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[python.git] / Lib / imghdr.py
blob1683024cb72923d6a02bf50230ad9860aa69875c
1 """Recognize image file formats based on their first few bytes."""
3 __all__ = ["what"]
5 #-------------------------#
6 # Recognize image headers #
7 #-------------------------#
9 def what(file, h=None):
10 if h is None:
11 if isinstance(file, basestring):
12 f = open(file, 'rb')
13 h = f.read(32)
14 else:
15 location = file.tell()
16 h = file.read(32)
17 file.seek(location)
18 f = None
19 else:
20 f = None
21 try:
22 for tf in tests:
23 res = tf(h, f)
24 if res:
25 return res
26 finally:
27 if f: f.close()
28 return None
31 #---------------------------------#
32 # Subroutines per image file type #
33 #---------------------------------#
35 tests = []
37 def test_jpeg(h, f):
38 """JPEG data in JFIF format"""
39 if h[6:10] == 'JFIF':
40 return 'jpeg'
42 tests.append(test_jpeg)
44 def test_exif(h, f):
45 """JPEG data in Exif format"""
46 if h[6:10] == 'Exif':
47 return 'jpeg'
49 tests.append(test_exif)
51 def test_png(h, f):
52 if h[:8] == "\211PNG\r\n\032\n":
53 return 'png'
55 tests.append(test_png)
57 def test_gif(h, f):
58 """GIF ('87 and '89 variants)"""
59 if h[:6] in ('GIF87a', 'GIF89a'):
60 return 'gif'
62 tests.append(test_gif)
64 def test_tiff(h, f):
65 """TIFF (can be in Motorola or Intel byte order)"""
66 if h[:2] in ('MM', 'II'):
67 return 'tiff'
69 tests.append(test_tiff)
71 def test_rgb(h, f):
72 """SGI image library"""
73 if h[:2] == '\001\332':
74 return 'rgb'
76 tests.append(test_rgb)
78 def test_pbm(h, f):
79 """PBM (portable bitmap)"""
80 if len(h) >= 3 and \
81 h[0] == 'P' and h[1] in '14' and h[2] in ' \t\n\r':
82 return 'pbm'
84 tests.append(test_pbm)
86 def test_pgm(h, f):
87 """PGM (portable graymap)"""
88 if len(h) >= 3 and \
89 h[0] == 'P' and h[1] in '25' and h[2] in ' \t\n\r':
90 return 'pgm'
92 tests.append(test_pgm)
94 def test_ppm(h, f):
95 """PPM (portable pixmap)"""
96 if len(h) >= 3 and \
97 h[0] == 'P' and h[1] in '36' and h[2] in ' \t\n\r':
98 return 'ppm'
100 tests.append(test_ppm)
102 def test_rast(h, f):
103 """Sun raster file"""
104 if h[:4] == '\x59\xA6\x6A\x95':
105 return 'rast'
107 tests.append(test_rast)
109 def test_xbm(h, f):
110 """X bitmap (X10 or X11)"""
111 s = '#define '
112 if h[:len(s)] == s:
113 return 'xbm'
115 tests.append(test_xbm)
117 def test_bmp(h, f):
118 if h[:2] == 'BM':
119 return 'bmp'
121 tests.append(test_bmp)
123 #--------------------#
124 # Small test program #
125 #--------------------#
127 def test():
128 import sys
129 recursive = 0
130 if sys.argv[1:] and sys.argv[1] == '-r':
131 del sys.argv[1:2]
132 recursive = 1
133 try:
134 if sys.argv[1:]:
135 testall(sys.argv[1:], recursive, 1)
136 else:
137 testall(['.'], recursive, 1)
138 except KeyboardInterrupt:
139 sys.stderr.write('\n[Interrupted]\n')
140 sys.exit(1)
142 def testall(list, recursive, toplevel):
143 import sys
144 import os
145 for filename in list:
146 if os.path.isdir(filename):
147 print filename + '/:',
148 if recursive or toplevel:
149 print 'recursing down:'
150 import glob
151 names = glob.glob(os.path.join(filename, '*'))
152 testall(names, recursive, 0)
153 else:
154 print '*** directory (use -r) ***'
155 else:
156 print filename + ':',
157 sys.stdout.flush()
158 try:
159 print what(filename)
160 except IOError:
161 print '*** not found ***'