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
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
|
/*
* Copyright (c) 2013-2016 Kurt Jung (Gmail: kurt.w.jung)
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
package gofpdf
import (
"bytes"
"fmt"
"strings"
)
func (f *Fpdf) pngColorSpace(ct byte) (colspace string, colorVal int) {
colorVal = 1
switch ct {
case 0, 4:
colspace = "DeviceGray"
case 2, 6:
colspace = "DeviceRGB"
colorVal = 3
case 3:
colspace = "Indexed"
default:
f.err = fmt.Errorf("unknown color type in PNG buffer: %d", ct)
}
return
}
func (f *Fpdf) parsepngstream(buf *bytes.Buffer, readdpi bool) (info *ImageInfoType) {
info = f.newImageInfo()
// Check signature
if string(buf.Next(8)) != "\x89PNG\x0d\x0a\x1a\x0a" {
f.err = fmt.Errorf("not a PNG buffer")
return
}
// Read header chunk
_ = buf.Next(4)
if string(buf.Next(4)) != "IHDR" {
f.err = fmt.Errorf("incorrect PNG buffer")
return
}
w := f.readBeInt32(buf)
h := f.readBeInt32(buf)
bpc := f.readByte(buf)
if bpc > 8 {
f.err = fmt.Errorf("16-bit depth not supported in PNG file")
}
ct := f.readByte(buf)
var colspace string
var colorVal int
colspace, colorVal = f.pngColorSpace(ct)
if f.err != nil {
return
}
if f.readByte(buf) != 0 {
f.err = fmt.Errorf("'unknown compression method in PNG buffer")
return
}
if f.readByte(buf) != 0 {
f.err = fmt.Errorf("'unknown filter method in PNG buffer")
return
}
if f.readByte(buf) != 0 {
f.err = fmt.Errorf("interlacing not supported in PNG buffer")
return
}
_ = buf.Next(4)
dp := sprintf("/Predictor 15 /Colors %d /BitsPerComponent %d /Columns %d", colorVal, bpc, w)
// Scan chunks looking for palette, transparency and image data
pal := make([]byte, 0, 32)
var trns []int
data := make([]byte, 0, 32)
loop := true
for loop {
n := int(f.readBeInt32(buf))
// dbg("Loop [%d]", n)
switch string(buf.Next(4)) {
case "PLTE":
// dbg("PLTE")
// Read palette
pal = buf.Next(n)
_ = buf.Next(4)
case "tRNS":
// dbg("tRNS")
// Read transparency info
t := buf.Next(n)
switch ct {
case 0:
trns = []int{int(t[1])} // ord(substr($t,1,1)));
case 2:
trns = []int{int(t[1]), int(t[3]), int(t[5])} // array(ord(substr($t,1,1)), ord(substr($t,3,1)), ord(substr($t,5,1)));
default:
pos := strings.Index(string(t), "\x00")
if pos >= 0 {
trns = []int{pos} // array($pos);
}
}
_ = buf.Next(4)
case "IDAT":
// dbg("IDAT")
// Read image data block
data = append(data, buf.Next(n)...)
_ = buf.Next(4)
case "IEND":
// dbg("IEND")
loop = false
case "pHYs":
// dbg("pHYs")
// png files theoretically support different x/y dpi
// but we ignore files like this
// but if they're the same then we can stamp our info
// object with it
x := int(f.readBeInt32(buf))
y := int(f.readBeInt32(buf))
units := buf.Next(1)[0]
// fmt.Printf("got a pHYs block, x=%d, y=%d, u=%d, readdpi=%t\n",
// x, y, int(units), readdpi)
// only modify the info block if the user wants us to
if x == y && readdpi {
switch units {
// if units is 1 then measurement is px/meter
case 1:
info.dpi = float64(x) / 39.3701 // inches per meter
default:
info.dpi = float64(x)
}
}
_ = buf.Next(4)
default:
// dbg("default")
_ = buf.Next(n + 4)
}
if loop {
loop = n > 0
}
}
if colspace == "Indexed" && len(pal) == 0 {
f.err = fmt.Errorf("missing palette in PNG buffer")
}
info.w = float64(w)
info.h = float64(h)
info.cs = colspace
info.bpc = int(bpc)
info.f = "FlateDecode"
info.dp = dp
info.pal = pal
info.trns = trns
// dbg("ct [%d]", ct)
if ct >= 4 {
// Separate alpha and color channels
var err error
data, err = sliceUncompress(data)
if err != nil {
f.err = err
return
}
var color, alpha bytes.Buffer
if ct == 4 {
// Gray image
width := int(w)
height := int(h)
length := 2 * width
var pos, elPos int
for i := 0; i < height; i++ {
pos = (1 + length) * i
color.WriteByte(data[pos])
alpha.WriteByte(data[pos])
elPos = pos + 1
for k := 0; k < width; k++ {
color.WriteByte(data[elPos])
alpha.WriteByte(data[elPos+1])
elPos += 2
}
}
} else {
// RGB image
width := int(w)
height := int(h)
length := 4 * width
var pos, elPos int
for i := 0; i < height; i++ {
pos = (1 + length) * i
color.WriteByte(data[pos])
alpha.WriteByte(data[pos])
elPos = pos + 1
for k := 0; k < width; k++ {
color.Write(data[elPos : elPos+3])
alpha.WriteByte(data[elPos+3])
elPos += 4
}
}
}
data = sliceCompress(color.Bytes())
info.smask = sliceCompress(alpha.Bytes())
if f.pdfVersion < "1.4" {
f.pdfVersion = "1.4"
}
}
info.data = data
return
}
|
