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path: root/libgo/go/image/png/reader.go
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Diffstat (limited to 'libgo/go/image/png/reader.go')
-rw-r--r--libgo/go/image/png/reader.go266
1 files changed, 212 insertions, 54 deletions
diff --git a/libgo/go/image/png/reader.go b/libgo/go/image/png/reader.go
index 2dd5ed80736..32f78f0ffe8 100644
--- a/libgo/go/image/png/reader.go
+++ b/libgo/go/image/png/reader.go
@@ -113,6 +113,11 @@ type decoder struct {
idatLength uint32
tmp [3 * 256]byte
interlace int
+
+ // useTransparent and transparent are used for grayscale and truecolor
+ // transparency, as opposed to palette transparency.
+ useTransparent bool
+ transparent [6]byte
}
// A FormatError reports that the input is not a valid PNG.
@@ -252,20 +257,51 @@ func (d *decoder) parsePLTE(length uint32) error {
}
func (d *decoder) parsetRNS(length uint32) error {
- if length > 256 {
- return FormatError("bad tRNS length")
- }
- n, err := io.ReadFull(d.r, d.tmp[:length])
- if err != nil {
- return err
- }
- d.crc.Write(d.tmp[:n])
switch d.cb {
- case cbG8, cbG16:
- return UnsupportedError("grayscale transparency")
+ case cbG1, cbG2, cbG4, cbG8, cbG16:
+ if length != 2 {
+ return FormatError("bad tRNS length")
+ }
+ n, err := io.ReadFull(d.r, d.tmp[:length])
+ if err != nil {
+ return err
+ }
+ d.crc.Write(d.tmp[:n])
+
+ copy(d.transparent[:], d.tmp[:length])
+ switch d.cb {
+ case cbG1:
+ d.transparent[1] *= 0xff
+ case cbG2:
+ d.transparent[1] *= 0x55
+ case cbG4:
+ d.transparent[1] *= 0x11
+ }
+ d.useTransparent = true
+
case cbTC8, cbTC16:
- return UnsupportedError("truecolor transparency")
+ if length != 6 {
+ return FormatError("bad tRNS length")
+ }
+ n, err := io.ReadFull(d.r, d.tmp[:length])
+ if err != nil {
+ return err
+ }
+ d.crc.Write(d.tmp[:n])
+
+ copy(d.transparent[:], d.tmp[:length])
+ d.useTransparent = true
+
case cbP1, cbP2, cbP4, cbP8:
+ if length > 256 {
+ return FormatError("bad tRNS length")
+ }
+ n, err := io.ReadFull(d.r, d.tmp[:length])
+ if err != nil {
+ return err
+ }
+ d.crc.Write(d.tmp[:n])
+
if len(d.palette) < n {
d.palette = d.palette[:n]
}
@@ -273,7 +309,8 @@ func (d *decoder) parsetRNS(length uint32) error {
rgba := d.palette[i].(color.RGBA)
d.palette[i] = color.NRGBA{rgba.R, rgba.G, rgba.B, d.tmp[i]}
}
- case cbGA8, cbGA16, cbTCA8, cbTCA16:
+
+ default:
return FormatError("tRNS, color type mismatch")
}
return d.verifyChecksum()
@@ -366,7 +403,7 @@ func (d *decoder) decode() (image.Image, error) {
// readImagePass reads a single image pass, sized according to the pass number.
func (d *decoder) readImagePass(r io.Reader, pass int, allocateOnly bool) (image.Image, error) {
- var bitsPerPixel int = 0
+ bitsPerPixel := 0
pixOffset := 0
var (
gray *image.Gray
@@ -394,16 +431,26 @@ func (d *decoder) readImagePass(r io.Reader, pass int, allocateOnly bool) (image
switch d.cb {
case cbG1, cbG2, cbG4, cbG8:
bitsPerPixel = d.depth
- gray = image.NewGray(image.Rect(0, 0, width, height))
- img = gray
+ if d.useTransparent {
+ nrgba = image.NewNRGBA(image.Rect(0, 0, width, height))
+ img = nrgba
+ } else {
+ gray = image.NewGray(image.Rect(0, 0, width, height))
+ img = gray
+ }
case cbGA8:
bitsPerPixel = 16
nrgba = image.NewNRGBA(image.Rect(0, 0, width, height))
img = nrgba
case cbTC8:
bitsPerPixel = 24
- rgba = image.NewRGBA(image.Rect(0, 0, width, height))
- img = rgba
+ if d.useTransparent {
+ nrgba = image.NewNRGBA(image.Rect(0, 0, width, height))
+ img = nrgba
+ } else {
+ rgba = image.NewRGBA(image.Rect(0, 0, width, height))
+ img = rgba
+ }
case cbP1, cbP2, cbP4, cbP8:
bitsPerPixel = d.depth
paletted = image.NewPaletted(image.Rect(0, 0, width, height), d.palette)
@@ -414,16 +461,26 @@ func (d *decoder) readImagePass(r io.Reader, pass int, allocateOnly bool) (image
img = nrgba
case cbG16:
bitsPerPixel = 16
- gray16 = image.NewGray16(image.Rect(0, 0, width, height))
- img = gray16
+ if d.useTransparent {
+ nrgba64 = image.NewNRGBA64(image.Rect(0, 0, width, height))
+ img = nrgba64
+ } else {
+ gray16 = image.NewGray16(image.Rect(0, 0, width, height))
+ img = gray16
+ }
case cbGA16:
bitsPerPixel = 32
nrgba64 = image.NewNRGBA64(image.Rect(0, 0, width, height))
img = nrgba64
case cbTC16:
bitsPerPixel = 48
- rgba64 = image.NewRGBA64(image.Rect(0, 0, width, height))
- img = rgba64
+ if d.useTransparent {
+ nrgba64 = image.NewNRGBA64(image.Rect(0, 0, width, height))
+ img = nrgba64
+ } else {
+ rgba64 = image.NewRGBA64(image.Rect(0, 0, width, height))
+ img = rgba64
+ }
case cbTCA16:
bitsPerPixel = 64
nrgba64 = image.NewNRGBA64(image.Rect(0, 0, width, height))
@@ -483,27 +540,75 @@ func (d *decoder) readImagePass(r io.Reader, pass int, allocateOnly bool) (image
// Convert from bytes to colors.
switch d.cb {
case cbG1:
- for x := 0; x < width; x += 8 {
- b := cdat[x/8]
- for x2 := 0; x2 < 8 && x+x2 < width; x2++ {
- gray.SetGray(x+x2, y, color.Gray{(b >> 7) * 0xff})
- b <<= 1
+ if d.useTransparent {
+ ty := d.transparent[1]
+ for x := 0; x < width; x += 8 {
+ b := cdat[x/8]
+ for x2 := 0; x2 < 8 && x+x2 < width; x2++ {
+ ycol := (b >> 7) * 0xff
+ acol := uint8(0xff)
+ if ycol == ty {
+ acol = 0x00
+ }
+ nrgba.SetNRGBA(x+x2, y, color.NRGBA{ycol, ycol, ycol, acol})
+ b <<= 1
+ }
+ }
+ } else {
+ for x := 0; x < width; x += 8 {
+ b := cdat[x/8]
+ for x2 := 0; x2 < 8 && x+x2 < width; x2++ {
+ gray.SetGray(x+x2, y, color.Gray{(b >> 7) * 0xff})
+ b <<= 1
+ }
}
}
case cbG2:
- for x := 0; x < width; x += 4 {
- b := cdat[x/4]
- for x2 := 0; x2 < 4 && x+x2 < width; x2++ {
- gray.SetGray(x+x2, y, color.Gray{(b >> 6) * 0x55})
- b <<= 2
+ if d.useTransparent {
+ ty := d.transparent[1]
+ for x := 0; x < width; x += 4 {
+ b := cdat[x/4]
+ for x2 := 0; x2 < 4 && x+x2 < width; x2++ {
+ ycol := (b >> 6) * 0x55
+ acol := uint8(0xff)
+ if ycol == ty {
+ acol = 0x00
+ }
+ nrgba.SetNRGBA(x+x2, y, color.NRGBA{ycol, ycol, ycol, acol})
+ b <<= 2
+ }
+ }
+ } else {
+ for x := 0; x < width; x += 4 {
+ b := cdat[x/4]
+ for x2 := 0; x2 < 4 && x+x2 < width; x2++ {
+ gray.SetGray(x+x2, y, color.Gray{(b >> 6) * 0x55})
+ b <<= 2
+ }
}
}
case cbG4:
- for x := 0; x < width; x += 2 {
- b := cdat[x/2]
- for x2 := 0; x2 < 2 && x+x2 < width; x2++ {
- gray.SetGray(x+x2, y, color.Gray{(b >> 4) * 0x11})
- b <<= 4
+ if d.useTransparent {
+ ty := d.transparent[1]
+ for x := 0; x < width; x += 2 {
+ b := cdat[x/2]
+ for x2 := 0; x2 < 2 && x+x2 < width; x2++ {
+ ycol := (b >> 4) * 0x11
+ acol := uint8(0xff)
+ if ycol == ty {
+ acol = 0x00
+ }
+ nrgba.SetNRGBA(x+x2, y, color.NRGBA{ycol, ycol, ycol, acol})
+ b <<= 4
+ }
+ }
+ } else {
+ for x := 0; x < width; x += 2 {
+ b := cdat[x/2]
+ for x2 := 0; x2 < 2 && x+x2 < width; x2++ {
+ gray.SetGray(x+x2, y, color.Gray{(b >> 4) * 0x11})
+ b <<= 4
+ }
}
}
case cbG8:
@@ -515,16 +620,37 @@ func (d *decoder) readImagePass(r io.Reader, pass int, allocateOnly bool) (image
nrgba.SetNRGBA(x, y, color.NRGBA{ycol, ycol, ycol, cdat[2*x+1]})
}
case cbTC8:
- pix, i, j := rgba.Pix, pixOffset, 0
- for x := 0; x < width; x++ {
- pix[i+0] = cdat[j+0]
- pix[i+1] = cdat[j+1]
- pix[i+2] = cdat[j+2]
- pix[i+3] = 0xff
- i += 4
- j += 3
+ if d.useTransparent {
+ pix, i, j := nrgba.Pix, pixOffset, 0
+ tr, tg, tb := d.transparent[1], d.transparent[3], d.transparent[5]
+ for x := 0; x < width; x++ {
+ r := cdat[j+0]
+ g := cdat[j+1]
+ b := cdat[j+2]
+ a := uint8(0xff)
+ if r == tr && g == tg && b == tb {
+ a = 0x00
+ }
+ pix[i+0] = r
+ pix[i+1] = g
+ pix[i+2] = b
+ pix[i+3] = a
+ i += 4
+ j += 3
+ }
+ pixOffset += nrgba.Stride
+ } else {
+ pix, i, j := rgba.Pix, pixOffset, 0
+ for x := 0; x < width; x++ {
+ pix[i+0] = cdat[j+0]
+ pix[i+1] = cdat[j+1]
+ pix[i+2] = cdat[j+2]
+ pix[i+3] = 0xff
+ i += 4
+ j += 3
+ }
+ pixOffset += rgba.Stride
}
- pixOffset += rgba.Stride
case cbP1:
for x := 0; x < width; x += 8 {
b := cdat[x/8]
@@ -575,9 +701,21 @@ func (d *decoder) readImagePass(r io.Reader, pass int, allocateOnly bool) (image
copy(nrgba.Pix[pixOffset:], cdat)
pixOffset += nrgba.Stride
case cbG16:
- for x := 0; x < width; x++ {
- ycol := uint16(cdat[2*x+0])<<8 | uint16(cdat[2*x+1])
- gray16.SetGray16(x, y, color.Gray16{ycol})
+ if d.useTransparent {
+ ty := uint16(d.transparent[0])<<8 | uint16(d.transparent[1])
+ for x := 0; x < width; x++ {
+ ycol := uint16(cdat[2*x+0])<<8 | uint16(cdat[2*x+1])
+ acol := uint16(0xffff)
+ if ycol == ty {
+ acol = 0x0000
+ }
+ nrgba64.SetNRGBA64(x, y, color.NRGBA64{ycol, ycol, ycol, acol})
+ }
+ } else {
+ for x := 0; x < width; x++ {
+ ycol := uint16(cdat[2*x+0])<<8 | uint16(cdat[2*x+1])
+ gray16.SetGray16(x, y, color.Gray16{ycol})
+ }
}
case cbGA16:
for x := 0; x < width; x++ {
@@ -586,11 +724,27 @@ func (d *decoder) readImagePass(r io.Reader, pass int, allocateOnly bool) (image
nrgba64.SetNRGBA64(x, y, color.NRGBA64{ycol, ycol, ycol, acol})
}
case cbTC16:
- for x := 0; x < width; x++ {
- rcol := uint16(cdat[6*x+0])<<8 | uint16(cdat[6*x+1])
- gcol := uint16(cdat[6*x+2])<<8 | uint16(cdat[6*x+3])
- bcol := uint16(cdat[6*x+4])<<8 | uint16(cdat[6*x+5])
- rgba64.SetRGBA64(x, y, color.RGBA64{rcol, gcol, bcol, 0xffff})
+ if d.useTransparent {
+ tr := uint16(d.transparent[0])<<8 | uint16(d.transparent[1])
+ tg := uint16(d.transparent[2])<<8 | uint16(d.transparent[3])
+ tb := uint16(d.transparent[4])<<8 | uint16(d.transparent[5])
+ for x := 0; x < width; x++ {
+ rcol := uint16(cdat[6*x+0])<<8 | uint16(cdat[6*x+1])
+ gcol := uint16(cdat[6*x+2])<<8 | uint16(cdat[6*x+3])
+ bcol := uint16(cdat[6*x+4])<<8 | uint16(cdat[6*x+5])
+ acol := uint16(0xffff)
+ if rcol == tr && gcol == tg && bcol == tb {
+ acol = 0x0000
+ }
+ nrgba64.SetNRGBA64(x, y, color.NRGBA64{rcol, gcol, bcol, acol})
+ }
+ } else {
+ for x := 0; x < width; x++ {
+ rcol := uint16(cdat[6*x+0])<<8 | uint16(cdat[6*x+1])
+ gcol := uint16(cdat[6*x+2])<<8 | uint16(cdat[6*x+3])
+ bcol := uint16(cdat[6*x+4])<<8 | uint16(cdat[6*x+5])
+ rgba64.SetRGBA64(x, y, color.RGBA64{rcol, gcol, bcol, 0xffff})
+ }
}
case cbTCA16:
for x := 0; x < width; x++ {
@@ -709,7 +863,11 @@ func (d *decoder) parseChunk() error {
d.stage = dsSeenPLTE
return d.parsePLTE(length)
case "tRNS":
- if d.stage != dsSeenPLTE {
+ if cbPaletted(d.cb) {
+ if d.stage != dsSeenPLTE {
+ return chunkOrderError
+ }
+ } else if d.stage != dsSeenIHDR {
return chunkOrderError
}
d.stage = dsSeentRNS
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