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image/jpeg: support 16-bit quantization tables and Extended Sequential

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frames.

Fixes #9888.

Change-Id: I60f1d843e72e1b7bc77ab984f149c9ddb5258a06
Reviewed-on: https://go-review.googlesource.com/5251
Reviewed-by: Rob Pike <r@golang.org>
This commit is contained in:
Nigel Tao 2015-02-19 14:00:16 +11:00
parent 1ae124b5ff
commit 270f8447d6
1 changed files with 34 additions and 12 deletions
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46
src/image/jpeg/reader.go
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@ -54,6 +54,7 @@ const (
soiMarker = 0xd8 // Start Of Image.
eoiMarker = 0xd9 // End Of Image.
sof0Marker = 0xc0 // Start Of Frame (Baseline).
sof1Marker = 0xc1 // Start Of Frame (Extended Sequential).
sof2Marker = 0xc2 // Start Of Frame (Progressive).
dhtMarker = 0xc4 // Define Huffman Table.
dqtMarker = 0xdb // Define Quantization Table.
@ -139,7 +140,7 @@ type decoder struct {
progCoeffs [maxComponents][]block // Saved state between progressive-mode scans.
huff [maxTc + 1][maxTh + 1]huffman
quant [maxTq + 1]block // Quantization tables, in zig-zag order.
tmp [blockSize + 1]byte
tmp [2 * blockSize]byte
}
// fill fills up the d.bytes.buf buffer from the underlying io.Reader. It
@ -387,21 +388,42 @@ func (d *decoder) processSOF(n int) error {
// Specified in section B.2.4.1.
func (d *decoder) processDQT(n int) error {
const qtLength = 1 + blockSize
for ; n >= qtLength; n -= qtLength {
if err := d.readFull(d.tmp[:qtLength]); err != nil {
loop:
for n > 0 {
n--
x, err := d.readByte()
if err != nil {
return err
}
pq := d.tmp[0] >> 4
if pq != 0 {
return UnsupportedError("bad Pq value")
}
tq := d.tmp[0] & 0x0f
tq := x & 0x0f
if tq > maxTq {
return FormatError("bad Tq value")
}
for i := range d.quant[tq] {
d.quant[tq][i] = int32(d.tmp[i+1])
switch x >> 4 {
default:
return FormatError("bad Pq value")
case 0:
if n < blockSize {
break loop
}
n -= blockSize
if err := d.readFull(d.tmp[:blockSize]); err != nil {
return err
}
for i := range d.quant[tq] {
d.quant[tq][i] = int32(d.tmp[i])
}
case 1:
if n < 2*blockSize {
break loop
}
n -= 2 * blockSize
if err := d.readFull(d.tmp[:2*blockSize]); err != nil {
return err
}
for i := range d.quant[tq] {
d.quant[tq][i] = int32(d.tmp[2*i])<<8 | int32(d.tmp[2*i+1])
}
}
}
if n != 0 {
@ -524,7 +546,7 @@ func (d *decoder) decode(r io.Reader, configOnly bool) (image.Image, error) {
}
switch marker {
case sof0Marker, sof2Marker:
case sof0Marker, sof1Marker, sof2Marker:
d.progressive = marker == sof2Marker
err = d.processSOF(n)
if configOnly {