Commit 737e96c7 authored by Dmitry Chestnykh's avatar Dmitry Chestnykh Committed by Nigel Tao

image/png: support encoding of paletted images with alpha channel.

Encoder now writes tRNS chunk for non-opaque paletted images.
CL includes new test images (basn3a08-trns.[ps]ng).

R=nigeltao, rsc, r
CC=golang-dev
https://golang.org/cl/4432078
parent bcf3bfe2
...@@ -28,6 +28,7 @@ var filenames = []string{ ...@@ -28,6 +28,7 @@ var filenames = []string{
"basn3p02", "basn3p02",
"basn3p04", "basn3p04",
"basn3p08", "basn3p08",
"basn3p08-trns",
"basn4a08", "basn4a08",
"basn4a16", "basn4a16",
"basn6a08", "basn6a08",
...@@ -98,17 +99,30 @@ func sng(w io.WriteCloser, filename string, png image.Image) { ...@@ -98,17 +99,30 @@ func sng(w io.WriteCloser, filename string, png image.Image) {
// (the PNG spec section 11.3 says "Ancillary chunks may be ignored by a decoder"). // (the PNG spec section 11.3 says "Ancillary chunks may be ignored by a decoder").
io.WriteString(w, "gAMA {1.0000}\n") io.WriteString(w, "gAMA {1.0000}\n")
// Write the PLTE (if applicable). // Write the PLTE and tRNS (if applicable).
if cpm != nil { if cpm != nil {
lastAlpha := -1
io.WriteString(w, "PLTE {\n") io.WriteString(w, "PLTE {\n")
for i := 0; i < len(cpm); i++ { for i, c := range cpm {
r, g, b, _ := cpm[i].RGBA() r, g, b, a := c.RGBA()
if a != 0xffff {
lastAlpha = i
}
r >>= 8 r >>= 8
g >>= 8 g >>= 8
b >>= 8 b >>= 8
fmt.Fprintf(w, " (%3d,%3d,%3d) # rgb = (0x%02x,0x%02x,0x%02x)\n", r, g, b, r, g, b) fmt.Fprintf(w, " (%3d,%3d,%3d) # rgb = (0x%02x,0x%02x,0x%02x)\n", r, g, b, r, g, b)
} }
io.WriteString(w, "}\n") io.WriteString(w, "}\n")
if lastAlpha != -1 {
io.WriteString(w, "tRNS {\n")
for i := 0; i <= lastAlpha; i++ {
_, _, _, a := cpm[i].RGBA()
a >>= 8
fmt.Fprintf(w, " %d", a)
}
io.WriteString(w, "}\n")
}
} }
// Write the IMAGE. // Write the IMAGE.
......
...@@ -10,6 +10,9 @@ The files basn0g01-30.png, basn0g02-29.png and basn0g04-31.png are in fact ...@@ -10,6 +10,9 @@ The files basn0g01-30.png, basn0g02-29.png and basn0g04-31.png are in fact
not part of pngsuite but were created from files in pngsuite. Their non-power- not part of pngsuite but were created from files in pngsuite. Their non-power-
of-two sizes makes them useful for testing bit-depths smaller than a byte. of-two sizes makes them useful for testing bit-depths smaller than a byte.
basn3a08.png was generated from basn6a08.png using the pngnq tool, which
converted it to the 8-bit paletted image with alpha values in tRNS chunk.
The *.sng files in this directory were generated from the *.png files The *.sng files in this directory were generated from the *.png files
by the sng command-line tool and some hand editing. The files by the sng command-line tool and some hand editing. The files
basn0g0{1,2,4}.sng were actually generated by first converting the PNG basn0g0{1,2,4}.sng were actually generated by first converting the PNG
......
#SNG: from basn3p08-trns.png
IHDR {
width: 32; height: 32; bitdepth: 8;
using color palette;
}
gAMA {1.0000}
PLTE {
(255, 3, 7) # rgb = (0xff,0x03,0x07)
(255, 4, 7) # rgb = (0xff,0x04,0x07)
(255, 9, 7) # rgb = (0xff,0x09,0x07)
(217, 14, 7) # rgb = (0xd9,0x0e,0x07)
(255, 14, 7) # rgb = (0xff,0x0e,0x07)
( 2, 22, 19) # rgb = (0x02,0x16,0x13)
(255, 26, 7) # rgb = (0xff,0x1a,0x07)
(255, 31, 7) # rgb = (0xff,0x1f,0x07)
( 10, 37, 14) # rgb = (0x0a,0x25,0x0e)
(179, 37, 6) # rgb = (0xb3,0x25,0x06)
(254, 42, 7) # rgb = (0xfe,0x2a,0x07)
(255, 45, 7) # rgb = (0xff,0x2d,0x07)
( 25, 46, 9) # rgb = (0x19,0x2e,0x09)
( 0, 48,254) # rgb = (0x00,0x30,0xfe)
( 0, 48,255) # rgb = (0x00,0x30,0xff)
( 0, 49,255) # rgb = (0x00,0x31,0xff)
( 0, 51,254) # rgb = (0x00,0x33,0xfe)
( 0, 52,255) # rgb = (0x00,0x34,0xff)
(255, 53, 7) # rgb = (0xff,0x35,0x07)
( 0, 54,252) # rgb = (0x00,0x36,0xfc)
(254, 57, 7) # rgb = (0xfe,0x39,0x07)
(251, 57, 7) # rgb = (0xfb,0x39,0x07)
(247, 59, 7) # rgb = (0xf7,0x3b,0x07)
( 0, 59, 61) # rgb = (0x00,0x3b,0x3d)
( 0, 62,255) # rgb = (0x00,0x3e,0xff)
(142, 63, 5) # rgb = (0x8e,0x3f,0x05)
( 0, 63,250) # rgb = (0x00,0x3f,0xfa)
(255, 63, 7) # rgb = (0xff,0x3f,0x07)
(253, 68, 7) # rgb = (0xfd,0x44,0x07)
( 0, 73,255) # rgb = (0x00,0x49,0xff)
( 0, 73,246) # rgb = (0x00,0x49,0xf6)
(255, 75, 7) # rgb = (0xff,0x4b,0x07)
( 82, 85, 9) # rgb = (0x52,0x55,0x09)
(255, 85, 7) # rgb = (0xff,0x55,0x07)
( 0, 89,255) # rgb = (0x00,0x59,0xff)
( 0, 91,237) # rgb = (0x00,0x5b,0xed)
(255, 94, 7) # rgb = (0xff,0x5e,0x07)
(241,100, 7) # rgb = (0xf1,0x64,0x07)
( 0,101,255) # rgb = (0x00,0x65,0xff)
(253,105, 7) # rgb = (0xfd,0x69,0x07)
( 0,107,223) # rgb = (0x00,0x6b,0xdf)
(255,106, 7) # rgb = (0xff,0x6a,0x07)
( 1,110, 95) # rgb = (0x01,0x6e,0x5f)
(255,115, 7) # rgb = (0xff,0x73,0x07)
( 0,117,255) # rgb = (0x00,0x75,0xff)
(255,124, 7) # rgb = (0xff,0x7c,0x07)
(118,126, 10) # rgb = (0x76,0x7e,0x0a)
( 0,130,250) # rgb = (0x00,0x82,0xfa)
( 0,132,255) # rgb = (0x00,0x84,0xff)
( 0,134,207) # rgb = (0x00,0x86,0xcf)
(255,134, 7) # rgb = (0xff,0x86,0x07)
( 0,136,249) # rgb = (0x00,0x88,0xf9)
(219,140, 6) # rgb = (0xdb,0x8c,0x06)
( 0,140,252) # rgb = (0x00,0x8c,0xfc)
( 0,140,255) # rgb = (0x00,0x8c,0xff)
( 1,142,136) # rgb = (0x01,0x8e,0x88)
(255,143, 7) # rgb = (0xff,0x8f,0x07)
(243,150, 7) # rgb = (0xf3,0x96,0x07)
(198,152, 7) # rgb = (0xc6,0x98,0x07)
(165,153, 7) # rgb = (0xa5,0x99,0x07)
( 0,157,255) # rgb = (0x00,0x9d,0xff)
(255,158, 7) # rgb = (0xff,0x9e,0x07)
( 70,159, 4) # rgb = (0x46,0x9f,0x04)
( 0,160,251) # rgb = (0x00,0xa0,0xfb)
(203,163, 6) # rgb = (0xcb,0xa3,0x06)
( 0,163,239) # rgb = (0x00,0xa3,0xef)
( 1,164,178) # rgb = (0x01,0xa4,0xb2)
(255,166, 7) # rgb = (0xff,0xa6,0x07)
( 1,169,165) # rgb = (0x01,0xa9,0xa5)
( 1,170,255) # rgb = (0x01,0xaa,0xff)
(232,172, 6) # rgb = (0xe8,0xac,0x06)
(255,175, 7) # rgb = (0xff,0xaf,0x07)
(185,176,131) # rgb = (0xb9,0xb0,0x83)
( 1,179,225) # rgb = (0x01,0xb3,0xe1)
(188,179,118) # rgb = (0xbc,0xb3,0x76)
(199,180, 6) # rgb = (0xc7,0xb4,0x06)
( 1,182,255) # rgb = (0x01,0xb6,0xff)
( 1,184,249) # rgb = (0x01,0xb8,0xf9)
(255,184, 7) # rgb = (0xff,0xb8,0x07)
(207,186, 71) # rgb = (0xcf,0xba,0x47)
(193,187, 6) # rgb = (0xc1,0xbb,0x06)
(253,191, 7) # rgb = (0xfd,0xbf,0x07)
(218,193, 48) # rgb = (0xda,0xc1,0x30)
( 1,193,157) # rgb = (0x01,0xc1,0x9d)
( 1,196,244) # rgb = (0x01,0xc4,0xf4)
( 1,196,254) # rgb = (0x01,0xc4,0xfe)
( 48,199, 3) # rgb = (0x30,0xc7,0x03)
(164,199, 5) # rgb = (0xa4,0xc7,0x05)
(220,202, 6) # rgb = (0xdc,0xca,0x06)
(253,203, 7) # rgb = (0xfd,0xcb,0x07)
( 1,204,204) # rgb = (0x01,0xcc,0xcc)
(251,209, 7) # rgb = (0xfb,0xd1,0x07)
(231,208, 24) # rgb = (0xe7,0xd0,0x18)
( 1,210,254) # rgb = (0x01,0xd2,0xfe)
( 2,211,146) # rgb = (0x02,0xd3,0x92)
( 1,212,156) # rgb = (0x01,0xd4,0x9c)
( 1,213,252) # rgb = (0x01,0xd5,0xfc)
(237,219, 15) # rgb = (0xed,0xdb,0x0f)
( 1,218,240) # rgb = (0x01,0xda,0xf0)
(165,220, 5) # rgb = (0xa5,0xdc,0x05)
( 1,221,250) # rgb = (0x01,0xdd,0xfa)
(249,221, 6) # rgb = (0xf9,0xdd,0x06)
(146,222, 4) # rgb = (0x92,0xde,0x04)
( 1,224,184) # rgb = (0x01,0xe0,0xb8)
( 2,224,155) # rgb = (0x02,0xe0,0x9b)
(244,225, 10) # rgb = (0xf4,0xe1,0x0a)
(249,227, 7) # rgb = (0xf9,0xe3,0x07)
( 2,229,133) # rgb = (0x02,0xe5,0x85)
(192,228, 6) # rgb = (0xc0,0xe4,0x06)
( 37,230, 3) # rgb = (0x25,0xe6,0x03)
(246,230, 7) # rgb = (0xf6,0xe6,0x07)
(143,232, 4) # rgb = (0x8f,0xe8,0x04)
(244,233, 8) # rgb = (0xf4,0xe9,0x08)
( 2,236,139) # rgb = (0x02,0xec,0x8b)
( 1,236,227) # rgb = (0x01,0xec,0xe3)
( 1,238,238) # rgb = (0x01,0xee,0xee)
(101,241, 4) # rgb = (0x65,0xf1,0x04)
( 1,241,218) # rgb = (0x01,0xf1,0xda)
( 1,240,232) # rgb = (0x01,0xf0,0xe8)
(167,240, 5) # rgb = (0xa7,0xf0,0x05)
( 27,243, 2) # rgb = (0x1b,0xf3,0x02)
(126,243, 4) # rgb = (0x7e,0xf3,0x04)
( 2,246,113) # rgb = (0x02,0xf6,0x71)
(133,248, 5) # rgb = (0x85,0xf8,0x05)
( 22,250, 1) # rgb = (0x16,0xfa,0x01)
( 2,249,219) # rgb = (0x02,0xf9,0xdb)
(148,250, 5) # rgb = (0x94,0xfa,0x05)
( 2,250,199) # rgb = (0x02,0xfa,0xc7)
(183,252, 5) # rgb = (0xb7,0xfc,0x05)
(176,252, 5) # rgb = (0xb0,0xfc,0x05)
( 2,252,211) # rgb = (0x02,0xfc,0xd3)
( 2,252,190) # rgb = (0x02,0xfc,0xbe)
(164,251, 5) # rgb = (0xa4,0xfb,0x05)
( 12,254,128) # rgb = (0x0c,0xfe,0x80)
(192,253, 5) # rgb = (0xc0,0xfd,0x05)
(164,253, 5) # rgb = (0xa4,0xfd,0x05)
( 26,254, 85) # rgb = (0x1a,0xfe,0x55)
( 14,254, 1) # rgb = (0x0e,0xfe,0x01)
(133,253, 5) # rgb = (0x85,0xfd,0x05)
( 4,253,180) # rgb = (0x04,0xfd,0xb4)
(196,253, 5) # rgb = (0xc4,0xfd,0x05)
( 2,253,198) # rgb = (0x02,0xfd,0xc6)
( 3,255, 91) # rgb = (0x03,0xff,0x5b)
( 3,255, 80) # rgb = (0x03,0xff,0x50)
(186,255, 5) # rgb = (0xba,0xff,0x05)
( 9,255, 2) # rgb = (0x09,0xff,0x02)
( 3,255,118) # rgb = (0x03,0xff,0x76)
( 9,255, 3) # rgb = (0x09,0xff,0x03)
( 10,255, 1) # rgb = (0x0a,0xff,0x01)
( 3,255, 76) # rgb = (0x03,0xff,0x4c)
( 3,255, 86) # rgb = (0x03,0xff,0x56)
( 3,255, 82) # rgb = (0x03,0xff,0x52)
( 13,255, 1) # rgb = (0x0d,0xff,0x01)
( 3,255, 49) # rgb = (0x03,0xff,0x31)
( 3,255,101) # rgb = (0x03,0xff,0x65)
( 61,255, 32) # rgb = (0x3d,0xff,0x20)
(129,255, 5) # rgb = (0x81,0xff,0x05)
(177,255, 5) # rgb = (0xb1,0xff,0x05)
( 3,255, 37) # rgb = (0x03,0xff,0x25)
(149,255, 5) # rgb = (0x95,0xff,0x05)
( 7,255, 6) # rgb = (0x07,0xff,0x06)
(192,255, 5) # rgb = (0xc0,0xff,0x05)
( 2,255,131) # rgb = (0x02,0xff,0x83)
( 3,255, 98) # rgb = (0x03,0xff,0x62)
( 85,255, 11) # rgb = (0x55,0xff,0x0b)
( 2,255,163) # rgb = (0x02,0xff,0xa3)
( 2,255,149) # rgb = (0x02,0xff,0x95)
( 4,255, 23) # rgb = (0x04,0xff,0x17)
( 6,255, 12) # rgb = (0x06,0xff,0x0c)
( 3,255, 67) # rgb = (0x03,0xff,0x43)
(160,255, 5) # rgb = (0xa0,0xff,0x05)
(119,255, 6) # rgb = (0x77,0xff,0x06)
(102,255, 8) # rgb = (0x66,0xff,0x08)
(255,255,255) # rgb = (0xff,0xff,0xff)
(254,254,254) # rgb = (0xfe,0xfe,0xfe)
(254,254,254) # rgb = (0xfe,0xfe,0xfe)
(252,252,252) # rgb = (0xfc,0xfc,0xfc)
(252,252,252) # rgb = (0xfc,0xfc,0xfc)
(250,250,250) # rgb = (0xfa,0xfa,0xfa)
(250,250,250) # rgb = (0xfa,0xfa,0xfa)
(248,248,248) # rgb = (0xf8,0xf8,0xf8)
(248,248,248) # rgb = (0xf8,0xf8,0xf8)
(247,247,247) # rgb = (0xf7,0xf7,0xf7)
(245,245,245) # rgb = (0xf5,0xf5,0xf5)
(245,245,245) # rgb = (0xf5,0xf5,0xf5)
(243,243,243) # rgb = (0xf3,0xf3,0xf3)
(243,243,243) # rgb = (0xf3,0xf3,0xf3)
(241,241,241) # rgb = (0xf1,0xf1,0xf1)
(241,241,241) # rgb = (0xf1,0xf1,0xf1)
(239,239,239) # rgb = (0xef,0xef,0xef)
(238,238,238) # rgb = (0xee,0xee,0xee)
(238,238,238) # rgb = (0xee,0xee,0xee)
(236,236,236) # rgb = (0xec,0xec,0xec)
(236,236,236) # rgb = (0xec,0xec,0xec)
(234,234,234) # rgb = (0xea,0xea,0xea)
(234,234,234) # rgb = (0xea,0xea,0xea)
(232,232,232) # rgb = (0xe8,0xe8,0xe8)
(231,231,231) # rgb = (0xe7,0xe7,0xe7)
(231,231,231) # rgb = (0xe7,0xe7,0xe7)
(229,229,229) # rgb = (0xe5,0xe5,0xe5)
(229,229,229) # rgb = (0xe5,0xe5,0xe5)
(227,227,227) # rgb = (0xe3,0xe3,0xe3)
(226,226,226) # rgb = (0xe2,0xe2,0xe2)
(226,226,226) # rgb = (0xe2,0xe2,0xe2)
(224,224,224) # rgb = (0xe0,0xe0,0xe0)
(224,224,224) # rgb = (0xe0,0xe0,0xe0)
(222,222,222) # rgb = (0xde,0xde,0xde)
(222,222,222) # rgb = (0xde,0xde,0xde)
(220,220,220) # rgb = (0xdc,0xdc,0xdc)
(219,219,219) # rgb = (0xdb,0xdb,0xdb)
(219,219,219) # rgb = (0xdb,0xdb,0xdb)
(217,217,217) # rgb = (0xd9,0xd9,0xd9)
(217,217,217) # rgb = (0xd9,0xd9,0xd9)
(215,215,215) # rgb = (0xd7,0xd7,0xd7)
(214,214,214) # rgb = (0xd6,0xd6,0xd6)
(214,214,214) # rgb = (0xd6,0xd6,0xd6)
(212,212,212) # rgb = (0xd4,0xd4,0xd4)
(212,212,212) # rgb = (0xd4,0xd4,0xd4)
(210,210,210) # rgb = (0xd2,0xd2,0xd2)
(209,209,209) # rgb = (0xd1,0xd1,0xd1)
(209,209,209) # rgb = (0xd1,0xd1,0xd1)
(207,207,207) # rgb = (0xcf,0xcf,0xcf)
(205,205,205) # rgb = (0xcd,0xcd,0xcd)
(205,205,205) # rgb = (0xcd,0xcd,0xcd)
(204,204,204) # rgb = (0xcc,0xcc,0xcc)
(204,204,204) # rgb = (0xcc,0xcc,0xcc)
(202,202,202) # rgb = (0xca,0xca,0xca)
(201,201,201) # rgb = (0xc9,0xc9,0xc9)
(201,201,201) # rgb = (0xc9,0xc9,0xc9)
(199,199,199) # rgb = (0xc7,0xc7,0xc7)
(199,199,199) # rgb = (0xc7,0xc7,0xc7)
(197,197,197) # rgb = (0xc5,0xc5,0xc5)
(196,196,196) # rgb = (0xc4,0xc4,0xc4)
(196,196,196) # rgb = (0xc4,0xc4,0xc4)
(194,194,194) # rgb = (0xc2,0xc2,0xc2)
(193,193,193) # rgb = (0xc1,0xc1,0xc1)
(193,193,193) # rgb = (0xc1,0xc1,0xc1)
(191,191,191) # rgb = (0xbf,0xbf,0xbf)
(191,191,191) # rgb = (0xbf,0xbf,0xbf)
(189,189,189) # rgb = (0xbd,0xbd,0xbd)
(188,188,188) # rgb = (0xbc,0xbc,0xbc)
(188,188,188) # rgb = (0xbc,0xbc,0xbc)
(186,186,186) # rgb = (0xba,0xba,0xba)
(185,185,185) # rgb = (0xb9,0xb9,0xb9)
(185,185,185) # rgb = (0xb9,0xb9,0xb9)
(183,183,183) # rgb = (0xb7,0xb7,0xb7)
(182,182,182) # rgb = (0xb6,0xb6,0xb6)
(182,182,182) # rgb = (0xb6,0xb6,0xb6)
(180,180,180) # rgb = (0xb4,0xb4,0xb4)
(178,178,178) # rgb = (0xb2,0xb2,0xb2)
(178,178,178) # rgb = (0xb2,0xb2,0xb2)
(177,177,177) # rgb = (0xb1,0xb1,0xb1)
(177,177,177) # rgb = (0xb1,0xb1,0xb1)
(175,175,175) # rgb = (0xaf,0xaf,0xaf)
(174,174,174) # rgb = (0xae,0xae,0xae)
(174,174,174) # rgb = (0xae,0xae,0xae)
}
tRNS {
197 187 190 194 186 4 186 189 4 195 84 191 5 193 175 163 205 150 191 213 88 75 67 8 147 191 220 203 95 151 223 199 8 207 156 227 199 65 163 98 226 204 12 202 167 201 11 65 178 228 205 74 59 87 178 19 201 99 18 14 184 204 184 96 22 61 227 199 22 193 97 197 254 59 253 28 192 102 199 247 58 198 244 30 109 202 188 32 96 196 60 203 239 202 230 41 207 237 119 53 213 209 37 55 45 230 214 233 92 185 223 50 230 57 124 217 43 133 221 95 198 47 233 99 194 221 107 138 152 144 226 140 133 220 172 125 218 196 118 225 161 223 235 238 200 155 147 146 172 236 236 151 183 150 234 216 217 211 151 219 132 185 145 147 217 138 144 137 142 151 217 217 213}
IMAGE {
pixels hex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}
...@@ -130,12 +130,8 @@ func (e *encoder) writePLTE(p image.PalettedColorModel) { ...@@ -130,12 +130,8 @@ func (e *encoder) writePLTE(p image.PalettedColorModel) {
e.err = FormatError("bad palette length: " + strconv.Itoa(len(p))) e.err = FormatError("bad palette length: " + strconv.Itoa(len(p)))
return return
} }
for i := 0; i < len(p); i++ { for i, c := range p {
r, g, b, a := p[i].RGBA() r, g, b, _ := c.RGBA()
if a != 0xffff {
e.err = UnsupportedError("non-opaque palette color")
return
}
e.tmp[3*i+0] = uint8(r >> 8) e.tmp[3*i+0] = uint8(r >> 8)
e.tmp[3*i+1] = uint8(g >> 8) e.tmp[3*i+1] = uint8(g >> 8)
e.tmp[3*i+2] = uint8(b >> 8) e.tmp[3*i+2] = uint8(b >> 8)
...@@ -143,6 +139,21 @@ func (e *encoder) writePLTE(p image.PalettedColorModel) { ...@@ -143,6 +139,21 @@ func (e *encoder) writePLTE(p image.PalettedColorModel) {
e.writeChunk(e.tmp[0:3*len(p)], "PLTE") e.writeChunk(e.tmp[0:3*len(p)], "PLTE")
} }
func (e *encoder) maybeWritetRNS(p image.PalettedColorModel) {
last := -1
for i, c := range p {
_, _, _, a := c.RGBA()
if a != 0xffff {
last = i
}
e.tmp[i] = uint8(a >> 8)
}
if last == -1 {
return
}
e.writeChunk(e.tmp[:last+1], "tRNS")
}
// An encoder is an io.Writer that satisfies writes by writing PNG IDAT chunks, // 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 // 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. // should be relatively infrequent, since writeIDATs uses a bufio.Writer.
...@@ -447,6 +458,7 @@ func Encode(w io.Writer, m image.Image) os.Error { ...@@ -447,6 +458,7 @@ func Encode(w io.Writer, m image.Image) os.Error {
e.writeIHDR() e.writeIHDR()
if pal != nil { if pal != nil {
e.writePLTE(pal.Palette) e.writePLTE(pal.Palette)
e.maybeWritetRNS(pal.Palette)
} }
e.writeIDATs() e.writeIDATs()
e.writeIEND() e.writeIEND()
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment