +func inverseCrossColor(t *transform, pix []byte, h int32) []byte { + var greenToRed, greenToBlue, redToBlue int32 + p, mask, tilesPerRow := int32(0), int32(1)<> t.bits) * tilesPerRow + for x := int32(0); x < t.oldWidth; x++ { + if x&mask == 0 { + redToBlue = int32(int8(t.pix[q+0])) + greenToBlue = int32(int8(t.pix[q+1])) + greenToRed = int32(int8(t.pix[q+2])) + q += 4 + } + red := pix[p+0] + green := pix[p+1] + blue := pix[p+2] + red += uint8(uint32(greenToRed*int32(int8(green))) >> 5) + blue += uint8(uint32(greenToBlue*int32(int8(green))) >> 5) + blue += uint8(uint32(redToBlue*int32(int8(red))) >> 5) + pix[p+0] = red + pix[p+2] = blue + p += 4 + } + } + return pix +} + +func inverseSubtractGreen(t *transform, pix []byte, h int32) []byte { + for p := 0; p < len(pix); p += 4 { + green := pix[p+1] + pix[p+0] += green + pix[p+2] += green + } + return pix +} + +func inverseColorIndexing(t *transform, pix []byte, h int32) []byte { + if t.bits == 0 { + for p := 0; p < len(pix); p += 4 { + i := 4 * uint32(pix[p+1]) + pix[p+0] = t.pix[i+0] + pix[p+1] = t.pix[i+1] + pix[p+2] = t.pix[i+2] + pix[p+3] = t.pix[i+3] + } + return pix + } + + vMask, xMask, bitsPerPixel := uint32(0), int32(0), uint32(8>>t.bits) + switch t.bits { + case 1: + vMask, xMask = 0x0f, 0x01 + case 2: + vMask, xMask = 0x03, 0x03 + case 3: + vMask, xMask = 0x01, 0x07 + } + + d, p, v, dst := 0, 0, uint32(0), make([]byte, 4*t.oldWidth*h) + for y := int32(0); y < h; y++ { + for x := int32(0); x < t.oldWidth; x++ { + if x&xMask == 0 { + v = uint32(pix[p+1]) + p += 4 + } + + i := 4 * (v & vMask) + dst[d+0] = t.pix[i+0] + dst[d+1] = t.pix[i+1] + dst[d+2] = t.pix[i+2] + dst[d+3] = t.pix[i+3] + d += 4 + + v >>= bitsPerPixel + } + } + return dst +} + +func abs(x int32) int32 { + if x < 0 { + return -x + } + return x +} + +func avg2(a, b uint8) uint8 { + return uint8((int32(a) + int32(b)) / 2) +} + +func clampAddSubtractFull(a, b, c uint8) uint8 { + x := int32(a) + int32(b) - int32(c) + if x < 0 { + return 0 + } + if x > 255 { + return 255 + } + return uint8(x) +} + +func clampAddSubtractHalf(a, b uint8) uint8 { + x := int32(a) + (int32(a)-int32(b))/2 + if x < 0 { + return 0 + } + if x > 255 { + return 255 + } + return uint8(x) +} -- cgit v1.2.3