1 """Recognize image file formats based on their first few bytes."""
2
3 from os import PathLike
4 import warnings
5
6 __all__ = ["what"]
7
8
9 warnings._deprecated(__name__, remove=(3, 13))
10
11
12 #-------------------------#
13 # Recognize image headers #
14 #-------------------------#
15
16 def what(file, h=None):
17 f = None
18 try:
19 if h is None:
20 if isinstance(file, (str, PathLike)):
21 f = open(file, 'rb')
22 h = f.read(32)
23 else:
24 location = file.tell()
25 h = file.read(32)
26 file.seek(location)
27 for tf in tests:
28 res = tf(h, f)
29 if res:
30 return res
31 finally:
32 if f: f.close()
33 return None
34
35
36 #---------------------------------#
37 # Subroutines per image file type #
38 #---------------------------------#
39
40 tests = []
41
42 def test_jpeg(h, f):
43 """JPEG data with JFIF or Exif markers; and raw JPEG"""
44 if h[6:10] in (b'JFIF', b'Exif'):
45 return 'jpeg'
46 elif h[:4] == b'\xff\xd8\xff\xdb':
47 return 'jpeg'
48
49 tests.append(test_jpeg)
50
51 def test_png(h, f):
52 if h.startswith(b'\211PNG\r\n\032\n'):
53 return 'png'
54
55 tests.append(test_png)
56
57 def test_gif(h, f):
58 """GIF ('87 and '89 variants)"""
59 if h[:6] in (b'GIF87a', b'GIF89a'):
60 return 'gif'
61
62 tests.append(test_gif)
63
64 def test_tiff(h, f):
65 """TIFF (can be in Motorola or Intel byte order)"""
66 if h[:2] in (b'MM', b'II'):
67 return 'tiff'
68
69 tests.append(test_tiff)
70
71 def test_rgb(h, f):
72 """SGI image library"""
73 if h.startswith(b'\001\332'):
74 return 'rgb'
75
76 tests.append(test_rgb)
77
78 def test_pbm(h, f):
79 """PBM (portable bitmap)"""
80 if len(h) >= 3 and \
81 h[0] == ord(b'P') and h[1] in b'14' and h[2] in b' \t\n\r':
82 return 'pbm'
83
84 tests.append(test_pbm)
85
86 def test_pgm(h, f):
87 """PGM (portable graymap)"""
88 if len(h) >= 3 and \
89 h[0] == ord(b'P') and h[1] in b'25' and h[2] in b' \t\n\r':
90 return 'pgm'
91
92 tests.append(test_pgm)
93
94 def test_ppm(h, f):
95 """PPM (portable pixmap)"""
96 if len(h) >= 3 and \
97 h[0] == ord(b'P') and h[1] in b'36' and h[2] in b' \t\n\r':
98 return 'ppm'
99
100 tests.append(test_ppm)
101
102 def test_rast(h, f):
103 """Sun raster file"""
104 if h.startswith(b'\x59\xA6\x6A\x95'):
105 return 'rast'
106
107 tests.append(test_rast)
108
109 def test_xbm(h, f):
110 """X bitmap (X10 or X11)"""
111 if h.startswith(b'#define '):
112 return 'xbm'
113
114 tests.append(test_xbm)
115
116 def test_bmp(h, f):
117 if h.startswith(b'BM'):
118 return 'bmp'
119
120 tests.append(test_bmp)
121
122 def test_webp(h, f):
123 if h.startswith(b'RIFF') and h[8:12] == b'WEBP':
124 return 'webp'
125
126 tests.append(test_webp)
127
128 def test_exr(h, f):
129 if h.startswith(b'\x76\x2f\x31\x01'):
130 return 'exr'
131
132 tests.append(test_exr)
133
134 #--------------------#
135 # Small test program #
136 #--------------------#
137
138 def test():
139 import sys
140 recursive = 0
141 if sys.argv[1:] and sys.argv[1] == '-r':
142 del sys.argv[1:2]
143 recursive = 1
144 try:
145 if sys.argv[1:]:
146 testall(sys.argv[1:], recursive, 1)
147 else:
148 testall(['.'], recursive, 1)
149 except KeyboardInterrupt:
150 sys.stderr.write('\n[Interrupted]\n')
151 sys.exit(1)
152
153 def testall(list, recursive, toplevel):
154 import sys
155 import os
156 for filename in list:
157 if os.path.isdir(filename):
158 print(filename + '/:', end=' ')
159 if recursive or toplevel:
160 print('recursing down:')
161 import glob
162 names = glob.glob(os.path.join(glob.escape(filename), '*'))
163 testall(names, recursive, 0)
164 else:
165 print('*** directory (use -r) ***')
166 else:
167 print(filename + ':', end=' ')
168 sys.stdout.flush()
169 try:
170 print(what(filename))
171 except OSError:
172 print('*** not found ***')
173
174 if __name__ == '__main__':
175 test()