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