summaryrefslogtreecommitdiffstats
path: root/Lib/imghdr.py
blob: b26792539d5be169b8a8fbc64cb46ffd49a14fcc (plain)
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
"""Recognize image file formats based on their first few bytes."""

__all__ = ["what"]

#-------------------------#
# Recognize image headers #
#-------------------------#

def what(file, h=None):
    f = None
    try:
        if h is None:
            if isinstance(file, str):
                f = open(file, 'rb')
                h = f.read(32)
            else:
                location = file.tell()
                h = file.read(32)
                file.seek(location)
        for tf in tests:
            res = tf(h, f)
            if res:
                return res
    finally:
        if f: f.close()
    return None


#---------------------------------#
# Subroutines per image file type #
#---------------------------------#

tests = []

def test_jpeg(h, f):
    """JPEG data in JFIF or Exif format"""
    if h[6:10] in (b'JFIF', b'Exif'):
        return 'jpeg'

tests.append(test_jpeg)

def test_png(h, f):
    if h.startswith(b'\211PNG\r\n\032\n'):
        return 'png'

tests.append(test_png)

def test_gif(h, f):
    """GIF ('87 and '89 variants)"""
    if h[:6] in (b'GIF87a', b'GIF89a'):
        return 'gif'

tests.append(test_gif)

def test_tiff(h, f):
    """TIFF (can be in Motorola or Intel byte order)"""
    if h[:2] in (b'MM', b'II'):
        return 'tiff'

tests.append(test_tiff)

def test_rgb(h, f):
    """SGI image library"""
    if h.startswith(b'\001\332'):
        return 'rgb'

tests.append(test_rgb)

def test_pbm(h, f):
    """PBM (portable bitmap)"""
    if len(h) >= 3 and \
        h[0] == ord(b'P') and h[1] in b'14' and h[2] in b' \t\n\r':
        return 'pbm'

tests.append(test_pbm)

def test_pgm(h, f):
    """PGM (portable graymap)"""
    if len(h) >= 3 and \
        h[0] == ord(b'P') and h[1] in b'25' and h[2] in b' \t\n\r':
        return 'pgm'

tests.append(test_pgm)

def test_ppm(h, f):
    """PPM (portable pixmap)"""
    if len(h) >= 3 and \
        h[0] == ord(b'P') and h[1] in b'36' and h[2] in b' \t\n\r':
        return 'ppm'

tests.append(test_ppm)

def test_rast(h, f):
    """Sun raster file"""
    if h.startswith(b'\x59\xA6\x6A\x95'):
        return 'rast'

tests.append(test_rast)

def test_xbm(h, f):
    """X bitmap (X10 or X11)"""
    if h.startswith(b'#define '):
        return 'xbm'

tests.append(test_xbm)

def test_bmp(h, f):
    if h.startswith(b'BM'):
        return 'bmp'

tests.append(test_bmp)

def test_webp(h, f):
    if h.startswith(b'RIFF') and h[8:12] == b'WEBP':
        return 'webp'

tests.append(test_webp)

def test_exr(h, f):
    if h.startswith(b'\x76\x2f\x31\x01'):
        return 'exr'

tests.append(test_exr)

#--------------------#
# Small test program #
#--------------------#

def test():
    import sys
    recursive = 0
    if sys.argv[1:] and sys.argv[1] == '-r':
        del sys.argv[1:2]
        recursive = 1
    try:
        if sys.argv[1:]:
            testall(sys.argv[1:], recursive, 1)
        else:
            testall(['.'], recursive, 1)
    except KeyboardInterrupt:
        sys.stderr.write('\n[Interrupted]\n')
        sys.exit(1)

def testall(list, recursive, toplevel):
    import sys
    import os
    for filename in list:
        if os.path.isdir(filename):
            print(filename + '/:', end=' ')
            if recursive or toplevel:
                print('recursing down:')
                import glob
                names = glob.glob(os.path.join(filename, '*'))
                testall(names, recursive, 0)
            else:
                print('*** directory (use -r) ***')
        else:
            print(filename + ':', end=' ')
            sys.stdout.flush()
            try:
                print(what(filename))
            except OSError:
                print('*** not found ***')

if __name__ == '__main__':
    test()