diff options
Diffstat (limited to 'vendor/golang.org/x/image/tiff/writer.go')
| -rw-r--r-- | vendor/golang.org/x/image/tiff/writer.go | 438 |
1 files changed, 0 insertions, 438 deletions
diff --git a/vendor/golang.org/x/image/tiff/writer.go b/vendor/golang.org/x/image/tiff/writer.go deleted file mode 100644 index c8a01ce..0000000 --- a/vendor/golang.org/x/image/tiff/writer.go +++ /dev/null @@ -1,438 +0,0 @@ -// Copyright 2012 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 tiff - -import ( - "bytes" - "compress/zlib" - "encoding/binary" - "image" - "io" - "sort" -) - -// The TIFF format allows to choose the order of the different elements freely. -// The basic structure of a TIFF file written by this package is: -// -// 1. Header (8 bytes). -// 2. Image data. -// 3. Image File Directory (IFD). -// 4. "Pointer area" for larger entries in the IFD. - -// We only write little-endian TIFF files. -var enc = binary.LittleEndian - -// An ifdEntry is a single entry in an Image File Directory. -// A value of type dtRational is composed of two 32-bit values, -// thus data contains two uints (numerator and denominator) for a single number. -type ifdEntry struct { - tag int - datatype int - data []uint32 -} - -func (e ifdEntry) putData(p []byte) { - for _, d := range e.data { - switch e.datatype { - case dtByte, dtASCII: - p[0] = byte(d) - p = p[1:] - case dtShort: - enc.PutUint16(p, uint16(d)) - p = p[2:] - case dtLong, dtRational: - enc.PutUint32(p, uint32(d)) - p = p[4:] - } - } -} - -type byTag []ifdEntry - -func (d byTag) Len() int { return len(d) } -func (d byTag) Less(i, j int) bool { return d[i].tag < d[j].tag } -func (d byTag) Swap(i, j int) { d[i], d[j] = d[j], d[i] } - -func encodeGray(w io.Writer, pix []uint8, dx, dy, stride int, predictor bool) error { - if !predictor { - return writePix(w, pix, dy, dx, stride) - } - buf := make([]byte, dx) - for y := 0; y < dy; y++ { - min := y*stride + 0 - max := y*stride + dx - off := 0 - var v0 uint8 - for i := min; i < max; i++ { - v1 := pix[i] - buf[off] = v1 - v0 - v0 = v1 - off++ - } - if _, err := w.Write(buf); err != nil { - return err - } - } - return nil -} - -func encodeGray16(w io.Writer, pix []uint8, dx, dy, stride int, predictor bool) error { - buf := make([]byte, dx*2) - for y := 0; y < dy; y++ { - min := y*stride + 0 - max := y*stride + dx*2 - off := 0 - var v0 uint16 - for i := min; i < max; i += 2 { - // An image.Gray16's Pix is in big-endian order. - v1 := uint16(pix[i])<<8 | uint16(pix[i+1]) - if predictor { - v0, v1 = v1, v1-v0 - } - // We only write little-endian TIFF files. - buf[off+0] = byte(v1) - buf[off+1] = byte(v1 >> 8) - off += 2 - } - if _, err := w.Write(buf); err != nil { - return err - } - } - return nil -} - -func encodeRGBA(w io.Writer, pix []uint8, dx, dy, stride int, predictor bool) error { - if !predictor { - return writePix(w, pix, dy, dx*4, stride) - } - buf := make([]byte, dx*4) - for y := 0; y < dy; y++ { - min := y*stride + 0 - max := y*stride + dx*4 - off := 0 - var r0, g0, b0, a0 uint8 - for i := min; i < max; i += 4 { - r1, g1, b1, a1 := pix[i+0], pix[i+1], pix[i+2], pix[i+3] - buf[off+0] = r1 - r0 - buf[off+1] = g1 - g0 - buf[off+2] = b1 - b0 - buf[off+3] = a1 - a0 - off += 4 - r0, g0, b0, a0 = r1, g1, b1, a1 - } - if _, err := w.Write(buf); err != nil { - return err - } - } - return nil -} - -func encodeRGBA64(w io.Writer, pix []uint8, dx, dy, stride int, predictor bool) error { - buf := make([]byte, dx*8) - for y := 0; y < dy; y++ { - min := y*stride + 0 - max := y*stride + dx*8 - off := 0 - var r0, g0, b0, a0 uint16 - for i := min; i < max; i += 8 { - // An image.RGBA64's Pix is in big-endian order. - r1 := uint16(pix[i+0])<<8 | uint16(pix[i+1]) - g1 := uint16(pix[i+2])<<8 | uint16(pix[i+3]) - b1 := uint16(pix[i+4])<<8 | uint16(pix[i+5]) - a1 := uint16(pix[i+6])<<8 | uint16(pix[i+7]) - if predictor { - r0, r1 = r1, r1-r0 - g0, g1 = g1, g1-g0 - b0, b1 = b1, b1-b0 - a0, a1 = a1, a1-a0 - } - // We only write little-endian TIFF files. - buf[off+0] = byte(r1) - buf[off+1] = byte(r1 >> 8) - buf[off+2] = byte(g1) - buf[off+3] = byte(g1 >> 8) - buf[off+4] = byte(b1) - buf[off+5] = byte(b1 >> 8) - buf[off+6] = byte(a1) - buf[off+7] = byte(a1 >> 8) - off += 8 - } - if _, err := w.Write(buf); err != nil { - return err - } - } - return nil -} - -func encode(w io.Writer, m image.Image, predictor bool) error { - bounds := m.Bounds() - buf := make([]byte, 4*bounds.Dx()) - for y := bounds.Min.Y; y < bounds.Max.Y; y++ { - off := 0 - if predictor { - var r0, g0, b0, a0 uint8 - for x := bounds.Min.X; x < bounds.Max.X; x++ { - r, g, b, a := m.At(x, y).RGBA() - r1 := uint8(r >> 8) - g1 := uint8(g >> 8) - b1 := uint8(b >> 8) - a1 := uint8(a >> 8) - buf[off+0] = r1 - r0 - buf[off+1] = g1 - g0 - buf[off+2] = b1 - b0 - buf[off+3] = a1 - a0 - off += 4 - r0, g0, b0, a0 = r1, g1, b1, a1 - } - } else { - for x := bounds.Min.X; x < bounds.Max.X; x++ { - r, g, b, a := m.At(x, y).RGBA() - buf[off+0] = uint8(r >> 8) - buf[off+1] = uint8(g >> 8) - buf[off+2] = uint8(b >> 8) - buf[off+3] = uint8(a >> 8) - off += 4 - } - } - if _, err := w.Write(buf); err != nil { - return err - } - } - return nil -} - -// writePix writes the internal byte array of an image to w. It is less general -// but much faster then encode. writePix is used when pix directly -// corresponds to one of the TIFF image types. -func writePix(w io.Writer, pix []byte, nrows, length, stride int) error { - if length == stride { - _, err := w.Write(pix[:nrows*length]) - return err - } - for ; nrows > 0; nrows-- { - if _, err := w.Write(pix[:length]); err != nil { - return err - } - pix = pix[stride:] - } - return nil -} - -func writeIFD(w io.Writer, ifdOffset int, d []ifdEntry) error { - var buf [ifdLen]byte - // Make space for "pointer area" containing IFD entry data - // longer than 4 bytes. - parea := make([]byte, 1024) - pstart := ifdOffset + ifdLen*len(d) + 6 - var o int // Current offset in parea. - - // The IFD has to be written with the tags in ascending order. - sort.Sort(byTag(d)) - - // Write the number of entries in this IFD. - if err := binary.Write(w, enc, uint16(len(d))); err != nil { - return err - } - for _, ent := range d { - enc.PutUint16(buf[0:2], uint16(ent.tag)) - enc.PutUint16(buf[2:4], uint16(ent.datatype)) - count := uint32(len(ent.data)) - if ent.datatype == dtRational { - count /= 2 - } - enc.PutUint32(buf[4:8], count) - datalen := int(count * lengths[ent.datatype]) - if datalen <= 4 { - ent.putData(buf[8:12]) - } else { - if (o + datalen) > len(parea) { - newlen := len(parea) + 1024 - for (o + datalen) > newlen { - newlen += 1024 - } - newarea := make([]byte, newlen) - copy(newarea, parea) - parea = newarea - } - ent.putData(parea[o : o+datalen]) - enc.PutUint32(buf[8:12], uint32(pstart+o)) - o += datalen - } - if _, err := w.Write(buf[:]); err != nil { - return err - } - } - // The IFD ends with the offset of the next IFD in the file, - // or zero if it is the last one (page 14). - if err := binary.Write(w, enc, uint32(0)); err != nil { - return err - } - _, err := w.Write(parea[:o]) - return err -} - -// Options are the encoding parameters. -type Options struct { - // Compression is the type of compression used. - Compression CompressionType - // Predictor determines whether a differencing predictor is used; - // if true, instead of each pixel's color, the color difference to the - // preceding one is saved. This improves the compression for certain - // types of images and compressors. For example, it works well for - // photos with Deflate compression. - Predictor bool -} - -// Encode writes the image m to w. opt determines the options used for -// encoding, such as the compression type. If opt is nil, an uncompressed -// image is written. -func Encode(w io.Writer, m image.Image, opt *Options) error { - d := m.Bounds().Size() - - compression := uint32(cNone) - predictor := false - if opt != nil { - compression = opt.Compression.specValue() - // The predictor field is only used with LZW. See page 64 of the spec. - predictor = opt.Predictor && compression == cLZW - } - - _, err := io.WriteString(w, leHeader) - if err != nil { - return err - } - - // Compressed data is written into a buffer first, so that we - // know the compressed size. - var buf bytes.Buffer - // dst holds the destination for the pixel data of the image -- - // either w or a writer to buf. - var dst io.Writer - // imageLen is the length of the pixel data in bytes. - // The offset of the IFD is imageLen + 8 header bytes. - var imageLen int - - switch compression { - case cNone: - dst = w - // Write IFD offset before outputting pixel data. - switch m.(type) { - case *image.Paletted: - imageLen = d.X * d.Y * 1 - case *image.Gray: - imageLen = d.X * d.Y * 1 - case *image.Gray16: - imageLen = d.X * d.Y * 2 - case *image.RGBA64: - imageLen = d.X * d.Y * 8 - case *image.NRGBA64: - imageLen = d.X * d.Y * 8 - default: - imageLen = d.X * d.Y * 4 - } - err = binary.Write(w, enc, uint32(imageLen+8)) - if err != nil { - return err - } - case cDeflate: - dst = zlib.NewWriter(&buf) - } - - pr := uint32(prNone) - photometricInterpretation := uint32(pRGB) - samplesPerPixel := uint32(4) - bitsPerSample := []uint32{8, 8, 8, 8} - extraSamples := uint32(0) - colorMap := []uint32{} - - if predictor { - pr = prHorizontal - } - switch m := m.(type) { - case *image.Paletted: - photometricInterpretation = pPaletted - samplesPerPixel = 1 - bitsPerSample = []uint32{8} - colorMap = make([]uint32, 256*3) - for i := 0; i < 256 && i < len(m.Palette); i++ { - r, g, b, _ := m.Palette[i].RGBA() - colorMap[i+0*256] = uint32(r) - colorMap[i+1*256] = uint32(g) - colorMap[i+2*256] = uint32(b) - } - err = encodeGray(dst, m.Pix, d.X, d.Y, m.Stride, predictor) - case *image.Gray: - photometricInterpretation = pBlackIsZero - samplesPerPixel = 1 - bitsPerSample = []uint32{8} - err = encodeGray(dst, m.Pix, d.X, d.Y, m.Stride, predictor) - case *image.Gray16: - photometricInterpretation = pBlackIsZero - samplesPerPixel = 1 - bitsPerSample = []uint32{16} - err = encodeGray16(dst, m.Pix, d.X, d.Y, m.Stride, predictor) - case *image.NRGBA: - extraSamples = 2 // Unassociated alpha. - err = encodeRGBA(dst, m.Pix, d.X, d.Y, m.Stride, predictor) - case *image.NRGBA64: - extraSamples = 2 // Unassociated alpha. - bitsPerSample = []uint32{16, 16, 16, 16} - err = encodeRGBA64(dst, m.Pix, d.X, d.Y, m.Stride, predictor) - case *image.RGBA: - extraSamples = 1 // Associated alpha. - err = encodeRGBA(dst, m.Pix, d.X, d.Y, m.Stride, predictor) - case *image.RGBA64: - extraSamples = 1 // Associated alpha. - bitsPerSample = []uint32{16, 16, 16, 16} - err = encodeRGBA64(dst, m.Pix, d.X, d.Y, m.Stride, predictor) - default: - extraSamples = 1 // Associated alpha. - err = encode(dst, m, predictor) - } - if err != nil { - return err - } - - if compression != cNone { - if err = dst.(io.Closer).Close(); err != nil { - return err - } - imageLen = buf.Len() - if err = binary.Write(w, enc, uint32(imageLen+8)); err != nil { - return err - } - if _, err = buf.WriteTo(w); err != nil { - return err - } - } - - ifd := []ifdEntry{ - {tImageWidth, dtShort, []uint32{uint32(d.X)}}, - {tImageLength, dtShort, []uint32{uint32(d.Y)}}, - {tBitsPerSample, dtShort, bitsPerSample}, - {tCompression, dtShort, []uint32{compression}}, - {tPhotometricInterpretation, dtShort, []uint32{photometricInterpretation}}, - {tStripOffsets, dtLong, []uint32{8}}, - {tSamplesPerPixel, dtShort, []uint32{samplesPerPixel}}, - {tRowsPerStrip, dtShort, []uint32{uint32(d.Y)}}, - {tStripByteCounts, dtLong, []uint32{uint32(imageLen)}}, - // There is currently no support for storing the image - // resolution, so give a bogus value of 72x72 dpi. - {tXResolution, dtRational, []uint32{72, 1}}, - {tYResolution, dtRational, []uint32{72, 1}}, - {tResolutionUnit, dtShort, []uint32{resPerInch}}, - } - if pr != prNone { - ifd = append(ifd, ifdEntry{tPredictor, dtShort, []uint32{pr}}) - } - if len(colorMap) != 0 { - ifd = append(ifd, ifdEntry{tColorMap, dtShort, colorMap}) - } - if extraSamples > 0 { - ifd = append(ifd, ifdEntry{tExtraSamples, dtShort, []uint32{extraSamples}}) - } - - return writeIFD(w, imageLen+8, ifd) -} |