mirror of
https://github.com/cwinfo/matterbridge.git
synced 2024-11-23 00:01:37 +00:00
53cafa9f3d
This commit adds support for go/cgo tgs conversion when building with the -tags `cgo` The default binaries are still "pure" go and uses the old way of converting. * Move lottie_convert.py conversion code to its own file * Add optional libtgsconverter * Update vendor * Apply suggestions from code review * Update bridge/helper/libtgsconverter.go Co-authored-by: Wim <wim@42.be>
714 lines
16 KiB
Go
714 lines
16 KiB
Go
// Original PNG code Copyright 2009 The Go Authors.
|
|
// Additional APNG enhancements Copyright 2018 Ketchetwahmeegwun
|
|
// Tecumseh Southall / kts of kettek.
|
|
// All rights reserved.
|
|
// Use of this source code is governed by a BSD-style
|
|
// license that can be found in the LICENSE file.
|
|
|
|
package apng
|
|
|
|
import (
|
|
"bufio"
|
|
"compress/zlib"
|
|
"encoding/binary"
|
|
"hash/crc32"
|
|
"image"
|
|
"image/color"
|
|
"io"
|
|
"strconv"
|
|
)
|
|
|
|
// Encoder configures encoding PNG images.
|
|
type Encoder struct {
|
|
CompressionLevel CompressionLevel
|
|
|
|
// BufferPool optionally specifies a buffer pool to get temporary
|
|
// EncoderBuffers when encoding an image.
|
|
BufferPool EncoderBufferPool
|
|
}
|
|
|
|
// EncoderBufferPool is an interface for getting and returning temporary
|
|
// instances of the EncoderBuffer struct. This can be used to reuse buffers
|
|
// when encoding multiple images.
|
|
type EncoderBufferPool interface {
|
|
Get() *EncoderBuffer
|
|
Put(*EncoderBuffer)
|
|
}
|
|
|
|
// EncoderBuffer holds the buffers used for encoding PNG images.
|
|
type EncoderBuffer encoder
|
|
|
|
type encoder struct {
|
|
enc *Encoder
|
|
w io.Writer
|
|
a APNG
|
|
write_type int // 0 = IDAT, 1 = fdAT
|
|
seq int
|
|
cb int
|
|
err error
|
|
header [8]byte
|
|
footer [4]byte
|
|
tmp [4 * 256]byte
|
|
cr [nFilter][]uint8
|
|
pr []uint8
|
|
zw *zlib.Writer
|
|
zwLevel int
|
|
bw *bufio.Writer
|
|
}
|
|
|
|
type CompressionLevel int
|
|
|
|
const (
|
|
DefaultCompression CompressionLevel = 0
|
|
NoCompression CompressionLevel = -1
|
|
BestSpeed CompressionLevel = -2
|
|
BestCompression CompressionLevel = -3
|
|
|
|
// Positive CompressionLevel values are reserved to mean a numeric zlib
|
|
// compression level, although that is not implemented yet.
|
|
)
|
|
|
|
type opaquer interface {
|
|
Opaque() bool
|
|
}
|
|
|
|
// Returns whether or not the image is fully opaque.
|
|
func opaque(m image.Image) bool {
|
|
if o, ok := m.(opaquer); ok {
|
|
return o.Opaque()
|
|
}
|
|
b := m.Bounds()
|
|
for y := b.Min.Y; y < b.Max.Y; y++ {
|
|
for x := b.Min.X; x < b.Max.X; x++ {
|
|
_, _, _, a := m.At(x, y).RGBA()
|
|
if a != 0xffff {
|
|
return false
|
|
}
|
|
}
|
|
}
|
|
return true
|
|
}
|
|
|
|
// The absolute value of a byte interpreted as a signed int8.
|
|
func abs8(d uint8) int {
|
|
if d < 128 {
|
|
return int(d)
|
|
}
|
|
return 256 - int(d)
|
|
}
|
|
|
|
func (e *encoder) writeChunk(b []byte, name string) {
|
|
if e.err != nil {
|
|
return
|
|
}
|
|
n := uint32(len(b))
|
|
if int(n) != len(b) {
|
|
e.err = UnsupportedError(name + " chunk is too large: " + strconv.Itoa(len(b)))
|
|
return
|
|
}
|
|
binary.BigEndian.PutUint32(e.header[:4], n)
|
|
e.header[4] = name[0]
|
|
e.header[5] = name[1]
|
|
e.header[6] = name[2]
|
|
e.header[7] = name[3]
|
|
crc := crc32.NewIEEE()
|
|
crc.Write(e.header[4:8])
|
|
crc.Write(b)
|
|
binary.BigEndian.PutUint32(e.footer[:4], crc.Sum32())
|
|
|
|
_, e.err = e.w.Write(e.header[:8])
|
|
if e.err != nil {
|
|
return
|
|
}
|
|
_, e.err = e.w.Write(b)
|
|
if e.err != nil {
|
|
return
|
|
}
|
|
_, e.err = e.w.Write(e.footer[:4])
|
|
}
|
|
|
|
func (e *encoder) writeIHDR() {
|
|
b := e.a.Frames[0].Image.Bounds()
|
|
binary.BigEndian.PutUint32(e.tmp[0:4], uint32(b.Dx()))
|
|
binary.BigEndian.PutUint32(e.tmp[4:8], uint32(b.Dy()))
|
|
// Set bit depth and color type.
|
|
switch e.cb {
|
|
case cbG8:
|
|
e.tmp[8] = 8
|
|
e.tmp[9] = ctGrayscale
|
|
case cbTC8:
|
|
e.tmp[8] = 8
|
|
e.tmp[9] = ctTrueColor
|
|
case cbP8:
|
|
e.tmp[8] = 8
|
|
e.tmp[9] = ctPaletted
|
|
case cbP4:
|
|
e.tmp[8] = 4
|
|
e.tmp[9] = ctPaletted
|
|
case cbP2:
|
|
e.tmp[8] = 2
|
|
e.tmp[9] = ctPaletted
|
|
case cbP1:
|
|
e.tmp[8] = 1
|
|
e.tmp[9] = ctPaletted
|
|
case cbTCA8:
|
|
e.tmp[8] = 8
|
|
e.tmp[9] = ctTrueColorAlpha
|
|
case cbG16:
|
|
e.tmp[8] = 16
|
|
e.tmp[9] = ctGrayscale
|
|
case cbTC16:
|
|
e.tmp[8] = 16
|
|
e.tmp[9] = ctTrueColor
|
|
case cbTCA16:
|
|
e.tmp[8] = 16
|
|
e.tmp[9] = ctTrueColorAlpha
|
|
}
|
|
e.tmp[10] = 0 // default compression method
|
|
e.tmp[11] = 0 // default filter method
|
|
e.tmp[12] = 0 // non-interlaced
|
|
e.writeChunk(e.tmp[:13], "IHDR")
|
|
}
|
|
|
|
func (e *encoder) writeacTL() {
|
|
binary.BigEndian.PutUint32(e.tmp[0:4], uint32(len(e.a.Frames)))
|
|
binary.BigEndian.PutUint32(e.tmp[4:8], uint32(e.a.LoopCount))
|
|
e.writeChunk(e.tmp[:8], "acTL")
|
|
}
|
|
|
|
func (e *encoder) writefcTL(f Frame) {
|
|
binary.BigEndian.PutUint32(e.tmp[0:4], uint32(e.seq))
|
|
e.seq = e.seq + 1
|
|
b := f.Image.Bounds()
|
|
binary.BigEndian.PutUint32(e.tmp[4:8], uint32(b.Dx()))
|
|
binary.BigEndian.PutUint32(e.tmp[8:12], uint32(b.Dy()))
|
|
binary.BigEndian.PutUint32(e.tmp[12:16], uint32(f.XOffset))
|
|
binary.BigEndian.PutUint32(e.tmp[16:20], uint32(f.YOffset))
|
|
binary.BigEndian.PutUint16(e.tmp[20:22], uint16(f.DelayNumerator))
|
|
binary.BigEndian.PutUint16(e.tmp[22:24], uint16(f.DelayDenominator))
|
|
e.tmp[24] = f.DisposeOp
|
|
e.tmp[25] = f.BlendOp
|
|
e.writeChunk(e.tmp[:26], "fcTL")
|
|
}
|
|
|
|
func (e *encoder) writefdATs(f Frame) {
|
|
e.write_type = 1
|
|
if e.err != nil {
|
|
return
|
|
}
|
|
if e.bw == nil {
|
|
e.bw = bufio.NewWriterSize(e, 1<<15)
|
|
} else {
|
|
e.bw.Reset(e)
|
|
}
|
|
e.err = e.writeImage(e.bw, f.Image, e.cb, levelToZlib(e.enc.CompressionLevel))
|
|
if e.err != nil {
|
|
return
|
|
}
|
|
e.err = e.bw.Flush()
|
|
}
|
|
|
|
func (e *encoder) writePLTEAndTRNS(p color.Palette) {
|
|
if len(p) < 1 || len(p) > 256 {
|
|
e.err = FormatError("bad palette length: " + strconv.Itoa(len(p)))
|
|
return
|
|
}
|
|
last := -1
|
|
for i, c := range p {
|
|
c1 := color.NRGBAModel.Convert(c).(color.NRGBA)
|
|
e.tmp[3*i+0] = c1.R
|
|
e.tmp[3*i+1] = c1.G
|
|
e.tmp[3*i+2] = c1.B
|
|
if c1.A != 0xff {
|
|
last = i
|
|
}
|
|
e.tmp[3*256+i] = c1.A
|
|
}
|
|
e.writeChunk(e.tmp[:3*len(p)], "PLTE")
|
|
if last != -1 {
|
|
e.writeChunk(e.tmp[3*256:3*256+1+last], "tRNS")
|
|
}
|
|
}
|
|
|
|
// An encoder is an io.Writer that satisfies writes by writing PNG IDAT chunks,
|
|
// including an 8-byte header and 4-byte CRC checksum per Write call. Such calls
|
|
// should be relatively infrequent, since writeIDATs uses a bufio.Writer.
|
|
//
|
|
// This method should only be called from writeIDATs (via writeImage).
|
|
// No other code should treat an encoder as an io.Writer.
|
|
func (e *encoder) Write(b []byte) (int, error) {
|
|
if e.write_type == 0 {
|
|
e.writeChunk(b, "IDAT")
|
|
} else {
|
|
c := make([]byte, 4)
|
|
binary.BigEndian.PutUint32(c[0:4], uint32(e.seq))
|
|
e.seq = e.seq + 1
|
|
b = append(c, b...)
|
|
e.writeChunk(b, "fdAT")
|
|
}
|
|
if e.err != nil {
|
|
return 0, e.err
|
|
}
|
|
return len(b), nil
|
|
}
|
|
|
|
// Chooses the filter to use for encoding the current row, and applies it.
|
|
// The return value is the index of the filter and also of the row in cr that has had it applied.
|
|
func filter(cr *[nFilter][]byte, pr []byte, bpp int) int {
|
|
// We try all five filter types, and pick the one that minimizes the sum of absolute differences.
|
|
// This is the same heuristic that libpng uses, although the filters are attempted in order of
|
|
// estimated most likely to be minimal (ftUp, ftPaeth, ftNone, ftSub, ftAverage), rather than
|
|
// in their enumeration order (ftNone, ftSub, ftUp, ftAverage, ftPaeth).
|
|
cdat0 := cr[0][1:]
|
|
cdat1 := cr[1][1:]
|
|
cdat2 := cr[2][1:]
|
|
cdat3 := cr[3][1:]
|
|
cdat4 := cr[4][1:]
|
|
pdat := pr[1:]
|
|
n := len(cdat0)
|
|
|
|
// The up filter.
|
|
sum := 0
|
|
for i := 0; i < n; i++ {
|
|
cdat2[i] = cdat0[i] - pdat[i]
|
|
sum += abs8(cdat2[i])
|
|
}
|
|
best := sum
|
|
filter := ftUp
|
|
|
|
// The Paeth filter.
|
|
sum = 0
|
|
for i := 0; i < bpp; i++ {
|
|
cdat4[i] = cdat0[i] - pdat[i]
|
|
sum += abs8(cdat4[i])
|
|
}
|
|
for i := bpp; i < n; i++ {
|
|
cdat4[i] = cdat0[i] - paeth(cdat0[i-bpp], pdat[i], pdat[i-bpp])
|
|
sum += abs8(cdat4[i])
|
|
if sum >= best {
|
|
break
|
|
}
|
|
}
|
|
if sum < best {
|
|
best = sum
|
|
filter = ftPaeth
|
|
}
|
|
|
|
// The none filter.
|
|
sum = 0
|
|
for i := 0; i < n; i++ {
|
|
sum += abs8(cdat0[i])
|
|
if sum >= best {
|
|
break
|
|
}
|
|
}
|
|
if sum < best {
|
|
best = sum
|
|
filter = ftNone
|
|
}
|
|
|
|
// The sub filter.
|
|
sum = 0
|
|
for i := 0; i < bpp; i++ {
|
|
cdat1[i] = cdat0[i]
|
|
sum += abs8(cdat1[i])
|
|
}
|
|
for i := bpp; i < n; i++ {
|
|
cdat1[i] = cdat0[i] - cdat0[i-bpp]
|
|
sum += abs8(cdat1[i])
|
|
if sum >= best {
|
|
break
|
|
}
|
|
}
|
|
if sum < best {
|
|
best = sum
|
|
filter = ftSub
|
|
}
|
|
|
|
// The average filter.
|
|
sum = 0
|
|
for i := 0; i < bpp; i++ {
|
|
cdat3[i] = cdat0[i] - pdat[i]/2
|
|
sum += abs8(cdat3[i])
|
|
}
|
|
for i := bpp; i < n; i++ {
|
|
cdat3[i] = cdat0[i] - uint8((int(cdat0[i-bpp])+int(pdat[i]))/2)
|
|
sum += abs8(cdat3[i])
|
|
if sum >= best {
|
|
break
|
|
}
|
|
}
|
|
if sum < best {
|
|
best = sum
|
|
filter = ftAverage
|
|
}
|
|
|
|
return filter
|
|
}
|
|
|
|
func zeroMemory(v []uint8) {
|
|
for i := range v {
|
|
v[i] = 0
|
|
}
|
|
}
|
|
|
|
func (e *encoder) writeImage(w io.Writer, m image.Image, cb int, level int) error {
|
|
if e.zw == nil || e.zwLevel != level {
|
|
zw, err := zlib.NewWriterLevel(w, level)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
e.zw = zw
|
|
e.zwLevel = level
|
|
} else {
|
|
e.zw.Reset(w)
|
|
}
|
|
defer e.zw.Close()
|
|
|
|
bitsPerPixel := 0
|
|
|
|
switch cb {
|
|
case cbG8:
|
|
bitsPerPixel = 8
|
|
case cbTC8:
|
|
bitsPerPixel = 24
|
|
case cbP8:
|
|
bitsPerPixel = 8
|
|
case cbP4:
|
|
bitsPerPixel = 4
|
|
case cbP2:
|
|
bitsPerPixel = 2
|
|
case cbP1:
|
|
bitsPerPixel = 1
|
|
case cbTCA8:
|
|
bitsPerPixel = 32
|
|
case cbTC16:
|
|
bitsPerPixel = 48
|
|
case cbTCA16:
|
|
bitsPerPixel = 64
|
|
case cbG16:
|
|
bitsPerPixel = 16
|
|
}
|
|
|
|
// cr[*] and pr are the bytes for the current and previous row.
|
|
// cr[0] is unfiltered (or equivalently, filtered with the ftNone filter).
|
|
// cr[ft], for non-zero filter types ft, are buffers for transforming cr[0] under the
|
|
// other PNG filter types. These buffers are allocated once and re-used for each row.
|
|
// The +1 is for the per-row filter type, which is at cr[*][0].
|
|
b := m.Bounds()
|
|
sz := 1 + (bitsPerPixel*b.Dx()+7)/8
|
|
for i := range e.cr {
|
|
if cap(e.cr[i]) < sz {
|
|
e.cr[i] = make([]uint8, sz)
|
|
} else {
|
|
e.cr[i] = e.cr[i][:sz]
|
|
}
|
|
e.cr[i][0] = uint8(i)
|
|
}
|
|
cr := e.cr
|
|
if cap(e.pr) < sz {
|
|
e.pr = make([]uint8, sz)
|
|
} else {
|
|
e.pr = e.pr[:sz]
|
|
zeroMemory(e.pr)
|
|
}
|
|
pr := e.pr
|
|
|
|
gray, _ := m.(*image.Gray)
|
|
rgba, _ := m.(*image.RGBA)
|
|
paletted, _ := m.(*image.Paletted)
|
|
nrgba, _ := m.(*image.NRGBA)
|
|
|
|
for y := b.Min.Y; y < b.Max.Y; y++ {
|
|
// Convert from colors to bytes.
|
|
i := 1
|
|
switch cb {
|
|
case cbG8:
|
|
if gray != nil {
|
|
offset := (y - b.Min.Y) * gray.Stride
|
|
copy(cr[0][1:], gray.Pix[offset:offset+b.Dx()])
|
|
} else {
|
|
for x := b.Min.X; x < b.Max.X; x++ {
|
|
c := color.GrayModel.Convert(m.At(x, y)).(color.Gray)
|
|
cr[0][i] = c.Y
|
|
i++
|
|
}
|
|
}
|
|
case cbTC8:
|
|
// We have previously verified that the alpha value is fully opaque.
|
|
cr0 := cr[0]
|
|
stride, pix := 0, []byte(nil)
|
|
if rgba != nil {
|
|
stride, pix = rgba.Stride, rgba.Pix
|
|
} else if nrgba != nil {
|
|
stride, pix = nrgba.Stride, nrgba.Pix
|
|
}
|
|
if stride != 0 {
|
|
j0 := (y - b.Min.Y) * stride
|
|
j1 := j0 + b.Dx()*4
|
|
for j := j0; j < j1; j += 4 {
|
|
cr0[i+0] = pix[j+0]
|
|
cr0[i+1] = pix[j+1]
|
|
cr0[i+2] = pix[j+2]
|
|
i += 3
|
|
}
|
|
} else {
|
|
for x := b.Min.X; x < b.Max.X; x++ {
|
|
r, g, b, _ := m.At(x, y).RGBA()
|
|
cr0[i+0] = uint8(r >> 8)
|
|
cr0[i+1] = uint8(g >> 8)
|
|
cr0[i+2] = uint8(b >> 8)
|
|
i += 3
|
|
}
|
|
}
|
|
case cbP8:
|
|
if paletted != nil {
|
|
offset := (y - b.Min.Y) * paletted.Stride
|
|
copy(cr[0][1:], paletted.Pix[offset:offset+b.Dx()])
|
|
} else {
|
|
pi := m.(image.PalettedImage)
|
|
for x := b.Min.X; x < b.Max.X; x++ {
|
|
cr[0][i] = pi.ColorIndexAt(x, y)
|
|
i += 1
|
|
}
|
|
}
|
|
|
|
case cbP4, cbP2, cbP1:
|
|
pi := m.(image.PalettedImage)
|
|
|
|
var a uint8
|
|
var c int
|
|
for x := b.Min.X; x < b.Max.X; x++ {
|
|
a = a<<uint(bitsPerPixel) | pi.ColorIndexAt(x, y)
|
|
c++
|
|
if c == 8/bitsPerPixel {
|
|
cr[0][i] = a
|
|
i += 1
|
|
a = 0
|
|
c = 0
|
|
}
|
|
}
|
|
if c != 0 {
|
|
for c != 8/bitsPerPixel {
|
|
a = a << uint(bitsPerPixel)
|
|
c++
|
|
}
|
|
cr[0][i] = a
|
|
}
|
|
|
|
case cbTCA8:
|
|
if nrgba != nil {
|
|
offset := (y - b.Min.Y) * nrgba.Stride
|
|
copy(cr[0][1:], nrgba.Pix[offset:offset+b.Dx()*4])
|
|
} else {
|
|
// Convert from image.Image (which is alpha-premultiplied) to PNG's non-alpha-premultiplied.
|
|
for x := b.Min.X; x < b.Max.X; x++ {
|
|
c := color.NRGBAModel.Convert(m.At(x, y)).(color.NRGBA)
|
|
cr[0][i+0] = c.R
|
|
cr[0][i+1] = c.G
|
|
cr[0][i+2] = c.B
|
|
cr[0][i+3] = c.A
|
|
i += 4
|
|
}
|
|
}
|
|
case cbG16:
|
|
for x := b.Min.X; x < b.Max.X; x++ {
|
|
c := color.Gray16Model.Convert(m.At(x, y)).(color.Gray16)
|
|
cr[0][i+0] = uint8(c.Y >> 8)
|
|
cr[0][i+1] = uint8(c.Y)
|
|
i += 2
|
|
}
|
|
case cbTC16:
|
|
// We have previously verified that the alpha value is fully opaque.
|
|
for x := b.Min.X; x < b.Max.X; x++ {
|
|
r, g, b, _ := m.At(x, y).RGBA()
|
|
cr[0][i+0] = uint8(r >> 8)
|
|
cr[0][i+1] = uint8(r)
|
|
cr[0][i+2] = uint8(g >> 8)
|
|
cr[0][i+3] = uint8(g)
|
|
cr[0][i+4] = uint8(b >> 8)
|
|
cr[0][i+5] = uint8(b)
|
|
i += 6
|
|
}
|
|
case cbTCA16:
|
|
// Convert from image.Image (which is alpha-premultiplied) to PNG's non-alpha-premultiplied.
|
|
for x := b.Min.X; x < b.Max.X; x++ {
|
|
c := color.NRGBA64Model.Convert(m.At(x, y)).(color.NRGBA64)
|
|
cr[0][i+0] = uint8(c.R >> 8)
|
|
cr[0][i+1] = uint8(c.R)
|
|
cr[0][i+2] = uint8(c.G >> 8)
|
|
cr[0][i+3] = uint8(c.G)
|
|
cr[0][i+4] = uint8(c.B >> 8)
|
|
cr[0][i+5] = uint8(c.B)
|
|
cr[0][i+6] = uint8(c.A >> 8)
|
|
cr[0][i+7] = uint8(c.A)
|
|
i += 8
|
|
}
|
|
}
|
|
|
|
// Apply the filter.
|
|
// Skip filter for NoCompression and paletted images (cbP8) as
|
|
// "filters are rarely useful on palette images" and will result
|
|
// in larger files (see http://www.libpng.org/pub/png/book/chapter09.html).
|
|
f := ftNone
|
|
if level != zlib.NoCompression && cb != cbP8 && cb != cbP4 && cb != cbP2 && cb != cbP1 {
|
|
// Since we skip paletted images we don't have to worry about
|
|
// bitsPerPixel not being a multiple of 8
|
|
bpp := bitsPerPixel / 8
|
|
f = filter(&cr, pr, bpp)
|
|
}
|
|
|
|
// Write the compressed bytes.
|
|
if _, err := e.zw.Write(cr[f]); err != nil {
|
|
return err
|
|
}
|
|
|
|
// The current row for y is the previous row for y+1.
|
|
pr, cr[0] = cr[0], pr
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// Write the actual image data to one or more IDAT chunks.
|
|
func (e *encoder) writeIDATs() {
|
|
e.write_type = 0
|
|
if e.err != nil {
|
|
return
|
|
}
|
|
if e.bw == nil {
|
|
e.bw = bufio.NewWriterSize(e, 1<<15)
|
|
} else {
|
|
e.bw.Reset(e)
|
|
}
|
|
e.err = e.writeImage(e.bw, e.a.Frames[0].Image, e.cb, levelToZlib(e.enc.CompressionLevel))
|
|
if e.err != nil {
|
|
return
|
|
}
|
|
e.err = e.bw.Flush()
|
|
}
|
|
|
|
// This function is required because we want the zero value of
|
|
// Encoder.CompressionLevel to map to zlib.DefaultCompression.
|
|
func levelToZlib(l CompressionLevel) int {
|
|
switch l {
|
|
case DefaultCompression:
|
|
return zlib.DefaultCompression
|
|
case NoCompression:
|
|
return zlib.NoCompression
|
|
case BestSpeed:
|
|
return zlib.BestSpeed
|
|
case BestCompression:
|
|
return zlib.BestCompression
|
|
default:
|
|
return zlib.DefaultCompression
|
|
}
|
|
}
|
|
|
|
func (e *encoder) writeIEND() { e.writeChunk(nil, "IEND") }
|
|
|
|
// Encode writes the APNG a to w in PNG format. Any Image may be
|
|
// encoded, but images that are not image.NRGBA might be encoded lossily.
|
|
func Encode(w io.Writer, a APNG) error {
|
|
var e Encoder
|
|
return e.Encode(w, a)
|
|
}
|
|
|
|
// Encode writes the Animation a to w in PNG format.
|
|
func (enc *Encoder) Encode(w io.Writer, a APNG) error {
|
|
// Obviously, negative widths and heights are invalid. Furthermore, the PNG
|
|
// spec section 11.2.2 says that zero is invalid. Excessively large images are
|
|
// also rejected.
|
|
mw, mh := int64(a.Frames[0].Image.Bounds().Dx()), int64(a.Frames[0].Image.Bounds().Dy())
|
|
if mw <= 0 || mh <= 0 || mw >= 1<<32 || mh >= 1<<32 {
|
|
return FormatError("invalid image size: " + strconv.FormatInt(mw, 10) + "x" + strconv.FormatInt(mh, 10))
|
|
}
|
|
|
|
var e *encoder
|
|
if enc.BufferPool != nil {
|
|
buffer := enc.BufferPool.Get()
|
|
e = (*encoder)(buffer)
|
|
|
|
}
|
|
if e == nil {
|
|
e = &encoder{}
|
|
}
|
|
if enc.BufferPool != nil {
|
|
defer enc.BufferPool.Put((*EncoderBuffer)(e))
|
|
}
|
|
|
|
e.enc = enc
|
|
e.w = w
|
|
e.a = a
|
|
|
|
var pal color.Palette
|
|
// cbP8 encoding needs PalettedImage's ColorIndexAt method.
|
|
if _, ok := a.Frames[0].Image.(image.PalettedImage); ok {
|
|
pal, _ = a.Frames[0].Image.ColorModel().(color.Palette)
|
|
}
|
|
if pal != nil {
|
|
if len(pal) <= 2 {
|
|
e.cb = cbP1
|
|
} else if len(pal) <= 4 {
|
|
e.cb = cbP2
|
|
} else if len(pal) <= 16 {
|
|
e.cb = cbP4
|
|
} else {
|
|
e.cb = cbP8
|
|
}
|
|
} else {
|
|
switch a.Frames[0].Image.ColorModel() {
|
|
case color.GrayModel:
|
|
e.cb = cbG8
|
|
case color.Gray16Model:
|
|
e.cb = cbG16
|
|
case color.RGBAModel, color.NRGBAModel, color.AlphaModel:
|
|
isOpaque := true
|
|
for _, v := range a.Frames {
|
|
if !opaque(v.Image) {
|
|
isOpaque = false
|
|
break
|
|
}
|
|
}
|
|
if isOpaque {
|
|
e.cb = cbTC8
|
|
} else {
|
|
e.cb = cbTCA8
|
|
}
|
|
default:
|
|
isOpaque := true
|
|
for _, v := range a.Frames {
|
|
if !opaque(v.Image) {
|
|
isOpaque = false
|
|
break
|
|
}
|
|
}
|
|
if isOpaque {
|
|
e.cb = cbTC16
|
|
} else {
|
|
e.cb = cbTCA16
|
|
}
|
|
}
|
|
}
|
|
|
|
_, e.err = io.WriteString(w, pngHeader)
|
|
e.writeIHDR()
|
|
if pal != nil {
|
|
e.writePLTEAndTRNS(pal)
|
|
}
|
|
if len(e.a.Frames) > 1 {
|
|
e.writeacTL()
|
|
}
|
|
if !e.a.Frames[0].IsDefault {
|
|
e.writefcTL(e.a.Frames[0])
|
|
}
|
|
e.writeIDATs()
|
|
for i := 0; i < len(e.a.Frames); i = i + 1 {
|
|
if i != 0 && !e.a.Frames[i].IsDefault {
|
|
e.writefcTL(e.a.Frames[i])
|
|
e.writefdATs(e.a.Frames[i])
|
|
}
|
|
}
|
|
e.writeIEND()
|
|
return e.err
|
|
}
|