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