Lib/test/test_imgfile.py

   1 #! /usr/bin/env python
   2
   3 """Simple test script for imgfile.c
   4    Roger E. Masse
   5 """
   6
   7 from test.test_support import verbose, unlink, findfile, import_module
   8
   9 imgfile = import_module('imgfile', deprecated=True)
  10 import uu
  11
  12
  13 def testimage(name):
  14     """Run through the imgfile's battery of possible methods
  15        on the image passed in name.
  16     """
  17
  18     import sys
  19     import os
  20
  21     outputfile = '/tmp/deleteme'
  22
  23     # try opening the name directly
  24     try:
  25         # This function returns a tuple (x, y, z) where x and y are the size
  26         # of the image in pixels and z is the number of bytes per pixel. Only
  27         # 3 byte RGB pixels and 1 byte greyscale pixels are supported.
  28         sizes = imgfile.getsizes(name)
  29     except imgfile.error:
  30         # get a more qualified path component of the script...
  31         if __name__ == '__main__':
  32             ourname = sys.argv[0]
  33         else: # ...or the full path of the module
  34             ourname = sys.modules[__name__].__file__
  35
  36         parts = ourname.split(os.sep)
  37         parts[-1] = name
  38         name = os.sep.join(parts)
  39         sizes = imgfile.getsizes(name)
  40     if verbose:
  41         print 'Opening test image: %s, sizes: %s' % (name, str(sizes))
  42     # This function reads and decodes the image on the specified file,
  43     # and returns it as a python string. The string has either 1 byte
  44     # greyscale pixels or 4 byte RGBA pixels. The bottom left pixel
  45     # is the first in the string. This format is suitable to pass
  46     # to gl.lrectwrite, for instance.
  47     image = imgfile.read(name)
  48
  49     # This function writes the RGB or greyscale data in data to
  50     # image file file. x and y give the size of the image, z is
  51     # 1 for 1 byte greyscale images or 3 for RGB images (which
  52     # are stored as 4 byte values of which only the lower three
  53     # bytes are used). These are the formats returned by gl.lrectread.
  54     if verbose:
  55         print 'Writing output file'
  56     imgfile.write (outputfile, image, sizes[0], sizes[1], sizes[2])
  57
  58
  59     if verbose:
  60         print 'Opening scaled test image: %s, sizes: %s' % (name, str(sizes))
  61     # This function is identical to read but it returns an image that
  62     # is scaled to the given x and y sizes. If the filter and blur
  63     # parameters are omitted scaling is done by simply dropping
  64     # or duplicating pixels, so the result will be less than perfect,
  65     # especially for computer-generated images.  Alternatively,
  66     # you can specify a filter to use to smoothen the image after
  67     # scaling. The filter forms supported are 'impulse', 'box',
  68     # 'triangle', 'quadratic' and 'gaussian'. If a filter is
  69     # specified blur is an optional parameter specifying the
  70     # blurriness of the filter. It defaults to 1.0.  readscaled
  71     # makes no attempt to keep the aspect ratio correct, so that
  72     # is the users' responsibility.
  73     if verbose:
  74         print 'Filtering with "impulse"'
  75     simage = imgfile.readscaled (name, sizes[0]/2, sizes[1]/2, 'impulse', 2.0)
  76
  77     # This function sets a global flag which defines whether the
  78     # scan lines of the image are read or written from bottom to
  79     # top (flag is zero, compatible with SGI GL) or from top to
  80     # bottom(flag is one, compatible with X). The default is zero.
  81     if verbose:
  82         print 'Switching to X compatibility'
  83     imgfile.ttob (1)
  84
  85     if verbose:
  86         print 'Filtering with "triangle"'
  87     simage = imgfile.readscaled (name, sizes[0]/2, sizes[1]/2, 'triangle', 3.0)
  88     if verbose:
  89         print 'Switching back to SGI compatibility'
  90     imgfile.ttob (0)
  91
  92     if verbose: print 'Filtering with "quadratic"'
  93     simage = imgfile.readscaled (name, sizes[0]/2, sizes[1]/2, 'quadratic')
  94     if verbose: print 'Filtering with "gaussian"'
  95     simage = imgfile.readscaled (name, sizes[0]/2, sizes[1]/2, 'gaussian', 1.0)
  96
  97     if verbose:
  98         print 'Writing output file'
  99     imgfile.write (outputfile, simage, sizes[0]/2, sizes[1]/2, sizes[2])
 100
 101     os.unlink(outputfile)
 102
 103
 104 def test_main():
 105
 106     uu.decode(findfile('testrgb.uue'), 'test.rgb')
 107     uu.decode(findfile('greyrgb.uue'), 'greytest.rgb')
 108
 109     # Test a 3 byte color image
 110     testimage('test.rgb')
 111
 112     # Test a 1 byte greyscale image
 113     testimage('greytest.rgb')
 114
 115     unlink('test.rgb')
 116     unlink('greytest.rgb')
 117
 118 if __name__ == '__main__':
 119     test_main()