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mirror of https://github.com/wader/fq.git synced 2024-12-24 05:41:38 +03:00
fq/format/png/png.go
2023-05-01 13:19:04 +02:00

238 lines
6.0 KiB
Go

package png
// http://www.libpng.org/pub/png/spec/1.2/PNG-Contents.html
// https://ftp-osl.osuosl.org/pub/libpng/documents/pngext-1.5.0.html
// https://wiki.mozilla.org/APNG_Specification
import (
"compress/zlib"
"hash/crc32"
"github.com/wader/fq/format"
"github.com/wader/fq/pkg/bitio"
"github.com/wader/fq/pkg/decode"
"github.com/wader/fq/pkg/interp"
"github.com/wader/fq/pkg/scalar"
)
var iccProfileGroup decode.Group
var exifGroup decode.Group
func init() {
interp.RegisterFormat(
format.PNG,
&decode.Format{
Description: "Portable Network Graphics file",
Groups: []*decode.Group{format.Probe, format.Image},
DecodeFn: pngDecode,
Dependencies: []decode.Dependency{
{Groups: []*decode.Group{format.ICC_Profile}, Out: &iccProfileGroup},
{Groups: []*decode.Group{format.Exif}, Out: &exifGroup},
},
})
}
const (
compressionDeflate = 0
)
var compressionNames = scalar.UintMapSymStr{
compressionDeflate: "deflate",
}
const (
disposeOpNone = 0
disposeOpBackground = 1
disposeOpPrevious = 2
)
var disposeOpNames = scalar.UintMapSymStr{
disposeOpNone: "none",
disposeOpBackground: "background",
disposeOpPrevious: "previous",
}
const (
blendOpNone = 0
blendOpBackground = 1
)
var blendOpNames = scalar.UintMapSymStr{
blendOpNone: "source",
blendOpBackground: "over",
}
const (
colorTypeGrayscale = 0
colorTypeRGB = 2
colorTypePalette = 3
colorTypeGrayscaleWithAlpha = 4
colorTypeRGBA = 6
)
var colorTypeMap = scalar.UintMapSymStr{
colorTypeGrayscale: "grayscale",
colorTypeRGB: "rgb",
colorTypePalette: "palette",
colorTypeGrayscaleWithAlpha: "grayscale_alpha",
colorTypeRGBA: "rgba",
}
func pngDecode(d *decode.D) any {
iEndFound := false
var colorType uint64
d.FieldRawLen("signature", 8*8, d.AssertBitBuf([]byte("\x89PNG\r\n\x1a\n")))
d.FieldStructArrayLoop("chunks", "chunk", func() bool { return d.NotEnd() && !iEndFound }, func(d *decode.D) {
chunkLength := d.FieldU32("length")
crcStartPos := d.Pos()
chunkType := d.FieldUTF8("type", 4)
// upper/lower case in chunk type is used for flags
d.SeekRel(-4 * 8)
d.SeekRel(3)
d.FieldBool("ancillary")
d.SeekRel(7)
d.FieldBool("private")
d.SeekRel(7)
d.FieldBool("reserved")
d.SeekRel(7)
d.FieldBool("safe_to_copy")
d.SeekRel(4)
d.FramedFn(int64(chunkLength)*8, func(d *decode.D) {
switch chunkType {
case "IHDR":
d.FieldU32("width")
d.FieldU32("height")
d.FieldU8("bit_depth")
colorType = d.FieldU8("color_type", colorTypeMap)
d.FieldU8("compression_method", compressionNames)
d.FieldU8("filter_method", scalar.UintMapSymStr{
0: "adaptive_filtering",
})
d.FieldU8("interlace_method", scalar.UintMapSymStr{
0: "none",
1: "adam7",
})
case "tEXt":
d.FieldUTF8Null("keyword")
d.FieldUTF8("text", int(d.BitsLeft())/8)
case "zTXt":
d.FieldUTF8Null("keyword")
compressionMethod := d.FieldU8("compression_method", compressionNames)
dataLen := d.BitsLeft()
// TODO: make nicer
d.FieldRawLen("compressed", dataLen)
d.SeekRel(-dataLen)
switch compressionMethod {
case compressionDeflate:
d.FieldFormatReaderLen("uncompressed", dataLen, zlib.NewReader, decode.FormatFn(func(d *decode.D) any {
d.FieldUTF8("text", int(d.BitsLeft()/8))
return nil
}))
default:
d.FieldRawLen("data", dataLen)
}
case "iCCP":
d.FieldUTF8Null("profile_name")
compressionMethod := d.FieldU8("compression_method", compressionNames)
dataLen := d.BitsLeft()
d.FieldRawLen("compressed", dataLen)
d.SeekRel(-dataLen)
switch compressionMethod {
case compressionDeflate:
d.FieldFormatReaderLen("uncompressed", dataLen, zlib.NewReader, &iccProfileGroup)
default:
d.FieldRawLen("data", dataLen)
}
case "pHYs":
d.FieldU32("x_pixels_per_unit")
d.FieldU32("y_pixels_per_unit")
d.FieldU8("unit")
case "bKGD":
switch colorType {
case colorTypePalette:
d.FieldU8("index")
case colorTypeGrayscale, colorTypeGrayscaleWithAlpha:
d.FieldU16("gray")
case colorTypeRGB, colorTypeRGBA:
d.FieldU16("r")
d.FieldU16("g")
d.FieldU16("b")
}
case "gAMA":
d.FieldU32("value")
case "cHRM":
df := func(d *decode.D) float64 { return float64(d.U32()) / 1000.0 }
d.FieldFltFn("white_point_x", df)
d.FieldFltFn("white_point_y", df)
d.FieldFltFn("red_x", df)
d.FieldFltFn("red_y", df)
d.FieldFltFn("green_x", df)
d.FieldFltFn("green_y", df)
d.FieldFltFn("blue_x", df)
d.FieldFltFn("blue_y", df)
case "eXIf":
d.FieldFormatLen("exif", d.BitsLeft(), &exifGroup, nil)
case "acTL":
d.FieldU32("num_frames")
d.FieldU32("num_plays")
case "fcTL":
d.FieldU32("sequence_number")
d.FieldU32("width")
d.FieldU32("height")
d.FieldU32("x_offset")
d.FieldU32("y_offset")
d.FieldU16("delay_num")
d.FieldU16("delay_sep")
d.FieldU8("dispose_op", disposeOpNames)
d.FieldU8("blend_op", blendOpNames)
case "fdAT":
d.FieldU32("sequence_number")
d.FieldRawLen("data", d.BitsLeft()-32)
case "PLTE":
d.FieldArray("palette", func(d *decode.D) {
for !d.End() {
d.FieldStruct("color", func(d *decode.D) {
d.FieldU8("r")
d.FieldU8("g")
d.FieldU8("b")
})
}
})
case "tRNS":
switch colorType {
case colorTypeGrayscale:
d.FieldU16("alpha")
case colorTypeRGB:
d.FieldU16("r")
d.FieldU16("g")
d.FieldU16("b")
case colorTypePalette:
d.FieldArray("alphas", func(d *decode.D) {
for !d.End() {
d.FieldU8("alpha")
}
})
}
default:
if chunkType == "IEND" {
iEndFound = true
} else {
d.FieldRawLen("data", d.BitsLeft())
}
}
})
chunkCRC := crc32.NewIEEE()
d.Copy(chunkCRC, bitio.NewIOReader(d.BitBufRange(crcStartPos, d.Pos()-crcStartPos)))
d.FieldU32("crc", d.UintValidateBytes(chunkCRC.Sum(nil)), scalar.UintHex)
})
return nil
}