| """Recognize image file formats based on their first few bytes.""" |
| |
| __all__ = ["what"] |
| |
| #-------------------------# |
| # Recognize image headers # |
| #-------------------------# |
| |
| def what(file, h=None): |
| 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) |
| f = None |
| else: |
| f = None |
| try: |
| 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_rgb(h, f): |
| """SGI image library""" |
| if h.startswith(b'\001\332'): |
| return 'rgb' |
| |
| tests.append(test_rgb) |
| |
| 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_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_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_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_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_bmp(h, f): |
| if h.startswith(b'BM'): |
| return 'bmp' |
| |
| tests.append(test_bmp) |
| |
| def test_png(h, f): |
| if h.startswith(b'\211PNG\r\n\032\n'): |
| return 'png' |
| |
| tests.append(test_png) |
| |
| #--------------------# |
| # 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 IOError: |
| print('*** not found ***') |
| |
| if __name__ == '__main__': |
| test() |