Tweak test/data/artif*/gif-transparent-index.gif

script/make-artificial.go

diff --git a/script/make-artificial.go b/script/make-artificial.go
index 9de99ab..7ebfb13 100644
--- a/script/make-artificial.go
+++ b/script/make-artificial.go
@@ -959,7 +959,7 @@
 
 		flags := uint8(0)
 		duration := uint32(0)
-		transparentIndex := uint32(0)
+		transparentIndex := uint8(0)
 		for s != "" {
 			term := ""
 			if i := strings.IndexByte(s, ' '); i >= 0 {
@@ -980,12 +980,12 @@
 			case term == "animationDisposalRestorePrevious":
 				flags |= 0x0C
 			case strings.HasPrefix(term, trans):
-				num, remaining, ok := parseNum(term[len(trans):])
-				if !ok || remaining != "" {
+				num, err := strconv.ParseUint(term[len(trans):], 0, 8)
+				if err != nil {
 					break outer
 				}
 				flags |= 0x01
-				transparentIndex = num
+				transparentIndex = uint8(num)
 			case strings.HasSuffix(term, ms):
 				num, remaining, ok := parseNum(term[:len(term)-len(ms)])
 				if !ok || remaining != "" {
@@ -1002,7 +1002,7 @@
 			flags,
 			uint8(duration>>0),
 			uint8(duration>>8),
-			uint8(transparentIndex),
+			transparentIndex,
 			0x00,
 		)
 		return stateGif, nil

test/data/artificial/gif-transparent-index.gif

diff --git a/test/data/artificial/gif-transparent-index.gif b/test/data/artificial/gif-transparent-index.gif
index a9f0e09..471ae7a 100644
--- a/test/data/artificial/gif-transparent-index.gif
+++ b/test/data/artificial/gif-transparent-index.gif
Binary files differ

test/data/artificial/gif-transparent-index.gif.make-artificial.txt

diff --git a/test/data/artificial/gif-transparent-index.gif.make-artificial.txt b/test/data/artificial/gif-transparent-index.gif.make-artificial.txt
index 96f05c0..61f2ca8 100644
--- a/test/data/artificial/gif-transparent-index.gif.make-artificial.txt
+++ b/test/data/artificial/gif-transparent-index.gif.make-artificial.txt
@@ -1,36 +1,67 @@
 # Feed this file to script/make-artificial.go
 
+# This GIF image has two frames. The first is 4x2 and contains 8 shades of red.
+# The second is 3x1, positioned at (1, 1), and nominally contains 3 shades of
+# blue but the middle pixel is transparent.
+
 make gif
 
 header
 
 image {
-	imageWidthHeight 4 1
-	# Four shades of red and then green, cyan, blue, white.
+	imageWidthHeight 4 2
+	# 16 shades of red and then 16 shades of blue.
 	palette {
+		0x00 0x00 0x00
+		0x10 0x00 0x00
+		0x20 0x00 0x00
+		0x30 0x00 0x00
+		0x40 0x00 0x00
+		0x50 0x00 0x00
+		0x60 0x00 0x00
+		0x70 0x00 0x00
+
 		0x80 0x00 0x00
 		0x90 0x00 0x00
 		0xA0 0x00 0x00
 		0xB0 0x00 0x00
-		0x00 0xC0 0x00
-		0x00 0xD0 0xD0
-		0x00 0x00 0xE0
-		0xF0 0xF0 0xF0
+		0xC0 0x00 0x00
+		0xD0 0x00 0x00
+		0xE0 0x00 0x00
+		0xF0 0x00 0x00
+
+		0x00 0x00 0x00
+		0x00 0x00 0x11
+		0x00 0x00 0x22
+		0x00 0x00 0x33
+		0x00 0x00 0x44
+		0x00 0x00 0x55
+		0x00 0x00 0x66
+		0x00 0x00 0x77
+
+		0x00 0x00 0x88
+		0x00 0x00 0x99
+		0x00 0x00 0xAA
+		0x00 0x00 0xBB
+		0x00 0x00 0xCC
+		0x00 0x00 0xDD
+		0x00 0x00 0xEE
+		0x00 0x00 0xFF
 	}
 }
 
 graphicControl animationDisposalNone 100ms
 
 frame {
-	frameLeftTopWidthHeight 0 0 4 1
+	frameLeftTopWidthHeight 0 0 4 2
 }
-lzw 7 0x00 0x01 0x02 0x03
+lzw 7 0x08 0x09 0x0A 0x0B 0x0C 0x0D 0x0E 0x0F
 
-graphicControl animationDisposalNone 200ms transparentIndex=5
+graphicControl animationDisposalNone 200ms transparentIndex=0x1A
 
 frame {
-	frameLeftTopWidthHeight 0 0 3 1
+	frameLeftTopWidthHeight 1 1 3 1
 }
-lzw 7 0x04 0x05 0x06
+lzw 7 0x1F 0x1A 0x15
 
 trailer