ccitt: fix byte align and invert flag
Change-Id: I49955017deb8243b19dc1bb222ff8622ac3ff6af
Reviewed-on: https://go-review.googlesource.com/c/image/+/190677
Run-TryBot: Benny Siegert <bsiegert@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Nigel Tao <nigeltao@golang.org>
diff --git a/ccitt/reader.go b/ccitt/reader.go
index 62986f9..680f8a6 100644
--- a/ccitt/reader.go
+++ b/ccitt/reader.go
@@ -269,6 +269,12 @@
}
byteValue := byte(0)
+ if z.invert {
+ // Set the end-of-row padding bits to 1 (if inverted) or 0. If inverted, the 1s
+ // are temporary, and will be flipped back to 0s by the invertBytes call below.
+ byteValue = 0xFF >> uint(numToPack)
+ }
+
for j := 0; j < numToPack; j++ {
byteValue |= (z.curr[z.ri] & 0x80) >> uint(j)
z.ri++
@@ -285,7 +291,6 @@
}
n := len(originalP) - len(p)
- // TODO: when invert is true, should the end-of-row padding bits be 0 or 1?
if z.invert {
invertBytes(originalP[:n])
}
@@ -369,6 +374,10 @@
z.atStartOfRow = true
z.penColorIsWhite = true
+ if z.align {
+ z.br.alignToByteBoundary()
+ }
+
switch z.subFormat {
case Group3:
for ; z.wi < len(z.curr); z.atStartOfRow = false {
@@ -379,10 +388,6 @@
return z.decodeEOL()
case Group4:
- if z.align {
- z.br.alignToByteBoundary()
- }
-
for ; z.wi < len(z.curr); z.atStartOfRow = false {
mode, err := decode(&z.br, modeDecodeTable[:])
if err != nil {
diff --git a/ccitt/reader_test.go b/ccitt/reader_test.go
index c582f16..0224618 100644
--- a/ccitt/reader_test.go
+++ b/ccitt/reader_test.go
@@ -14,6 +14,7 @@
"os"
"path/filepath"
"reflect"
+ "strings"
"testing"
"unsafe"
)
@@ -198,25 +199,23 @@
}
}
-func TestReadRegular(t *testing.T) { testRead(t, false) }
-func TestReadInvert(t *testing.T) { testRead(t, true) }
-
-func testRead(t *testing.T, invert bool) {
+func testRead(t *testing.T, fileName string, sf SubFormat, align, invert bool) {
t.Helper()
const width, height = 153, 55
opts := &Options{
+ Align: align,
Invert: invert,
}
got := ""
{
- f, err := os.Open("testdata/bw-gopher.ccitt_group3")
+ f, err := os.Open(fileName)
if err != nil {
t.Fatalf("Open: %v", err)
}
defer f.Close()
- gotBytes, err := ioutil.ReadAll(NewReader(f, MSB, Group3, width, height, opts))
+ gotBytes, err := ioutil.ReadAll(NewReader(f, MSB, sf, width, height, opts))
if err != nil {
t.Fatalf("ReadAll: %v", err)
}
@@ -261,9 +260,6 @@
}
}
}
- if invert {
- invertBytes(wantBytes)
- }
want = string(wantBytes)
}
@@ -292,6 +288,27 @@
}
}
+func TestRead(t *testing.T) {
+ for _, fileName := range []string{
+ "testdata/bw-gopher.ccitt_group3",
+ "testdata/bw-gopher-aligned.ccitt_group3",
+ "testdata/bw-gopher-inverted.ccitt_group3",
+ "testdata/bw-gopher-inverted-aligned.ccitt_group3",
+ "testdata/bw-gopher.ccitt_group4",
+ "testdata/bw-gopher-aligned.ccitt_group4",
+ "testdata/bw-gopher-inverted.ccitt_group4",
+ "testdata/bw-gopher-inverted-aligned.ccitt_group4",
+ } {
+ subFormat := Group3
+ if strings.HasSuffix(fileName, "group4") {
+ subFormat = Group4
+ }
+ align := strings.Contains(fileName, "aligned")
+ invert := strings.Contains(fileName, "inverted")
+ testRead(t, fileName, subFormat, align, invert)
+ }
+}
+
func TestDecodeIntoGray(t *testing.T) {
for _, tt := range []struct {
fileName string
diff --git a/ccitt/testdata/bw-gopher-aligned.ccitt_group3 b/ccitt/testdata/bw-gopher-aligned.ccitt_group3
new file mode 100644
index 0000000..cba6634
--- /dev/null
+++ b/ccitt/testdata/bw-gopher-aligned.ccitt_group3
Binary files differ
diff --git a/ccitt/testdata/bw-gopher-aligned.ccitt_group4 b/ccitt/testdata/bw-gopher-aligned.ccitt_group4
new file mode 100644
index 0000000..8ff8653
--- /dev/null
+++ b/ccitt/testdata/bw-gopher-aligned.ccitt_group4
Binary files differ
diff --git a/ccitt/testdata/bw-gopher-inverted-aligned.ccitt_group3 b/ccitt/testdata/bw-gopher-inverted-aligned.ccitt_group3
new file mode 100644
index 0000000..0c9c55a
--- /dev/null
+++ b/ccitt/testdata/bw-gopher-inverted-aligned.ccitt_group3
Binary files differ
diff --git a/ccitt/testdata/bw-gopher-inverted-aligned.ccitt_group4 b/ccitt/testdata/bw-gopher-inverted-aligned.ccitt_group4
new file mode 100644
index 0000000..263aafd
--- /dev/null
+++ b/ccitt/testdata/bw-gopher-inverted-aligned.ccitt_group4
Binary files differ
diff --git a/ccitt/testdata/bw-gopher-inverted.ccitt_group3 b/ccitt/testdata/bw-gopher-inverted.ccitt_group3
new file mode 100644
index 0000000..753bd09
--- /dev/null
+++ b/ccitt/testdata/bw-gopher-inverted.ccitt_group3
Binary files differ
diff --git a/ccitt/testdata/bw-gopher-inverted.ccitt_group4 b/ccitt/testdata/bw-gopher-inverted.ccitt_group4
new file mode 100644
index 0000000..a4b062a
--- /dev/null
+++ b/ccitt/testdata/bw-gopher-inverted.ccitt_group4
Binary files differ
