1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
|
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package png
import (
"bufio"
"fmt"
"image"
"io"
"os"
"testing"
)
// The go PNG library currently supports only a subset of the full PNG specification.
// In particular, bit depths other than 8 or 16 are not supported, nor are grayscale-
// alpha images.
var filenames = []string{
//"basn0g01", // bit depth is not 8 or 16
//"basn0g02", // bit depth is not 8 or 16
//"basn0g04", // bit depth is not 8 or 16
"basn0g08",
"basn0g16",
"basn2c08",
"basn2c16",
//"basn3p01", // bit depth is not 8 or 16
//"basn3p02", // bit depth is not 8 or 16
//"basn3p04", // bit depth is not 8 or 16
"basn3p08",
//"basn4a08", // grayscale-alpha color model
//"basn4a16", // grayscale-alpha color model
"basn6a08",
"basn6a16",
}
func readPng(filename string) (image.Image, os.Error) {
f, err := os.Open(filename, os.O_RDONLY, 0444)
if err != nil {
return nil, err
}
defer f.Close()
return Decode(f)
}
// An approximation of the sng command-line tool.
func sng(w io.WriteCloser, filename string, png image.Image) {
defer w.Close()
bounds := png.Bounds()
cm := png.ColorModel()
var bitdepth int
switch cm {
case image.RGBAColorModel, image.NRGBAColorModel, image.AlphaColorModel, image.GrayColorModel:
bitdepth = 8
default:
bitdepth = 16
}
cpm, _ := cm.(image.PalettedColorModel)
var paletted *image.Paletted
if cpm != nil {
bitdepth = 8
paletted = png.(*image.Paletted)
}
// Write the filename and IHDR.
io.WriteString(w, "#SNG: from "+filename+".png\nIHDR {\n")
fmt.Fprintf(w, " width: %d; height: %d; bitdepth: %d;\n", bounds.Dx(), bounds.Dy(), bitdepth)
switch {
case cm == image.RGBAColorModel, cm == image.RGBA64ColorModel:
io.WriteString(w, " using color;\n")
case cm == image.NRGBAColorModel, cm == image.NRGBA64ColorModel:
io.WriteString(w, " using color alpha;\n")
case cm == image.GrayColorModel, cm == image.Gray16ColorModel:
io.WriteString(w, " using grayscale;\n")
case cpm != nil:
io.WriteString(w, " using color palette;\n")
default:
io.WriteString(w, "unknown PNG decoder color model\n")
}
io.WriteString(w, "}\n")
// We fake a gAMA output. The test files have a gAMA chunk but the go PNG parser ignores it
// (the PNG spec section 11.3 says "Ancillary chunks may be ignored by a decoder").
io.WriteString(w, "gAMA {1.0000}\n")
// Write the PLTE (if applicable).
if cpm != nil {
io.WriteString(w, "PLTE {\n")
for i := 0; i < len(cpm); i++ {
r, g, b, _ := cpm[i].RGBA()
r >>= 8
g >>= 8
b >>= 8
fmt.Fprintf(w, " (%3d,%3d,%3d) # rgb = (0x%02x,0x%02x,0x%02x)\n", r, g, b, r, g, b)
}
io.WriteString(w, "}\n")
}
// Write the IMAGE.
io.WriteString(w, "IMAGE {\n pixels hex\n")
for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
switch {
case cm == image.GrayColorModel:
for x := bounds.Min.X; x < bounds.Max.X; x++ {
gray := png.At(x, y).(image.GrayColor)
fmt.Fprintf(w, "%02x", gray.Y)
}
case cm == image.Gray16ColorModel:
for x := bounds.Min.X; x < bounds.Max.X; x++ {
gray16 := png.At(x, y).(image.Gray16Color)
fmt.Fprintf(w, "%04x ", gray16.Y)
}
case cm == image.RGBAColorModel:
for x := bounds.Min.X; x < bounds.Max.X; x++ {
rgba := png.At(x, y).(image.RGBAColor)
fmt.Fprintf(w, "%02x%02x%02x ", rgba.R, rgba.G, rgba.B)
}
case cm == image.RGBA64ColorModel:
for x := bounds.Min.X; x < bounds.Max.X; x++ {
rgba64 := png.At(x, y).(image.RGBA64Color)
fmt.Fprintf(w, "%04x%04x%04x ", rgba64.R, rgba64.G, rgba64.B)
}
case cm == image.NRGBAColorModel:
for x := bounds.Min.X; x < bounds.Max.X; x++ {
nrgba := png.At(x, y).(image.NRGBAColor)
fmt.Fprintf(w, "%02x%02x%02x%02x ", nrgba.R, nrgba.G, nrgba.B, nrgba.A)
}
case cm == image.NRGBA64ColorModel:
for x := bounds.Min.X; x < bounds.Max.X; x++ {
nrgba64 := png.At(x, y).(image.NRGBA64Color)
fmt.Fprintf(w, "%04x%04x%04x%04x ", nrgba64.R, nrgba64.G, nrgba64.B, nrgba64.A)
}
case cpm != nil:
for x := bounds.Min.X; x < bounds.Max.X; x++ {
fmt.Fprintf(w, "%02x", paletted.ColorIndexAt(x, y))
}
}
io.WriteString(w, "\n")
}
io.WriteString(w, "}\n")
}
func TestReader(t *testing.T) {
for _, fn := range filenames {
// Read the .png file.
image, err := readPng("testdata/pngsuite/" + fn + ".png")
if err != nil {
t.Error(fn, err)
continue
}
piper, pipew := io.Pipe()
pb := bufio.NewReader(piper)
go sng(pipew, fn, image)
defer piper.Close()
// Read the .sng file.
sf, err := os.Open("testdata/pngsuite/"+fn+".sng", os.O_RDONLY, 0444)
if err != nil {
t.Error(fn, err)
continue
}
defer sf.Close()
sb := bufio.NewReader(sf)
if err != nil {
t.Error(fn, err)
continue
}
// Compare the two, in SNG format, line by line.
for {
ps, perr := pb.ReadString('\n')
ss, serr := sb.ReadString('\n')
if perr == os.EOF && serr == os.EOF {
break
}
if perr != nil {
t.Error(fn, perr)
break
}
if serr != nil {
t.Error(fn, serr)
break
}
if ps != ss {
t.Errorf("%s: Mismatch\n%sversus\n%s\n", fn, ps, ss)
break
}
}
}
}
|
