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