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