Lib/plat-irix6/jpeg.py

   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
   8 error = 'jpeg.error' # Exception
   9
  10 options = {'quality': 75, 'optimize': 0, 'smooth': 0, 'forcegray': 0}
  11
  12 comp = None
  13 decomp = None
  14
  15 def compress(imgdata, width, height, bytesperpixel):
  16         global comp
  17         import cl
  18         if comp is None: comp = cl.OpenCompressor(cl.JPEG)
  19         if bytesperpixel == 1:
  20                 format = cl.GRAYSCALE
  21         elif bytesperpixel == 4:
  22                 format = cl.RGBX
  23         if options['forcegray']:
  24                 iformat = cl.GRAYSCALE
  25         else:
  26                 iformat = cl.YUV
  27         # XXX How to support 'optimize'?
  28         params = [cl.IMAGE_WIDTH, width, cl.IMAGE_HEIGHT, height,
  29                   cl.ORIGINAL_FORMAT, format,
  30                   cl.ORIENTATION, cl.BOTTOM_UP,
  31                   cl.QUALITY_FACTOR, options['quality'],
  32                   cl.INTERNAL_FORMAT, iformat,
  33                  ]
  34         comp.SetParams(params)
  35         jpegdata = comp.Compress(1, imgdata)
  36         return jpegdata
  37
  38 def decompress(jpegdata):
  39         global decomp
  40         import cl
  41         if decomp is None: decomp = cl.OpenDecompressor(cl.JPEG)
  42         headersize = decomp.ReadHeader(jpegdata)
  43         params = [cl.IMAGE_WIDTH, 0, cl.IMAGE_HEIGHT, 0, cl.INTERNAL_FORMAT, 0]
  44         decomp.GetParams(params)
  45         width, height, format = params[1], params[3], params[5]
  46         if format == cl.GRAYSCALE or options['forcegray']:
  47                 format = cl.GRAYSCALE
  48                 bytesperpixel = 1
  49         else:
  50                 format = cl.RGBX
  51                 bytesperpixel = 4
  52         # XXX How to support 'smooth'?
  53         params = [cl.ORIGINAL_FORMAT, format,
  54                   cl.ORIENTATION, cl.BOTTOM_UP,
  55                   cl.FRAME_BUFFER_SIZE, width*height*bytesperpixel]
  56         decomp.SetParams(params)
  57         imgdata = decomp.Decompress(1, jpegdata)
  58         return imgdata, width, height, bytesperpixel
  59
  60 def setoption(name, value):
  61         if type(value) <> type(0):
  62                 raise TypeError, 'jpeg.setoption: numeric options only'
  63         if name == 'forcegrey':
  64                 name = 'forcegray'
  65         if not options.has_key(name):
  66                 raise KeyError, 'jpeg.setoption: unknown option name'
  67         options[name] = int(value)
  68
  69 def test():
  70         import sys
  71         if sys.argv[1:2] == ['-g']:
  72                 del sys.argv[1]
  73                 setoption('forcegray', 1)
  74         if not sys.argv[1:]:
  75                 sys.argv.append('/usr/local/images/data/jpg/asterix.jpg')
  76         for file in sys.argv[1:]:
  77                 show(file)
  78
  79 def show(file):
  80         import gl, GL, DEVICE
  81         jpegdata = open(file, 'r').read()
  82         imgdata, width, height, bytesperpixel = decompress(jpegdata)
  83         gl.foreground()
  84         gl.prefsize(width, height)
  85         win = gl.winopen(file)
  86         if bytesperpixel == 1:
  87                 gl.cmode()
  88                 gl.pixmode(GL.PM_SIZE, 8)
  89                 gl.gconfig()
  90                 for i in range(256):
  91                         gl.mapcolor(i, i, i, i)
  92         else:
  93                 gl.RGBmode()
  94                 gl.pixmode(GL.PM_SIZE, 32)
  95                 gl.gconfig()
  96         gl.qdevice(DEVICE.REDRAW)
  97         gl.qdevice(DEVICE.ESCKEY)
  98         gl.qdevice(DEVICE.WINQUIT)
  99         gl.qdevice(DEVICE.WINSHUT)
 100         gl.lrectwrite(0, 0, width-1, height-1, imgdata)
 101         while 1:
 102                 dev, val = gl.qread()
 103                 if dev in (DEVICE.ESCKEY, DEVICE.WINSHUT, DEVICE.WINQUIT):
 104                         break
 105                 if dev == DEVICE.REDRAW:
 106                         gl.lrectwrite(0, 0, width-1, height-1, imgdata)
 107         gl.winclose(win)
 108         # Now test the compression and write the result to a fixed filename
 109         newjpegdata = compress(imgdata, width, height, bytesperpixel)
 110         open('/tmp/j.jpg', 'w').write(newjpegdata)