1 # Implement 'jpeg' interface using SGI's compression library

     2 

     3 # XXX Options 'smooth' and 'optimize' are ignored.

     4 

     5 # XXX It appears that compressing grayscale images doesn't work right;

     6 # XXX the resulting file causes weirdness.

     7 from warnings import warnpy3k

     8 warnpy3k("the jpeg module has been removed in Python 3.0", stacklevel=2)

     9 del warnpy3k

    10 

    11 class error(Exception):

    12     pass

    13 

    14 options = {'quality': 75, 'optimize': 0, 'smooth': 0, 'forcegray': 0}

    15 

    16 comp = None

    17 decomp = None

    18 

    19 def compress(imgdata, width, height, bytesperpixel):

    20     global comp

    21     import cl

    22     if comp is None: comp = cl.OpenCompressor(cl.JPEG)

    23     if bytesperpixel == 1:

    24         format = cl.GRAYSCALE

    25     elif bytesperpixel == 4:

    26         format = cl.RGBX

    27     if options['forcegray']:

    28         iformat = cl.GRAYSCALE

    29     else:

    30         iformat = cl.YUV

    31     # XXX How to support 'optimize'?

    32     params = [cl.IMAGE_WIDTH, width, cl.IMAGE_HEIGHT, height, \

    33               cl.ORIGINAL_FORMAT, format, \

    34               cl.ORIENTATION, cl.BOTTOM_UP, \

    35               cl.QUALITY_FACTOR, options['quality'], \

    36               cl.INTERNAL_FORMAT, iformat, \

    37              ]

    38     comp.SetParams(params)

    39     jpegdata = comp.Compress(1, imgdata)

    40     return jpegdata

    41 

    42 def decompress(jpegdata):

    43     global decomp

    44     import cl

    45     if decomp is None: decomp = cl.OpenDecompressor(cl.JPEG)

    46     headersize = decomp.ReadHeader(jpegdata)

    47     params = [cl.IMAGE_WIDTH, 0, cl.IMAGE_HEIGHT, 0, cl.INTERNAL_FORMAT, 0]

    48     decomp.GetParams(params)

    49     width, height, format = params[1], params[3], params[5]

    50     if format == cl.GRAYSCALE or options['forcegray']:

    51         format = cl.GRAYSCALE

    52         bytesperpixel = 1

    53     else:

    54         format = cl.RGBX

    55         bytesperpixel = 4

    56     # XXX How to support 'smooth'?

    57     params = [cl.ORIGINAL_FORMAT, format, \

    58               cl.ORIENTATION, cl.BOTTOM_UP, \

    59               cl.FRAME_BUFFER_SIZE, width*height*bytesperpixel]

    60     decomp.SetParams(params)

    61     imgdata = decomp.Decompress(1, jpegdata)

    62     return imgdata, width, height, bytesperpixel

    63 

    64 def setoption(name, value):

    65     if type(value) is not type(0):

    66         raise TypeError, 'jpeg.setoption: numeric options only'

    67     if name == 'forcegrey':

    68         name = 'forcegray'

    69     if not options.has_key(name):

    70         raise KeyError, 'jpeg.setoption: unknown option name'

    71     options[name] = int(value)

    72 

    73 def test():

    74     import sys

    75     if sys.argv[1:2] == ['-g']:

    76         del sys.argv[1]

    77         setoption('forcegray', 1)

    78     if not sys.argv[1:]:

    79         sys.argv.append('/usr/local/images/data/jpg/asterix.jpg')

    80     for file in sys.argv[1:]:

    81         show(file)

    82 

    83 def show(file):

    84     import gl, GL, DEVICE

    85     jpegdata = open(file, 'r').read()

    86     imgdata, width, height, bytesperpixel = decompress(jpegdata)

    87     gl.foreground()

    88     gl.prefsize(width, height)

    89     win = gl.winopen(file)

    90     if bytesperpixel == 1:

    91         gl.cmode()

    92         gl.pixmode(GL.PM_SIZE, 8)

    93         gl.gconfig()

    94         for i in range(256):

    95             gl.mapcolor(i, i, i, i)

    96     else:

    97         gl.RGBmode()

    98         gl.pixmode(GL.PM_SIZE, 32)

    99         gl.gconfig()

   100     gl.qdevice(DEVICE.REDRAW)

   101     gl.qdevice(DEVICE.ESCKEY)

   102     gl.qdevice(DEVICE.WINQUIT)

   103     gl.qdevice(DEVICE.WINSHUT)

   104     gl.lrectwrite(0, 0, width-1, height-1, imgdata)

   105     while 1:

   106         dev, val = gl.qread()

   107         if dev in (DEVICE.ESCKEY, DEVICE.WINSHUT, DEVICE.WINQUIT):

   108             break

   109         if dev == DEVICE.REDRAW:

   110             gl.lrectwrite(0, 0, width-1, height-1, imgdata)

   111     gl.winclose(win)

   112     # Now test the compression and write the result to a fixed filename

   113     newjpegdata = compress(imgdata, width, height, bytesperpixel)

   114     open('/tmp/j.jpg', 'w').write(newjpegdata)