cpython/Lib/imghdr.py

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# Recognizing image files based on their first few bytes.
#-------------------------#
# Recognize sound headers #
#-------------------------#
def what(filename):
f = open(filename, 'r')
h = f.read(32)
for tf in tests:
res = tf(h, f)
if res:
return res
return None
#---------------------------------#
# Subroutines per image file type #
#---------------------------------#
tests = []
def test_rgb(h, f):
# SGI image library
if h[:2] == '\001\332':
return 'rgb'
tests.append(test_rgb)
def test_gif(h, f):
# GIF ('87 and '89 variants)
if h[:6] in ('GIF87a', 'GIF89a'):
return 'gif'
tests.append(test_gif)
def test_pnm(h, f):
# PBM, PGM, PPM (portable {bit,gray,pix}map; together portable anymap)
if len(h) >= 3 and \
h[0] == 'P' and h[1] in '123456' and h[2] in ' \t\n\r':
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return 'pnm'
tests.append(test_pnm)
def test_tiff(h, f):
# TIFF (can be in Motorola or Intel byte order)
if h[:2] in ('MM', 'II'):
return 'tiff'
tests.append(test_tiff)
def test_rast(h, f):
# Sun raster file
if h[:4] == '\x59\xA6\x6A\x95':
return 'rast'
tests.append(test_rast)
def test_xbm(h, f):
# X bitmap (X10 or X11)
s = '#define '
if h[:len(s)] == s:
return 'xbm'
tests.append(test_xbm)
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#--------------------#
# 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 + '/:',
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 + ':',
sys.stdout.flush()
try:
print what(filename)
except IOError:
print '*** not found ***'